Sun still main force in climate change
Rebuts widely publicized study this summer by UK scientists
October 3, 2007
Despite the claim of a heavily publicized recent study, the sun still appears to be the main agent in global climate change, according to new research by Danish scientists.
The study by the Danish National Space Center rebuts a July study by UK scientists who allege there has not been a solar-climate link in the past 20 years.
The Danish researchers, Henrik Svensmark and Eigil Friis-Christensen, contend the UK study erroneously relies on surface air temperature, which, they say, "does not respond to the solar cycle."
Over the past 20 years, however, the Danes argue, the solar cycle remains fully apparent in variations both of tropospheric air temperature and of ocean sub-surface water temperature.
"When the response of the climate system to the solar cycle is apparent in the troposphere and ocean, but not in the global surface temperature, one can only wonder about the quality of the surface temperature record," Svensmark and Friis-Christensen say.
The surface air temperature, they argue, is "a poor guide to sun-driven physical processes that are still plainly persistent in the climate system."
The researchers explained it's "customary to attribute to greenhouse gases any increase in global temperatures not due to solar changes."
"While that is reasonable," they say, "one cannot distinguish between the effects of anthropogenic gases such as carbon dioxide and of natural greenhouse gases."
Increased evaporation, for example, means "infrared radiation from water vapor, by far the most important greenhouse gas, will tend to provide positive feedback for any global warming, whether driven by anthropogenic or solar forcing."
"In any case," they emphasize, "the most recent global temperature trend is close to zero."
The study, led by University of Southern California geologist Lowell Stott, concluded deep-sea temperatures rose 1,300 years before the rise in atmospheric CO2, which would rule out the greenhouse gas as the main agent of the meltdown.
"There has been this continual reference to the correspondence between CO2 and climate change as reflected in ice core records as justification for the role of CO2 in climate change," said Stott. "You can no longer argue that CO2 alone caused the end of the ice ages."
Another new study published in Science refutes the "Hockey Stick" temperature graph, used by man-made global warming theorists such as former Vice President Al Gore to argue for a recent spike in average global temperature after centuries of relative stability.