Study: sun not linked to current global warming
Experts: sun not linked to current global warming
July 11, 2007
Changes in the sun’s output is not linked to recently observed global warming, reports a study published in the journal Proceedings of the Royal Society A.
The research shows that for the last twenty years, Earth’s temperatures have climbed despite a decline in solar output. The scientists–Mike Lockwood of the Rutherford Appleton Laboratory in the U.K. and Claus Fröhlich of the World Radiation Center in Switzerland, say that while the sun may have been a factor in past climate change, the present trend cannot be explained by changes in solar output.
“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,” write the authors. “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.”
Photo by R. Butler
The study appears to undermine the “cosmic ray hypothesis” put forth by Henrik Svensmark and Eigil Friis-Christensen of the Danish National Space Center, according to BBC News. The theory links cloud formation to the sun’s rays, such that when solar activity increases, cloud formation decreases, causing Earth to warm.
“I do think there is a cosmic ray effect on cloud cover. It works in clean maritime air where there isn’t much else for water vapour to condense around,” Lockwood told the BBC.
“It might even have had a significant effect on pre-industrial climate; but you cannot apply it to what we’re seeing now, because we’re in a completely different ball game.”
Mike Lockwood and Claus Fröhlich (2007). Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. Proc. R. Soc. A. 10.1098/rspa.2007.1880. Tuesday, July 10, 2007