Thawing¹（融化） permafrost will have far-reaching ramifications²（分枝，分叉） for populated areas, infrastructure³ and ecosystems⁴. A geographer⁵ from the University of Zurich reveals where it is important to confront the issue based on new permafrost maps -- the most precise global maps around. They depict⁶ the global distribution of permafrost in high-resolution images and are available on Google Earth. Unstable⁷ cable-car and electricity pylons⁸ and rock fall -- Alpine⁹ countries like Switzerland have already had first-hand experience of thawing permafrost as a result of climate change. If temperatures continue to rise, the problem will intensify¹⁰ in many places. Permafrost, namely rock or soil with a negative temperature for at least two years, occurs in the subsurface and therefore cannot be mapped directly. The existing maps are thus fraught¹¹ with major uncertainties¹² that have barely been studied or formulated¹³. Furthermore, due to the different modeling methods used the maps are difficult to compare.

Now, however, glaciologist（冰河学家） Stephan Gruber from the University of Zurich has modeled the global permafrost zones for the first time in high resolution and using a consistent method. In his study recently published in The Cryosphere, the scientist estimates the global permafrost regions at 22 million square kilometers -- a sixth of the world's exposed land surface. With a grid¹⁴ resolution of one square kilometer, Gruber's maps are the most precise permafrost maps in the world..

A large proportion of the permafrost zones lie outside the areas that exhibit continuous permafrost in the subsurface. At relatively¹⁵ small distance, permafrost can here occur right next to non-permafrost ground. In other words, the spatial¹⁶ distribution（空间分布） of permafrost resembles a patchwork¹⁷ quilt, which makes it extremely difficult to identify zones with permafrost in such areas. This is where Gruber's innovative¹⁸ permafrost maps come in: They are based on high-resolution air temperature and elevation¹⁹（高地，海拔） data. Moreover, they reveal an index that indicates the probability of permafrost. The permafrost areas are depicted²⁰ in grades -- from dark blue for near-continuous permafrost to yellow for areas with little permafrost. In contrast to previous permafrost maps, which show clearly defined zones, Gruber's maps also
illustrate²¹ the uncertainty²² of the state of research.

The scientist explains his motivation with the urgency of the matter: "As a result of climate change, areas with permafrost have great potential for unpleasant surprises. That is why it is all the more important for politics and the public to be aware of the problem of thawing permafrost. My maps visualize²³ the otherwise barely visible phenomenon of permafrost."