Warming effects of spring rainfall increase methane emissions from thawing permafrost: Site level data from bog complex I Water Table Depth 2014 2016

Methane emissions regulate the near-term global warming potential of permafrost thaw, particularly where loss of ice-rich permafrost converts forest and tundra into wetlands. Northern latitudes are expected to get warmer and wetter, and while there is consensus that warming will increase thaw and methane emissions, effects of increased precipitation are uncertain. At a thawing wetland complex in Interior Alaska, we found that interactions between rain and deep soil temperatures controlled methane emissions. In rainy years, recharge from the watershed rapidly altered wetland soil temperatures, warming the top~ 80 cm of soil in spring and summer, and cooling it in autumn. When soils were warmed by spring rainfall, methane emissions increased by~ 30%. The warm, deep soils early in the growing season likely supported both microbial and plant processes that enhanced emissions. Our study identifies an important and unconsidered role of rain in governing the radiative forcing of thawing permafrost landscapes. All site-level data from the studied bog, eddy covariance and micrometeorological data referenced in the published manuscript are available in the LTER data repository. These data are related to the following data package: Surface carbon, water and energy fluxes measured by eddy covariance at 3 sites within the Alaska Peatlands Experiment and Bonanza Creek Experimental Forest 2013-2016 (http://dx. doi. org/10.6073/pasta/4fabab3846113a1866b06f1b3d6d52a3).