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abstracts
New high-precision, high-resolution records of atmospheric methane from Greenland and Antarctic ice cores: AD 1000 – present
Logan Mitchell, Ed Brook
Atmospheric methane has caused the second largest increase in radiative forcing from greenhouse gases since the start of the industrial revolution. Here we present a high-precision, high-resolution, 1000 year long record of atmospheric methane from the West Antarctic Ice Sheet Divide 05A (WDC05A) shallow gas core and preliminary results from the Greenland ice core GISP2D. These records have an average temporal resolution of ~9 years and an analytical precision of <3 ppb. Preliminary high resolution data from GISP2D show patterns similar to those in Antarctic records. These records allow us to begin constructing the first high resolution interpolar gradient (IPG) which will enable us to investigate geographical changes in atmospheric methane source regions on a multi-decadal timescale. The Law Dome and WDC05A methane records are highly correlated (r2 = 0.77) which increases confidence in the accuracy of both records. An offset between the gas age timescales is apparent and the maximum correlation (r2 = 0.81) is attained when one of the timescales is shifted by 8 years. This demonstrates that high resolution analysis of methane can be used to synchronize gas age timescales between different ice cores during climatically stable periods. We compare these atmospheric methane records with various paleoclimate archives and have identified a possible correlation with a proxy for East Asian monsoon strength.
Logan Mitchell, Department of Geosciences, Oregon State University,104 Wilkinson Hall, Corvallis, OR 97330, United States, mitchelo@geo.oregonstate.edu
Ed Brook, Oregon State University, Department of Geosciences, United States
Session: F1: Climate Forcings
Download Poster:
> Mitchell 2009 PAGES poster.pdf
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