Warming caused by sun?

You may remember news last year that photos of Mars suggested that some possible ice had melted on Mars and created a small flow in what one might call a riverbed. It was fascinating to scientists as evidence that there was water still on Mars, if probably not much of it, which makes the notion of looking for life forms more interesting.

A Russian scientist, however, has drawn some interesting conclusions from that phenomenon and the fact that the carbon dioxide "ice caps" have been diminishing for three summers in a row. As the National Geographic News Service (!) wrote: "Habibullo Adussamotov, head of St. Petersburg's Pulkovo Astronomical Observatory in Russia, says the Mars data is evidence that the current global warming on Earth is being caused by changes in the sun."

"The long-term increases in solar irradiance is heating both Earth and Mars," he said. He thinks it is possible that man-made greenhouse gases have made a small contribution to the current warming, but a pittance compared to the importance of changes in the sun, which he has been tracking through history. He thinks he sees a relationship between sun activity and climate change in the past.

His theory is controversial, of course. Many scientists reject it. But it's worth pondering.