The permafrost response to the Arctic vegetation variation is controversial. We simulated the consequences of the Arctic vegetation variation in the recent three decades in the Community Earth System Model, and found the Arctic vegetation variation is too weak to directly affect the permafrost. However, it induces the air temperature perturbation, which is amplified by the snow cover variation, and finally leaves a footprint on the soil temperature. On the location of the maximum LAI increase, the soil temperature at 1m depth is affected little, however, we found significant soil warming along the summer snowline between the Low and High Arctic, indicating the direct impact of the snow cover variation. In the Low Arctic, the winter snowpack insulates the soil from the colder air, and results in less permafrost; in the High Arctic, the snow persists in the summer and has a stronger opposite effect on the permafrost, by insulating the soil from the warmer summer air, and reflecting the solar radiation.

Acknowledgments: This work was supported by the Korea Polar Research Institute (KOPRI, PN17081 and PE17900) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2015R1C1A2A01054800).