Atmospheric constraints on changing Arctic CH4 emissions

• Published in: Frontiers in Environmental Science
• Main Authors: Lan, Xin, Dlugokencky, Edward J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Frontiers Media SA 2024
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.3389/fenvs.2024.1382621; https://www.frontiersin.org/articles/10.3389/fenvs.2024.1382621/full

Rapid warming in the Arctic has the potential to release vast reservoirs of carbon into the atmosphere as methane (CH 4 ) resulting in a strong positive climate feedback. This raises the concern that, after a period of near-zero growth in atmospheric CH 4 burden from 1999 to 2006, the increase since then may be in part related to increased Arctic emissions. Measurements of CH 4 in background air samples provide useful, direct information to determine if Arctic CH 4 emissions are increasing. One sensitive first-order indicator for large emission change is the Interpolar Difference, that is the difference in surface atmospheric annual means between polar northern and southern zones (53°–90°), which has varied interannually, but did not increase from 1992 to 2019. The Interpolar Difference has increased moderately during 2020–2022 when the global CH 4 burden increased significantly, but not yet to its peak values in the late-1980s. For quantitative assessment of changing Arctic CH 4 emissions, the atmospheric measurements must be combined with an atmospheric tracer transport model. Based on multiple studies including some using CH 4 isotopes, it is clear that most of the increase in global atmospheric CH 4 burden is driven by increased emissions from microbial sources in the tropics, and that Arctic emissions have not increased significantly since the beginning of our measurement record in 1983 through 2022.