Interhemispheric climate links revealed by a late-glacial cooling episode in southern Chile

Understanding the relative timings of climate events in the Northern and So uthern hemispheres is a prerequisite for determining the causes of abrupt c limate changes. But climate records from the Patagonian Andes(1-4) and New Zealand(5-8) for the period of transition from glacial to interglacial cond itions-about 14.6-10 kyr before present, as determined by radiocarbon datin g-show varying degrees of correlation with similar records from the Norther n Hemisphere. It is necessary to resolve these apparent discrepancies in or der to be able to assess the relative roles of Northern Hemisphere ice shee ts and oceanic, atmospheric and astronomical influences in initiating clima te change in the late-glacial period. Here we report pollen records from th ree sites in the Lake District of southern Chile (41 degrees S) from which we infer conditions similar to modern climate between about 13 and 12.2 C-1 4 kyr before present (BP), followed by cooling events at about 12.2 and 11. 4 (14)Ckyr BP, and then by a warming at about 9.8 (14)Ckyr BP. These events were nearly synchronous with important palaeoclimate changes recorded in t he North Atlantic region(9), supporting the idea that interhemispheric link age through the atmosphere was the primary control on climate during the la st deglaciation. In other regions of the Southern Hemisphere, where climate events are not in phase with those in the Northern Hemisphere, local ocean ic influences may have counteracted the effects that propagated through the atmosphere.