HR: 15:00h
AN: PP53B-05    [Abstracts]
TI: A 3-million-year reconstruction of climate, ice volume and sea level; identifying mechanisms behind the inception of Northern-Hemisphere glaciation and the mid-Pleistocene transition
AU: * Bintanja, R
EM: bintanja@gmail.com
AF: Royal Dutch Meteorological Institute, Wilhelminalaan 10, De Bilt, 3732GK, Netherlands
AU: van de Wal, R
EM: r.vandewal@phys.uu.nl
AF: Institute for Marine and Atmospheric research Utrecht, Utrecht University, Princetonplein 5, Utrecht, 3584CC, Netherlands
AB: A coupled ice-sheet ocean-temperature model was used to extract three-million-year records of surface air temperature, ice volume, and sea level from deep-sea oxygen isotopes. The results show that a 5 °C cooling between 3 and 2.5 million years ago (Ma) initiated Northern Hemispheric glaciation around 2.7 Ma with low amplitude obliquity-scale (41-kyr) glacials - dominated by the sluggish Eurasian ice sheets - prevailing. Prior to about 1 Ma, ice volume lagged behind air temperature by 5 kyr in quasi-linear 41-kyr cycles. Ongoing climate cooling enabled the Cordilleran and Laurentide ice sheets to survive insolation maximums, causing them to eventually merge and to expand rapidly during glacial conditions. Once the huge North-American ice sheet reached a certain extent and/or thickness, the subsequent insolation maximum-related warming then initiated deglaciation, presumably through basal sliding related instabilities. The 100-kyr glacials arose gradually between 1.4 and 0.6 Ma, with the different response time and geometrical constraints of the Eurasian and North-American ice sheets being key factors.
DE: 0700 CRYOSPHERE (4540)
DE: 0726 Ice sheets
DE: 1621 Cryospheric change (0776)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4946 Milankovitch theory
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting