Precipitation drives ice growth in Tibetan permafrost despite warming
Researchers found that increased rainfall is causing ground ice to grow in parts of the Tibetan Plateau even as temperatures rise.
A new study led by Li Dongfeng at Peking University discovered that over a third of the plateau permafrost gained ice since 2000. Stronger westerly winds brought more rain and snow which seeped into the ground during summer months.
The team compared boreholes drilled before and after the year 2000 to measure how much underground ice was present in specific locations. They found that newer holes generally held more ice, especially near the lowest part of the seasonal melt zone.
Weather records indicate that annual precipitation in the westerly-influenced interior area increased significantly by 60% following the year 2000. This extra moisture soaks deep into the soil and freezes again in the permanently cold subsoil layers over time.
A computer model simulation confirmed that rapid increases in precipitation may outweigh temperature changes in driving ground ice evolution on the plateau. When temperature was held steady while rain levels increased, the model showed that ground ice continued to grow significantly.