We investigated a response of permafrost using an Earth system model driven by an idealized overshooting carbon emission scenario, and found that the permafrost response to warming and cooling is reversible in the area but irreversible in its property. The permafrost response shows hysteresis, arising from a slow soil response tied to heat conductivity and specific heat of water phase change. A carbon release from thawed permafrost accounts for 0.6–41% of the cumulative carbon emission.