Here is a link to a statement by Nir Shaviv with a better perspective.
Some excerpts follow.
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Summary
1. There is no direct evidence demonstrating that large CO2 variations cause large temperature variations. There is evidence for the opposite.
2. The two arguments used by the IPCC to “prove” the catastrophic AGW picture are flawed—warming over the 20th century is not unique, while the claim that there is nothing else to explain the 20th century warming is simply wrong.
3. There are many other pseudo-arguments which are simply irrelevant. This includes the often heard appeal to authority (the 97% claim) as well as arguments based on evidence for warming, which is not evidence for warming by humans.
4. The sun has a large but ignored effect on the climate. With it, one obtains a consistent picture for 20th century climate change, one in which more than half of the 20th century is due to solar activity increase and in which climate sensitivity is low (and consistent with empirical data).
5. The low climate sensitivity implies that future climate warming will be benign and within the goals set by the Copenhagen and Paris summits without having to take particular steps. One has to rethink how much resources we wish to spend on the problem which is much more benign than commonly believed.
2. The two arguments used by the IPCC to “prove” the catastrophic AGW picture are flawed—warming over the 20th century is not unique, while the claim that there is nothing else to explain the 20th century warming is simply wrong.
3. There are many other pseudo-arguments which are simply irrelevant. This includes the often heard appeal to authority (the 97% claim) as well as arguments based on evidence for warming, which is not evidence for warming by humans.
4. The sun has a large but ignored effect on the climate. With it, one obtains a consistent picture for 20th century climate change, one in which more than half of the 20th century is due to solar activity increase and in which climate sensitivity is low (and consistent with empirical data).
5. The low climate sensitivity implies that future climate warming will be benign and within the goals set by the Copenhagen and Paris summits without having to take particular steps. One has to rethink how much resources we wish to spend on the problem which is much more benign than commonly believed.
What’s wrong with the present day view of climate change?
Let me start by asking a question, one which you should either ask yourself or ask the experts you rely on. What is the evidence proving that anthropogenic global warming will lead to a catastrophic climate change?
As I demonstrate below, this idea is in fact a misconception, and the so called evidence that we constantly hear is simply based on various fallacious arguments. Moreover, critical evidence that proves that it is wrong is actually blatantly ignored by the IPCC and alike.
The first and foremost argument that should simply be ignored is the appeal to authority or to a majority. Science is not a democracy and the fact that many believe one thing does not make them correct. If people have good arguments to convince you, let them stick to scientific arguments, not logical fallacies.
Other irrelevant arguments may appear scientific, but they are not. Evidence for warming is not evidence for warming by humans. Seeing a poor polar bear floating on an iceberg does not mean that humans caused warming. 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 just as well caused an 8°C increase or an 0.08°C.
The simple fact is, there is no single piece of evidence that proves that a given amount of CO2 increase should cause a large increase in temperature. As a matter of fact, there is evidence to the contrary! For example, over geological time scales, there were huge variations in the atmospheric CO2 levels (by as much as a factor of 10) and they show no correlation whatsoever with the temperature . 450 million years ago there was 10 times as much CO2 in the atmosphere but more 1 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. 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 stick so extensively featured in the third assessment report of the IPCC in 2001. The “climategate” e-mails demonstrate 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 medieval warming period, it could have been just as warm as the 20th century, while the little ice-age was at least a degree cooler. 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 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 in the Charney US federal committee in 1979. 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 euros) invested in climate research, we don’t know the answer to the most important question any better.
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 aforementioned 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, around 1 to 1.5°C per CO2 doubling.
So, how do we know that the sun has a large effect on climate? Fig. 1 below is probably one of the most important graphs to the understanding of climate change , but 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 protagonists of the IPCC view are willing to admit there is. The IPCC only considers changes in the irradiance, while this (and other such data) unequivocally demonstrate that there is an amplifying mechanism linking solar activity and climate.
Although extremely interesting, the details of the mechanism (actually 3 separate microphysical effects) are beyond the scope of this summary. They are related to the amount of atmospheric ionization which is governed by solar activity. Basically, when the sun is more active, we have less clouds that are generally less white.
The main conclusion is therefore that climate is not sensitive to changes in the radiative forcing. There are in fact several red flags that people do their best to ignore. For example, the temperature failed to rise according to the predictions made in previous IPCC scientific reports.
In Paris and Copenhagen it was agreed upon that we should ensure the warming will be less than 2°C. It will be less than 2°C even if we do nothing.
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