HR: 1330h
AN: PP22A-1206    [PDF]
TI: A Meta-analysis of Tropical Surface Temperatures at the Last Glacial Maximum
AU: * Ballantyne, A
EM: apb14@duke.edu
AF: Duke University, Nicholas School of the Environment, Box 90229, Durham, NC 27708 United States
AU: Crowley, T
EM: tjcrowley@duke.edu
AF: Duke University, Nicholas School of the Environment, Box 90229, Durham, NC 27708 United States
AU: Baker, P
EM: pbaker@duke.edu
AF: Duke University, Nicholas School of the Environment, Box 90229, Durham, NC 27708 United States
AU: Lavine, M
EM: michael.lavine@duke.edu
AF: Duke University, Institute of Statistics and Decision Science, Box 90229, Durham, NC 27708
AB: Based on direct measurements of gas trapped in ice cores, we know that fluctuations in CO2 levels and glacial periods are highly synchronous. However, we have no direct means of measuring past temperature, so we must rely on proxies that correlate with temperature to infer temperature variability through time. A concerted effort to measure the change in global temperature since the Last Glacial Maximum (LGM) was undertaken by CLIMAP (1980) who estimated tropical sea surface temperatures during the LGM to be 1.5$\deg$ $\pm$ 1.2 C cooler than today. Since the first estimates of temperature at the LGM, numerous biological, chemical and physical temperature proxies have been developed. Estimates of tropical surface cooling at the LGM from these proxies have varied considerably (0-8$\deg$C). Here we conduct a meta-analysis of proxy estimates to arrive at an impartial approximation of tropical cooling at the LGM: 3.3$\deg$ $\pm$ 2.0 C. This approximation of tropical surface temperature would suggest a mid-range climate sensitivity of about 3.5 $\deg$ C for the anticipated doubling of CO2. Developing more paleo-temperature proxies and evaluating existing proxies is critical to our understanding of how Earth's temperature responds to changes in CO2.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1610 Atmosphere (0315, 0325)
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting