How permafrost will react to global warming: scientists' predictions

This leads to the melting of permafrost, soil that has remained frozen since the ice ages. There is about twice as much carbon under this soil as there is in the entire atmosphere of the planet. If the permafrost is actively thawing, the carbon could be released as greenhouse gases (CO₂ or methane) and increase global warming.

Source: Philipp de Vrese et al, Permafrost Cloud Feedback May Amplify Climate Change, Geophysical Research Letters (2024). DOI: 10.1029/2024GL109034

David M. Nielsen et al, Reduced Arctic Ocean CO2 uptake due to coastal permafrost erosion, Nature Climate Change (2024). DOI: 10.1038/s41558-024-02074-3

Meike Schickhoff et al, Effects of land surface model resolution on fluxes and soil state in the Arctic, Environmental Research Letters (2024). DOI: 10.1088/1748-9326/ad6019

Scientists at the Max Planck Institute for Meteorology (MPI-M) are investigating exactly how this warming will affect permafrost. One of the most important questions is whether the region will become wetter or, conversely, drier.

If the soil is overwatered, it lacks oxygen and produces more methane, which is many times stronger than carbon dioxide in terms of heating. However, if the soil dries out, this can also increase warming: less cloud cover means more solar heat, which stimulates plant growth and, as a result, increases methane emissions.

Another aspect is coastal dynamics. The shores of melting permafrost are being eroded by wave action, and carbon from the ground is being released into the ocean. There, organic material decomposes, increasing the concentration of CO₂ at the water surface. As a result, the ocean absorbs less carbon dioxide from the atmosphere, and in addition, the water becomes more acidic, harming marine ecosystems.

To predict the future, scientists use sophisticated " Earth System Models " (Earth System Models). However, most of the processes in the Arctic take place on very small scales, such as a few metres of soil, whereas the models work in kilometre increments. In order to combine the different levels, the researchers are developing a new approach: they take into account in each "cell" of the model the features of the landscape, moisture distribution and vegetation. The first results have already shown that if the impact of small ponds or wetlands is taken into account in the calculations, the prediction of carbon uptake and emissions becomes more accurate.

The questions remain complex: the precise impact of permafrost processes, the extent of greenhouse gas emissions, and interactions with the atmosphere and ocean are all being explored by researchers using observational data and new modelling techniques to improve their predictions for the future.