HR: 11:50h
AN: PP42B-07 INVITED    [Abstracts]
TI: North Atlantic Deepwater Responses to Obliquity and Precession
AU: * Lisiecki, L E
EM: lisiecki@bu.edu
AF: Boston University, 675 Commonwealth Ave, Boston, MA 02215,
AU: Raymo, M E
EM: raymo@bu.edu
AF: Boston University, 675 Commonwealth Ave, Boston, MA 02215,
AB: Many studies have shown that times of increased ice volume, particularly the last glacial maximum (LGM), correspond to decreases in North Atlantic deepwater (NADW) at depths below ~2000 m. Here we investigate the different effects of obliquity and precession forcing on NADW using 30 benthic δ¹³C records spanning the last 425 kyr. We find that obliquity-forced minima in high latitude summer insolation correlate with lower benthic δ¹³C values at Atlantic sites below 2500 m, consistent with reduced production of lower NADW as at the LGM. In contrast, precession-forced minima in northern hemisphere summer insolation correspond with greater benthic δ¹³C values at Atlantic sites from 2500-4000 m water depth, suggesting increased production of lower NADW. Because obliquity and precession produce different responses to the same change in high-latitude northern insolation at the summer solstice, lower NADW production is likely more sensitive to insolation at a different latitude or season, perhaps due to sea ice formation, freshwater flux, or meridional heat transport.
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4910 Astronomical forcing
DE: 4934 Insolation forcing
DE: 4946 Milankovitch theory
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting