Sorry deniers, research finds (once again) that climate change is NOT caused by cosmic rays
One more denier talking point has been debunked by scientists using actual observations. You can read the Science News article here, which explains, “New research has dealt a blow to the skeptics who argue that climate change is all due to cosmic rays rather than to man-made greenhouse gases.”
You can read the original article, just published by the Institute of Physics’ Environmental Research Letters, “Testing the proposed causal link between cosmic rays and cloud cover” online here. The major finding:
[N]o evidence could be found of changes in the cloud cover from known changes in the cosmic ray ionization rate.
Here is the full abstract:
A decrease in the globally averaged low level cloud cover, deduced from the ISCCP infrared data, as the cosmic ray intensity decreased during the solar cycle 22 was observed by two groups. The groups went on to hypothesize that the decrease in ionization due to cosmic rays causes the decrease in cloud cover, thereby explaining a large part of the currently observed global warming. We have examined this hypothesis to look for evidence to corroborate it. None has been found and so our conclusions are to doubt it. From the absence of corroborative evidence, we estimate that less than 23%, at the 95% confidence level, of the 11 year cycle change in the globally averaged cloud cover observed in solar cycle 22 is due to the change in the rate of ionization from the solar modulation of cosmic rays.
You can read more debunking here.
Yes, I know, the whole idea should have died last year with the study in Proceedings of the Royal Society A, “Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature” that I blogged about here. That study found:
There is considerable evidence for solar influence on the Earth’s pre-industrial climate and the Sun may well have been a factor in post-industrial climate change in the first half of the last century. Here we show that over the past 20 years, all the trends in the Sun that could have had an influence on the Earth’s climate have been in the opposite direction to that required to explain the observed rise in global mean temperatures.
The authors specifically looked at trends in cosmic ray intensity as part of their analysis. As Britain’s Royal Society said in an accompanying statement at the time:
Can we finally bury this myth once and for all?
April 4th, 2008 at 11:04 pm
It’s hard to trust climate change enthusiasts who scare school children with stories about starving polar bears and compare climate change skeptics with holocaust deniers.Why don’t climate change enthusiasts evey say, “I disagree with what you say but I will defend to the death your right to say it?” Well, they don’t defend your right to say it because when push comes to shove they don’t think you have any right to say it.
April 5th, 2008 at 12:36 pm
Duscany — Sorry, but I don’t beleive that people have the right to utter known untruths. It is a form of lying.
Climate change is upon us. Deal with it responsibly.
April 6th, 2008 at 8:48 am
David,
If we applied your logic to both sides equally, this website would not exist. For example, the headline of this article states “…that climate change is not caused by cosmic rays.” Yet the ‘proof’ of this statement is a study that states in the abstract “…we estimate that less than 23%, at the 95% confidence level, of the 11 year cycle change in the globally averaged cloud cover observed in solar cycle 22 is due to the change in the rate of ionization from the solar modulation of cosmic rays.”
Last time I checked, less than 23% is not equal to zero. Therefore, cosmic rays do have an impact on cloud cover. Of course, the cosmic ray theory is not based on fluxes in the ll-year sunspot cycle, but on fluctuations in cosmic rays over much longer periods of time, so the value of this report in the debate is questionable. It would be the same as looking for the warming signal of CO2 in the last 10 years of global temperatures, and, upon finding little change, assert that increasing CO2 has no effect on global temperatures!
Now that I have demonstrated that Joe is uttering known untruths, will you demand that he shut down this website? I doubt it.
A principle administered selectively is tyranny!
April 6th, 2008 at 1:53 pm
Jim Clarke — Your logic is deeply flawed when you writie “Therefore, cosmic rays do have an impact on cloud cover.”
The cosmic ray hypothesis has already been thoroughly discussed on RealClimate. The current paper is simply the latest nail in the coffin.
April 8th, 2008 at 10:12 pm
Whatever you say David. Just a little friendly suggestion…when Realclimate starts passing out the Kool-Aid, don’t drink it and just play possum!
April 9th, 2008 at 6:39 am
“Here we show that over the past 20 years, all the trends in the Sun that could have had an influence on the Earth’s climate have been in the opposite direction to that required to explain the observed rise in global mean temperatures”
That statement is false. We are near the end of cycle 23, which has been longer than usual. It is predicted to finish by 2009 or tomorrow, depending on who you ask at the NASA. The peak solar activity was around 2001, so before that, and for about 7 years, warming was expected. From 2001 solar activity has been declining and temperatures didn’t rise, in fact they average some cooling. The previous minimum-maximum-minimum were in 1985-1990-1996 respectively. Pick any temperature graphs you want, it shows an average rise-then drop for those years after proper smoothing. Overall, it rises, because of us being in the ENSO part of the cycle that brings warming (more El Niño than La Niña ocurrences). We are about to change to more La Niñas, by the way.
But even if the statement was true, I can also point you to some 30 years trend between 1940-1970 where temperatures didn’t quite follow CO2 either. And they did follow the sun.