By ANNE JOLIS

In April 1990, Al Gore published an open letter in the New York Times “To Skeptics on Global Warming” in which he compared them to medieval flat-Earthers. He soon became vice president and his conviction that climate change was dominated by man-made emissions went mainstream. Western governments embarked on a new era of anti-emission regulation and poured billions into research that might justify it. As far as the average Western politician was concerned, the debate was over.

But a few physicists weren’t worrying about Al Gore in the 1990s. They were theorizing about another possible factor in climate change: charged subatomic particles from outer space, or “cosmic rays,” whose atmospheric levels appear to rise and fall with the weakness or strength of solar winds that deflect them from the earth. These shifts might significantly impact the type and quantity of clouds covering the earth, providing a clue to one of the least-understood but most important questions about climate. Heavenly bodies might be driving long-term weather trends. (more…)