Changes in global fire regimes under idealized overshoot scenarios

Within the framework of the project IMPOSE (Emit now, mitigate later? IMPlications of temperature OverShoots for the Earth system) six idealized emission-overshoot simulations have been performed with the Earth System Model NorESM2-LM2 and used as forcing for the 2^nd generation dynamic global vegetation model LPJ-GUESS with its fire-model SIMFIRE-BLAZE to investigate the impact of different CO₂ overshoots on global wildfire regimes.

The simulations describe a set of scenarios with high, medium, and low accumulative CO₂ emissions and each of which has a short (immediate) and a long (100 years) peak of accumulative CO₂ emissions before declining towards a baseline simulation of 1500 PgC accumulatively emitted within the first 100 years.

The results show that the height of the overshoot has an impact on global fire regimes while its duration does not seem to play a significant role 200 years after peak CO₂. Overall, we can see that changes in vegetation composition following the temperature anomaly are the main driver for changes in global wildfire frequency. While in the low overshoot scenarios burnt area has almost converged towards the baseline simulation, the extremest scenarios show the lowest burnt area at the end of the simulation period, indicating that vegetation changes, especially in low latitudes, have been most significant and/or are still ongoing.