Threshold sensitivity of shallow Arctic lakes and sublake permafrost to changing winter climate

摘要: Interactions and feedbacks between abundant surface waters permafrost fundamentally shape lowland Arctic landscapes. Sublake is maintained when the maximum ice thickness (MIT) exceeds lake depth mean annual bed temperatures (MABTs) remain below freezing. However, declining MIT since 1970s likely causing talik development shallow lakes. Here we show high-temperature sensitivity to winter growth at water-sediment interface of lakes based on year-round sensor data. Empirical model experiments suggest that (1m depth) have warmed substantially over last 30years (2.4°C), withMABT above freezing5 7years.This incomparison slower ratesofwarming in deeper (3 m) (0.9°C), with already well-developed taliks. Our findings indicate has begun crossing a critical thawing threshold approximately 70 years prior predicted terrestrial thaw northern Alaska.