Current climate change models greatly underestimate the amount of methane being released by thawing permafrost in the Canadian Arctic, according to Canada's National Institute of Scientific Research (INRS).
Canadian, French and US researchers from the INRS have been studying the methane and greenhouse gas emissions in small thaw ponds, concluding that the emissions could have a significant climate impact.
"We discovered that although the small shallow ponds we studied represent only 44 percent of the water-covered surface in a Bylot Island valley, they generate 83 percent of its methane emissions," said Karita Negandhi, a water sciences doctoral student at the INRS's Environment Research Center.
The researchers conducted a field study on Bylot Island in the northern Nunavut territory's Sirmilik National Park. There, they analyzed ponds of different shapes and sizes and studied the ponds' various physicochemical properties and microbial ecology. By employing radiocarbon dating techniques, as well as new-generation molecular tools to study the sediment and water microbial communities involved in carbon transformation processes, the researchers were able to calculate the greenhouse gas emissions from the Arctic ponds.
"The isotopic signatures of the methane emitted by these small ponds indicate that this greenhouse gas comes partly from old carbon reserves that have been sequestered in the permafrost for millennia. As the permafrost thaws, organic matter is becoming more abundant, promoting the proliferation of aquatic microbes such as methanogenic Archaea, which use various sources of carbon, then release it into the atmosphere in the form of methane and CO2," the researchers said in a statement. "Consequently, longer summers could lead to an increase in these emissions."
Until now, these small ponds have been studied very little, largely due to their remote location and the logistical restraints of studying in the Canadian Arctic.
"However in the context of global warming, they are worth examining more closely, as they could have an increasingly significant incidence on the transfer of greenhouse gases into the atmosphere in the future," the statement concluded.
The INRS research is published in the journal PLOS One in an article titled "Small thaw ponds: an unaccounted source of methane in the Canadian High Arctic."
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