A theory that global warming is caused by increased solar output is bunk, according to climate-change scientists. Although the world has grown hotter over the last 20 years, solar activity has actually dropped, the BBC reports, and an international panel concluded that greenhouse gases are 13 times more responsible for global warming than the sun.
"The warming in the last 20 to 40 years can't have been caused by solar activity," the lead scientist in the latest study said. Researchers examined the issue in response to a recent British TV documentary advancing the solar theory. "This should settle the debate," said one investigator. (Read more climate change stories.)