Doddridge, E. W., Hobbs, W. R., Auger, M., Boyd, P. W., Chua, S. M. T., Cook, S., Corney, S., Emmerson, L., Fraser, A. D., Heil, P., Kelly, N., Lannuzel, D., Li, X., Liniger, G., Massom, R. A., Meyer, A., Reid, P., Southwell, C., Spence, P., Steketee, A., Swadling, K., Teder, N., Wienecke, B., Wongpan, P., & Yamazaki, K. (2025).
PNAS Nexus, 4(7), pgaf164. 
https://doi.org/10.1093/pnasnexus/pgaf164

Abstract

Antarctic sea ice plays many crucial roles in the physical environments and ecosystems of Antarctica and the Southern Ocean. In this study, we synthesize the physical, biogeochemical, ecosystem, and societal impacts of summers with extreme low Antarctic sea-ice coverage. These extreme events result in the loss of multiyear landfast ice and changes in sea-ice seasonality. Following extreme low sea-ice events, we find surface warming of the Southern Ocean and changes to the formation rate of Antarctic Intermediate Water, likely affecting heat and carbon uptake. Ice-shelf calving is negatively correlated with sea-ice area, so that years with less sea ice show increased calving. Prolonged open water affects the magnitude and seasonality of surface-phytoplankton blooms. The impacts on higher trophic levels are species-specific and occur through habitat loss and changes to prey availability. Extreme sea-ice lows will adversely impact krill, a foundational prey species that relies on sea ice for nourishment and refuge. The loss of stable landfast ice in austral spring and summer hampers Antarctic operations and resupply missions. Understanding the full impacts of recent, and future, sea-ice extremes is of utmost importance and requires an enhanced observational network that spans the physical and ecological systems of Antarctica and the Southern Ocean.

High resolution figures

Supplementary Information

Media pieces featuring this work

A world with less ice – a multimedia feature about this paper

Antarctic summer sea ice is at record lows. Here’s how it will harm the planet – and us – The Conversation

Tracking sea ice is ‘early warning system’ for global heating – but the US is halting data sharing – The Guardian

Shrinking Antarctic sea ice is warming the ocean faster than expected – New Scientist

What happens if Antarctica continues losing ice? – ABC Radio National

Access to critical US satellite data lost as Antarctic sea ice drops to record lows – COSMOS Magazine

Sea ice loss risks more icebergs, threatens wildlife – Australian Associated Press

Trump cuts satellite data on Antarctic sea ice just as it’s needed most – The Sydney Morning Herald

Press releases and institute stories

Antarctic summer sea ice: Global impacts of extreme lows – Australian Antarctic Program Partnership

GOING TO EXTREMES – UNDERSTANDING ANTARCTIC SEA-ICE DECLINE – Australian Antarctic Division

NEWS BRIEFING: More icebergs, fewer penguins: What happens when we lose sea ice? – Australian Science Media Exchange

Consequences of low Antarctic sea ice – EurekAlert!