EOS, Transactions, American Geophysical Union Global Methane Emissions From

• Main Author: Rice Paddies
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.159.3359; http://www.nceas.ucsb.edu/files/news/Zhuang-et-al-2009EO050001.pdf

The current concentration of atmospheric methane is 1774±1.8 parts per billion, and it accounts for 18 % of total greenhouse gas radiative forcing [Forster et al., 2007]. Atmospheric methane is 22 times more effective, on a per-unit-mass basis, than carbon dioxide in absorbing long-wave radiation on a 100-year time horizon, and it plays an important role in atmospheric ozone chemistry (e.g., in the presence of nitrous oxides, tropospheric methane oxidation will lead to the formation of ozone). Wetlands are a large source of atmospheric methane, Arctic lakes have recently been recognized as a major source [e.g., Walter et al., 2006], and anthropogenic activities—such as rice agriculture—also make a considerable contribution. However, the quantification of methane emissions still has large uncertainties. In this article, we identify some causes for the uncertainty; illustrate the challenges of reducing the uncertainty; and highlight opportunities for research from the global perspective and also from the perspective of three principal sources of methane: the Arctic, the Amazon basin, and rice paddies. surveys of vegetation and wetland types should be continued as a means to further develop data on global lake and wetland distribution and extent. Methane flux measurements, which are lacking from a variety of ecosystems, as noted below, are needed to improve emission estimates and the accuracy of biogeochemical models and atmospheric transport inversion models [e.g., Zhuang and Reeburgh, 2008]. Data acquisition of in situ and satellite atmospheric concentrations and their profiles should be maintained to more Volume 90 number 5