More than 80% of studies reporting the area on Earth underlain by permafrost refer to the extent of the permafrost region, which accounts for around 21 million km² (22% of the Northern Hemisphere's exposed land surface). Since each permafrost zone (continuous, discontinuous, sporadic, and isolated, which combined represent the permafrost region) is not entirely underlain by permafrost, the actual area underlain by permafrost (permafrost area) accounts for approximately 14 million km² (15% of the exposed land surface area in the Northern Hemisphere). Such overstatements create a general impression that there is 6 million km² more permafrost than currently estimated. I highlight the known differences between the terms permafrost region and permafrost area, along with explaining the possible reasons leading to these overstatements. Recent studies estimating permafrost area extent are summarized to provide a baseline for the geoscientific community and general public about the actual area underlain by permafrost for different parts of the globe.

中文翻译：

---

多年冻土层覆盖了地球表面的多少？

研究报告下伏冻土地球上面积超过80％指的程度多年冻土区，占公里左右2100万²（北半球的暴露陆地表面的22％）。由于每个多年冻土带（连续，不连续，零星和孤立的区域，总起来代表了多年冻土区域）并不完全被永久冻土覆盖，因此，实际的永久冻土覆盖区域（永久冻土区域）约占1400万km ²（占总冻土的15％）。北半球裸露的陆地表面积）。这种夸大的说法给人的总体印象是，有600万公里²多年冻土比目前估计的多。我重点介绍了多年冻土区和多年冻土区这两个术语之间的已知差异，并解释了导致这些高估的可能原因。总结了估计多年冻土面积范围的最新研究，为地球科学界和公众提供了全球不同地区多年冻土所覆盖的实际面积的基准。