HR: 10:35h
AN: PP22B-02 [Abstracts]
TI: Published GISP2 Methane Results for Dansgaard-Oeschger Events 19-21 Compared With N2, Ar Isotopes:
A Need for a Higher Resolution CH4 Dataset.
AU: * Grachev, A M
EM: gracheal@geo.oregonstate.edu
AF: Department of Geosciences
Oregon State University, 104 Wilkinson Hall, Corvallis, OR 97331
United States
AU: Brook, E J
EM: brooke@geo.oregonstate.edu
AF: Department of Geosciences
Oregon State University, 104 Wilkinson Hall, Corvallis, OR 97331
United States
AU: Severinghaus, J P
EM: jseveringhaus@ucsd.edu
AF: 9500 Gilman Drive, Scripps Institution of Oceanography, La Jolla, CA 92093
United States
AU: Landais, A
EM: landais@vms.huji.ac.il
AF: IPSL/LSCE, CEA/CNRS, Orme des merisiers, Gif s/ Yvette, 91191
France
AU: Barnola, J M
EM: barnola@lgge.obs.ujf-grenoble.fr
AF: LGGE, CNRS, 53 Rue Moliere, St Martin d'Heres, 38 402
France
AB:
Few thousand years after the onset of the last glaciation three large climate fluctuations occurred at ~70 ka, with only
one of them accompanied by a large change in atmospheric methane. These Dansgaard-Oeschger events, numbered 19, 20, and 21,
are prominently recorded in the GISP2 ice core (Dansgaard W. et al., Nature 1993, vol. 364, p.218). Oxygen isotopes of
the ice matrix suggest Greenland temperature changes in excess of 10° C, with part of the change likely caused by changes
in seasonality and storm tracks. Recent nitrogen and argon isotope work has shown that purely temperature signal of DO-19 and
DO-20 is equal to ~11-14° C (Grachev A. M., Severinghaus J. P., Landais A., Barnola J. M., in prep.). Methane change
is rather small for DO-19 and 20 (<100 ppb) and very dramatic for DO-21 (~300 ppb) (Brook E. J. et al. Global
Biogeochem. Cycles 2000, vol. 14, p. 559). Direct comparison of the methane signal and the gas isotope signal for this time
interval could reveal the relative timing of high Northern latitude temperature change and changes in global biogeochemical
cycles that control atmospheric methane (Severinghaus J. P. and Brook E. J., Science 1999, vol. 286, p. 930). Work is
planned aimed at producing a next-generation methane record for DO 19-21 in GISP2 that would allow making such a comparison.
DE: 0490 Trace gases
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4926 Glacial
DE: 4932 Ice cores (0724)
DE: 9315 Arctic region (0718, 4207)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005