PALEOCLIMATE:
A Variable Sun Paces Millennial Climate
Richard A. Kerr
Most scientists have viewed the sun's unvarying brightness as the one constant in the ever-changing climate system. Now, in a paper published online this week by Science (www.sciencexpress.org), paleoceanographers report that the climate of the northern North Atlantic has warmed and cooled nine times in the past 12,000 years in step with the waxing and waning of the sun. Some researchers say the data make solar variability the leading hypothesis to explain the roughly 1500-year oscillation of climate seen since the last ice age, and that the sun could also add to the greenhouse warming of the next few centuries.