Scientists have long suspected that the sun affects climate on Earth, but that connection has proved hard to pin down. Researchers recently demonstrated that the 11-year cycle of solar activity influences weather in the tropical Pacific Ocean. Even then the exact cause remained obscure, since the sun’s brightness varies by just one-tenth of a percent. Two studies from 2009 are filling in the gaps.
In August an international team led by Gerald Meehl, a climatologist with the National Center for Atmospheric Research, announced that the sun’s outsize influence results from its combined effects on our atmosphere and oceans. When the sun is at its most intense, ozone in the stratosphere absorbs more ultraviolet energy, making areas near the equator warmer than usual. The added heat changes wind patterns, bringing more rain to the western tropics. At the same time, the extra sunlight causes more evaporation off the ocean, which adds ...
