20th century global warming - "There is nothing new under the Sun" - Part II

July 30, 2010, 2:09 am

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Solar Activity and Climate

It is already more than 200 years since Sir William Herschel claimed that variations in solar activity affect climate on Earth. Since he did not have any reliable temperature measurements, Herschel looked for indirect proxies. He compared the price of wheat in the London wheat exchange to the solar activity as mirrored in the sunspot number, and found a correlation between them.

In the 1970’s, it was Jack Eddy who pushed the idea that solar activity may be affecting the terrestrial climate. He found a correlation between long term variations in solar activity and different climate indicators. For example, he found that the nadir of the period called “the little ice age” in Europe during the latter half of the 17th century took place in a period during which solar activity was very low. This low activity culminated in a several decade period during which there were almost no apparent sunspots, which was called the “Maunder minimum”. On the other hand, there were other periods, such as the end of the middle ages, during which solar activity was as high as the latter half of the 20^th century, and the temperatures were roughly as warm as today. During the “medieval optimum”, Vikings could settle in Greenland (and call it a “green land”) and catholic monks adopted sandals suitable for warm climates.

Presently, there is a large number of different empirical indicators showing that changes in solar activity has a non negligible effect on the climate. Changes in solar activity manifest themselves as changes in the strength of the solar magnetic field, changes in the sunspot number, in the strength of the solar wind (which is responsible for the impressive cometary tails) and other phenomena. These changes can be separated into three time scales.

The basic variation is an activity cycle of about 11 years, which arises from quasi-periodic reversals of the solar magnetic dipole filed. On longer time scales (of decades to millennia) there are irregular variations which modulate the 11-year cycle. For example, during the middle ages and during the latter half of the 20^th century, the peaks in the 11-year cycles were notably strong, while these peaks were almost absent during the Maunder minimum. On the other hand, eruptions may appear on the time scale of days. Today there is evidence linking solar activity to the terrestrial climate on all these scales.

Since the work of Jack Eddy, many empirical results show a correlation between different climatic reconstructions and different solar activity proxies. One of the most beautiful results is of a correlation between the temperature of the Indian Ocean and solar activity (see fig. 5).

[collapse title="Figure 5"]

Figure 5: The correlation between solar activity—as mirrored in the ¹⁴C flux, and a climate proxy, the ¹⁸O/¹⁶O isotope ratio derived from stalagmites in a cave in Oman, over a centennial to millennial time scale. The ¹⁴C is reconstructed from tree rings. It is a proxy of solar activity since a more active sun has a stronger solar wind which reduces the flux of cosmic rays reaching Earth from outside the solar system. A reduced cosmic ray flux, will in turn reduce the spallation of nitrogen and oxygen and with it the formation of ¹⁴C. On the other hand, ¹⁸O/¹⁶O reflects the temperature of the Indian ocean—the source of the water that formed the stalagmites. (From Neff et al., nature 411, 290, 2001). [/collapse]
It is much harder to see climate variations over the 11-year solar cycle. There are two reasons for that. First, if we study the climate on short time scales, we find that there are large annual variations (for example, due to the el-Ñino oscillation) which introduce cluttering “noise”, hindering the observation of solar related signals. Second, because of the large oceanic heat capacity, it takes decades until it is possible to see the full effects of given changes in the radiative budget, including those associated with solar variability. It is for this reason, that climates of continental regions are typically much more extreme than their marine counterparts.

If, for example, a given change in solar forcing is expected to give rise to a temperature change of 1°C after several centuries, then the same radiative forcing varying over the 11-year solar cycle is expected to give rise to temperature variations of only 0.1°C or so. This is because on short time scales, most of the energy goes into heating the oceans, but because of their very large heat capacity, large changes in the ocean heat content do not translate into large temperature variations.

Nevertheless, if the global temperature is carefully analyzed (for example, by folding the global temperature of the past 120 years over the 11-year solar cycle), it is possible to see variations of about 0.1°C in the land temperature, and slightly less in the ocean surface temperature.

Moreover, when studying directly the total ocean heat content, it is possible to see that the amount of heat going into the oceans is at least 5 times larger than can be expected from just the changes in the total solar irradiance (e.g., see this blog entry and references therein). Thus, one can conclude that there must be at least one mechanism amplifying the link between solar activity and climate.

Theoretically, there are two types of mechanisms which can amplify solar activity. The first type is hypersensitivity to one of the non-thermal solar components. One such mechanism was proposed by Joanna Haigh from the UK, and it is hypersensitivity to variations in the UV. This kind of sensitivity can arise because UV is almost entirely absorbed in the stratosphere and although it only includes about 1% of the solar output, the stratospheric structure (and = thus the tropospheric-stratospheric interface) is determined by this 1%. Numerical simulations have shown that by including the variations in the UV and their effects on the stratosphere, one can amplify the surface climate variations by as much as a factor of two, namely, it can be a large effect. However, it still cannot explain the large amounts of heat seen entering the oceans every solar cycle.

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20th century global warming - "There is nothing new under the Sun" - Part III

July 30, 2010, 2:12 am

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Cosmic Rays and Climate

The second type of mechanisms is indirect, through the solar modulation of the cosmic ray flux and the effect that the latter may have on the climate. Cosmic rays are high energy particles (primarily protons) which appear to originate from supernova remnants (the leftovers from the explosive death of massive stars). A possible climatic link through cosmic rays was first suggested by Edward Ney already in 1959. It was well known that the solar wind decreases the flux of these high energy particles and that these particles are the primary source of ionization in the troposphere (which is the lower part of the atmosphere). Ney proposed that the changing levels of ionization can play some climatic role.

In the 1970's, Robert Dickenson proposed the possibility that the atmospheric ion density could play a role in the formation of cloud condensation nuclei. When air reaches saturation, that is, 100% humidity, the preferred equilibrium state is that of liquid water. However, if the water vapor has nothing to condense upon, it will not do so. In fact, under very clean environments, it is possible to reach 400% humidity before the vapor condenses spontaneously. In order to get clouds at 100%, as we see in nature, we need cloud condensation nuclei (CCNs). Over land, there are many natural sources for CCNs, however, this is not the case over the oceans, were the CCNs must be grown out of something. Dickenson suggested that this growth process of CCNs could be affected by the amount of atmospheric charge.

In the 1990's, Henrik Svensmark and his colleagues found empirically that clouds, and in particular low altitude clouds, appear to vary in sync with the solar activity (see fig. 6). The change in the energy budget associated with this change in the cloud cover is consistent with the amount of heat we find enters the oceans every solar cycle.

[collapse title="Figure 6"]

Figure 6: The correlation between cosmic ray flux (orange) as measured in neutron count monitors in low magnetic latitudes, and the low altitude cloud cover (blue) using ISCCP satellite data set, following Marsh & Svensmark (JGR, 108 (D6), 6, 2003). [/collapse]
Since Svensmark’s work, more evidence was found to support this link, the full picture of which is the following. When the sun is more active, it has a stronger solar wind. The stronger wind slows the cosmic rays as they propagate into the inner solar system. As a consequence, the amount of atmospheric ionization is reduced. Less ions reduce the efficiency with which new cloud condensation nuclei can grow, especially over the oceans, such that the clouds that later form have fewer but larger droplets. These clouds are less white, they reflect sunlight less efficiently and therefore cause more warming.

[collapse title="Figure 7"]

Figure 7: The cosmic ray link between solar activity and the terrestrial climate. The changing solar activity is responsible for a varying solar wind. A stronger wind will reduce the flux of cosmic ray reaching Earth, since a larger amount of energy is lost as they propagate up the solar wind. The cosmic rays themselves come from outside the solar system (cosmic rays with energies below the "knee" at 10¹⁵eV, are most likely accelerated by supernova remnants). Since cosmic rays dominate the tropospheric ionization, an increased solar activity will translate into a reduced ionization, and empirically (as shown below), also to a reduced low altitude cloud cover. Since low altitude clouds have a net cooling effect (their "whiteness" is more important than their "blanket" effect), increased solar activity implies a warmer climate. Intrinsic cosmic ray flux variations will have a similar effect, one however, which is unrelated to solar activity variations. [/collapse]
The evidence to this particular link comes from experimental results and from correlations between independent cosmic ray flux variations and climate changes on different time scale. Just by itself, a cosmic ray climate correlation over the 11-year solar cycle does not necessarily imply a causal link. One could imagine that the solar activity affects both the cosmic ray flux and the climate, making it appear that there is a causal relation between the latter two. Nevertheless, there are indications that it is not just an apparent link. For example, the dependence of the relative cloud cover variations with the magnetic latitude is the same as the latitudinal dependence of the relative change in the atmospheric ionization, over the solar cycle. Another important fact is that the full solar cycle is not that of 11-years, but 22-years instead. It takes 11-years for the magnetic field to flip, but 22-years for it to return to the original state. However, all the solar activity proxies are “blind” to the polarity of the magnetic field, all except the cosmic ray flux which exhibits a clear asymmetry between odd and even solar cycles. This asymmetry is seen in the change of the low altitude cloud cover, implying that the cloud cover variations originate from cosmic ray flux variations.

On short time scales, the sun can undergo flaring activity which is caused from the reconnection of magnetic loops. These flare are accompanied by a strong solar wind “gust” which later causes a decrease in the cosmic ray flux for several days. If the cosmic ray flux has an effect on clouds, then cloud properties should change following these events, known also as Forbush decreases. Several results indicate that clouds are affected during Forbush decreases. In particular, recent results by Bondo et al. have shown the cosmic ray mechanism at work. Not only was a cloud signal observed, the intermediate step of affecting the aerosol size distributed was detected as well.

Over longer time scales, of decades to millennia, there are the aforementioned solar climate links, however, even though they demonstrate a clear causal link between solar activity and climate change, it is hard to prove with them that this link is specifically due to solar modulation of the cosmic ray flux. If we however go to longer time scale still, there is evidence from cosmic ray flux variations which are not associated with solar activity.

On the time scale of tens of thousands of years, Earth’s magnetic field varies and with it the flux of cosmic rays which can penetrate the atmosphere. Because however the magnetic field can only prevent the penetration of cosmic rays which are anyway severely attenuated by the atmosphere, changing the magnetic field, and even altogether switching it off is not expected to give rise to significant climate effects. A rough estimate gives that switching the magnetic field will only cool the Earth by typically 1°C. However, over the time scale that the magnetic field changes, Earth witnesses variations which are 5 times larger from other natural causes. That is, it is not easy to detect the terrestrial field effects, but they were claimed to be detected nonetheless.

Over geological time scale, the cosmic ray flux changes because of our motion around the Milky Way and the changing solar neighborhood. Because the cosmic ray flux originates from the death of the short living massive stars, in events called supernovae, passage through regions with a higher star formation rate is associated with an elevated cosmic ray flux level. The largest variations actually originate from the solar system's passage through the milky way spiral arms.

As it turns out, it is possible to reconstruct the changes in the cosmic ray flux originating from these passages, using iron meteorites. This reconstructed flux shows variations by as much as a factor of 3 between the flux between the spiral arms and the flux in them. And indeed, when the global climate is studied over this time scale, it is possible to see all the past seven passages of the solar system through the arms of the galaxy over the past billion years. Every spiral arm passage, the increased cosmic ray flux manifested itself as a cold epoch during which Earth's poles are glaciated. In between the arms, it was much warmer than the present climate.

[collapse title="Figure 8"]

Figure 8: An iron meteorite. A large sample of these can be used to reconstruct the past cosmic ray flux variations. The reconstructed signal reveals a 145 Million year periodicity. The meteorite in the picture is part of the Sikhote Alin meteorite that fell over Siberia in the middle of the 20^th century. The cosmic-ray exposure age of the meteorite implies that it broke off its parent body about 300 Million years ago. [/collapse] [collapse title="Figure 9"]

Figure 9: The correlation between the cosmic ray flux reconstruction (based on the exposure ages of Iron meteorites) and the geochemically reconstructed tropical temperature. The comparison between the two reconstructions reveals the dominant role of cosmic rays and the galactic “geography” as a climate driver over geological time scales. (Shaviv & Vezier GSA Today 13, No. 7, 4, 2003) [/collapse] In addition to the empirical evidence, an experiment was carried out by Svensmark's group. This experiment was carried out to simulate marine air conditions and study how the changed atmospheric ionization affects the growth of condensation nuclei under controlled laboratory conditions. The experiment demonstrated that elevated ionization rates give rise to a more efficient formation of condensation nuclei. Today, this experiment is carried out in a mine in the UK to see how the total removal of ions affect the formation of condensation nuclei, and also at CERN, to corroborate the effects of ionization, this time with high energy particle ionization as opposed to UV.

[collapse title="Figure 10"]

Figure 10: The Danish National Space Center SKY reaction chamber experiment. The experiment was built with the goal of pinning down the microphysics behind the cosmic ray/cloud cover link found through various empirical correlations. From left to right: Nigel Marsh, Jan Veizer, Henrik Svensmark. [/collapse]
And the forecast?

The fact that the sun plays a decisive role in climate change has important implications to the understanding of the causes of 20^th century global warming and the expected temperature change in the coming century. The increased solar activity over the 20^th century can be translated into a radiative forcing contribution. Since the solar/climate link was already quantified, it is possible to estimate the solar contribution, which turns out to be about half of the measured warming.

Thus, the warming component left to be explained by humans is much smaller than is often claimed by the proponents of the anthropogenic warming. However, if we are to predict the temperature change over the 21^st century, we have to know what is the expected human contribution to the radiative budget, but equally important, also the climate sensitivity to these changes in the energy budget.

As we have seen above, the answer to the second question is that the sensitivity is most likely small. In fact, this sensitivity is about 1 degree increase per doubling of CO₂. When answering the first question, we have to make a distinction between natural causes, such as solar activity, cosmic ray flux variations and volcanic activity, and between human activity. Unfortunately, it is impossible to predict most of the natural variations. We have no tools with which we can predict when a volcano will erupt, nor can we predict how solar activity will vary from one solar cycle to the next. All that can be done is to estimate the probability for different variations based on historic changes. Regarding solar activity, we can see for example that over the past several thousand years, solar activity did not rise significantly above its levels over the latter half of the 20^th century. Therefore, we can expect, with reasonable confidence, that solar activity will diminish over the 21^st century, and cause a temperature decrease of several tenths of a degree.

It is also impossible to predict human activity. At most, we can estimate it. The IPCC published several scenarios describing how human activity is expected to increase and with it, how the amount of atmospheric CO₂ is expected to rise, under several different sets of assumptions, for example, according to how fast humanity will switch to alternative energy sources. Under pessimistic scenarios of “business as usual”, we see that doubling the amount of CO₂ over the 21^st century is a realistic possibility. However, given the low climate sensitivity, we can expect a total increase of about 1 degree from such a pessimistic scenario. This is similar in size to the natural variations Earth has witnessed over the past several millennia. For comparison, the doomsdays scenarios we hear about daily talk about increases of typically between 3 to 5°C.

The evidence shows therefore that even if we continue with “business as usual”, we will not cause a climate catastrophe. It is also possible to estimate the sea level increase, which will be of order 10 cm over the coming century, much less than the meters talked about in Gore's movie.

An optimist’s note

At this point, I would like to make a personal note. Perhaps I am an optimist, but I think that the likelihood that our economies will rely on fossil fuels several decades into the future is relatively small. If we would have been asked a century ago what would life be at the beginning of the 21^st century, we would not have been able to think about the existence of computers, mobile phones, nuclear reactors, spaceships, the internet or even seemingly trivial things such as plastic or coke with artificial sweeteners. The speed with which technology advances is so rapid, that in the not so distance future we will have cheaper energy sources than coal and oil, based perhaps on organic based photovoltaic cells, nuclear fusion, or energy sources based on a yet to be discovered technology. Thus, it would be naive on our part to even try to predict how much CO₂ we will emit in the coming century.

Secondly, I am not the enemy of the environment movement. I believe that humans should take full responsibility over their activity and the damage they inflict on the environment. However, I claim that global warming is not a real issue. The are many pressing problems which do deserve our immediate attention, which because of global warming are neglected. Many people with good intentions are acting out of emotion and gut feeling, not out of reason, and as a result, they waste precious resources without doing any substantial good.

And now for the really last point. Don’t believe a word I write. If you are a genuine scientist, or wish to think like one, you should base your beliefs on facts you see and scrutinize for yourself. On the same token, do not blindly believe the climate alarmists. In particular, be ready to ask deep questions. Does the evidence you are shown prove the points that are being made? Is the evidence reliable? Sometimes you'll be amazed from the answers you find.

Let me end with a few millennia old quote often attributed to king Solomon, and which I find most appropriate:
"מה שהיה הוא שיהיה, ומה שנעשה הוא שיעשה ואין כל חדש תחת השמש"קהלת א'פסוק ט'.

“What has been will be again and what has been done will be done again and there is nothing new under the sun”. Qohelet (Ecclesiastes 1:9).

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The CLOUD is clearing

August 26, 2011, 1:53 pm

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The CLOUD collaboration from CERN finally had their results published in nature, showing that ionization increases the nucleation rate of condensation nuclei. The results are very beautiful and they demonstrate, yet again, how cosmic rays (which govern the amount of atmospheric ionization) can in principle have an affect on climate.

What do I mean? First, it is well known that solar variability has a large effect on climate. In fact, the effect can be quantified and shown to be 6 to 7 times larger than one could naively expect from just changes in the total solar irradiance. This was shown by using the oceans as a huge calorimeter (e.g., as described here). Namely, an amplification mechanism must be operating.

One mechanism which was suggested, and which now has ample evidence supporting it, is that of solar modulation of the cosmic ray flux, known to govern the amount of atmospheric ionization. This in turn modifies the formation of cloud condensation nuclei, thereby changing the cloud characteristics (e.g., their reflectivity and lifetime). For a few year old summary, take a look here.

So, how do we know that this mechanism is necessarily working? Well, we know that cosmic rays have a climatic effect because of clear correlations between unique cosmic ray flux variations and different climate variability. One nice example (and not because I discovered it ;-) ) is the link between cosmic ray flux variations over geological times scales (caused by spiral arm passages) and the appearance of glaciations (more about it here). We also know empirically that the effect of the cosmic rays is through the tampering in the properties of cloud. This is through the study of Forbush decreases which are several day long decreases in the galactic cosmic ray flux reaching the Earth. Following such events, one clearly sees a change in the aerosol and cloud properties (more about it here).

So, what is new?

Well, the new results just published in nature by Kirkby and company are the results of the CLOUD experiment. This experiment mimics the conditions found in the atmosphere (i.e., air, water vapor, and trace gasses, such as sulfuric acid and ammonia). It is a repeat of the Danish SKY experiment carried out by Henrik Svensmark and his colleagues (e.g., read about it here), and it produces the same results—namely, they show that an increase in the rate of atmospheric ionization increases the formation rate of condensation nuclei. The only difference is that the CLOUD experiment with its considerably higher budget, has a better control on the different setup parameters. Moreover, those parameters can be measured over a wider range. This allows the CLOUD experiment to more vividly see the effect.

The results can be seen in this graph:

What does it mean?

The first thing to know is that when 100% humidity is reached in pure air, clouds don't form just like that. This is because there is an energy barrier for the droplets to form. To get over this barrier, the water vapor condenses on small particles called cloud condensation nuclei (CCNs). Some of these CCNs can be naturally occurring particles, such as dust, biologically produced particles, pollution or sea salts. However, over a large part of the globe, most of the CCNs have to be grown from basic constituents, in particular, clusters of sulfuric acid and water molecules. As the CLOUD and SKY experiments demonstrate, the ionization helps stabilize the clusters, such that they can more readily grow to become stable "condensation nuclei" (CNs). These CNs can later coalesce to become the CCNs upon which water vapor can condense.

Moreover, the number density of CCNs can clearly have an effect on different cloud properties. This can be readily seen by googling "Ship Tracks" where more CCNs (in the form of exhaust particles) serve as extra CCNs (You can also read about it here). It should be stressed that although the results are extremely impressive (it is a hard measurement because of the very precise control over the conditions which it requires), they are not new, just a formidable improvement. This implies that anyone who chose to ignore all the evidence linking solar activity, through cosmic ray flux modulation, to climate change, and the evidence demonstrating that the link can be naturally explained as ion induced nucleation, will continue to do so now. For example, you will hear the real climate guys down playing it as much as possible.

Ok, so what do these results imply?

The first point was essentially pointed above. The results unequivocally demonstrate that atmospheric ionization can very easily affect the formation of condensation nuclei (CNs). Since many regions of earth are devoid of natural sources for CCNs (e.g., dust), the CCNs have to grow from the smaller CNs, hence, the CCN density will naturally be affected by the ionization, and therefore, the cosmic ray flux. This implies that ion induced nucleation is the most natural explanation linking between observed cosmic ray flux variations and climate. It has both empirical and beautify experimental results to support it.

Second, given that the cosmic ray flux climate link can naturally be explained, the often heard "no proven mechanism and therefore it should be dismissed" argument should be tucked safely away. In fact, given the laboratory evidence, it should have been considered strange if there were no empirical CRF/climate links!

Last, given that the CRF/climate link is alive and kicking, it naturally explains the large solar/climate links. As a consequence, anyone trying to understand past (and future) climate change must consider the whole effect that the sun has on climate, not just the relatively small variations in the total irradiance (which is the only solar influence most modelers consider). This in turn implies (and I will write about it in the near future), that some of the 20th century warming should be attributed to the sun, and that the climate sensitivity is on the low side (around 1 deg increase per CO₂ doubling).

Oh, and of course kudos to Jasper Kirkby and friends!

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What is your expertise, and what is the cause of 20th century climate change?

December 22, 2011, 6:39 am

≫ Next: On IPCCs exaggerated climate sensitivity and the emperor’s new clothes

≪ Previous: The CLOUD is clearing

Laymen, mostly anthropogenic

2% (8 votes)

Laymen, mostly natural

45% (193 votes)

Laymen, nobody knows

7% (31 votes)

General scientist, mostly anthropogenic

1% (6 votes)

General scientist, mostly natural

33% (142 votes)

General scientist, nobody knows

6% (26 votes)

Climate scientist, mostly anthropogenic

0% (0 votes)

Climate scientist, mostly natural

3% (11 votes)

Climate scientist, nobody knows

1% (6 votes)

Have absolutely no idea what to answer

1% (6 votes)

Total votes: 429

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On IPCCs exaggerated climate sensitivity and the emperor’s new clothes

January 8, 2012, 9:00 pm

≫ Next: Causes of Climate Change - Poll Results

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A few days ago I had a very pleasant meeting with Andrew Bolt. He was visiting Israel and we met for an hour in my office. During the discussion, I mentioned that the writers of the recent IPCC reports are not very scientific in their conduct and realized that I should write about it here.

Normal science progresses through the collection of observations (or measurements), the conjecture of hypotheses, the making of predictions, and then through the usage of new observations, the modification of the hypotheses accordingly (either ruling them out, or improving them). In the global warming “science”, this is not the case.

What do I mean?

From the first IPCC report until the previous IPCC report, climate predictions for future temperature increase where based on a climate sensitivity of 1.5 to 4.5°C per CO₂ doubling. This range, in fact, goes back to the 1979 Charney report published by the National Academy of Sciences. That is, after 33 years of climate research and many billions of dollars of research, the possible range of climate sensitivities is virtually the same! In the last (AR4) IPCC report the range was actually slightly narrowed down to 2 to 4.5°C increase per CO2 doubling (without any good reason if you ask me). In any case, this increase of the lower limit will only aggravate the point I make below, which is as follows.

Because the possible range of sensitivities has been virtually the same, it means that the predictions made in the first IPCC report in 1990 should still be valid. That is, according to the writers of all the IPCC reports, the temperature today should be within the range of predictions made 22 years ago. But they are not!

The business as usual predictions made in 1990, in the first IPCC report, are given in the following figure.

The business-as-usual predictions made in the first IPCC report, in 1990. Since the best range for the climate sensitivity (according to the alarmists) has not changed, the global temperature 22 years later should be within the predicted range. From this graph, we take the predicted slopes around the year 2000.

How well do these predictions agree with reality? In the next figure I plot the actual global and oceanic temperatures (as made by the NCDC). One can argue that either the ocean temperature or the global (ocean+land) temperature is better. The Ocean temperature includes smaller fluctuations than the land (and therefore less than the global temperature as well), however, if there is a change in the average global state, it should take longer for the oceans to react. On the other hand, the land temperature (and therefore the global temperature) is likely to include the urban heat island effect.

The NCDC ocean (blue) and global (brown) monthly temperature anomalies (relative to the 1900-2000 average temperatures) since 1980. The observed temperatures compared to the predictions made in the first IPCC report. Note that the width of the predictions is ±0.1°C, which is roughly the size of the month to month fluctuations in the temperature anomalies.

From the simulations that my student Shlomi Ziskin has carried out for the 20th century, I think that the rise in the ocean temperature should be only about 90% of the global temperature warming since the 1980's, i.e., the global temperature rise should be no more than about 0.02-0.03°C warmer than the oceanic warming (I'll write more about this work soon). As we can see from the graph, the difference is larger, around 0.1°C. It would be no surprise if this difference is due to the urban heat island effect. We know from McKitrick and Michaels' work, that there is a spatial correlation between the land warming and different socio-economic indices (i.e., places which developed more, had a higher temperature increase). This clearly indicates that the land data is tainted by some local anthropogenic effects and should therefore be considered cautiously. In fact, they claim that in order to remove the correlation, the land warming should be around 0.17°C per decade instead of 0.3. This implies that the global warming over 2.2 decades should be 0.085°C cooler, i.e., consistent with the difference!

In any case, irrespective of whether you favor the global data, or the oceanic data, it is clear the the temperature with its fluctuations is inconsistent with the "high estimate" in the IPCC-FAR (and it has been the case for a decade if you take the oceanic temperature, or half a decade, if you take the global temperature, not admitting that it is biased). In fact, it appears that only the low estimate can presently be consistent with the observations. Clearly then, earth's climate sensitivity should be revised down, and the upper range of sensitivities should be discarded and with it, the apocalyptic scenarios which they imply. For some reason, I doubt that the next AR5 report will consider this inconsistency, nor that they will revise down the climate sensitivity (and which is consistent with other empirical indicators of climate sensitivity). I am also curious when will the general public realize that the emperor has no clothes.

Of course, Andrew commented that the alarmists will always claim that there might be something else which has been cooling, and we will pay for our CO2 sevenfold later. The short answer is that “you can fool some of the people some of the time, but you cannot fool all of the people all of the time!” (or as it should be adapted here, “you cannot fool most of the people indefinitely!”).

The longer answer is that even climate alarmists realize that there is a problem, but they won’t admit it in public. In private, as the climategate e-mails have revealed, they know it is a problem. In October 2009, Kevin Trenberth wrote his colleagues:

The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't. The CERES data published in the August BAMS 09 supplement on 2008 shows there should be even more warming: but the data are surely wrong. Our observing system is inadequate.

However, instead of reaching the reasonable conclusion that the theory should be modified, the data are "surely wrong". (This, btw, is a sign of a new religion, since no fact can disprove the basic tenets).

When you think of it, those climatologists are in a rather awkward position. If you exclude the denial option (apparent in the above quote), then the only way to explain the “travesty” is if you have a joker card, something which can provide warming, but which the models don’t take into account. It is a catch-22 for the modelers. If they admit that there is a joker, it disarms their claim that since one cannot explain the 20th century warming without the anthropogenic contribution, the warming is necessarily anthropogenic. If they do not admit that there is a joker, they must conclude (as described above) that the climate sensitivity must be low. But if it is low, one cannot explain the 20th century without a joker. A classic Yossarian dilemma.

This joker card is of course the large solar effects on climate.

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Causes of Climate Change - Poll Results

January 16, 2012, 8:42 am

≫ Next: Does the global temperature lag CO2? More flaws in the Shakun et al. paper in Nature.

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Out of curiosity, I opened a few weeks ago a poll asking the visitors of this site, what do they think is the primary cause of global warming. 429 people answered the poll (thanks to all of you!).

The results can be summarized as follows.

First, the visitors of this site have the following background:

Background	Fraction (Votes)
Layman	54.9% (232)
General Scientist	41.1% (174)
Climate Scientist	4.0% (17)

i.e., The audience of this website is clearly scientifically oriented (almost half are scientists). And what does this educated audience think about global warming?

Cause of 20th century warming	Fraction (Votes)
Mostly Anthropogenic	5.2% (22)
Mostly Natural	81.8% (346)
Nobody knows	14.9% (63)

Clearly, the highly educated visitors of this site have proven that global warming is mostly natural. Moreover, one can clearly see that the ratio of "mostly anthropogenic" to "mostly natural" decreases as the relevant scientific background increases: 0.04 in the laymen and general scientists groups, and 0%(!) in the climate scientists group.

Ok, so seriously, what have I demonstrated? It is no surprise that my site attracts doubters of the anthropogenic global warming story. After all, I have been labeled as a "skeptic" (which I proudly am, since any real scientist should never take anything for granted). For this reason, the poll results are biased. But on the same token, it is clear that when someone says that 99% of all the scientists think this or that, it is totally meaningless. The reason is that mainstream science, whether it is correct or not, tends to inflate those that think alike. It is easier for them to publish and it is easier for the to get research grants to pay their salary or their students salary. Clearly, the mainstream will always have a stronger visibility (e.g., in terms of number of publications, citations, or even the number of people), but it doesn't prove that the mainstream is correct (see also what I wrote about it here).

And now, after having carried out this poll, let me end with what different poll results really mean (with no offese to pollsters!)

87.547% of all statistical polls are meaningless.
66.666% of all statistical polls are carried out with a very small sample.
99% of all statistical polls are pure propaganda!

Anyway, the moral of this experiment is that you should never trust a poll if you don't know who made it. And even if you do trust that person, [ like you trust me ;-) ], polls can be biased!

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Science

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Does the global temperature lag CO2? More flaws in the Shakun et al. paper in Nature.

April 21, 2012, 7:49 am

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Over the past two weeks, perhaps a dozen people asked me about the recently published paper of Shakun et al. in Nature. It allegedly demonstrates that the global temperature followed CO₂ around the warming associated with the last interglacial warming, between 20 to 10 thousand years ago. (Incidentally, if you don't have a subscription to nature, take a look here). One guy even sent the story as a news item on NPR. So, having no other choice, I decided to actually read the paper and find what is it all about. Should I abandon all that I advocated over the past decade?

First some prologue. One of the annoying facts for alarmists is that ice cores with a sufficiently high resolution generally show that CO₂ variations lag temperature variations by typically several hundred years. Thus, the ice cores cannot be used to quantify how large is the effect that CO₂ has on the climate. In fact, there is no single time scale whatsoever over which CO₂ variations can be shown to be the origin of temperature variations (not that such an effect shouldn’t be present, but because of its size, no fingerprint was actually found yet, even if you hear otherwise!). This fact stands as a nasty thorn in the alarmist story. So, it is no surprise that when Nature recently published that (finally) there is an observation showing that the temperature (and in particular, the average global temperature) lags CO₂, that the alarmist community had a field day over it.

The abstract specifically writes (my emphasis):

These observations, together with transient global climate model simulations, support the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO₂ concentrations is an explanation for much of the temperature change at the end of the most recent ice age.

So, is there a catch?

It turns out that there are several problems with the Shakun et al. analysis. Some have already been pointed by other people (e.g., this, or that). I will concentrate on two new problems that particularly offended my intelligence.

First point: Lags, what do they mean?

I usually start “reading” an article by studying the figures, this way I am not distracted by the interpretation of the authors. And, one of the first things I noticed over this first glance was that indeed the global temperature appears to lag the CO₂ variations, however, if you look at each hemisphere separately, it appears that the northern hemisphere lags the CO₂ by 720±330 years, but the Southern hemisphere temperature leads the CO₂ variations by 620±660 years. The same figure also reveals that the global temperature lags the CO₂ by 460±340 years, which is the main find of the paper. Here are these graph (and the original caption).

a. The global proxy temperature stack (blue) as deviations from the early Holocene (11.5–6.5 kyr ago) mean, an Antarctic ice-core composite temperature record42 (red), and atmospheric CO₂ concentration (refs 12, 13 [in the nature paper, n.s.]; yellow dots). The Holocene, Younger Dryas (YD), Bølling–Allerød (B–A), Oldest Dryas (OD) and Last Glacial Maximum (LGM) intervals are indicated. Error bars, 1σ (Methods); p.p.m.v., parts per million by volume. b, The phasing of CO₂ concentration and temperature for the global (grey), Northern Hemisphere (NH; blue) and Southern Hemisphere (SH; red) proxy stacks based on lag correlations from 20–10 kyr ago in 1,000 Monte Carlo simulations (Methods). The mean and 1σ of the histograms are given. CO₂ concentration leads the global temperature stack in 90% of the simulations and lags it in 6%.

But what do the lags mean? First, it is clear from causality arguments that CO₂ is probably affected by the temperature of the southern hemisphere. I write "probably" and not "definitely", because from a logical point of view, we cannot rule out that some other thing affects both the SH temperature and the CO₂ with a larger lag. Nevertheless, this relation is actually quite reasonable given that the ocean temperature affects the equilibrium between carbon present in the oceans and CO₂ in the air. Since there is way more water volume in the southern oceans than there is in the northern hemisphere, it is clear that the CO₂ should be more sensitive to variations in the southern hemisphere than to variations in the northern hemisphere.

However, the fact that the northern hemisphere temperature lags the CO₂ does not imply that the NH is actually affected by the CO₂. Compare the following:

I. Southern Hemisphere T -> CO₂ -> NH Temperature

with

II.Southern Hemisphere T -> CO₂ with one lag, Southern Hemisphere T -> Northern Hemisphere T with a larger lag (say, through global ocean currents).

How can you differentiate between the two options? You can't! This means that the above result means nothing in particular, except as mentioned before, that CO₂ is probably affected by temperature, in particular, that of the southern hemisphere. In defense of the authors, I must say that when they have written in the abstract "an explanation" and not "the explanation" (see quote above), they were accurately portraying the indecisiveness of their results...

Second point: Global temperature?

Given the fact that the global temperature is composed of the SH and NH and that one precedes and the other lags the CO₂, is there any meaning to averaging the two? Perhaps not if the physical behavior is different (at least for the particular temporal window studied in their paper). Even so, one would imagine that such an average for the global temperature should be half of the NH and half of the SH. This is because, at least last that I checked, exactly half of the Earth's surface area is in the Northern hemisphere and half is in the southern hemisphere (unlike comparison of the land area, or the temperature proxy data in the Shakun et al. paper).

With this in mind, I started playing with the data. I was utterly surprised to learn that in order to recover their average "global" temperature, I needed to mix about 37% of their southern hemisphere temperature with 63% of their northern hemisphere temperature. In other words, their "global" temperature is highly distorted towards the Northern hemisphere! It is therefore no surprise that once they do find a northern hemisphere temperature lag, also their global temperature exhibits a similar lag, but it is not a global temperature by any means!

My suspicion is that the authors have a different averaging weight to the two hemispheres because of the asymmetry in their data distribution, however, their global temperature is close to but not exactly the ratio in the number of datasets in each hemisphere, so I don't actually know what they did.

Together with the faults pointed out by other people (most notably on WUWT), the Shakun et al. paper should not be considered as anything which proves that CO₂ has a large effect on climate. My prophesy, though, is that the Shakun et al. paper will become a major hallmark in the next IPCC scientific report. This is because the alarmist community needs it badly as evidence that CO₂ has a large effect of climate. They will also ignore all the major flaws which exist in it, because it will be convenient for them to do so. I hope I'm wrong, but I feel I'm right, and not only because one of the co-authors on the paper is also a lead author of the upcoming IPCC AR5 report.

How much of the warming since the last ice-age should be attributed to CO₂?

Since this is a science blog after all, I thought it would be appropriate to end this post with more solid science in it.

Overall, there was a 3.5°C degree increase taking place concurrently to a CO₂ increase from 180 to 280 ppm. If the warming is entirely due to CO₂, then the climate sensitivity should be ΔT_x2 ~ 3.5°C/log₂(280/180), or about 5.5°C per CO₂ doubling. But as I explained above, this conclusions is not supported at all by the above correlation. However, it does imply that if anyone is calculating a probability distribution function for the temperature sensitivity to CO2, then they should cut it at 5.5°C, because it simply cannot be any larger than that.

On the other hand, my best estimate for the climate sensitivity, is that CO₂ doubling should cause a 1 to 1.5°C temperature increase, or about 0.65 to 1°C for a 180 to 280 increase in the CO₂. In other words, at most a quarter of the observed 3.5°C should have been caused by the CO₂ feedback. The rest is something else.

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Science

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A friend has passed away

July 1, 2014, 11:36 am

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general science, global warming, weather & climate

In 1977 he made the movie "the weather machine" about how Earth is doomed to enter a new ice-age. Since those apocalyptic predictions did not materialize, he knew better once the wheels have turned and people talked about imminent warming. That is, his immune system developed immunity against blindly accepting alarmist predictions.

When he learned of my friend Henrik Svensmark's work, he of course found it interesting, which is why several years later they ended up writing a book together, the Chilling Stars.

As for myself, I met him just once. We had lunch in the restaurant opposite to the British Museum, but had plenty of e-mail correspondence. He will be fondly remembered. This is his last blog post.

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Euthanizing Overholt et al.: How bad can a bad paper be?

April 25, 2015, 10:31 pm

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Blog topic:

astronomy, global warming, personal research, weather & climate

An artists conception of the Milky Way with its spiral arms

Last month I visited the U of Washington to give a talk in which I discussed the effects of cosmic rays on climate. At the end of it, not one, but two people independently asked me about Overholt et al., which supposedly ruled out the idea that passages through the galactic spiral arms affect the appearance of glaciations on Earth (see summary I wrote a few years ago, which includes links to PDFs the actual papers). I told them that the paper had really stupid mistakes and it should be discarded in the waste bin of history, but given that Overholt et al. is still considered at all, I have no choice but to more openly euthanize it.

Before I get into the technical details (which will cause many of the readers to click their way out of here), I do want to say something general about the refereeing process and how it can easily break down, as it did here.

Given that there are many more people who are eager to shoot down the cosmic ray climate link than people researching it, very often I find that the criteria used to accept papers which refute the link are way more lenient than the criteria needed to accept papers that supposedly refute it. This is because the refuters don't have an incentive to find errors in refuting papers (e.g., as I demonstrated with the Shakun et al. paper supposedly finding that CO₂ leads the average global temperature). This is because any paper has a much higher probability of getting refereed by the refuter camp than the proponents camp. Simple statistics.

The second comment is that I wrote them politely, it ended up with an erratum, but to save face they continued claiming the that their paper supports the erroneous claim that my original conclusions are unsubstantiated. One can show that even those leftover criticisms are plagued with errors.

Main Problem

In the their paper, Overholt et al. try to estimate previous passages through the galactic spiral arms, and compare those passages to the appearance of ice-age epochs on Earth, over the past billion years. The gravest error is that the analysis was carried out using a spiral arm pattern speed that was totally different from the range of pattern speed they actually wrote they used!

They wrote that they take 10.1 to 13.7 (km/s)/kpc as the possible range for the relative motion of the spiral arm pattern speed with respect to the solar angular velocity (i.e., a nominal value of about 11.9 (km/s)/kpc). However, if one looks at the average spiral arm crossing as obtained in their analysis, it is about 100 Myr (the first of their group of 4 arm passages is at roughly at 275 Myr and their second group is at roughly 670 Myr). This implies an average spiral arm passage every (670 Myr - 275 Myr)/4 ~ 100 Myr, which is inconsistent with the above pattern speed. In fact, an average spiral arm passage every 100 Myr implies a relative pattern speed of about: $$ \Omega_\odot - \Omega_\mathrm{arm} \approx 15.4 (km/s)/kpc, $$ I am pretty sure that the source of error is the fact that they accidentally took the absolute pattern speed when calculating the spiral arm passages. For their nominal 217 km/s solar velocity at 8 kpc, one gets $\Omega_\odot = 27.1 (km/s)/kpc$, such that the absolute pattern speed obtained for the nominal 11.9 (km/sec)/kpc relative speed, is: $$\Omega_\mathrm{arm} = \Omega_\odot - (\Omega_\odot-\Omega_\mathrm{arm}) = 27.1 − 11.9 = 15.2 (km/s)/kpc$$ i.e., roughly the value I read by eye from their graph describing the spiral arm passages.

Because they accidentally took the absolute pattern speed, they obtained spiral arm crossings which are much more frequent that the climatic data or meteoritic data. If they would have taken the 10.1 to 13.7 range instead, the spiral arm passages would have been 112 to 152 Myr, which includes the ice-age epoch occurrences and the cosmic ray flux variations based on iron meteorites. The phase would have agreed as well.

I then suggested that they publish an erratum to that paper, which they did. However, to save face, they claimed that their re-calculated spiral passages are still inconsistent with the meteoritic data or with the climate record, which brings me to the additional problems still present in their analysis.

Additional Problems

A few more problems relate to the way Overholt et al. derive the spiral arm crossing (which is why even with their erratum, their manuscript is pointless).

First, they take the spiral arm model of Englmaier et al. 2009, but they trace the spiral arms by eye, and as a consequence get a distorted result which gives highly unlikely “tight” clusters of 4 consecutive passages each rotation. In fact, it is so distorted that 2 consecutive arm crossings are of the same arm, which even with the radial epicyclic motion of the solar system is ridiculous.

Second, they assume that their highly asymmetric (and unlikely) spiral arm configuration should remain as such for many spiral arm passages, but because the arms are dynamic, without more information, a more reasonable assumption would have been that the arms would have tended to be separated by 90 degrees instead of the “tight” clusters of 4 consecutive passages.

Third, they didn’t consider the fact that supernovae are biased to take place about 10 to 20 million years after the spiral arm passage because of the finite lifetime of the stars that end their lives as supernova explosions.

Fourth, they don’t actually carry out any statistical analysis how likely or unlikely is it to find all the ice-age epochs as close to the estimated spiral arm passages, not that a statistical analysis would have helped any given their problematic determination of the arm passages.

Last, and perhaps most important. The cosmic ray flux can be shown using Iron meteorites to be periodic with a roughly constant 145 Myr period, and in phase with the appearance of ice-age epochs, which means that any distorted reconstruction such as that of Overholt et al. is inconsistent with the data, which they have totally ignored.

Summary

Overhaul et al. analysis of the spiral arm passages is bad at so many levels it is not really worth ever considering again. However, will people still quote it and claim that it refutes the galactic spiral arm explanation for the appearance of spiral arm passages? Probably, but now you know better.

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Bill Nye, the not-so-good-science guy

June 5, 2015, 10:29 pm

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general science, global warming, politics, weather & climate

Bill "the science guy" Nye says that I am a denier.

I recently stumbled on a transcript of Bill “the science guy” Nye’s interview on CNN last week. In it, he said that climate skeptics (i.e., people like myself), are at least as bad as people who deny that smoking causes cancer. There are quite a few things he misses, in fact, he got things totally wrong, but I do like the his analogy to smoking and cancer as you’ll see.

First, what did he actually say? During his appearance on CNN, Bill Nye compared the link between denying a link between climate change and anthropogenic activity to denying a link between smoking and cancer:

“I just want to remind voters that suppose you had somebody running for congressional office in your district who insisted there was no connection between cigarette smoking and cancer. Would you vote for that person? You might, but if this person were adamant — ‘No, the scientists who studied cigarette smoking, they don’t know what…’ — if they were adamant, would you vote for them? And so, in the same way the connection between climate change and human activity is at least as strong as cigarettes and cancer. And so, I just want everybody to keep this in mind: that it’s very reasonable that the floods in Texas, the strengthening storms, especially — the president was in Florida — these things are a result of human activity making things worse. It’s very bad. I get this that people died in Texas, and I am reminding you what else. This is a very expensive business. When you flood the fourth largest city in the United States, somebody is going to pay for it, and it’s you and me. And so, the sooner we get to work on climate change, the better.”

Here’s the actual video:

These short comments and comparison he made are inappropriate for several major reasons.

To begin with, he follows the usual alarmist assertion that every calamity is necessarily due to global warming (now known as “climate change” so that they can cover more ground) and that all the climate change is necessarily anthropogenic. Since bizarre weather patterns can happen all the time with some probability, and since part of the climate change is also natural, these implicit “logical” steps would not make sense, at least in any other scientific discipline. I won’t dwell on this since others already did.

Second, the global warming debate is mostly a quantitative one. While the IPCC claims that climate sensitivity can be very large (e.g., a 4.5°C increase per CO₂ doubling which would be catastrophic), I claim that such high values are ruled as they are inconsistent with a lot of empirical data (e.g., see this). In other words, skeptics like myself don’t argue that CO₂ has no effect on climate, only that the IPCC story is highly exaggerated. On the other hand, whether smoking contributes 90% or 10% of the cases of lung cancer would be good enough reason for any rational person to quit smoking (well, rational and able to overcome his or her addiction). On the other hand, if a given emission scenario over the 21^st century will cause a 1°C or 4°C could make a huge difference. This means that denying that smoking causes cancer is a yes/no question while most skeptics don’t “deny anthropogenic global warming”, instead, they only claim it is minor.

The third point is the main one I want to make. The reasoning behind the attribution of lung cancer to smoke and behind attributing global warming to anthropogenic activity is conceptually different, so different, that putting both on the same pedestal is simply wrong. The evidence linking lung cancer to smoking is in the form highly statistically significant increase in the incidence rate of lung cancer when comparing smoking to non-smoking groups. So, either smoking or something very closely related to it is clearly carcinogenic. The assertion that climate sensitivity is large, that most of the 20^th century warming is necessarily anthropogenic and that temperature increase over the 21^st century will be large are the result of model predictions, not on empirical evidence. In fact, empirical evidence such as the small response to volcanic eruptions (e.g., Lindzen and Giannitsis 1998, see also note on climate effects of volcanoes here), or the lack of correlation between the order of magnitude CO₂ variations over geological time scales and the global temperature (e.g., this discussion on cosmic rays and climate), or of course, the lack of warming over the past nearly two decades, counter to all the model predictions (e.g., see this discussion of the hiatus long before the term was used).

If we use the cancer analogy it would be as if we had a model that can predict, at the biochemical level that some of the chemicals in cigarettes are carcinogenic, and that smoking should cause cancer, but, while the model would say that the incidence rate should be high and should explain most of the lung cancer cases, comparing the actual incidence rate would show that only some modest fraction of the lung cancer cases are attributed to smoking, but the rest are not. Yet, even with the evidence showing only a small difference in the incidence rate between the smoker and non-smoker group, the model will still be believed and it would be used to make predictions to other types of cancers, e.g., saying that they happen at a huge rate while they don’t. Sounds ridiculous? Well, this is what’s happening in climate science.

Anyway, the last time I had any thought about the “science guy”, was when I heard he was to give the commencement speech at my wife’s graduation from Caltech (roughly when the global warming hiatus began!). Back then I thought of how uninspiring it is. I am not saying that publicizing science to the public is not important (which is what Bill Nye did so well), but I didn’t think that this is the kind of figure that will push the young cadet of scientists and engineers into new frontiers. Its isn’t as if he is doing rocket science. In retrospect, I now think it was even less appropriate to have him.

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The Sunspots 2.0? Irrelevant. The Sun, still is.

August 10, 2015, 6:40 am

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cosmic rays, global warming, personal research, weather & climate

After being asked by 5 independent people about the new sunspot number reconstruction and that it doesn’t show that the sun should have contributed any warming to the 20^th century, I decided to write about it here. I have one word to describe it – irrelevant. It is also a good opportunity to write about new results (well, one that saw the light of day a few months ago) showing again that the sun has a large effect on climate. Yet, the world will still continue to ignore it. Am I surprised? No I’m not.

First, what’s the story? A group led by Frédéric Clette had a presentation at the IAU assembly in Hawaii. In it, they argued that the sunspot number suffers from various systematic errors as it is a subjective measurement. Because those systematic errors vary with time (with the different observers and observational methods), the SN reconstruction can exhibit a fictitious long term trend. They also attempted to calibrate the data, and obtain a more homogeneous dataset. This is described at length in their arXiv preprint.

The most interesting aspect about their new sunspot reconstruction is that there is significantly less variation in the sunspot number between the different solar maxima since the Maunder minimum. This implies, according to them, that there wasn't a significant increase in solar activity over the 20^th century (no "20^th century Grand Maximum"), and therefore the sun should not have contributed anything towards increased temperatures. This point was of course captured by the media (e.g., here).

The old and new sunspot number reconstructions

Figure 1: The old (red) and new (blue) sunspot number reconstructions of Clette et al.

So, what do I think about it? First, I have no idea whether the calibration is correct. They do make a good argument that the SN reconstruction is problematic. Namely, some corrections are probably necessary and there is no reason a priori to think that what they did is invalid. However, their claim about solar activity in general not varying much since the sun came out from the Mounder minimum is wrong. There are other more objective ways to reconstruct solar activity than subjective sunspot counting, and they do show us that solar activity increased over the 20^th century. So at most, one can claim that solar activity has various facets, and that the maximum sunspot number is not a good indicator of all of them. This is not unreasonable since the number of sunspots would more directly reflect the amount of closed magnetic field lines, but not the open ones blowing in the solar wind.

The two important objective proxies for solar activity are cosmogenic isotopes (¹⁴C and ¹⁰Be), and the geomagnetic AA index. The AA index (measured since the middle of the 19^th century) clearly shows that the latter part of the 20^th century was more active than the latter half of the 19th century. The longer ¹⁰Be data set reveals that the latter half of the 20^th century was more active than any preceding time since the Maunder minimum. (The ¹⁴C is a bit problematic because human nuclear bombs from the 1940's onwards generated a lot of atmospheric ¹⁴C so it cannot be used to reconstruct solar activity in the latter part of the 20^th century).

The Geomagnetic AA index showing an increase in solar activity

Figure 2: The AA geomagnetic index showing a clear increase in solar activity over the 20^th century (From here).

The Beryllium 10 decrease from solar activity increase

Figure 3: The ¹⁰Be production showing again, that the sun was particularly active in the latter half of the 20^th century. The sunspot number is the "old" reconstructions without Clette's et al. corrections.

What does it tell us? Given that long term variations in Earth's climate do correlate with long term solar activity (e.g., see the first part of this) and given that some solar activity indicators (presumably?) don't show an increase from the Maunder minimum, but some do, it means that climate is sensitivite to those aspects of the solar activity that increased (e.g., solar wind), but not those more directly associated with the number of sunspots (e.g., UV or total solar irradiance). Thus, this result on the sunspots maxima (again, if true), only strengthens the idea that the solar climate link is through something related to the open magnetic field lines, such as the strength of the solar wind or the cosmic ray flux which it modulates.

The second point I wanted to write about is a recently published analysis showing that the sun has a large effect on climate, and quantifying it. In an earlier work, I showed that you can use the oceans as a calorimeter to see that the solar radiative forcing over the solar cycle is very large, by looking at various oceanic data sets (heat content, sea surface temperature and tide gauges). How large? About 6-7 times large than one can naively expect from changes in the solar irradiance.

More recently, Daniel Howard, Henrik Svesmark and I looked at the satellite altimetry data. It is similar to the tide gauge records in that it measures how much heat goes into the ocean by measuring the sea level change (most of the sea level on short time scales is due to thermal expansion). Unsurprisingly, we found that the satellite altimetry showed the same solar-cycle synchronized sea level change as the tide gauge records. However, because the satellite data is of such high quality, it is has a higher temporal resolution than the tide gauge records which allows singling out the thermal expansion component from other terms (e.g., associated with trapping of water on land). This allows for an even better estimate of the solar forcing, which is 1.33±0.34 W/m² over the last solar cycle. You can see in fig. 4 how much the sun and el-Niño can explain a large fraction of the sea level change over yearly to decadal time scales.

Altimetry based sea level data showing the solar influence

Figure 4: Sea level data and the model fit. The blue dots are the linearly detrended global sea level measured with satellite altimetry. The purple line is the model fit to the data which includes both a harmonic solar component and an ENSO contribution. The shaded regions denote the one sigma and 1% to 99% confidence regions. The fit explains 71% of the observed variance in the filtered detrended data.

The bottom line is that the sun appears to have a large effect on the climate on various time scales. Whether or not the sunspots reflect the increase in solar activity since the Maunder minimum (as reflected in other datasets) is not very important. At most, if they don't reflect, it only strengthen's the idea that something associated with the solar wind does (such as the cosmic rays which they modulate).

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Climate debate at the Cambridge Union - a 10 minute summary of the main problems with the standard alarmist polemic

November 2, 2017, 2:35 pm

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Blog topic:

general science, global warming, politics, weather & climate

Last week I participated in an interesting debate that was held at the Cambridge Union, the oldest debating club in the world (dating back to 1815. The invite was to be on the side opposing the proposition “This house would rather cool the planet than warm the economy”.

Although I think the phrasing of the question is problematic to begin with, since it assumes that “warming the economy” necessary would cool the climate, I should applaud the Cambridge Union for supporting free speech and allowing people on both side to voice their arguments, especially given how many on the alarmist side refuse to do so, claiming that there is nothing to debate anymore.

I should also add that I was quite shocked to see how the audience was so one sided (though far less than the ridiculous 97:3 ratio we hear about!) and unwilling to listen to scientific arguments. I am actually quite lucky to be living in Israel where free speech and free thought are really more than lip service. Having honest debates in Israeli academia or in the media is actually the norm.

Below you will find the summary I wrote myself before the debate. Since it is rather concise I thought it would be a good idea to bring it here as well.

Have fun

— Nir

Let me begin by asking you a question. What is the evidence that people, like the proponents here, use to prove that we humans are responsible for global warming and that future warming will be catastrophic if we don’t get our act together?

The fact is that this idea is a misconception and the so called evidence we constantly hear is simply based on fallacious arguments.

To begin with, any one who appeals to authority or to a majority to substantiate his or her claim is proving nothing. Science is not a democracy and the fact that many believe one thing does not make them right. If people have good arguments to convince you, let them use the scientific arguments, not logical fallacies. Repeating it ad nauseam does not make it right!

Other irrelevant arguments may appear scientific, but they are not. Evidence for warming is not evidence for warming byhumans. Seeing a poor polar bear floating on an iceberg does not mean that humans caused warming. (Actually, the bear population is now probably at its highest in modern times!). The same goes to receding glaciers. Sure, there was warming and glaciers are receding, but the logical leap that this warming is because of humans is simply an unsubstantiated claim, even more so when considering that you can find Roman remains under receded glaciers in the Alps or Viking graves in thawed permafrost in Greenland.

Other fallacious arguments include using qualitative arguments and the appeal to gut feelings. The fact that humanity is approaching 10 billion people does not prove that we caused a 0.8°C temperature increase. We could have just as much caused an 8°C increase or an 0.08°C. If all of humanity spits into the ocean, will sea level rise appreciably?

In fact, there is no single piece of evidence that proves that a given amount of CO2 increase should cause a large increase in temperature. You may say, “just a second, we saw Al Gore’s movie, in which he presented a clear correlation between CO2 and temperature from Antarctic ice cores”. Well, what he didn’t tell you is that one generally sees in the ice cores that CO2 lags the temperature by typically a few hundred years, not vice versa! The simple truth is that Al Gore simply showed us how the amount of CO2 dissolved as carbonic acid in the oceans changes with temperature. As a matter of fact, over geological time scales, there were huge variations in the CO2 (a factor of 10) and they have no correlation whatsoever with the temperature. 450 million years ago there was 10 times as much CO2 in the atmosphere but more extensive glaciations.

When you throw away the chaff of all the fallacious arguments and try to distill the climate science advocated by the IPCC and alike, you find that there are actually two arguments which appear as legitimate scientific arguments, but unfortunately don’t hold water. Actually, fortunately! The first is that the warming over the 20th century is unprecedented, and if so, it must be human. This is the whole point of the hockey so extensively featured in the third assessment report of the IPCC in 2001. However if you would google “climategate” you would find that this is a result of shady scientific analysis - the tree ring data showing that there was little temperature variation over the past millennium showed a decline after 1960, so, they cut it off and stitched thermometer data. The simple truth is that in the height of the middle ages it was probably just as warm as the latter half of the 20th century. You can even see it directly with temperature measurements in boreholes.

The second argument is that there is nothing else to explain the warming, and if there is nothing else it must be the only thing that can, which is the anthropogenic contribution. However, as I mention below, there is something as clear as daylight… and that is the sun.

Before explaining why the sun completely overturns the way we should see global warming and climate change in general. It is worth while to say a few words on climate sensitivity and why it is impossible to predict ab initio the anthropogenic contribution.

The most important question in climate science is climate sensitivity, by how much will the average global temperature increase if you say double the amount of CO2. Oddly enough, the range quoted by the IPCC, which is 1.5 to 4.5°C per CO2 doubling was set, are you ready for this, in a federal committee in 1979! (Google the Charney report). All the IPCC scientific reports from 1990 to 2013 state that the range is the same. The only exception is the penultimate report which stated it is 2 to 4.5. The reason they returned to the 1.5 to 4.5 range is because there was virtually no global warming since 2000 (the so called “hiatus”), which is embarrassingly inconsistent with a large climate sensitivity. What’s more embarrassing is that over almost 4 decades of research and billions of dollars (and pounds) invested in climate research we don’t know the answer to the most important question any better? This is simply amazing I think.

The body of evidence however clearly shows that the climate sensitivity is on the low side, about 1 to 1.5 degree increase per CO2 doubling. People in the climate community are scratching their heads trying to understand the so called hiatus in the warming. Where is the heat hiding? While in reality it simply points to a low sensitivity. The “missing” heat has actually escaped Earth already! If you look at the average global response to large volcanic eruptions, from Krakatoa to Pinatubo, you would see that the global temperature decreased by only about 0.1°C while the hypersensitive climate models give 0.3 to 0.5°C, not seen in reality. Over geological time scales, the lack of correlation between CO2 and temperature places a clear upper limit of a 1.5°C per CO2 doubling sensitivity. Last, once we take the solar contribution into account, a much more consistent picture for the 20th century climate changes arises, one in which the climate drivers (humans AND solar) are notably larger, and the sensitivity notably smaller.

So, how do we know that the sun has a large effect on climate? If you search on google images “oceans as a calorimeter”, you would find one of the most important graphs to the understanding of climate change which is simply ignored by the IPCC and alarmists. You can see that over more than 80 years of tide gauge records there is an extremely clear correlation between solar activity and sea level rise - active sun, the oceans rise. Inactive sun - the oceans fall. On short time scales it is predominantly heat going to the oceans and thermal expansion of the water. This can then be used to quantify the radiative forcing of the sun, and see that it is about 10 times larger than what the IPCC is willing to admit is there. They only take into account changes in the irradiance, while this (and other such data) unequivocally demonstrate that there is an amplifying mechanism linking solar activity and climate.

The details of this mechanism are extremely interesting. I can tell you that it is related to the ions in the atmosphere which are governed by solar activity and in fact, there are three microphysical mechanisms linking these ions to the nucleation and growth of cloud condensation nuclei. Basically, when the sun is more active, we have less clouds that are generally less white.

So, the main conclusion is that climate is not sensitive to changes in the radiative forcing.

This means that we are not required to “cool the economy” in order to cool earth. In Paris and Copenhagen the leaders of the world said that we should make sure that the total global warming will be less than 2°C. It will be less than 2°C even if we do nothing. There are several red flags that people do their best to ignore. The lack of warming in the past 2 decades is a clear sign that sensitivity is low, but people ignore it.

Last point. People say that we should at least curb the emissions as a precautionary step. However, resources are not infinite. Most people in developed nations can pay twice for their energy, but for third world nations? It would mean more expensive food, hunger and poverty, and many in the developed world actually freezing in winter. So in fact, taking unnecessary precautionary steps when we know they are unnecessary is immoral. It is even committing statistical murder.

Now the really last point, I am also optimist that humanity will switch to alternative energy sources in less than 2-3 decades just because they will become cheap enough, and just for the reason that people want to save money. Just like the price of computers has plummeted exponentially (Moore’s law— number of transistors doubles every 18 months) so does the cost of energy from photovoltaic cells (cost halves every 10 years). Once they will be really cost effective, without subsidies, suddenly we won’t be burning fossil fuels because it would be the expensive thing to do!

Let us use our limited resources to treat real problems.

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Finally! The missing link between exploding stars, clouds and climate on Earth

December 19, 2017, 4:30 am

≫ Next: Climate debate at the Cambridge Union - The Video

≪ Previous: Climate debate at the Cambridge Union - a 10 minute summary of the main problems with the standard alarmist polemic

Blog topic:

astronomy, cosmic rays, global warming, personal research, weather & climate

By Henrik Svensmark and Nir shaviv

Our new results published today innature communications provide the last piece of a long studied puzzle. We finally found the actual physical mechanism linking between atmospheric ionization and the formation of cloud condensation nuclei. Thus, we now understand the complete physical picture linking solar activity and our galactic environment (which govern the flux of cosmic rays ionizing the atmosphere) to climate here on Earth though changes in the cloud characteristics. In short, as small aerosols grow to become cloud condensation nuclei, they grow faster under higher background ionization rates. Consequently, they have a higher chance of surviving the growth without being eaten by larger aerosols. This effect was calculated theoretically and measured in a specially designed experiment conducted at the Danish Space Research Institute at the Danish Technical University, together with our colleagues Martin Andreas Bødker Enghoff and Jacob Svensmark.

Background:

It has long been known that solar variations appear to have a large effect on climate. This was alreadysuggested by William Herschel over 200 years ago. Over the past several decades, more empirical evidence have unequivocally demonstrated the existence of such a link, as exemplified in the examples in the box below.

Box 1: Examples demonstrating the Solar/Climate link

Below are several examples showing that the sun has a large effect on climate. The first example is the beautiful correlation between solar activity (as mirrored in theCarbon 14 extracted from tree rings) and Oxygen 18 to Oxygen 16 isotope ratio is stalagmites in a cave in Oman, measured byNeff et al. (2001). The former is a proxy of solar activity (as the solar wind modulates the flux of cosmic rays reaching the terrestrial atmosphere and producing Carbon 14 through spallation).Oxygen 18 is a well known climate proxy (in this case, of the monsoon rain coming from the Indian ocean).

Figure 1: A correlation between ¹⁴C/¹²C from tree rings (a proxy of solar activity) and ¹⁸O/¹⁶O from stalagmites in a cave in Oman in the southern Arabian peninsula by Neff et al. (2001) (which is a proxy of the temperature of the Indian ocean). A large correlation is apparent.

The second example, by Bond et al. (2001), shows a clear correlation between solar activity (again as recovered using ¹⁴C) and the climate of the North Atlantic, as can be reconstructed from ice rafted debris in cores from the ocean floor.

Figure 2: A correlation between ¹⁴C/¹²C from tree rings (a proxy of solar activity) and the amount of ice rafted debris left on the ocean floor in the Northern Atlantic. Again, a large correlation is apparent.

The third example, on shorter time scales, is the clear correlation between solar activity over the past century, exhibiting the quasi periodic 11 year solar cycle, and the rate of change of the sea level.

Figure 3: The correlation between solar activity (in red) and the sea level rate of change from tide gauges across the globe.

Unlike the previous results which qualitatively demonstrate the existence of a strong solar/climate link, the last correlation, byShaviv (2008), can be used to quantify the link and show that the solar minimum to solar maximum variations in the solar activity translates into a 1 to 1.5 W/m² change in Earth’s energy budget. A more recent analysis of satellite altimetry data reveals that the correlation continues. In fact, if one removes the linear trend from glacier melting, almost all the sea level change can be attributed to the sun and the el Niño southern oscillation (Howard et al. 2015).

Figure 4: The correlation between the linearly detrended sea level measured using satellite altimetry (blue dots) and a model fit which includes just two components: The sun and el Niño southern oscillation. The excellent fit implies that the two components are by far the dominant source of sea level change on short time scales.

The fact that the ocean sea level changes with solar activity (see Box 1 above) clearly demonstrates that there is a link between solar activity climate, but it can be used to quantify the solar climate link and show that it is very large. In fact, this “calorimetric” measurement of the solar radiative forcing is about 1 to 1.5 W/m² over the solar cycle, compared with the 0.1-0.2 W/m² change expected from just changes in the solar irradiance. This means that a mechanism amplifying solar activity should be operating—the sun has a much larger effect on climate than can be naively expected from just changes in the solar output.

Over the years, a couple of mechanisms were suggested to explain the large solar climate link. However, one particular mechanism has accumulated a significant amount of evidence in its support. The mechanism is that of solar wind modulation of the cosmic rays, which govern the amount of atmospheric ionization, and which in turn affect the formation of cloud condensation nuclei and therefore how much light do the clouds reflect back to space, as we now explain.

Cosmic Rays are high energy particles originating from supernova remnants. These particles diffuse through the Milky Way. When they reach the solar system they can diffuse into the inner parts (where Earth is) but lose some energy along the way as they interact with the solar wind. Here on Earth they are responsible for most of the ionization in the Troposphere (the lower 10-20 km of the atmosphere where most of the “weather” takes place). We now know that this ionization plays a role in the formation of cloud condensation nuclei (CCNs). The latter are small (typically 50nm or larger) aerosols upon which water vapor can condense when saturation (i.e., 100% humidity) is reached in the atmosphere. Since the properties of clouds, such as their lifetime and reflectivity, depends on the number of CCNs, changing the CCNs formation rate will impact Earth’s energy balance.

The full link is therefore as follows: A more active sun implies a lower CR flux reaching Earth and with it, lower ionization. This in turn implies that fewer cloud condensation nuclei are produced such that the clouds that later form live shorter lives and are less white, thereby allowing more solar radiation to pass through and warm our planet.

Figure 5: The link between solar activity and climate: A more active sun reduces the amount of cosmic rays coming from supernovae around us in the galaxy. The cosmic rays are the dominant source of atmospheric ionization. It turns out that these ions play an important role in (a) increasing the nucleation of small condensation nuclei (a few nm) and (b) increasing the growth rate of the condensation nuclei (which is the effect just published). The larger growth rates imply that they are less likely to stick to pre-existing aerosols and thus have a larger chance of reaching the sizes of cloud condensation nuclei (CCNs, typically > 50 nm in diameter). Thus, a more active sun decreases the formation of CCNs, making the clouds less white, reflecting less sunlight and therefore warming Earth.

Until today we had just empirical results which demonstrate that this link is indeed taking place. The main results are summarized in Box 2 below. In particular, we have seen correlations between solar activity and cloud cover variations, as well as between cosmic ray flux variations arising from changes in our galactic environment and long term climate change using geological data.

Box 2: Examples showing the cosmic ray climate link

The first empirical evidence linking solar activity with cloud cover was the correlation between solar activity (as proxied by the cosmic rays) and changing cloud cover (Svensmark & Friis-Christensen 1997), in particular, the low altitude cloud cover (seeMarsh & Svensmark 2000). Although later data has cross-satellite calibration problems, the correlation continued. Interestingly, Cosmic rays exhibit an odd/even asymmetry because they are the only solar modulated component that “sees” the fact that subsequent solar cycles have opposite magnetic field polarity. The cloud cover appears to exhibit the same asymmetry.

Figure 6: The correlation between low altitude cloud cover (blue) and the cosmic ray flux reaching earth (red).

Later, more evidence for the fact that cosmic rays are not only the proxy of solar activity but are an actual part of the climate mechanism appeared in the form of correlations between cosmic ray flux variations that have nothing to do with solar activity and climate variations. Such variations in the cosmic ray flux exit over geological time scales. We showed that one can use Iron meteorites to reconstruct the cosmic ray flux variations over the past billion years. These variations exhibit seven increases due to passages through the galactic spiral arms, on one hand, but appear to correlate with the appearance of ice age epochs on Earth, on the other (Shaviv, 2002, Shaviv 2003, Shaviv & Veizer 2003). Clearly, cosmic ray flux variations that are independent of solar activity appear to have a large effect on climate as well.

The first suggestion for an actual physical mechanism was that ions increase the nucleation of small (2-3 nm sized) aerosols called condensation nuclei (CNs). The idea is that small clusters of sulfuric acid and water (the main building blocks of small aerosols) are much more stable if they are charged. That is, the charge allows the aerosols to grow from a very small (few molecule) cluster to a small stable CN without breaking apart in the process. This effect was first seen in our lab (Svensmark 2006). The effect was seen again in the CLOUD experiment running at CERN (Kirkby 2011). Later experiments have shown that ions accelerate also other nucleation routes in which the small clusters are stabilized by a third molecule (such as Ammonia). That is, ions play a dominant role in accelerating almost all nucleation routes (as long as the total nucleation rate is lower than the ion formation rate).

Figure 7: The Ion induced nucleation effect measured in the lab. Left: The first demonstration in our SKY experiment showing that increased ionization increases the nucleation of small aerosols (typically 3 nm in size). Right: Corroboration of the results in the CLOUD experiment at CERN.

In the meantime, a number of research groups aimed at testing the idea that cosmic ray ionization could help the formation of cloud condensation nuclei (CCN). This was done by using large global circulation models coupled with aerosol physics. The idea was to see if an added number of small aerosols would grow into more CCNs. All of the numerical models gave the result that the small aerosols were lost before they could become large enough, leading to the conclusion that the effect of cosmic rays on the number of CCN over a solar cycle was insignificant (e.g., Pirece and Adams 2009). This could also be explained analytically (Smith et al. 2016). It was therefore proclaimed that the theory was dead.

Given the empirical evidence, it was clear to us that a link must be present, even if the ion induced nucleation mechanism itself is insufficient to explain the link. Thus, our response was to address the same question without using models but instead to test it experimentally. Therefore, in 2012 we tested if small nucleated aerosols could grow into CCN in our laboratory and discovered that without ions present, the response to increased nucleation was severely damped, just like the above-mentioned models; however with ions present, all the extra nucleated particles grew to CCN sizes, in contrast to the numerical model results (Svensmark et al. 2013). So, experiments contradicted the models. The logical conclusion was that some unknown ion-mechanism is operating, helping the growth.

Figure 8: Left: When injecting small aerosols, the relative increase decreases with aerosol size because as aerosols grow they tend to coagulate with larger aerosols. Right: However, when increasing the ionization in the chamber, not only are more aerosols nucleated, the relative increase survives to larger sizes implying that some mechanism is increasing the survivability of the aerosols as they grow.

Following the experimental results showing that increased ionization does indeed increase the number of large CCNs, the natural question to ask was whether these results were caused by the particular experimental conditions—perhaps this mechanism does not work in the real atmosphere. It is therefore fortunate that our Sun carries out natural experiments with the whole Earth.

On rare occasions, “explosions” on the Sun called coronal mass ejections result in a plasma cloud passing the Earth, with the effect that the cosmic rays flux decreases suddenly and remains low for about a week. Such events, with a significant reduction in the cosmic ray flux, are called Forbush decreases, and are ideal to test the link between cosmic rays and clouds. Finding the strongest Forbush decreases and using three independent cloud satellite datasets and one dataset for aerosols, we clearly found a response to Forbush decreases. These results validated the whole chain from solar activity, to cosmic rays, to aerosols (CCN), and finally to clouds, in Earth’s atmosphere (Svensmark et al 2009, Svensmark et al. 2016).

Figure 9: The average effect of the 5 strongest Forbush decreases in the 1987-2007 period on cloud properties. Plotted in red is the reduction in the cosmic ray flux following “gusts” in the solar wind (from Coronal Mass Ejections). In black we see the reduction in aerosols over the oceans and three different cloud parameters from three different datasets (Svensmark et al 2009). These results provide an in situ demonstration of the effect of cosmic rays on aerosols and cloud properties.

With the accumulating empirical and experimental evidence, it was clear that atmospheric ionization is playing a role in the generation of the aerosols needed for cloud formation, however, the exact mechanism proved to be elusive. For this reason, we decided to setup another laboratory experiment mimicking conditions found in the real atmosphere and study how atmospheric ions may be affecting the production of CCNs. This also led us to look for alternative mechanisms which will increase the survivability of the CNs as they growth. Indeed, after several years of research, one was found.

The discovery

A little more than 2 years ago, we made the realization that charge will play a role in accelerating the growth rate of small aerosols. When more ions are present in the atmosphere, more of them end up sitting on sulfuric acid clusters of a few molecules. Moreover, the charge makes the sulfuric acid clusters stick to the growing aerosols much faster, as we explain in the box below. Since faster growing aerosols have lower chances of coagulating with larger aerosols, more of the growing aerosols can then survive to reach larger sizes. In other words, when the ionization rate is higher, more CCNs can are formed.

Box 3: The physics behind the new mechanism

The physics responsible for the accelerated growth is actually relatively simple. A charged cluster of a few molecules of sulfuric acid and water will induce a polarization on the growing aerosols—charge will move from one side of the aerosol to the other, such that one side will be positively charged, while the other negatively charged (with no net charging of the aerosols). Through interaction with this polarization (called Debye force), the cluster and aerosols are attracted. This means that charged clusters stick onto the aerosols notably faster than neutral clusters. Thus, when more ions are present, aerosols can grow faster, and if so, the probability that they stick onto larger aerosols (and thus lost from the system) is smaller.

Figure 10: A negatively charged cluster induces a polarization of the neutral aerosol and then gets attracted to it (since the pull from the positive side of the aerosol is stronger than the push from the negative side).

After realizing that this effect should be taking place we did two things. First, we calculated how large it should be and found that for the typical conditions present in the pristine air above oceans, in which the typical sulfuric acid density is a few 10⁶ molecules/cm³, the ions accelerate the growth by typically 1 to 4%. However, because the number of aerosols surviving the growth is exponentially small (typically several e-folds), the relative change in the CCN density is a few times larger still (by the number of e-folds in the exponential damping to be precise). Thus, over the solar cycle (which changes the tropospheric ionization by typically 20%), we expect a several percent variation in the CCN density and with it, the cloud properties, as is observed.

The second thing we did was go to the lab and design an experiment in which we can see this effect taking place (and also validate our theoretical calculations). This is not trivial because the effect is larger for lower sulfuric acid levels (as a larger percentage of the molecules would be charged). However we cannot measure at very low sulfuric acid levels because the aerosols then grow very slowly such that they stick to the chamber walls before their growth can be reliably measured. This forced us to measure at high sulfuric acid levels for which the effect is smaller. This posed a formidable technological challenge. To overcome this, we designed an experiment which can keep relatively stable conditions over long periods (up to several weeks at a time) during which we could automatically increase or decrease the ionization rate at the chamber. This allowed us to collect a large amount of data and get high quality signals (e.g., see fig. 11 in the box below).

We found that aerosols indeed grow faster when the ionization rate is higher, totally consistent with the theoretical predictions (as can be seen in fig. 12 in the box below). This allows them to survive the growth period without coagulating with larger aerosols.

Box 4: Sample Results

Although the reader is can read the article online, here are a few sample results.

Figure 11: The growth of aerosols in the experiment. Lower panel: Color coded is the number density of aerosols as a function of time (horizontal axis), and diameter of aerosols in nm (vertical axis). Every 2 hours the γ-ray sources are opened/closed. Thus, part of the growth is with high ionization and part with low such that the growth rates can be compared. Top: Since the differences are not large under the experimental conditions, the ionizing sources can be switched on/off over many cycles to get high quality statistics. The reason that the signal is small in the experiment is because growth in the chamber has to be an order of magnitude faster than in the atmosphere, otherwise the aerosols would stick to the chamber walls. Under the faster growth conditions, the effect is smaller.

Figure 12: Difference in the γ-ray open and closed growth times (from 6 to 12 nm), in 11 runs with different sulfuric acid densities (and therefore growth rates) and different change in ionization. The dashed lines are the theoretical predictions.

So, what do the results imply? Until now we had significant amount of empirical evidence which demonstrated that cosmic rays affect climate, but we didn't have the actual underlying physical mechanism pinned down. Now we have. It means that we not only see the existence of a link, we now understand it. Thus, if the solar activity climate link was until now ignored under the pretext that it cannot be real, this will have to change. But perhaps more interestingly, it also explains how long term variations in our galactic environment end up affecting our climate over geological time scales.

Box 5: Why is the CR/climate link ignored?

Given all the empirical evidence that has accumulated until now, the climate community should have considered it seriously, and even if the actual mechanism was until now missing, the empirical evidence showing and quantifying the solar climate link shouldn’t have been ignored by most of the community.

The reason is actually very simple and lays in the implication of the link. If the sun has a large effect on climate, then its increase activity over the 20^th century should have contributed at least some of the global warming. In fact, the calorimetric sea level based measurements imply that a bit more than half of the 20^th century warming should be attributed to the sun. If so, the role that humans have had is diminished. In fact, when one considers the role that the sun has had over the 20^thcentury, one finds that a) the temperature variations can actually be much better explained (with a smaller residual) and the required climate sensitivity is on the low side (about 1 to 1.5°C increase per CO₂ doubling, compared with the canonical range of 1.5 to 4.5°C advocated by the IPCC, see Ziskin & Shaviv, 2012). The low climate sensitivity implies that the same emission scenarios will give rise to more modest temperature increases over the 21^st century. These good news imply that we are not in as dire a situations as we often hear. But many do not like hearing this.

Now that the mechanism is actually known, there should be no excuse in ignoring it any further, but given the above implications, it would most likely still be ignored.

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Climate debate at the Cambridge Union - The Video

January 6, 2018, 9:22 am

≫ Next: My experience at the German Bundestag's Environment Committee in a pre-COP24 discussion

≪ Previous: Finally! The missing link between exploding stars, clouds and climate on Earth

Blog topic:

general science, global warming, personal research, politics, weather & climate

Two months ago I wrote about the Cambridge Union Debate I participated in. The Cambridge Union has meanwhile posted the debate online. Here is my part of it. (It starts at 32m31s.)

I should add that the debate was a real eye opener. By living in Israel, I have had the luxury of experiencing a mostly diverse society, open to a wide range of scientific (and other) opinions. This has allowed me to carry out research without having to care about what other people think. It stands however in stark contrast to the body of Cambridge students I addressed. They are well intentioned but unfortunately completely brainwashed. They cite the 97% polemic about most scientists believing in anthropogenic global warming without stopping for a second to think about it, or the evidence that supposedly supports it. They want to think of themselves as liberals, but in fact, they have the most conservative mindset unable to even attempt objective thinking.

The only exception, which stood out as remarkable contrast to the rest, was the remark made by a historian named Josh from Christ college (at 1h 21m 21s).

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My experience at the German Bundestag's Environment Committee in a pre-COP24 discussion

December 7, 2018, 6:17 am

≫ Next: 22 minute talk summarizing my views on global warming

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Blog topic:

general science, global warming, politics, weather & climate

Last week I had the opportunity to talk in front of the Environment committee of the German Bundestag. It was quite an interesting experience, and frankly, something I would have considered unlikely before receiving the invitation. It was in fact the first time a climate "skeptic" like myself appeared behind those doors in many years.

As I understand, the committee was used to inviting Prof. Schellnhuber, formerly the director of the Potsdam Institute for Climate Impact Research. However, as he recently retired, there were voices that the committee should freshen up and invite someone else, and the name that came up was that of Prof. Anders Levermann, also from the same PIK. That however triggered some of the parties to request other people as well, and the committee ended up inviting 6 specialists. Two were bona fide scientists (including myself and Levermann) while the four other were experts on other topics. My name popped up by the right wing AfD party who's climate agenda is consistent with my climate findings—that global warming is a highly exaggerated scare.

The earliest flight from Israel that day would have brought me to the Bundestag awfully close to the beginning of the discussion. So I flew in the day before. I landed in a freezing cold Berlin (-3°C) but sunny! Actually exhilarating weather I quite like.

The next day I showed up at the committee. I was interviewed by someone form a local news outlet that I was told has the tendency to distort the interviews with people like myself (if anyone knows about it, I'm curious, so leave a comment about it if you have seen it).

As I entered the committee room and sat down, Levermann past by and told me in hebrew, אתה יודע שאתה טועה (You know that you're wrong). Which of course caught me in a bit of surprise. It turns out that Levermann did his PhD with Prof. Itamar Procaccia at the Weizmann institute, a world expert in turbulence, nonlinear phenomena and statistical mechanics. Anyway, my German can be described as somewhere between nonexistent and really awful (I studied for a year when I was in high school in the US but forgot most), but enough to say, Ich glaube ich bin recht (I believe I am right).

The discussion started with each one of the experts allowed to talk for 3 minutes. It is actually quite a problem. People have been brain washed to think about global warming as mostly anthropogenic and almost unavoidably catastrophic. How do you prove to people that they are all wrong (or more precisely, that they were told highly exaggerated tales) in such a short time? To make things worse, I was told at the last minute that their TV is broken. Thus, the powerpoint slides I prepared were actually printed out and given to the committee members.

Given that, I had I think no choice but to concentrate on what I think is the biggest error you find in the IPCC, and which clearly overturns the standard polemic, and that is that the sun has a large effect on climate.

Here is what I prepared (what I said was pretty close but not all verbatim):

Three minutes is not a lot of time, so let me be brief. I’ll start with something that might shock you. There is no evidence that CO2 has a large effect on climate. The two arguments used by the IPCC to so called “prove” that humans are the main cause of global warming, and which implies that climate sensitivity is high, are that: a) 20th century warming is unprecedented, and b) there is nothing else to explain the warming.

These arguments are faulty. Why you ask?

We know from the climate-gate e-mails that the hockey stick was an example of shady science. The medieval warm period and little ice ages were in fact global and real. And, although the IPCC will not admit so, we know that the sun has a large effect on climate, and on the 20th century warming in particular.
In the first slide we see one of the most important graphs that the IPCC is simply ignoring. Published already in 2008, you can see a very clear correlation between sea level change rate from tide gauges, and solar activity. This proves beyond any doubt that the sun has a large effect on climate. But it is ignored.

To see what it implies, we should look at figure 2.
This is the contribution to the radiative forcing from different components, as summarized in the IPCC AR5. As you can see, it is claimed that the solar contribution is minute (tiny gray bar). In reality, we can use the oceans to quantify the solar forcing, and see that it was probably larger than the CO2 contribution (large light brown bar).

Any attempt to explain the 20th century warming should therefore include this large forcing. When doing so, one finds that the sun contributed more than half of the warming, and climate has to be relatively insensitive. How much? Only 1 to 1.5°C per CO2 doubling, as opposed to the IPCC range of 1.5 to 4.5. This implies that without doing anything special, future warming will be around another 1 degree over the 21st century, meeting the Copenhagen and Paris goals.

The fact that the temperature over the past 20 years has risen significantly less than IPCC models, should raise a red flag that something is wrong with the standard picture.

I should also add that science is not a democracy. The majority is not necessarily right! You should also be careful and make the distinction between evidence for warming and evidence for warming by humans. There is in fact no evidence for the latter. Last, people may frighten you with secondary climate effects associated with global warming, on the sea level, cryosphere, droughts floods or economic effects. However, if the underlying climate model is fundamentally wrong, all the ensuing predictions are irrelevant.

The fear of global warming, and with it the denouncement of any other voice, is now part of our Zeitgeist. However instead of blindly flowing with the flow, we should stop for a minute and think before we waste so much of our precious public resources. Maybe we will find out the that the emperor has new clothes.

When invited, I was also told that I can submit a written statement, which is what I did. It is a few times longer and has a bit more information. You can find it on the Bundestag's website, with a German translation.

Then came the questions, which were mostly guiding questions - each party asked the expert close to its heart to basically continue saying whatever they wanted to hear. One of the questions I was asked was about the determination of the global temperature, but frankly I didn't understand it. I should add that I had to rely on simultaneous translatation (there were two translators brought in especially for me, I think), and the translated question I heard in English sounded like somethig a bit convoluted and hard to address.

Anyway, during the whole discussion I was directly criticized by Levermann and by Lorenz Beutin, MdB (Bundestag member from Die Linke - the "The Left").

The first such critique was prompted by a request to Levermann, to address why I was wrong in my speech. I should say that Levermann seems nice at the personal level. I have nothing against him, but I his response at this round was totally unscientific. He said that everything I said is rubbish (at least that was the English translation I heard), which of course is not a scientific argument.

The second round came from Beutin. He actually raised two interesting specific points which Levermann pickup on as well, which is great, because this is what science is all about. Argue about specific scientific facts and the conclusions that can be drawn from them.

So what were the points that were raised by Beutin and Levermann?

1) The average sea level change rate (in the solar / sea level change rate graph) is above zero, proving that there was long term sea level rise.

2) From about 1990, solar activity has decreased but the temperature increased. So the sun cannot cause the warming.

3) It is all just correlations (and therefore proving nothing).

Why are these arguments either irrelevant or wrong?

1) Indeed as Beutin noted, the average of the sea level rise is above zero. This is of course true. I should say that I am actually really happy that a politician takes notice of such a subtle point. Sea level has increased over the 20th century (because of warming, melting, and glacial rebound), but the sea level rise is not the signal I am looking at. It is an interesting consequence of the global warming. However, I am looking for the drivers of the warming, not the consequences at this point! And the fact that sea level is rising does not contradict the fact that you see the sun’s 11-year signature clearly, with which you can quantify the solar radiative forcing. Clearly then, this argument is irrelevant. The logical leap from a rising sea level to the fact that the sun is not a major climate driver is baseless.

2) Rising temperatures with falling solar activity from the 1990's. The argument here is of course that the negative correlation over this period tells us that the sun cannot be the major climate driver. This too is wrong.

First, even if the sun was the only climate driver (which I never said is the case), this anti-correlation would not have contradicted it. Following this simple logic, we could have ruled out that the sun is warming us during the day because between noon and say 2pm, when it is typically warmest, the amount of solar radiation decreases while the temperature increases. Similarly, one could rule out the sun as our source of warmth because maximum radiation is obtained in June while July and August are typically warmer. Over the period of a month or more, solar radiation decreases but the temperature increases! The reason behind this behavior is of course the finite heat capacity of the climate system. If you heat the system for a given duration, it takes time for the system to reach equilibrium. If the heating starts to decrease while the temperature is still below equilibrium, then the temperature will continue rising as the forcing starts to decrease. Interestingly, since the late 1990’s (specifically the 1997 el Niño) the temperature has been increasing at a rate much lower than predicted by the models appearing in the IPCC reports (the so called “global warming hiatus”).

Having said that, it is possible to actually model the climate system while including the heat capacity, namely diffusion of heat into and out of the oceans, and include the solar and anthropogenic forcings and find out that by introducing the the solar forcing, one can get a much better fit to the 20th century warming, in which the climate sensitivity is much smaller. (Typically 1°C per CO2 doubling compared with the IPCC's canonical range of 1.5 to 4.5°C per CO2 doubling).

You can read about it here: Ziskin, S. & Shaviv, N. J., Quantifying the role of solar radiative forcing over the 20th century, Advances in Space Research 50 (2012) 762–776

The low climate sensitivity one obtains this way is actually consistent with other empirical determinations, for example, the lack of any correlation between CO2 variations over the past half billion years and temperature variations. See in particular fig. 6 of a sensitivity analysis I published in 2005.

Fig. 6 from Shaviv (2005) in which I carried out a senisitivity analysis assuming that the sun has a large effect on climate through cosmic ray modulation (right) or that it doesn't (left). Each error bar is the 1σ sensitiviy range obtain from radiative forcing variations over different periods as a function of the average tempeature relative to today.

3) The third point raised is that the allegedly large solar climate link is just based on correlations. This is wrong as well.

To begin with, if the correlations where just spurious, then there would have been no reason for them to continue, but since the analysis that gave the above graph was published, a new one based on 2 more solar cycles worth of satellite altimetry was published as well. If the first correlation was a mere fluke, then there should be no reason for the correlation to continue, but they very clearly do. See Howard, D., Shaviv, N. J., & Svensmark, H. (2015). The Solar and Southern Oscillation Components in the Satellite Altimetry Data. Journal of Geophysical Research: Space Physics, 120, 3297-3306.

In fact, the sun + ENSO explain 71% of the variance in the linearly detrended sea level change. You could think that it doesn't get any better than that! But it does.

This correlation has the correct amplitude and phase that you would expect from (a) the low altitude cloud cover variations seen in sync with the solar cycle which were estimate to cause drive a 1W/m² variation and with (b) the change in the sea surface temperature of 0.1°C over the solar cycle (e.g., see the above paper on climate sensitivity over different time scales where the cloud forcing and sea surface temperatures are discussed). You could again think that it doesn't get any better than that, but it does yet again! We have a mechanism to explain it all. It is through modulation of the cloud cover.

Linearly de-trended altimetry based Sea level (blue dots) and a fit which includes only the solar cycle and el Ñino (from Howard et al. 2015). One can clearly see that the solar cycle has a prominant contribution. It is in fact consistent in phase and in amplitude to the Shaviv (2008) result (local copy).

You can read more about the big picture in a summary I wrote a couple of years ago when on sabbatical at the Inistute for Advanced Studies in Princeton. So it isn't correlations. It is part of a wider consistent picture with endless empirical results and physical mechanisms to explain it.

To sum up, one cannot avoid the conclusion that the sun has a much larger effect on climate than the IPCC is willing to admit. It is not rubbish, or just correlations, nor is it inconsistent with observations on temperature or sea level.

After the committee, I was taken for a tour of the Bundestag by the nuclear physicist Dr. Götz Ruprecht, which of course includes the Reichstag building. Besides seeing interesting architecture, the most interesting thing was a discussion with Ruprecht on the Dual Fluid reactor concept that he and his colleagues are working on. It is a fast reactor that can use natural Uranium and Thorium, it can treat high-level waste (i.e., ensure there is no waste with a half life longer than a few centuries), it is inherently safe because it has such a strong negative temperature dependence of the reaction rates (as opposed for example to Graphite reactors like Chernobyl's) and because it includes passive heat based safety valves as well. Because of its high operating temperature, it can be used for additional things such as generation of hydrogen for clean fuel. And, electricity production should be less than 1 cent per kWhr (even cheaper than the typical 3 cents for present day nuclear, and compared with the 30 euro-cents per kWhr that one pays in Germany because of all the effective subsidies of ineffective alternative energy sources, or the 11 euro-cents per kWhr I pay in Israel, where there are much less of these subsidies). Of course, there is no chance that something like that will be developed in Europe with the current atmosphere in Europe and Germany in particular, where nuclear is phasing out (and soon coal... at least until the first catastrophic power outage that they will sure have). If you're a billionaire that wants to invest in a project that will lead the future energy production, contact me :-)

Another interesting thing that happened to me last week is that I lost my hearing in one ear (possibly from swimming a few days earlier, or the flights I had), and regained it after 5 days or so, quite a strange experience I'll write soon about. It included the very strange effect of diplacusis in which I heard a different pitch in each ear (up to a 1.5 semitone difference). I'll write about this strange experience in my next post.

↧

22 minute talk summarizing my views on global warming

August 4, 2019, 1:46 pm

≫ Next: Forbes censored an interview with me

≪ Previous: My experience at the German Bundestag's Environment Committee in a pre-COP24 discussion

Blog topic:

cosmic rays, global warming, personal research, politics, weather & climate

Just over a week ago I gave a 20 minute talk (which lasted almost 22 min) about the role that the sun plays in global warming in the Heartland institute's climate conference in DC. Since it came online and since I think this is about as good a summary I can make in 20 odd minutes, here it is brought again for posterity.

↧

Forbes censored an interview with me

August 10, 2019, 9:13 am

≫ Next: Solar Debunking Arguments are Defunct

≪ Previous: 22 minute talk summarizing my views on global warming

Blog topic:

cosmic rays, global warming, personal research, politics, weather & climate

A few days ago I was interviewed by Doron Levin, for an article to appear online on forbes.com. After having seen a draft (to make sure that I am quoted correctly), I told him good luck with getting it published, as I doubted it will. Why? Because a year ago I was interviewed by a reporter working for Bloomberg, while the cities of San Francisco and Oakland were deliberating a climate change lawsuit against Exxon-Mobil (which the latter won!), only to find out that their editorial board decided that it is inappropriate to publish an interview with a heretic like me. Doron’s reply was to assure me that Forbes’ current model of the publication online allows relative freedom with “relatively little interference from editors”. Yeah Sure.

After the article went online yesterday and Doron e-mailed so, I saw how much relative exposure it received. It had already more than 40000 impressions in a matter of a couple of hours. Impressive. All that took place while I was relaxing with my family on a Tel-Aviv beach. But this didn’t last long. Although I continued to relax at the beach, the article was taken down for “failing to meet our editorial standards”, which apparently means conforming to whatever is considered politically correct about climate change.

The piece itself is (or was, or will be?) found here. A copy was posted here.

In any case, the main goal of this post is to provide the scientific backing for the main points I raised in the interview. Here it comes.

First and foremost, I claim that the sun has a large effect on climate and that the IPCC is ignoring this effect. This I showed when I studied the heat going into the oceans using 3 independent datasets - ocean heat content, sea surface temperature, and most impressively, tide gauge records (see reference #1 below), and found the same thing in a subsequent study based on another data set, that of satellite altimetry (see reference #2 below). Note that both are refereed publications in the journal of geophysical research, which is the bread and butter journal of geophysics. So no one can claim it was published in obscure journals, yet, even though the first paper has been published already in 2008, it has been totally ignored by the climate community. In fact, there is no paper (right or wrong) that tried to invalidate it. Clearly then, the community has to take it into consideration. Moreover, when one considers that the sun has a large effect on climate, the 20th century warming is much better explained (with a much smaller residual). See reference #3 below, again refereed).

I should add that there are a few claims that the sun cannot affect the climate because of various reasons, none holds water. Here is why:

The first claims is that “the sun cannot have a large effect on climate because changes in the irradiance are too small to do so, and we don’t know of a mechanism that can”. This is irrelevant because given that the oceans prove that the sun has a large effect on climate, we must consider it even if we don’t know how it comes about. Often in science we are forced to accept a theory we don’t fully understand because the empirical evidence suggests so. Mendelian genetics explained reality pretty well (though we now know it is a bit more complicated) a century before Watson and Crick showed what the underlying mechanism is. Does it mean that we should have discarded Mendelian genetics for a century without knowing the mechanism? Pauli postulated the existence of the neutrino a quarter of a century before it was actually detected. Similarly, almost all cosmologists and particle physicists assume that dark matter exists, because an overwhelming amount of evidence suggests so, and because alternatives simply don’t work (mainly MOND, e.g., as a post-doc and I have shown in a paper as well as many others). However, we don’t really know what dark matter really is (there are many suggestions), but its existance has to be considered. Having said that, we actually do see very clear empirical evidence pointing to the link, as I describe below.
The second claim is that “solar activity decreased from the 1990’s but the temperature continued to increase. So the sun cannot be the reason for the heating”. It is wrong at several levels. First, one has to realize that the temperature anomaly at a given time is not some fixed factor times the forcing at the time. This is because the system has a finite heat capacity and various interesting feedbacks. Without properly modeling it, erroneous conclusions can be reached. A simple example is ruling out the solar flux as the major source of heat because between noon time and say 2pm, the solar flux is decreasing but the temperature is increasing! (Similarly, the average solar flux is decreasing during the month of July in the northern hemisphere, but the temperature is increasing). Solar activity has been high over the latter half of the 20th century such that even after solar activity started to decreases, the temperature should continue increasing for a decade or so, albeit at a lower pace. Second, the above argument is extremely simplistic. Proper modeling has to consider that human have contributed as well to the net positive forcing. And indeed, when one considers both the large effect that the sun has, and the anthropogenic forcing, one can explain 20th century climate change if climate sensitivity is on the low side, much better than the IPCC models that exclude the large effect that the sun has, but assume a large climate sensitivity instead. See reference #3 below, as well as Roy Spencer’s short talk showing that climate models generally give a much larger temperature increase than has been observed over the past 2 decades.
The third claim is that when 20th temperature changes are compared with solar activity and anthropogenic forcing, one doesn’t see the 11 year solar cycle in the temperature data, which can be used to place an upper limit on the solar effect. This faulty argument is related to the previous one. It too assumes that the temperature should be proportional to the radiative forcing at any instant, and because the temperature variations over the 11 year solar cycle are only of order 0.1°C, the contribution to 20th century warming should be similar since the secular increase in the solar forcing is comparable to the variations over the 11 year solar cycle. However, the large heat capacity of the oceans damps any temperature variations on short time scales. Proper modeling reveals that an 0.1°C variation over the solar cycle should actually correspond to a variation much larger on the centennial time scale, in fact, about half to two thirds of the warming (see reference #3 below and my comments about the BEST analysis from Berkeley who “proved” that the sun cannot have a large climate effect based on the above argument).

[Edit: See my more detailed rebuttal of the attack on solar forcing that appeared a day later on Forbes]

As I said above, we now know from significant empirical data where the solar climate link comes from. It is through solar wind modulation of the galactic cosmic ray flux which governs the amount of atmospheric ionization, and which in turn affects the formation of cloud condensation nuclei and therefore cloud properties (e.g., lifetime and reflectivity). How do we know that?

When the sun has gusts in the solar wind, it causes several day long reductions in the flux of cosmic rays reaching Earth, called Forbush decreases. We see as a response changes in the aerosols and in cloud properties, just as expected. See references 4 & 5 below.
There are large cosmic ray flux variations over geological time scales that are not related to solar activity but instead to our location in the Milky Way and the changing galactic environment. You can reconstruct the cosmic ray flux using meteorites and find that the 7 ice-age epochs over the past 1 billion years all appeared when the cosmic ray flux was high (see references 6 & 7 below). On a bit shorter time scales, the vertical motion of the solar system clearly manifests itself as a 32 million year oscillations in the temperature (15 periods over the past half billion years! See reference 8 below). Namely, there are very clear indications that independent variations in the cosmic ray flux affect the climate.
Cloud cover varies over the 11 year solar cycle (e.g., reference 9 below). This by itself is not proof that the link is through cosmic rays, since there are several things that change with the solar cycle. However, one particularly interesting aspect is that the cloud cover variation are asymmetrical between odd and even cycles, just as cosmic rays are, and unlike other solar related variables that are blind to the fact that the real cycle is 22 years (Polarity returns back to the same state after two switches, hence, 22 years. The asymmetry arises from the fact that cosmic rays are primarily positive particles, and the sun is rotating such that there is a clear helicity to the field configuration).
There are several experimental results showing that ions increase the nucleation and formation of a few nm sized aerosols and increase the survival of those aerosols as they grow to become 50 nm sized cloud condensation nuclei. A few examples are given in references 10-13.

One should be aware that we are still missing the last piece of the puzzle, which is to take the various mechanisms, plug them into a global aerosol model and see that there is a sufficiently large variation in the cloud condensation nuclei. This takes time, but compared with the aforementioned examples of genetics, neutrinos or dark matter, it will definitely take us much less to provide this last piece, but in any case, the evidence should have forced the community to seriously consider it already.

Nonetheless, even with the above large body of empirical evidence, the link has been attacked left and right. A really small number has been valid and interesting, but not to the extent to invalidate the existence of a cosmic ray climate link, just to modify our understanding of it. The rest has been mostly bad science, as I exemplify below.

One of the main critiques arises when people look for the cosmic ray climate link but find none. In all those cases were no effect is seen, the authors didn’t estimate the size of the effect they expected and compare it with the noise level in the data. For example, if one considers only a small patch of the atmosphere above oceans, then the day to day fluctuations in the cloud cover are large compared with the Forbush decrease signal. Similarly, not seeing an effect over 10’s of thousands of years because of Earth’s magnetic field changes, is not surprising because switching off Earth’s magnetic field altogether is expected to give rise to a 1°C effect, which is notably smaller than the climate variations seen over these time scales (presumably because of the Milankovich cycles).
The cosmic ray climate link over geological time scales was attacked by several papers. Only one raised a valid scientific point, which is that the original analysis of Jan Veizer and I didn’t consider the effect that the ocean pH (affected by atmospheric CO2) has on the Oxygen 18 data. When that was taken into account, we modified our best estimate for climate sensitivity to be 1 to 1.5°C per CO2 doubling. Other analyses are blatantly wrong, such as faulty statistical analysis or data handling (see summaries here and here), or even simple arithmetic mistakes! (see here).
The last set of critiques are actually part of a healthy scientific discourse about the mechanism that is responsible for linking atmospheric ionization with cloud condensation nuclei. Papers like this discuss the possibility that ion induced nucleation could be the physical mechanism linking ionization changes with variations in the cloud condensation nuclei number density. However, even if we don’t fully understand the underlaying mechanism, ruling out a particular suggested mechanism doesn’t mean that other possibilities do not exist (in fact, they do, see ref #13 below). When Pauling and Corey suggested the triple helix model for DNA in 1953, they were off, but it wasn’t a reason to discard the whole idea of genetics.

References:

Shaviv, N. J. Using the oceans as a calorimeter to quantify the solar radiative forcing. J. Geophys. Res. (Space Phys.) 113, 11101 (2008) local version (not paywalled)
Howard, D., Shaviv, N. J., Svensmark, H., The solar and Southern Oscillation components in the satellite altimetry data, J. Geophys. Res. Space Physics, 120, 3297–3306 (2015)
Ziskin, S., Shaviv, N. J., Quantifying the role of solar radiative forcing over the 20th century, Advances in Space Research 50, 762–776, (2012). local version (not paywalled)
Svensmark, H., Bondo, T. & Svensmark, J. Cosmic ray decreases affect atmospheric aerosols and clouds. Geophys. Res. Lett. 36, 15101–1510 (2009)
Svensmark, J., Enghoff, M. B., Shaviv, N. J. & Svensmark, H. The response of clouds and aerosols to cosmic ray decreases. J. Geophys. Res.: Space Phys. 121, 8152–8181 (2016).
Shaviv, N. J. Cosmic ray diffusion from the galactic spiral arms, iron meteorites, and a possible climatic connection. Phys. Rev. Lett. 89, 051102–05110 (2002)
Shaviv, N. J. The spiral structure of the Milky Way, cosmic rays, and ice age epochs on Earth. New Astron. 8, 39–77 (2003)
Shaviv, N. J., Prokoph, A., Veizer, J., Is the Solar System's Galactic Motion Imprinted in the Phanerozoic Climate? Scientific Reports volume 4, Article number: 6150 (2014)
Svensmark, H. & Friis-Christensen, E. Variation of cosmic ray flux and global cloud coverage—a missing link in solar-climate relationships. J. Atmos. Sol. -Terr. Phys. 59, 1225–1232 (1997).
Svensmark, H., Pedersen, J. O. P., Marsh, N. D., Enghoff, M. B. & Uggerhøj, U. I. Experimental evidence for the role of ions in particle nucleation under atmospheric conditions. Proc. R. Soc. A 463, 385–396 (2007)
Kirkby, J. et al. Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation. Nature 476, 429–433 (2011).
Svensmark, H., Enghoff, M. B. & Pedersen, J. O. P. Response of cloud condensation nuclei (>50 nm) to changes in ion-nucleation. Phys. Lett. A 377, 2343–2347 (2013).
Svensmark, H., Enghoff, M. B., Shaviv, N. J., Svensmark J., Increased ionization supports growth of aerosols into cloud condensation nuclei, Nature Communications 8, Article number: 2199 (2017)

↧

Solar Debunking Arguments are Defunct

August 11, 2019, 6:58 am

≫ Next: Critique of “Discrepancy in scientific authority and media visibility of climate change scientists and contrarians”

≪ Previous: Forbes censored an interview with me

Blog topic:

global warming, personal research, weather & climate

An article interviewing me was removed yesterday from forbes. Instead, they published an article by Meteorologist Prof. Marshall Shepherd that claims that the sun has no effect on climate. That article, however, falls to the same pitfalls that pointed out on my blog yesterday.

Specifically, why is Shepherd’s arguments faulty? Although I addressed them yesterday, here they are brought again more explicitly and with figures.

First, and foremost, Shepherd ignores the clear evidence that shows that the sun has a large effect on climate, and quantifies it. This graph is from the Shaviv 2008 (#1 in the reference below):

Figure 1: Reconstructed Solar constant (dashed red line) and sea level change rate based on Tide Gauge records as a function of time (solid blue line with 1 sigma error region in gray).

As you can see, there is a very clear correlation between solar activity and the rate of change of the sea level. On short time scales most of the sea level change is due to changes in the heat going into the oceans, such that we can quantify the solar radiative forcing this way. It is found to be an order of magnitude larger than changes in the irradiance, which is what the IPCC is claiming is to be the solar contribution.

After that work was published there was not a single paper that tried to refute it. Instead, additional satellite altimetry data covering two more solar cycles just revealed the same. In fact, the sun + el Niño Southern Oscillation can explain almost all the sea level variations minus the long term linear trend (caused by ice caps melting). This is from Howard et al. 2015 (see ref. #2 at the end):

Figure 2: Satellite Altimetry based sea level (minus linear trend) in dashed blue points. Red is best fit model which includes solar cycle + el niño souther oscillation.

Clearly, the sun continues to have a clear effect on the climate. Note that it is impossible to explain the large variations through a feedback in the system because that would give the wrong phase in the heat content response.

What does that imply?

First, since solar activity increased over the 20th century, it should be taken into account. Shepherd’s radiative forcing graph should be modified to be:

Figure 3: Radiative forcing contributions (graph from Shepherd's article) with the following added. The beige is the real solar contribution over the 20^th century. The green is the total forcing (natural + anthropogenic) we get once we include the real solar effect.

The next point to note is that Shepherd claimed that because solar activity stopped increasing from the 1990’s it cannot explain any further warming. This is plain wrong. Consider this example in false logic. The sun cannot be warming us because between noon and 2pm (or so), solar flux decreases while the temperature increases. As a Professor of meteorology, Prof. Shepherd should know about the heat capacity of the oceans such that assuming that the global temperature is something times the CO₂ forcing plus something else times the solar forcing is too much of a simplification.

Instead, one can and should simulate the 20^th century, and beyond, and see that when taking the sun into account, it explains about 1/2 to 2/3s of the 20^th century warming, and that the best climate sensitivity is around 1 to 1.5°C per CO₂ doubling (compared with the 1.5 to 4.5°C of the IPCC). Two points to note here. First, although the best estimate of the solar radiative forcing is a bit less than the combined anthropogenic forcing, because it is spread more evenly over the 20th century, its contribution is larger than the anthropogenic contribution the bulk of which took place more recently. That's why the best fit gives that the solar contribution is 1/2 to 2/3s of the warming. Second, the reason that the best fit requires a smaller climate sensitivity is because the total net radiative forcing is about twice larger. This implies that a smaller sensitivity is required to fit the same observed temperature increase.

Here is my best fit to the 20th century. Solid line is model and dashed is the observed global temperate (See Ziskin & Shaviv, ref. #3 below).

Figure 4: Best fit for a model which allows for a larger solar forcing and a smaller climate sensitivity than the IPCC is willing to admit is there. Top: Model = solid line, NCDC Observations = dashed line). The bottom is the different between the two.

As you can see, the residual of the fit is typically 0.1°C, which is twice smaller than typical fits by CMIP 5 models.

Once we fit the 20th century, we can integrate forward in time. Here I plot the expected warming for many realizations assuming a vanilla flavored emission scenario:

Figure 5: Using best fit models for the 20th century, we can integrate forward in time while making random realizations for volcanoes, solar activity etc.

The actual temperature increase witnessed is totally consistent with the observations. It is much smaller than the CMIP 5 models which the IPCC is using. See image capture from Roy Spencer’s ICCC13 talk:

Figure 6: CMIP5 models vs. actual temperature change based on satellite (RSS/UAH) or reanalyses datasets.

And average warming slopes, together with my predictions:

Figure 7: Warming trends in CMIP5 models vs. actual warming trends based on satellite (RSS/UAH) or reanalyses datasets. The orange bar is our predicted warming trend. Error is from the range of realizations.

Namely, our predictions are totally consistent with the satellite (RSS / UAH, whichever you prefer) and the Reanalyses datasets. Remember, this was obtained for a model which included the real solar contribution which requires a small climate sensitivity.

Shepherd also mentions that the link through cosmic ray flux variations has been debunked. I point the reader to a summary of why those attacks don’t hold any water, which I wrote yesterday.

To summarize, Shepherd did not debunk the solar forcing. His arguments are defunct. Unless he comes up with a very good explanation to the first graph above, he should instead advocate taking solar forcing into account. The fact that forbes hushes up any possibility for having a scientific debate should be considered truly bothersome by anyone who values free speech and scientific debate. Truth will prevail irrespectively.

References:

Shaviv, N. J. Using the oceans as a calorimeter to quantify the solar radiative forcing. J. Geophys. Res. (Space Phys.) 113, 11101 (2008) local version (not paywalled)
Howard, D., Shaviv, N. J., Svensmark, H., The solar and Southern Oscillation components in the satellite altimetry data, J. Geophys. Res. Space Physics, 120, 3297–3306 (2015)
Ziskin, S., Shaviv, N. J., Quantifying the role of solar radiative forcing over the 20th century, Advances in Space Research 50, 762–776, (2012). local version (not paywalled)

↧

Critique of “Discrepancy in scientific authority and media visibility of climate change scientists and contrarians”

August 17, 2019, 2:21 pm

≫ Next: How Climate Change Pseudoscience Became Publicly Accepted

≪ Previous: Solar Debunking Arguments are Defunct

Blog topic:

general science, global warming, politics, weather & climate

A paper that recently received some media attention is the “Discrepancy in scientific authority and media visibility of climate change scientists and contrarians” by Alexander Michael Petersen, Emmanuel M. Vincent & Anthony LeRoy Westerling, Nature Communications, volume 10, Article number: 3502 (2019). Here is what I think of it.

The critique of this paper is going to be very short, because it has a MAJOR flaw that renders all the results totally meaningless (even as an anecdotal curiosity). The underlying problem with the whole analysis is the way that the lists were composed. Here is how they composed each list:

“Selection of contrarians (CCC). We compiled a list of 386 contrarians by merging three overlapping name lists obtained from three public sources. The first source is the list of former speakers at The Heartland Institute ICCC conference (http://climateconferences.heartland.org/speakers/) over the period 2008–present, providing a representative sample across time; the second source is the list of individuals profiled by the DeSmogblog project; and the third source is drawn from the list of lead authors of the most recent 2015 NIPCC report (the principal summary of CC denial argumentation produced in conjunction with The Heartland Institute, http://climatechangereconsidered.org/).”

“Selection of scientists (CCS). We ranked individuals’ publication profiles according to the net citations $C_i = \sum_{i \in p} c_p$ calculated by summing individual article citation totals ($c_p$) for only the individual articles (indexed by p) included within our WOS CC dataset. In this way, the CCS group is comprised of the 386 most-cited CC scientists, based solely on their CC research.”

As you can see, the selection criteria is completely different. While the list of alarmists, acryonymed CCS (climate change shouters, I think) is selected by the the citations, the list of anti-alarmists, acronymed CCC (Climate Change Comforters, I think ;-) was selected by those who already have more exposure to the media. Then they compare the groups, and what do you know, the group that was selected according to bibliometric impact has a higher bibliometric impact and those selected through public exposure, namely, because they were active in the media, have more public exposure. Duh! (https://www.youtube.com/watch?v=nE7J5zLaefs). This is one of the most obvious selection biases I have seen in my scientific life. It's not a compliment.

Because of this distorted selection, the top CCC is Marc Morano. He isn’t a scientist nor does he pretend to be one, so why do the authors of this “research” compare his null scientific citation record to media appearance ratio with that of scientists? I don’t see that they put Al Gore in the top of the CCS list! He too has a very poor bibliometric impact.

A correct methodology would have been to comprise similar length lists of the top CCC and CCS based on citations alone, and then compare. But I guess it was a little too hard. Let me quote Mark Twain who said that there are “Lies, damned lies, and statistics”. In this case, it is statistics based on highly biased data.

I said before and I’ll say it again. Alarmists should use scientific arguments to bolster their case. The more they use chaff arguments, the more it reflects badly on their ability to defend their scientific case, perhaps because they can’t (e.g., see this).

↧

How Climate Change Pseudoscience Became Publicly Accepted

September 24, 2019, 1:07 pm

≪ Previous: Critique of “Discrepancy in scientific authority and media visibility of climate change scientists and contrarians”

Blog topic:

economics, general science, global warming, personal research, politics, weather & climate

The I recently wrote an OpEd for the Epoch Times which tries to succinctly capture my main grievances with the global warming scare. Here is brought again with a few comments (and references) added at its end.

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The climate week that is being held in New York City has urged significant action to fight global warming. Given the high costs of the suggested solutions, could it be that the suggested cure is worse than the disease?

As a liberal who grew up in a solar house, I have always been energy conscious and inclined towards activist solutions to environmental issues. I was therefore extremely surprised when my research as an astrophysicist led me to the conclusion that climate change is more complicated than we are led to believe. The disease is much more benign; and a simple palliative solution lies in front of our eyes.

To begin with, the story we hear in the media, that most of the 20th century warming is anthropogenic, that the climate is very sensitive to changes in CO2, and that future warming will therefore be large and will happen very soon, is simply not supported by any direct evidence, only a shaky line of circular reasoning. We “know” that humans must have caused some warming, we see warming, we don’t know of anything else that could have caused the warming, so it adds up.

However, there is no calculation based on first principles that leads to a large warming by CO2, none. Mind you, the IPCC (Intergovernmental Panel on Climate Change) reports state that doubling CO2 will increase the temperatures by anywhere from 1.5 to 4.5°C, a huge range of uncertainty that dates back to the Charney committee from 1979.

In fact, there is no evidence on any time scale showing that CO2 variations or other changes to the energy budget cause large temperature variations. There is however evidence to the contrary. 10-fold variations in the CO2 over the past half billion years have no correlation whatsoever with temperature; likewise, the climate response to large volcanic eruptions such as Krakatoa.

Both examples lead to the inescapable upper limit of 1.5°C per CO2 doubling—much more modest than the sensitive IPCC climate models predict. However, the large sensitivity of the latter is required in order to explain 20th century warming, or so it is erroneously thought.

In 2008 I showed, using various data sets that span as much as a century, that the amount of heat going into the oceans in sync with the 11-year solar cycle is an order of magnitude larger than the relatively small effect expected from just changes in the total solar output. Namely, solar activity variations translate into large changes in the so called radiative forcing on the climate.

Since solar activity significantly increased over the 20th century, a significant fraction of the warming should be then attributed to the sun, and because the overall change in the radiative forcing due to CO2 and solar activity is much larger, climate sensitivity should be on the low side (about 1 to 1.5°C per CO2 doubling).

In the decade following the publication of the above, not only was the paper uncontested, more data, this time from satellites, confirmed the large variations associated with solar activity. In light of this hard data, it should be evident by now that a large part of the warming is not human, and that future warming from any given emission scenario will be much smaller.

Alas, because the climate community developed a blind spot to any evidence that should raise a red flag, such as the aforementioned examples or the much smaller tropospheric warming over the past two decades than models predicted, the rest of the public sees a very distorted view of climate change — a shaky scientific picture that is full of inconsistencies became one of certain calamity.

With this public mindset, phenomena such as that of child activist Greta Thunberg are no surprise. Most bothersome however is that this mindset has compromised the ability to convey the science to the public.

One example from the past month is an interview I gave Forbes. A few hours after the article was posted online, it was removed by the editors “for failing to meet our editorial standards”. The fact that it has become politically incorrect to have any scientific discussion has led the public to accept the pseudo-argumentation supporting the catastrophic scenarios.

Evidence for warming doesn’t tell us what caused the warming, and any time someone has to appeal to the so called 97 percent consensus he or she is doing so because his or her scientific arguments are not strong enough. Science is not a democracy.

Whether or not the Western world will overcome this ongoing hysteria in the near future, it is clear that on a time scale of a decade or two it would be a thing of the past. Not only will there be growing inconsistencies between model and data, a much stronger force will change the rules of the game.

Once China realizes it cannot rely on coal anymore it will start investing heavily in nuclear power to supply its remarkably increasing energy needs, at which point the West will not fall behind. We will then have cheap and clean energy producing carbon neutral fuel, and even cheap fertilizers that will make the recently troubling slash and burn agriculture redundant.

The West would then realize that global warming never was and never will be a serious problem. In the meantime, the extra CO2 in the atmosphere would even increase agriculture yields, as it has been found to do in arid regions in particular. It is plant food after all.

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