Airborne Mapping Reveals Emergent Power Law of Arctic Methane Emissions

Methane (CH₄) emissions from thawing permafrost amplify a climate warming feedback. However, upscaling of site-level CH₄ observations across diverse Arctic landscapes remains highly uncertain, compromising accuracy of current pan-Arctic CH₄ budgets and confidence in model forecasts. We report a 30,000-km² survey at 25-m² resolution (~1 billion observations) of CH₄ hotspot patterns across Alaska and northwestern Canada using airborne imaging spectroscopy. Hotspots covered 0.2% of the surveyed area, concentrated in the wetland-upland ecotone, and followed a two-component power law as a function of distance from standing water. Hotspots decreased sharply over the first 40 m from standing water (y = 0.21×^-0.649, R² = 0.97), mirroring in situ flux observations. Beyond 40 m, CH₄ hotspots diminished gradually over hundreds of meters (y = 0.004×^-0.164, R² = 0.99). This emergent property quantifies the distribution of strong methanogenic zones from site to regional scales, vastly improving metrics for scaling ground-based CH₄ inventories and validation of land models.