Measurement and Interpretation of d13C of Atmospheric Methane from the Law Dome Ice Cores

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

0087357 White This award supports a project to examine and compare high resolution methane concentration and isotopic histories during the last millennium from the Law Dome ice core in coastal Antarctica. Atmospheric methane is an important chemical component of both the stratosphere and troposphere, and is a major contributor to the anthropogenic enhancement of the greenhouse effect. Quantifying the budget of methane has proven difficult because of the wide range of sources and locations from which it is emitted. Measurements of the atmospheric concentration and the carbon isotopic composition of methane have enabled a greater understanding of the controls over the modern methane budget. Studies of the methane budget prior to and during industrialization and the emergence of large human populations can help in the understanding of the controls on this budget. Measurements of the carbon-13:carbon 12 ratio and of the carbon isotopic composition (d 13C) of methane in air from the last millenium trapped in polar ice will be made to aid in understanding of the paleo-methane budget. This is a collaborative effort between the stable isotope laboratory and the University of Colorado and the New Zealand National Institute of Water and Atmospheric Research, the Australian Antarctic program and the NOAA carbon cycle group. The Australian and New Zealand groups will provide the ice and past results of Antarctic firn air measurements and the stable isotope lab will provide expertise on isotopic measurements of very small firn air samples. The carbon cycle group will assist in the calibration of standards and analysis of firn air samples. All groups will participate in the modeling and interpretation of results.