Reversibility of permafrost carbon pool changes under temperature overshoot scenarios

Most pathways that meet the Paris Agreement goal of limiting the global temperature increase to well below 2°C above preindustrial levels will require a temporary exceedance ("overshoot") of the target temperature. If the target temperature is exceeded, a larger proportion of high-latitude permafrost soils will thaw, releasing additional carbon. The goal of this thesis is to examine whether permafrost carbon loss during the temperature overshoot phase is reversible if the temperature is restored to its target level. To attain this goal, we force an Earth system model of intermediate complexity with a set of scenarios with varying magnitudes and durations of overshoot. Results show that high-latitude soil carbon changes in response to overshoot are dependent on peak warming and the duration of time that excess warming is held. Continued decline of the permafrost region soil carbon pool following temperature restoration suggests that changes are irreversible for at least several centuries.