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Permafrost researchers analyze the drivers of rapidly changing Arctic coasts

Credit: Unsplash/CC0 Public Domain
Credit: Unsplash/CC0 Public Domain

January 11 2022 by Alfred Wegener Institute

Arctic coasts are characterized by sea ice, permafrost and ground ice. This makes them particularly vulnerable to the effects of climate change, which is already accelerating rapid coastal erosion. The increasing warming is affecting coast stability, sediments, carbon storage, and nutrient mobilization. Understanding the correlation of these changes is essential to improve forecasts and adaptation strategies for Arctic coasts. In a special issue of the journal Nature Reviews Earth & Environment, researchers from the Alfred Wegener Institute describe the sensitivity of Arctic coasts to climate change and the challenges for humans and nature.

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Irrgang, A.M., M. Bendixen, L.M. Farquharson, A.V. Baranskaya, L.H. Erikson, A.E. Gibbs, S.A. Ogorodov, P.P. Overduin, H. Lantuit, M.N. Grigoriev, and B.M. Jones. (2022). Drivers, dynamics and impacts of changing Arctic coasts. Nature Reviews Earth and Environment. (RGMA)

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Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models

Cai, L., Alexeev, V.A., and Walsh, J.E., 2020. “Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models” Journal of Climate 33 (14), DOI:  https://doi.org/10.1175/JCLI-D-19-0326.1. (RMGA)

Abstract. We explore the response of wintertime Arctic sea ice growth to strong cyclones and to large-scale circulation patterns on the daily scale using Earth system model output in phase 5 of the Coupled Model Intercomparison Project (CMIP5). A combined metrics ranking method selects three CMIP5 models that are successful in reproducing the wintertime Arctic dipole (AD) pattern.

A cyclone identification method is applied to select strong cyclones in two subregions in the North Atlantic to examine their different impacts on sea ice growth. The total change of sea ice growth rate (SGR) is split into those respectively driven by the dynamic and thermodynamic atmospheric forcing. Three models reproduce the downward longwave radiation anomalies that generally match thermodynamic SGR anomalies in response to both strong cyclones and large-scale circulation patterns. For large-scale circulation patterns, the negative AD outweighs the positive Arctic Oscillation in thermodynamically inhibiting SGR in both impact area and magnitude. Despite the disagreement on the spatial distribution, the three CMIP5 models agree on the weaker response of dynamic SGR than thermodynamic SGR. As the Arctic warms, the thinner sea ice results in more ice production and smaller spatial heterogeneity of thickness, dampening the SGR response to the dynamic forcing. The higher temperature increases the specific heat of sea ice, thus dampening the SGR response to the thermodynamic forcing. In this way, the atmospheric forcing is projected to contribute less to change daily SGR in the future climate.

Cai, L., Alexeev, V.A., and Walsh, J.E., 2020. “Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models” Journal of Climate 33 (14), DOI:  https://doi.org/10.1175/JCLI-D-19-0326.1. (RMGA)