HR: 15:10h
AN: PP43C-07 INVITED     [Abstracts]
TI: Warm upwelling regions during a period of global warmth
AU: * Dekens, P
EM: dekens@ucsc.edu
AF: University of California, Santa Cruz, Ocean Sciences Department University of California, Santa Cruz 1156 High Street , Santa Cruz, Ca 95060
AU: Ravelo, A C
EM: acr@ucsc.edu
AF: University of California, Santa Cruz, Ocean Sciences Department University of California, Santa Cruz 1156 High Street , Santa Cruz, Ca 95060
AU: McCarthy, M
EM: mccarthy@pmc.ucsc.edu
AF: University of California, Santa Cruz, Ocean Sciences Department University of California, Santa Cruz 1156 High Street , Santa Cruz, Ca 95060
AB: The early Pliocene represents the most recent period in Earth's history when long-term equilibrium temperatures exceeded those of today. While it is not a direct analog for an anthropogenically warmed climate, it can serve as a useful test case for understanding warm climates, particularly since many of the boundary conditions (including position of continents, major ocean currents, small northern hemisphere ice sheets, and atmospheric pCO₂) were similar to today. Upwelling regions are key features of the modern climate that participate in air-sea interactions, regulate regional climate, and play an important role in the global carbon cycle through the biological pump. The Pliocene warm period gives us insight into how global climate change may be influenced by and have an impact on upwelling systems. We generated U^k'₃₇ SST records through the last 5 million years in three important upwelling locations: ODP site 847 in the eastern equatorial Pacific, ODP Site 1014 on the California margin, and ODP Site 1237 on the Peru margin. All sites indicate significantly warmer sea surface temperature (SST) during the early Pliocene (3 - 4.6 Ma), ranging from 3.3°C to 9.6°C warmer than late Pleistocene (0 - 0.5 Ma) SST and from 2.9°C to 8.8°C warmer than the modern mean annual SST, indicating that the warm Pliocene represents a fundamentally different climate regime in which cold upwelling regions did not exist. Our U^k'₃₇ SST record in the eastern equatorial Pacific is consistent with previous work demonstrating permanent El Niño like conditions in the tropical Pacific. Assuming teleconnections in the modern climate system can be used as analogs, warmer upwelling regions along the California and Peru margins are consistent with a permanent El Niño-like pattern. Taken together with other Pliocene data, our data indicate that while the average SST of low latitudes may not have been substantially warmer, the spatial distribution of SST across the low latitudes was different in the early Pliocene compared to today. In order to further understand the role of low latitude climate on Pliocene warmth, the global impacts of alterations in the spatial pattern of low latitude SST should be investigated.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4279 Upwelling and convergences (4964)
DE: 4522 ENSO (4922)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005