Using Ancient Ice from Taylor Glacier, Antarctica to Study the Past Methane Budget and in situ Cosmogenic 14C Production Rates in Ice

Abstract

We present radiocarbon and stable isotopes measurements from Taylor Glacier, Antarctica. Measurements of 14CH4, 14CO, δ13CH4, and δD-CH4 were conducted on 13 samples with ages ranging from 18-8.2 kilo year before present (kyr BP). The CH4 isotopes (both radiocarbon and stable isotopes) were used to constrain the deglacial CH4 budget. From the 14CH4 data, we show that emissions from old carbon reservoirs were small (50 kyr BP for 14CO, 14CO2, 14CH4 measurements to calibrate the production rates of in situ cosmogenic 14C from negative muon capture and fast muon reactions. We find that the literature values of muon 14C production rates (Heisinger et al., 2002a, 2002b) are overestimated by factors of 5 (2.8-10.8, 95% confidence interval) and 3.9 (0-14.2, 95% confidence interval) for negative muon capture and fast muon interactions respectively