New evidence for subtropical warming during the late Paleocene thermal maximum: Stable isotopes from Deep Sea Drilling Project Site 527, Walvis Ridge

The late Paleocene thermal maximum (LPTM) was a dramatic, short-term global warming event that occurred similar to 55 Ma. Warming of high-latitude sur face waters and global deep waters during the LPTM has been well documented ; however, current data suggest that subtropical and tropical sea surface t emperatures (SSTs) did not change during the event. Conventional paradigms of global climate change, such as CO2-induced greenhouse warming, predict g reater warming in the high latitudes than in the tropics or subtropics but, nonetheless, cannot account for the stable tropical/subtropical SSTs. We m easured the stable isotope values of well-preserved late Paleocene to early Eocene planktonic foraminifera from South Atlantic Deep Sea Drilling Proje ct (DSDP) Site 527 to evaluate the subtropical response to the climatic and environmental changes of the LPTM. Planktonic foraminiferal delta(18)O val ues at Site 527 decrease by similar to 0.94 parts per thousand from pre-LPT M to excursion values, providing the first evidence for subtropical warming during the LPTM. We estimate that subtropical South Atlantic SSTs warmed b y at least similar to 1 degrees - 4 degrees C, on the basis of possible cha nges in evaporation and precipitation. The new evidence for subtropical SST warming supports a greenhouse mechanism for global warming involving eleva ted atmospheric CO2 levels.