Time sequence of permafrost sensitivity. The change in permafrost volume divided by the change in global mean surface air temperature [ratio/degree] is shown. The width of the colored bands represents the maximum and minimum values of the simulated results forced by the five GCMs; the average value is represented by the bold lines. The simulations with the improved (left) and conventional (right) schemes under RCP2.6 (blue) and RCP8.5 (red) scenarios are shown. Anomaly of permafrost volume and surface air temperature is calculated with respect to the 1995–2014 average.