Permafrost is a sub-ground phenomenon and therefore cannot be directly observed from space. It is an Essential Climate Variable and associated with climate tipping points. Multi-annual time series of permafrost ground temperatures can be, however, derived through modelling of the heat transfer between atmosphere and ground using landsurface temperature, snow- and landcover observations from space. Results show that the northern hemisphere permafrost ground temperatures have increased on average by about one degree Celsius since 2000. This is in line with trends of permafrost proxies observable from space: surface water extent has been decreasing across the Arctic; the landsurface is subsiding continuously in some regions indicating ground ice melt; hot summers triggered increased subsidence as well as thaw slumps; rock glaciers are accelerating in some mountain regions. The applicability of satellite data for permafrost proxy monitoring has been demonstrated mostly on a local to regional scale only. There is still a lack of consistency of acquisitions and of very high spatial resolution observations. Both are needed for implementation of circumpolar monitoring of lowland permafrost. In order to quantify the impacts of permafrost thaw on the carbon cycle, advancement in wetland and atmospheric greenhouse gas concentration monitoring from space is needed.

永久冻土是一种地下现象，因此无法从太空直接观察到。它是一个基本气候变量，与气候临界点有关。然而，多年冻土地面温度的多年时间序列可以通过使用地表温度、积雪和空间土地覆盖观测资料对大气和地面之间的热传递进行建模来导出。结果表明，自 2000 年以来，北半球永久冻土层地面温度平均增加了约 1 摄氏度。这与从太空观测到的永久冻土代理趋势一致：整个北极的地表水范围一直在减少；地表在一些地区持续下沉，表明地面冰融化；炎热的夏季引发了更多的沉降以及解冻坍塌；一些山区的岩石冰川正在加速形成。卫星数据对永久冻土代理监测的适用性主要仅在局部到区域范围内得到证明。采集和非常高空间分辨率的观测仍然缺乏一致性。两者都是实施低地永久冻土的极地监测所必需的。为了量化永久冻土融化对碳循环的影响，需要在湿地和大气温室气体浓度监测方面取得进展。两者都是实施低地永久冻土的极地监测所必需的。为了量化永久冻土融化对碳循环的影响，需要在湿地和大气温室气体浓度监测方面取得进展。两者都是实施低地永久冻土的极地监测所必需的。为了量化永久冻土融化对碳循环的影响，需要在湿地和大气温室气体浓度监测方面取得进展。