Observation-constrained sensitivities of Arctic methane emissions to warming.
basic_science · Level V
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- Record sourced from PubMed, PMID 42372146.
- Also identified by DOI 10.1073/pnas.2523274123.
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Abstract
The sensitivity of pan-Arctic (60 to 90°N) natural methane emissions to climate warming lacks direct observational constraints. Long-term atmospheric measurements of methane, which reflect integrated Arctic fluxes and atmospheric transport, show that in the pan-Arctic the autumn-to-winter CH<sub>4</sub> build-up (as indicated by the "autumn zero crossing date") is becoming earlier. This advancing trend in autumn zero crossing date is explained by growing natural Arctic CH<sub>4</sub> emissions in response to climate warming in July, August and September, with a rate of increase of 0.14 ± 0.04 Tg CH<sub>4</sub> y<sup>-2</sup> during the period 1998-2020. Atmospheric <i>δ</i><sup>13</sup>C<sub>CH4</sub> observational records allowed us to attribute this increase to 0.08 ± 0.02 Tg CH<sub>4</sub> y<sup>-2</sup> from natural biogenic emissions (wetlands, lakes, permafrost soils) and 0.06 ± 0.02 Tg CH<sub>4</sub> y<sup>-2</sup> from wildfire emissions. Our results point to a larger warming sensitivity of natural emissions (3.1 ± 0.9 Tg CH<sub>4</sub> y<sup>-1</sup> per °C) than previous estimates, and potentially a larger positive feedback on climate warming.