CMIP6 model projections leave no room for permafrost to persist in Western Siberia under the SSP5-8.5 scenario

The outputs of the Earth system models (ESM) provided by the sixth phase of the Coupled Models Intercomparison Project (CMIP6) reflect the current state of scientific knowledge on climate change and make it possible not only to draw conclusions about the adverse consequences of climate change but also to evaluate the certainty of such conclusions. This study is aimed to check if the CMIP6 model projections of mean annual air temperature (MAAT) allow us to make a robust conclusion about the possibility of adverse consequences of climate change in the northern part of Western Siberia. With this purpose in mind, we construct the weighted multi-model ensemble and find that it reproduces with 30% accuracy the observation-based MAAT anomalies over this region. Then, we use this weighted multi-model ensemble to predict MAAT changes and find that under the SSP5-8.5 scenario, MAAT will exceed 0 °C almost everywhere in the North of Western Siberia by the end of this century. Since permafrost occurs sporadically over the territories where MAAT is above − 2 °C, this result suggests that permafrost will not persist in Western Siberia under the SSP5-8.5 scenario.