One of the global warming skeptics who reads this blog said he would be persuaded if direct measurements of solar output, rather than models, showed that changes in Sun were not contributing to the rise in Earth’s average temperature.
This blog entry is for him. It discusses an article that shows that, if anything, the recent IPCC report OVERestimated when it stated the Sun’s contribution to global warming is approximately 10% of anthropogenic effects. In fact, over the last 20 years, solar changes have been in the opposite direction.
My source is New Scientist online article that cites this journal reference: Mike Lockwood and Claus Fröhlich, “Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature,” Proceedings of the Royal Society A (DOI:10.10.98.rspa.2007.1880).
To quote the opening paragraphs of the New Scientist article:
Direct satellite measurements of solar activity show it has been declining since the mid-1980s and cannot account for recent rises in global temperatures, according to new research.
The findings debunk an explanation for climate change that is often cited by people who are not convinced that greenhouse gas emissions from human activities are causing the Earth’s climate to warm.
Sceptics commonly point to climate research’s reliance on computer models as a reason for doubting the link between global warming and human greenhouse gas emissions.
“We decided to do a simple and direct analysis of the potential role of the Sun in recent climate change without using any model output,” says Lockwood [of the Rutherford Appleton Laboratory, part of the Science and Technology Facilities Council in the UK].
Please read the New Scientist article and, if possible, the original journal article before commenting here.