Natural greenhouse gas emissions could speed up climate change more than expected

Natural greenhouse gas emissions contribute to climate change alongside man-made gasses– and the rate of natural emissions will rise as the climate changes, meaning that the effects of global warming will progress more quickly than previously believed, researchers at Linköping University’s Tema Environmental Change center report in a new study.

Sivakiruthika Natchimuthu, a doctoral student at the university has spent the last two years examining greenhouse gas emissions alongside her colleagues, including their most recent project measuring natural methane emissions. Each study came to effectively the same conclusion: as the temperature rises, natural greenhouse gas emissions will increase.

As Natchimuthu explained in a statement, “Everything indicates that global warming caused by humans leads to increased natural greenhouse gas emissions. Our detailed measurements reveal a clear pattern of greater methane emissions from lakes at higher temperatures.”

She and her co-authors examined methane emissions from three lakes, and found that emissions of the gas increased exponentially along with temperature. As the team wrote in the latest issue of the journal Limnology and Oceanography, a temperature increase of 15 to 20 degrees Celsius nearly doubled the methane level at those lakes.

Reducing human-caused gas emissions twice as effective

While anthropogenic (human-caused) greenhouse gas emissions are regularly included in climate models, the future behavior of naturally-occurring emissions has been unclear, the study authors explained. Their findings indicate that there is a cycle in which human-caused emissions result in higher temperatures, in turn leading to increased natural emissions and higher temperatures.

“We’re not talking about hypotheses anymore,” said co-author David Bastviken, a professor at Tema Environmental Change, Linköping University. “The evidence is growing and the results of the detailed studies are surprisingly clear. The question is no longer if the natural emissions will increase but rather how much they will increase with warming.”

As a result, he said, climate change will take place faster than had been anticipated by models using anthropogenic greenhouse gas emissions alone. In addition, this indicates that reductions in the burning of fossil fuels or other human-caused activity would be twice as effective – not only would it reduce the direct impact on climate change, but it would lessen the ensuing natural greenhouse gas emissions that would result from hotter conditions.

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