Earth’s high latitudes are projected to experience warmer and wetter summers in the future but ramifications for soil thermal processes and permafrost thaw are poorly understood. Here we present 2750 end of summer thaw depths representing a range of vegetation characteristics in Interior Alaska measured over a 5 year period. This included the top and third wettest summers in the 91-year record and three summers with precipitation close to mean historical values. Increased rainfall led to deeper thaw across all sites with an increase of 0.7 ± 0.1 cm of thaw per cm of additional rain. Disturbed and wetland sites were the most vulnerable to rain-induced thaw with ~1 cm of surface thaw per additional 1 cm of rain. Permafrost in tussock tundra, mixed forest, and conifer forest was less sensitive to rain-induced thaw. A simple energy budget model yields seasonal thaw values smaller than the linear regression of our measurements but provides a first-order estimate of the role of rain-driven sensible heat fluxes in high-latitude terrestrial permafrost. This study demonstrates substantial permafrost thaw from the projected increasing summer precipitation across most of the Arctic region.

预计地球的高纬度地区将来会经历更温暖和潮湿的夏天，但对土壤热过程和永冻土融化的后果知之甚少。在这里，我们介绍了5750年夏季融化深度的2750年底，代表了阿拉斯加内陆地区一系列植被特征。这包括91年记录中最潮湿的夏季和第三个夏季，以及降水接近历史平均水平的三个夏季。降雨的增加导致所有站点的融化都更深，每厘米额外的降雨使融化增加0.7±0.1厘米。受干扰和湿地地区最容易受到雨水诱导的解冻，每增加1 cm的雨量约有1 cm的表面解冻。丛状冻原，混交林和针叶林的多年冻土对雨水融化的敏感性较低。一个简单的能源预算模型产生的季节解冻值小于我们测量值的线性回归，但提供了降雨驱动的感热通量在高纬度陆地多年冻土中作用的一级估算。这项研究表明，预计北极地区大部分地区夏季降水会增加，从而导致多年冻土融化。