Methane: Signs of progress along the road

摘要

Analyses of air bubbles within ice cores suggest that the concentration of atmospheric methane remained fairly steady from 1500 BC to 1700 AD. However, with the dawn of the Industrial Revolution atmospheric methane concentrations began to increase. Recent findings of Simpson et al. (2006) have shown that the growth in the concentration of tropospheric methane has leveled off based on air sampling conducted throughout the Pacific basin (71 deg N-47 deg S) over the last seven years. Methane is second only to carbon dioxide in terms of importance in climatic greenhouse warming scenarios. This plateau is in stark contrast to the increasing atmospheric methane concentrations during the 1980s, where the concentration grew by an average of 15 ppbv yr~(-1) (Blake and Rowland, 1988). This slow-down in the growth of methane is positive news in terms of human interaction in reducing greenhouse gas emissions. In my view, there are two important thoughts related to these recent findings that I would like to share: (1) the reduction in the sources of methane, and (2) the importance of actual measurements versus modeled data.