Permafrost Thaw Impact on Remaining Carbon Budgets and Emissions Pathways in 2°C and 3°C Global Warming Scenarios
High-latitude frozen soils contain a large amount of organic matter that could release greenhouse gases as permafrost thaws. This study uses a climate model to explore how thawing permafrost affects efforts to limit global warming to 2°C and 3°C above preindustrial levels. The research finds that thawing permafrost and the deepening of the active layer make an additional 120 PgC (for 2°C warming) and 230 PgC (for 3°C warming) available for decomposition into greenhouse gases. In both cases, about 75% of that carbon reaches the atmosphere as carbon dioxide by the year 2300. This release reduces the remaining carbon budget by about 13% for the 2°C and 11% for the 3°C warming scenarios. Permafrost emissions could average 0.3 to 0.7 PgC per year, with temporary peaks possible. Notably, negative emissions are needed for the 3°C scenario when considering permafrost carbon, highlighting the importance of including permafrost emissions in climate mitigation strategies.
Permafrost thaw: Gradual change or climate tipping point?
Global warming leads to Arctic permafrost thaw and the subsequent release of carbon dioxide and methane into the atmosphere. These changes are considered irreversible and, in some cases, abrupt, which has led to discussion whether permafrost might be a tipping element in the climate system. Researchers have compiled the currently available knowledge on how permafrost responds to climate change. They concluded that changes in permafrost are gradual at the global scale but abrupt on a local scale, and that the loss of carbon is irreversible.
The precarious future of permafrost
The Arctic is heating up particularly fast as a result of global warming – with serious consequences. The widespread permafrost in this region, where soils currently store twice as much carbon as the atmosphere, is thawing. Scientists are using increasingly detailed climate models to investigate what this means for the global climate and which striking feedbacks need to be taken into account.
Climate change amplified by permafrost cloud feedback
Researchers at the Max Planck Institute for Meteorology shed light on what may happen if the frozen soils thaw in response to global heating. Landscapes in the Arctic and subarctic zone are often very wet with water saturated soils and an extensive lake- and wetland cover shaping the moisture and energy exchange with the atmosphere. To some extent, the abundance of water is caused by the presence of permafrost, that is those parts of the ground that remain perennially frozen. Such soil layers have underlain large parts of the region since the last glacial maximum and strongly inhibit the movement of water below the surface.
Russian collaboration loss risks permafrost carbon emissions network
The Russian Federation contains two-thirds of the northern permafrost area. The loss of access to permafrost carbon flux sites and data within Russia, linked to the Russian invasion of Ukraine, threatens the ability of the international science community to detect and quantify the current state of the permafrost-climate feedback. This disruption of science collaboration undermines the effectiveness of the Arctic carbon monitoring network as a tool for monitoring climate change in quantifiable ways. This study found that the representativeness of the pan-Arctic network of eddy covariance flux towers is reduced to about 66% of its full impact when removing the 27 sites located in Russian territory. This loss can only partly be compensated for when installing new sites in Arctic regions outside of Russia. Expanding e.g. North American infrastructure could be shown to be a way forward for climate science, and also satellite remote sensing observations may partly fill the gap, but since there are permafrost ecosystems in Russia that do not have environmental analogs elsewhere, there does not appear to exist an equivalent solution to Russian science collaboration.
