Another Study Identifies Wetlands as a Primary Driver of Global Methane Levels

by Ryan Streams, Manager of Regulatory Affairs on August 30, 2017 - 11:43am

The Proceedings of the National Academy of Sciences recently published a study by scientists from the Swiss Federal Research Institute, Montana State University, and the Chinese Academy of Sciences that joins the growing body of evidence that natural sources of methane far outpace those from the oil and natural gas industry.

Study authors conclude, “climate mitigation policies must consider mitigation of wetland [methane] feedbacks to maintain average global warming below 2°C.” Currently, that policy gap is largely unaddressed.

Instead, we’ve seen intense focus on oil and natural gas production emissions while much larger sources remain unaddressed. Methane emissions from the oil and natural gas industry globally are about 67 teragrams (Tg) according to EPA estimates. That figure includes all aspects of industry, from drilling and production through the local distribution networks that deliver natural gas into homes. By comparison, wetlands contribute 2.6 times that amount, at 172 Tg. By the end of the century, study authors predict that number will increase to 221-338 Tg per year.

As industry continues its success in reducing emissions while wetland methane continue to grow, these natural sources could overwhelm industry’s contribution to global methane levels. The study finds that under certain scenarios, wetlands could “dominate anthropogenic [methane]” by the end of the century. The study did not look at other sources of methane such as oceans and natural seeps.

While industry emissions remain an easy target for regulators, the study calls into question whether they’re the most effective path to reducing global methane levels. In fact, it appears that one of the primary tools for evaluating the sources and impacts of climate change doesn’t even contemplate increases in methane from wetlands and other natural sources. The study authors note that the Integrated Assessment Models assume anthropogenic sources are the only drivers of increased atmospheric methane even though natural sources are large and increasing. Integrated Assessment Models are used by policymakers to estimate the costs and risk of climate changes, as encapsulated in the social cost of carbon and methane, and to develop rules to address it.

The failure to include natural sources is a weakness in the Integrated Assessment Models. How can policymakers assume that regulating oil and natural gas emissions is an effective way to reduce atmospheric methane when sources nearly three times as big aren’t even contemplated in the models? If they truly want to get serious about addressing global methane levels, they need to stop nibbling around the edges by focusing on just one industry and avoiding larger sources.

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