While discussing the September 17 dismissal of a global warming lawsuit that then-California Attorney General Bill Lockyer filed in September 2006 against six major automakers, Newsradio 850 KOA host Mike Rosen claimed on his September 19 show that the sun “is the principal contributing factor” in global warming. In fact, as Colorado Media Matters has noted, the argument that the sun -- and not human activity -- is primarily responsible for current climate change echoes a conservative talking point that rejects overwhelming scientific consensus. Rosen has promoted this and other misinformation about global warming on numerous broadcasts.

Reading from a September 18 San Francisco Chronicle article about U.S. district judge Martin Jenkins' dismissal of the suit, Rosen read a quote from the decision in which Jenkins stated that “there are multiple worldwide sources of atmospheric warming across myriad industries and multiple countries” -- to which Rosen added, "[H]e might have thrown in the sun as well, which is the principal contributing factor. So perhaps this former California attorney general could have sued the sun."

From the September 19 broadcast of Newsradio 850 KOA's The Mike Rosen Show:

ROSEN: Don't want to spend a lot of time on this, but I thought you'd like an update. There was a suit filed in September 2006 in California by then-state Attorney General Bill Lockyer. The suit was filed against General Motors, Toyota, Ford Motor Company, Honda North America, Chrysler Motors Corp., and Nissan North America. This is a classic example of a frivolous lawsuit filed by a publicity hound with a political agenda. This is theatrical.

“In announcing the suit last year, Bill Lockyer, who was then the attorney general, noted that cars produce about 30 percent of the carbon dioxide emitted in California. He said, 'It's time to hold these companies responsible for their contribution to the global warming crisis.' Global warming, he went on to say, 'is harming California, its environment, its economy and the health and well being of its citizens.' ” Well, a federal judge in San Francisco has thrown out this lawsuit. “In a 24-page decision on Monday, U.S. District Judge Martin Jenkins said it would be inappropriate for the court to wade into the 'global warming thicket' as it pertained to interstate commerce and foreign policy -- matters he said should be left to the political branches of government. 'In this case, said the judge, by seeking to impose damages for the defendant automakers' lawful worldwide sale of automobiles, plaintiff's nuisance claims sufficiently implicate the political branches' powers over interstate commerce and foreign policy.' He said the automakers aren't the only companies responsible for global warming. 'In this case, there are multiple worldwide sources of atmospheric warming across myriad industries and multiple countries.' ” And he might have thrown in the sun as well, which is the principal contributing factor. So perhaps this former California attorney general could have sued the sun.

Contradicting the assertion that “the sun ... is the principal contributing factor” in global warming, the 2007 Report of the Intergovernmental Panel on Climate Change (IPCC) found that "[t]he rapid warming observed since the 1970s has occurred in a period when the increase in greenhouse gases has dominated over all other factors." The report further stated: “The human influence on climate very likely dominates over all other causes of change in global average surface temperature during the past half century.” Specifically addressing the possible contributions of solar activity to warming, the report concluded:

It is extremely unlikely (<5%) that the global pattern of warming during the past half century can be explained without external forcing, and very unlikely that it is due to known natural external causes alone. The warming occurred in both the ocean and the atmosphere and took place at a time when natural external forcing factors would likely have produced cooling.

Greenhouse gas forcing has very likely caused most of the observed global warming over the last 50 years. This conclusion takes into account observational and forcing uncertainty, and the possibility that the response to solar forcing could be underestimated by climate models. It is also robust to the use of different climate models, different methods for estimating the responses to external forcing and variations in the analysis technique. [emphasis in original]