Reduced net methane emissions due to microbial methane oxidation in a warmer Arctic
Methane emissions from organic-rich soils in the Arctic have been extensively studied due to their potential to increase the atmospheric methane burden as permafrost thaws 1 – 3 . However, this methane source might have been overestimated without considering high-affinity methanotrophs (HAMs; methan...
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Published in | Nature climate change Vol. 10; no. 4; pp. 317 - 321 |
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Main Authors | , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
01.04.2020
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | Methane emissions from organic-rich soils in the Arctic have been extensively studied due to their potential to increase the atmospheric methane burden as permafrost thaws
1
–
3
. However, this methane source might have been overestimated without considering high-affinity methanotrophs (HAMs; methane-oxidizing bacteria) recently identified in Arctic mineral soils
4
–
7
. Herein we find that integrating the dynamics of HAMs and methanogens into a biogeochemistry model
8
–
10
that includes permafrost soil organic carbon dynamics
3
leads to the upland methane sink doubling (~5.5 Tg CH
4
yr
−1
) north of 50 °N in simulations from 2000–2016. The increase is equivalent to at least half of the difference in net methane emissions estimated between process-based models and observation-based inversions
11
,
12
, and the revised estimates better match site-level and regional observations
5
,
7
,
13
–
15
. The new model projects doubled wetland methane emissions between 2017–2100 due to more accessible permafrost carbon
16
–
18
. However, most of the increase in wetland emissions is offset by a concordant increase in the upland sink, leading to only an 18% increase in net methane emission (from 29 to 35 Tg CH
4
yr
−1
). The projected net methane emissions may decrease further due to different physiological responses between HAMs and methanogens in response to increasing temperature
19
,
20
.
Models overestimate Arctic methane emissions compared to observations. Incorporating microbial dynamics into biogeochemistry models helps reconcile this discrepancy; high-affinity methanotrophs are an important part of the Arctic methane budget and double previous estimates of methane sinks. |
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ISSN: | 1758-678X 1758-6798 1758-6798 |
DOI: | 10.1038/s41558-020-0734-z |