A recent study published in the journal Nature Communications by an international team of climate scientists and permafrost experts indicates that global warming will accelerate permafrost thawing, leading to an increase in wildfires in the Subarctic and Arctic regions of northern Canada and Siberia. The study uses new climate computer model simulations to demonstrate how future anthropogenic warming will affect wildfire occurrences, taking into account the role of accelerated permafrost thawing in controlling soil water content, which is a key factor in wildfires. Previous climate models did not fully consider this interaction between global warming, permafrost thawing, soil water, and fires.
The study utilizes data generated by the Community Earth System Model, one of the most comprehensive earth system models available. This model is unique in that it captures the coupling between soil water, permafrost, and wildfires in an integrated manner. To isolate the anthropogenic effect of increasing greenhouse gas emissions from natural climate variations, the scientists conducted an ensemble of 50 simulations covering the period from 1850-2100 CE using the SSP3-7.0 greenhouse gas emission scenario on the IBS supercomputer Aleph. The results show that by the mid to late 21st century, anthropogenic permafrost thawing in the Subarctic and Arctic regions will be extensive, leading to a drop in soil moisture, surface warming, and atmospheric drying, ultimately intensifying wildfires.
The study predicts an abrupt increase in wildfires in the second half of the century, with a switch from virtually no fires to very intensive fires within just a few years. This trend is expected to be further exacerbated by the CO2 fertilization effect, which increases vegetation biomass in high latitude areas due to rising atmospheric CO2 concentrations. The release of carbon dioxide, black carbon, and organic carbon into the atmosphere from wildfires can impact climate and feedback into the permafrost thawing processes in the Arctic. However, current earth system computer models do not fully integrate interactions between fire emissions and atmospheric processes, suggesting the need for further research in this area.
To better simulate the future degradation of the complex permafrost landscape, the study emphasizes the importance of improving small-scale hydrological processes in earth system models using expanded observational datasets. Associate Prof. Hanna Lee at the Norwegian University of Science and Technology in Trondheim, Norway, highlights the necessity of enhancing these models to accurately capture the impact of permafrost thawing on wildfires and the climate. Prof. Axel Timmermann, director of the IBS Center for Climate Physics, emphasizes the need to integrate fire emissions and atmospheric processes into earth system models to provide a more comprehensive understanding of the interactions between wildfires and permafrost thawing.
In conclusion, the study demonstrates that global warming will accelerate permafrost thawing, leading to an increase in wildfires in the Subarctic and Arctic regions. By the second half of the 21st century, there is a projected switch from no fires to intense fires within a short period due to extensive permafrost thawing. The CO2 fertilization effect is expected to further fuel wildfires by increasing vegetation biomass in high latitude areas. To improve the accuracy of future climate predictions, it is essential to enhance earth system models to better represent the complex interactions between permafrost thawing, wildfires, and the climate system. Further research is needed to fully integrate fire emissions and atmospheric processes into these models for a more comprehensive understanding of the feedback mechanisms between wildfires and permafrost thawing in the Arctic.