Quantifying Arctic-boreal methane emissions using atmospheric observations and a global inverse model

Area of Science:

• Earth and Environmental Sciences
• Atmospheric Science
• Climate Science

Background:

• The Arctic-Boreal region is highly susceptible to climate change, with permafrost thaw and warming potentially increasing methane (CH4) emissions.
• This region is anticipated to become a major source of atmospheric CH4.

Purpose of the Study:

• To estimate CH4 fluxes in the Arctic-Boreal region using a global atmospheric inverse model.
• To analyze trends and regional variations in CH4 emissions from 2010 to 2021.
• To understand the influence of environmental factors on CH4 emissions.

Main Methods:

• Assimilation of atmospheric CH4 mixing ratio data from a regional network into a global atmospheric inverse model.
• Quantification of CH4 fluxes and uncertainty reduction across the Arctic-Boreal domain.
• Analysis of CH4 emission trends and their correlation with temperature and hydroclimate variables.

Main Results:

• The Arctic-Boreal region emitted an average of 45.4 ± 0.7 TgCH4 y-1 (approximately 7% of global emissions) between 2010 and 2021, with no significant overall trend.
• A positive CH4 emission trend was observed in the Western Siberia Lowlands.
• Arctic-Boreal wetland emissions correlated positively with warmer years, and winter hydroclimate changes influenced emissions in Western Siberia.

Conclusions:

• While overall Arctic-Boreal CH4 emissions show no significant trend, regional hotspots like Western Siberia are increasing.
• Future increases in Arctic-Boreal CH4 emissions are possible due to continued warming.
• Accurate assessment of future Arctic CH4 emissions requires consideration of both temperature and wetness changes.