Atmospheric feedback explains disparate climate response to regional Arctic sea ice loss

Sea ice loss results from anthropogenic global warming and can itself be a driver of climate change in the Arctic and at lower latitudes, with extreme events over Europe and North America having been attributed to sea ice minima in recent years. Yet the role that sea ice plays in ongoing climate change remains uncertain, partly due to a limited understanding of whether and how the exact geographical distribution of sea ice loss impacts climate.

Here we analyse idealised AMIP-like simulations to compare the atmospheric response to various patterns of regional sea ice loss. We find that climatic anomalies can vary widely depending on where sea ice is reduced, with changes in the zonal-mean component of the tropospheric circulation being seemingly inconsistent among experiments. We attribute this disparate climatic response to an atmospheric feedback mechanism, which can either warm or cool the Arctic troposphere depending on the relative magnitude of the changes in poleward eddy heat flux and latent heat release over the Arctic in response to a specific sea ice loss pattern. We discuss the implications of our results for interpreting the apparent discrepancies in the climate response to Arctic sea ice variability among studies.

Our study highlights the need to better constrain the spatial pattern of future sea ice when assessing its impacts on the climate in the Arctic. By explaining the link between sea ice pattern and Arctic climate variability, our study will inform the design and analysis of future climate simulations and multi-model comparison protocols.