Arctic and sub-Arctic soil emissions: possible implications for global climate change

• Published in: Polar Record
• Main Author: Christensen, Torben
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1991
• Subjects: General Earth and Planetary Sciences; Ecology; Geography, Planning and Development; Arctic; Climate change; Polar Record; Thermokarst; Tundra
• Online Access: http://dx.doi.org/10.1017/s0032247400012584; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0032247400012584

Abstract Climate models predict a substantial warming at high latitudes following the enhanced greenhouse effect caused by anthropogenic emissions of carbon dioxide (CO 2 ), methane (CH 4 ), and various other trace gases. Arctic and sub-Arctic soils contain large amounts of organic carbon that could be made increasingly available for decomposition in a wanner climate due to deepening of the biologically-active layer and increased thermokarst erosion. This produces the potential for increased emissions of CO 2 and CH 4 from tundra areas and thus positive (enhancing) feedback effects on the greenhouse effect. From being a net absorber of CO 2 the global tundra areas could become a net source of up to 1.25 Gt C yr 1 as a result of the predicted warmer and dryer conditions during the thaw period. CH 4 is at least 21 times more effective as a greenhouse gas than CO 2 . How the CH 4 balance in the tundra will respond to climate change is therefore very important but also much less certain. Estimates of total present CH 4 emissions from northern wetlands vary greatly, ranging from 2.4 to 106 Tg CH 4 yr 1 and little is known about the mechanisms controlling the flux. There are indications, however, that if the tundra becomes wetter under warming, CH 4 emissions would probably increase. If it becomes dryer, the emissions could cease or even turn the tundra into a sink for atmospheric CH 4 , partly due to increasing microbial consumption of CH 4 in the soil. There is an urgent need for more research into the processes controlling the CH 4 flux in Arctic and sub-Arctic soils.