Polar Summer Snow and Ice Albedo Feedbacks Assessed by Satellite Observations and Radiative Kernels

Abstract

Snow and ice albedo feedback (SIAF) is a key process linking cryospheric changes to global warming. Satellite radiative kernels provide another choice for estimating radiative feedbacks, bypassing the complexity of climate model radiative transfer processes. Based on the established method for estimating SIAF, we use the longest available satellite-derived surface albedo record together with a satellite radiative kernel to quantify the summer SIAF over the Arctic and Antarctic. The summer SIAF was 0.08 ± 0.04 W·W· m−2 for the Arctic and −0.11 ± 0.11 W·m−2 for the Antarctic, respectively, averaged over 1979–2024. An overall positive SIAF is observed in the Arctic, while Antarctic SIAF shows pronounced spatial heterogeneity, with negative feedback mainly over the East Antarctic coastal sea-ice regions and positive feedback over the West Antarctic marginal seas. Spatial patterns of SIAF trends closely match the climatological feedback, with strong positive (negative) feedback regions generally showing enhanced positive (negative) trends. This implies that current feedback regimes tend to persist and even intensify over time. Separating terrestrial and sea-ice components further reveals contrasting evolutionary pathways between the two hemispheres. Terrestrial SIAF over both the Greenland and Antarctic Ice Sheets gradually shifted from weak negative toward positive trends, with an enhancement in recent decades. In the Arctic, sea-ice SIAF experienced rapid intensification during 1996–2011, followed by a substantial slowdown after 2012 due to a decline in summer sea-ice loss rate and ice and sheet surface melting. In contrast, Antarctic sea-ice SIAF remained in a persistent negative trend during 1979–2015, associated with sea-ice expansion, but rapidly reversed toward a positive feedback regime after the abrupt sea-ice decline in 2016.