The extended growing season in the Arctic that has occurred as a result of the warming climate does not offset the carbon emissions being caused by permafrost thaw, according to a study by the Woods Hole Research Center.

According to Permafrost degradation stimulates carbon loss from experimentally warmed tundra, published in the journal Ecology, results show that while permafrost degradation increased carbon uptake during the growing season, in line with decadal trends of “greening” tundra, warming and permafrost thaw also enhanced winter respiration, which doubled annual carbon losses.

Permafrost contains three-to-seven times the amount of carbon sequestered in tropical forests. The warming climate threatens to thaw permafrost, which will result in the release of carbon dioxide and methane into the atmosphere creating feedbacks to climate change – more warming and greater permafrost thaw, according to the study, which was lead by Susan M. Natali.

The three-year-long Carbon in Permafrost Experimental Heating Research project warmed air and soil and thawed permafrost using two warming experiments. The “winter warming” treatment consisted of snow packs, which functioned like down comforters insulating the ground during the winter until the snow was removed at the start of the growing season. The “summer warming” treatment consisted of open-topped greenhouses that warmed the air during the summer. The team measured warming effects on CO2 uptake by plants and release by plants and microbes.

Scientists estimate that within the next century permafrost will have declined 30 percent to 70 percent and there is limited accounting of how much carbon is stored in these frozen soils or the rate at which it will be released.

Click here for projections of emissions as a result of permafrost thaw from 2100 to 2300.