A new study from Portland State University shows methane emissions from fossil fuel production have been on the rise since 1984.
The study, published in Proceedings of the National Academy of Sciences, found evidence that methane emissions from gas and oil extraction increased significantly between 1984 and 2009.
The results challenge two previous studies, including one published in Science earlier this year, that suggest that methane emissions from fossil fuels have declined since the early 1980s.
“The results surprised us,” said Dr. Andrew Rice, an associate professor of physics and fellow of the Institute for Sustainable Solutions at PSU. “We anticipated the modeling would indicate what other scientists had concluded, that methane emissions from oil and gas production were trending down globally, but we found the opposite.”
Studies have identified multiple sources that contribute to global methane emissions, including farms, wetlands, and wildfire, as well as oil and gas production. Identifying sources responsible for changes in atmospheric methane concentrations, however, proved more difficult.
“Regulators at agencies like the EPA need a comprehensive understanding of what’s driving the shift in greenhouse gas concentrations if they are going to regulate their emissions,” said Rice.
In addition to increases from oil and gas, the research team identified other anthropogenic sources of methane production, all of which were slightly offset by reductions in emissions from wetland and wildfires.
To arrive at their results, the research team analyzed the isotopic composition of atmospheric methane in air samples collected from sites around the world between 1977 and 1998. The results of that analysis was combined with contemporary data to model changes in methane sources between 1984 and 2009. Findings indicate methane emissions from fossil fuel sources were level in the 1980s and 1990s, but increased throughout the following decade.
The research was funded through support from the US National Science Foundation, the Miller Foundation, and the MJ Murdock Charitable Trust.