Last month, Rush Limbaugh referenced my “Planet Gore” post on the new data showing that 2007 saw the largest one-year temperature drop ever recorded. The researchers quoted in the article attributed the decline to a dramatic decrease in solar activity. They are far from alone in that conclusion.

Harvard astrophysicist Dr. Sallie Baliunas suggested last month in Tyler that solar variability is more directly responsible for warming than CO2. Baliunas’ research-performed in conjunction with astronomer Willie Soon of the Harvard-Smithsonian Center for Astrophysics-found historical warm and cool periods resulted from increases and decreases in solar output.

The Max Planck Institute for Solar Research had previously found that the sun has burned more brightly during the past 60 years.

A Hoover Institution study finding “the effects of solar activity and volcanoes are impossible to miss” but that “could not find any relationship between industrial activity, energy consumption and changes in global temperatures;” and

R. Timothy Patterson’s (geology professor and director of the Ottawa-Carleton Geoscience Center of Canada’s Carleton University) findings that “CO2 variations show little correlation with our planet’s climate on long, medium, and even short time scales.”

Last September, the Hudson Institute published a list of more than 500 scientists who have disputed man-made global warming theory. Most had concluded that warming is strongly linked to variations in the sun’s irradiance.

Finally, what to make of the fact that Mars has also warmed? Since Mars has no SUVs or factories, could the sun be a factor?

– Drew Thornley