Atmospheric methane and global change

Abstract

Methane (CH 4 ) is the most abundant organic trace gas in the atmosphere. In the distant past, variations in natural sources of methane were responsible for trends in atmospheric methane levels recorded in ice cores. Since the 1700s, rapidly growing human activities, particularly in the areas of agriculture, fossil fuel use, and waste disposal, have more than doubled methane emissions. Atmospheric methane concentrations have increased by a factor of 2 -3 in response to this increase, and continue to rise. These increasing concentrations have raised concern due to their potential effects on atmospheric chemistry and climate. Methane is important to both tropospheric and stratospheric chemistry, significantly affecting levels of ozone, water vapor, the hydroxyl radical, and numerous other compounds. In addition, methane is currently the second most important greenhouse gas emitted from human activities. On a per molecule basis, it is much more effective a greenhouse gas than additional CO 2 . In this review, we examine past trends in the concentration of methane in the atmosphere, the sources and sinks that determine its growth rate, and the factors that will affect its growth rate in the future. We also present current understanding of the effects of methane on atmospheric chemistry, and examine the direct and indirect impacts of atmospheric methane on climate. D

Climate Change detection over different land surface vegetation classes

“…For example, the atmospheric methane concentration has a close relationship to the atmospheric temperature record (Wuebbles and Hayhoe, 2001), and the emission of methane from melting tundra increases in association with surface warming of this region. Different biota also respond to surface temperature changes through different mechanisms.…”

Methane production induced by dimethylsulfide in surface water of an upwelling ecosystem

“…It is mainly produced by biological (anaerobic) activity and accumulated through geological processes such as gas hydrate or other CH 4 deposition pathways (Wuebbles and Hayhoe, 2002). The ocean surface acts as a net source of atmospheric CH 4 , although its release is minor compared with natural emissions on land (Cicerone and Oremland, 1988).…”

Quantifying rates of methanogenesis and methanotrophy in Lake Kinneret sediments (Israel) using pore‐water profiles

“…Among the natural sources, continental emissions contribute more than 70% (Wuebbles and Hayhoe 2002); however, the parameters controlling these emissions are not well understood. Therefore, it is essential to resolve the rate of the processes behind CH 4 emissions from continental systems.…”