Last Monday the ‘cosmic ray’ theory of climate change struck again when Amanda Vanstone at ABC RN’s Counterpoint found:
Climate change may be largely caused by solar events, letting humans off the hook, claims Danish researcher Henrik Svensmark.
The missing link between exploding stars, clouds, and climate on Earth
Breakthrough in understanding of how cosmic rays from supernovae can influence Earth’s cloud cover and thereby climate
Svensmark has also claimed:
- “Finally we have the last piece of the puzzle explaining how particles from space affect climate on Earth.”
I’ll endeavor to summarise what Svensmark is saying.
He says that the earth is continually bombarded by cosmic rays from exploding stars in outer space which arrive as small particles which can form the nucleus which attracts moisture to form droplets and hence clouds. The suns ray to some extent protect us from this cosmic ray bombardment. When solar activity through sunspot activity increases, there is more protection, less clouds and the planet warms. Moreover, he now believes that as the Milky Way galaxy and the solar system cruise through space the amount of cosmic ray bombardment varies. That part appears to be new.
What he has done is conduct experiments in an 8 cubic metre box, where the measured changes were less than 1 per cent. How he comes to conclusions on this basis is mathematically beyond me, but I suspect that this is not the Nobel Prize-winning paper that turns climate science on it’s head. The actual claim in the paper seems reasonably modest:
- The mechanism of ion-induced condensation may be relevant in the Earth’s atmosphere under pristine conditions, and able to influence the formation of CCN. It is conjectured that this mechanism could be the explanation for the observed correlations between past climate variations and cosmic rays, modulated by either solar activity or supernova activity in the solar neighborhood on very long time scales. The theory of ion-induced condensation should be incorporated into global aerosol models, to fully test the atmospheric implications.
However, his verbal claims, as in the media release for the paper and the interview with Vanstone, claim that the cosmic ray/solar variance story, is the main story explaining climate change and human activity with greenhouse gases has been sidelined.
For perspective take a look at a standard graph of relative forcings:
That is from my files and I think comes from NASA GISS, where James Hansen worked for many years. Hansen tells a coherent story of what happened in climate change over the last 65 million years in the Iowa Testimony, where he was telling the authorities why we should not be mining coal. Clouds have a role, but it is modest in the scheme of things.
This story can’t be set aside because of one experiment in a box.
Then look at the Gizmodo article No, Supernovae Aren’t Changing Earth’s Climate. There is a huge experiment in CERN investigating cloud formation, which is not settled science.
Hamish Gordon, research fellow at CERN in Geneva, working on a similar experiment called CLOUD, wrote that:
the experiment itself offers “an interesting and plausible result,” and “if it stands up to more detailed scrutiny it may prove an important contribution to aerosol microphysics.”
However, Gordon objected to Svensmark’s subsequent claims. The CERN research:
- stands in contrast to Svensmark’s results, and found that, given the present day atmosphere and all of its particles, “cosmic ray intensity cannot meaningfully affect climate via nucleation.” Basically, particles here on Earth released by trees and humans have a much stronger influence on cloud formation and creating Earth-cooling clouds.
It definitely appears that charged particles have some effect on cloud formation in a lab, sure. But global climate change can’t been explained away that easily — especially given the truckloads of evidence that humans are driving it by emitting greenhouse gases.
Tim Wallace in Cosmic ray theory of global warming gets cold response at Cosmos rounds up more scientific opinion.
“The authors need to quantify the effects in an atmospheric model rather than just speculating,” says Ken Carslow, of the University of Leeds, UK, who has also studied potential links between cosmic rays and aerosol formation as part of CERN’s Cosmics Leaving Outdoor Droplets (CLOUD) experiment. “It’s a tiny effect and previous studies suggest it will not be important,” he states.
Terry Sloan, of the University of Lancaster, UK, whose own research has calculated the contribution of cosmic rays at less than 10% of the global warming seen in the 20th century, is also dubious. He points out that other atmospheric “impurities”, such as dust and salt particles, play more important roles as cloud-condensing nuclei.
“The effects [of ionisation] are too small to measure except in the dust- and impurity-free atmosphere such as in their experiments,” Sloan says. “Dust in the atmosphere plays a much bigger part in cloud formation.”
Steven Sherwood [an expert in atmospheric climate dynamics at the University of New South Wales] concurs. The paper itself, he notes, only suggests the result “may be relevant in the Earth’s atmosphere under pristine conditions”. Even if things do work in the real world the same way as in a laboratory, cloud growth due to ions would only make up “several per cent” of the total.
“Several per cent ain’t much, and the real atmosphere is not pristine,” Sherwood says. While the new research has shown that cosmic rays can produce particles big enough to seed clouds, that was never “the real problem” with Svensmark’s ideas. A bigger issue is the number of such particles, which “would be negligible compared with the background aerosol and the aerosol humans are adding by burning things, tilling soil, etc.”
“If clouds were affected by cosmic rays,” he adds, “they would have been affected a hundred times more strongly by human air pollution, and the world would have cooled over the past century, rather than warmed.”
An article in The Independent Sun sets on sceptics’ case against climate change back in 2009 tells the story of the first outing of the cosmic ray theory. Essentially it tells that back then their results depended on artificially introduced arithmetic errors.
Svensmark appears to have done some decent science this time, but can’t help himself in his interpretation of what it means. Clouds are a minor part of the climate forcing story, and cosmic rays perform a very minor role within the cloud formation story.
It would help if ABC programs like Counterpoint were truth-seeking instead of promoting shonk theories about global warming and climate change.