Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl
Methane is the second strongest anthropogenic greenhouse gas and its atmospheric burden has more than doubled since 1850. Methane concentrations stabilized in the early 2000s and began increasing again in 2007. Neither the stabilization nor the recent growth are well understood, as evidenced by multiple competing hypotheses in the literature over the past 12 months. Current hypotheses in the literature include: Asian livestock, tropical wetlands, US methane, and Northern hemispheric fossil fuels. This talk will address two main questions: (1) "What are the drivers of the decadal trends in atmospheric methane?" and (2) "Why do so many, apparently, plausible explanations disagree with each other?"