Huybers, P. 2009. “Antarctica’s Orbital Beat.” Science 325 (5944) (August 27): 1085–1086. doi:10.1126/science.1176186.
Alternating glacial and interglacial conditions have dominated Earth's climate for at least the past 800,000 years (1, 2). Such a global rhythm of glaciation is surprising—at least if summer solar radiation controls glaciation (3)—because variations in Earth's orbit cause opposite changes in the intensity of northern and southern summer radiation. Deciphering the origins of the orbital period variations found in Antarctic proxies of climate may tell us why glaciations are global.