David R. Thompson Andrew K Thorpe Hrishikesh Chandanpurkar Philip J Hanke Nicholas Hasson Stephanie R. James Burke J. Minsley Neal J. Pastick David Olefeldt Katey M Walter Anthony Charles E. Miller Clayton D. Elder 2021 <div class="article-section__content en main"><p>Methane (CH₄) emissions from climate-sensitive ecosystems within the northern permafrost region represent a potentially large but highly uncertain source, with current estimates spanning a factor of seven (11–75&nbsp;Tg CH₄<span>&nbsp;</span>yr⁻¹). Accelerating permafrost thaw threatens significant increases in pan-Arctic CH₄<span>&nbsp;</span>emissions, amplifying the permafrost carbon feedback. We used airborne imaging spectroscopy with meter-scale spatial resolution and broad coverage to identify a previously undiscovered CH₄<span>&nbsp;</span>emission hotspot adjacent to a thermokarst lake in interior Alaska. Hotspot emissions were confined to &lt;1% of the 10&nbsp;ha lake study area. Ground-based chamber measurements confirmed average daily fluxes from the hotspot of 1,170&nbsp;mg CH₄<span>&nbsp;</span>m⁻²&nbsp;d⁻¹, with extreme daily maxima up to 24,200&nbsp;mg CH₄<span>&nbsp;</span>m⁻²&nbsp;d⁻¹. Ground-based geophysical measurements revealed thawed permafrost directly beneath the CH₄<span>&nbsp;</span>hotspot, extending to a depth of ∼15&nbsp;m, indicating that the intense CH₄<span>&nbsp;</span>emissions likely originated from recently thawed permafrost. Hotspot emissions accounted for ∼40% of total diffusive CH₄<span>&nbsp;</span>emissions from the lake study site. Combining study site findings with hotspot statistics from our 70,000&nbsp;km²<span>&nbsp;</span>airborne survey across Alaska and northwestern Canada, we estimate that pan-Arctic terrestrial thermokarst hotspots currently emit 1.1 (0.1–5.2) Tg CH₄<span>&nbsp;</span>yr⁻¹, or roughly 4% of the annual pan-Arctic wetland budget from just 0.01% of the northern permafrost land area. Our results suggest that significant proportions of pan-Arctic CH₄<span>&nbsp;</span>emissions originate from disproportionately small areas of previously undetermined thermokarst emissions hotspots, and that pan-Arctic CH₄<span>&nbsp;</span>emissions may increase non-linearly as thermokarst processes increase under a warming climate.</p></div> application/pdf 10.1029/2020GB006922 en Wiley Characterizing methane emission hotspots from thawing permafrost article