The Weather Magnet

摘要

It never fails. every 100,000 years, just when the glaciers have retreated and you ve been enjoying 10,000 years of balmy weather, another ice age comes along. It's been that way for the past million years, with Earth's climate swinging between glacial and interglacial (warm) periods. Scientists generally ascribe long climate change cycles to wobbles in Earth's orbit, a theory first proposed in 1912 by Serbian astronomer Milutin Milankovitch. But the Milankovitch theory does not satisfactorily explain the 100,000-year ice age cycle of the past million years. Now Dartmouth College geochemist Mukul Sharma says he may have found a connection berween Earth's climate and magnetic activity in the sun.