An important study on methane emissions was recently published in the journal Science which rules out fossil fuels as the major cause in the rise of methane levels in the atmosphere since 2007.
The study was conducted by scientists at the National Institute of Water and Atmospheric Research (NIWA) in Wellington, New Zealand, and U.S. researchers from the National Oceanic and Atmospheric Administration and the Institute of Arctic and Alpine Research at the University of Colorado.
This finding is important to energy supply chain companies in context with the Obama Administration's recent announcement of a new rulemaking mandating aggressive and costly new requirements for reduction of methane release from oil and gas operations. According to a release by the American Petroleum Institute, "President Obamas plans to add costly new regulations on methane when emissions are already falling could harm Americas shale energy revolution", potentially discouraging oil and gas exploration and production.
The new research, led by NIWA atmospheric scientist Hinrich Schaefer, has concluded that increasing levels of methane in the atmosphere since 2007 are most likely due to agricultural practices, and not fossil fuel production as previously thought.
Between 1999 and 2006 scientists observed a plateau in the amount of methane in the atmosphere. The amount had been steadily increasing since pre-industrial times but then levelled out for about seven years. After 2006 it began to rise again and continues to do so.
As Dr. Schaefer explains, "We found we could distinguish three different types of methane emissions. One is the burning of organic material, such as forest fires. Another is fossil fuel production the same processes that form natural oil and gas - and the third is formed by microbes which come from a variety of sources such as wetlands, rice paddies and livestock." Analysis rules out fossil fuel production as the source of methane increasing again.
"The finding of a primarily biogenic post-2006 increase [in methane] is robust. Further, it seems that fossil-fuel emissions stagnated or diminished in the 1990s. Importantly, they are a minor contributor to the renewed [CH4]-rise," said the article. The "most probable causes" of the methane spike are "either food production or climate-sensitive natural emissions," the study concluded.
"That was a real surprise, because at that time the US started fracking and we also know that the economy in Asia picked up again, and coal mining increased. However, that is not reflected in the atmosphere," Dr Schaefer said.
"Our data indicate that the source of the increase was methane produced by bacteria, of which the most likely sources are natural, such as wetlands or agricultural, for example from rice paddies or livestock."