Global warming will progress faster than what was previously believed as greenhouse gas emissions that arise naturally are also affected by increased temperatures, a new study from Linköping University that measures natural methane emissions has confirmed.

“Everything indicates that global warming caused by humans leads to increased natural greenhouse gas emissions,” said Sivakiruthika Natchimuthu, doctoral student at Tema Environmental Change, Linköping University, Sweden, and lead author of the latest publication on this topic from her group. “Our detailed measurements reveal a clear pattern of greater methane emissions from lakes at higher temperatures.”

Over the past two years the research team at Linköping University has contributed to numerous studies that all point in the same direction: natural greenhouse gas emissions will increase when the climate gets warmer.

In the latest study appearing in the journal Limnology and Oceanography, the researchers examined the emissions of the greenhouse gas methane from three lakes and the effects were clear: the methane emissions increased exponentially with temperature.

Their measurements show that a temperature increase from 15 to 20 degrees Celsius almost doubled the methane level.

While increased anthropogenic emissions of greenhouse gases are expected and included in climate predictions, the future development of the natural emissions has been less clear.

Exponential relationship of lake average total CH4 fluxes from all depths with average water (a,b,c) and air temperature (d,e,f). Open circles denote data from 2012 and closed circles. The arrows indicate data during the low pressure event in September, 2013. ERS, FJS and SKS denote Erssjön, Följesjön and Skottenesjön respectively. The water temperature was measured frequently and averaged over the deployment period in Erssjön and Följesjön. In Skottenesjön water temperature was measured during start and stop of deployment only, which could explain the stronger relationship with air temperature than the water temperature.

The recent findings point to a vicious circle: greenhouse gas emissions from the burning of fossil fuels lead to higher temperatures, which in turn lead to increased natural emissions and further warming.

“We’re not talking about hypotheses anymore,” said David Bastviken, 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,”

Their findings, the researchers conclude, means that warming will be faster than expected from anthropogenic greenhouse gas emissions alone.

Professor Bastviken has a message for the world leaders heading to France for the 2015 Paris Climate Conference – COP21: any reductions in anthropogenic greenhouse emissions is a double victory, by both reducing the direct effect on warming, but also by preventing the feedback with increased natural emissions.