Constraining the sources of the CH4 increase during the Oldest Dryas-Bølling abrupt warming event using 14CH4 measurements from Taylor Glacier, Antarctica
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Date
2016-03-07
Journal Title
Journal ISSN
Volume Title
Publisher
Antarctic Climate and Ecosystems Cooperative Research Centre
Abstract
Methane (CH4) is an important greenhouse gas with both natural and anthropogenic
sources. Understanding how the natural CH4 budget has changed in response to changing
climate in the past can provide insights on the sensitivity of the natural CH4 emissions to the
current anthropogenic warming. Low latitude wetlands are the largest natural source of
CH¬4 to the atmosphere. It has been proposed, however, that in the future warming world
emissions from marine CH4 clathrates and Arctic permafrost might increase significantly.
CH4 isotopes from ice cores in Greenland and Antarctica have been used to constrain the
past CH¬4 budget. 14CH4 is unique in its ability to unambiguously distinguish between
“old” CH4 sources (e.g. marine clathrate, geologic sources, old permafrost) and “modern”
CH4 sources (e.g. tropical and boreal wetlands). We have successfully collected six large
volume (~1000 kg) samples of ancient ice from Taylor Glacier, Antarctica that span the
Oldest Dryas – Bølling (OD-BO) CH4 transition (~14.5ka). The OD-BO is the first large
abrupt CH4 increase following the Last Glacial Maximum, with atmospheric CH4 increasing
by ≈30% in the span of ≈ 200 years. All samples have recently been successfully measured
for 14CH4, δ13C-CH4, and δD-CH4. 14CH4 measurements of accompanying procedural
blanks show that effects from extraneous carbon addition during processing are small.
Results are currently undergoing corrections for in-situ cosmogenic 14C based on 14CO
measurements in the same samples. We will present the corrected 14CH4 results and
preliminary interpretation with regard to causes of the OD-BO CH4 increase.
Description
Keywords
Methane, Glaciers, Antarctic regions, Climates, Paleoclimatology, Climatic change, Greenhouse effect, Drill cores, Greenland, Permafrost
Citation
Doyonisius, M., Petrenko, V. V., Smith, A., Hmiel, B., Hua, Q., Harth, C., Baggenstos, D., Bauska, T., Bauska, T., Bock, M., Beck, J., Seth, B., Baudette, R., Schmitt, J., Palardy, A., Brooks, E., Weiss, R., Fischer, H., & Severinghaus, J. (2016). Constraining the sources of the CH4 increase during the Oldest Dryas-Bølling abrupt warming event using 14CH4 measurements from Taylor Glacier, Antarctica. Paper presented at the IPICS 2016, International Partnerships in Ice Core Sciences, Second Open Science Conference, 7-11 March 2016, Hobart, Tasmania.