Tropical Atlantic SSTs over the last 20,000 years: Implications on the mechanism and synchroneity of interhemispheric climate change.

摘要

Coral based estimates of sea surface temperature from the deep mixed layer of the western tropical Atlantic, the Atlantic "warm pool," from two independent paleothermometers document variable sea surface temperatures over the last astronomical climate cycle. These results are in contrast to the previous dogma regarding the stability of tropical sea surface temperatures (SST) over the Cenozoic. The Laurentide and Fennoscandian Ice Sheets supplied the bulk of ice during the last ice age. The relative rate of sea level change during the deglacial recorded in Barbados corals reflects the destruction of these masses, and is therefore a proxy for high latitude climate. Barbados data indicate that rising tropical SSTs lead the major recessions of the continental ice sheets during the last deglaciation.;The seasonal cycle of sea surface temperature can be a powerful diagnostic in determining the mechanism of climate change. Sea surface temperature seasonality as recorded in the ;Cold western tropical Atlantic SSTs are not the result of an advective phenomenon and are shown to reflect a tropic-wide cooling. The spatial pattern implies that the cooling is not the consequence of changes in deep thermohaline circulation. Radiative changes due to cloud type and cloud cover are plausible mechanisms for maintaining cooler tropical SST's in the past. Modulating tropical temperatures provides a direct, and first link between hemispheres through changes in the meridional export of energy tying together tropical SSTs, ice volume, and high latitude climate.