Climate-carbon feedback tradeoff between Arctic and alpine permafrost under warming

Area of Science:

• Environmental Science
• Climate Science
• Ecology

Background:

• Permafrost thaw due to global warming may release greenhouse gases (GHGs), potentially creating positive climate feedbacks.
• The net effect of permafrost GHG emissions on global warming remains uncertain, particularly across different regions.

Purpose of the Study:

• To synthesize the impact of experimental warming (~2°C) on growing season carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from alpine and Arctic permafrost.
• To determine regional differences in permafrost's response to warming and its implications for climate feedback.

Main Methods:

• Experimental warming of ~2°C applied to permafrost in alpine and Arctic regions.
• Measurement of growing season carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions.
• Analysis of soil moisture effects on GHG emissions in response to warming.

Main Results:

• Warming weakened the GHG sink in alpine permafrost, increasing its global warming potential by 13%.
• Warming strengthened the GHG sink in Arctic permafrost, decreasing its global warming potential by 10%.
• Warming-induced drying in alpine permafrost weakened CO2 uptake but enhanced CH4 uptake, while warming wet Arctic permafrost increased CO2 uptake and CH4 emissions. N2O emissions increased more in alpine than Arctic permafrost.

Conclusions:

• Keeping additional warming below 2°C in permafrost regions can potentially avoid a positive permafrost-climate feedback.
• Measures are necessary to preserve the vulnerable carbon sink function of alpine permafrost ecosystems.