Lawrence Berkeley National Laboratory scientists determined that increased levels of methane in the atmosphere cause an increase in the greenhouse gas effect — a discovery that has never been made before in the field.
The greenhouse effect is when the sun’s warmth is trapped by greenhouse gases such as carbon dioxide and methane. The study, which was published in the journal Nature Geoscience on April 2, utilized the instruments and data at the U.S. Department of Energy Atmospheric Radiation Measurement, or ARM, Southern Great Plains central facility. The researchers used a spectrometer, which measures light at different wavelengths, to measure methane’s greenhouse effect.
“People have been measuring concentrations for a long time, but it’s actually much less straightforward to measure the greenhouse effect,” said Daniel Feldman, the study’s lead author and Berkeley Lab research scientist.
To ensure accurate results, the research group took into account the effects of clouds, temperature and humidity with various instruments.
“It is insufficient to just have measurements of the concentration,” Feldman said, stressing the importance of factors that contribute to the signal.
The facility gathered data from 2002 to 2012. It found that after a stable concentration until 2006, methane concentration in the atmosphere increased across time.
Methane was studied specifically because it is a much stronger greenhouse gas than carbon dioxide on a molecular basis, according to Feldman. Global Warming Potential, or GWP, compares the global warming impacts of different gases. While methane ranges from 28-36 GWP, carbon dioxide has a GWP of 1, according to the Environmental Protection Agency — methane has roughly 30 times more potential to trap heat.
Methane is also classified as a long-lived greenhouse gas, which means it can stay in the atmosphere for a long time, according to the Intergovernmental Panel on Climate Change.
The Berkeley Lab research group collected its observations in the field, whereas all previous estimates of methane’s greenhouse effect were derived from laboratory data.
“No one’s done it before — we have the tools to do it,” Feldman said. “I was lucky enough to be the beneficiary of a large number of contributors, co-authors, and data sets that have built of over time to understand the different aspects of the earth atmosphere system.”