Rapid climate change in the ocean west of the Antarctic Peninsula during the second half of the 20th century

TLDR

The Western Antarctic Peninsula is experiencing the fastest warming in the Southern Hemisphere, with atmospheric temperatures rising ~3 °C since 1951, and its marine ecosystem—particularly krill—faces severe ecological risks from even modest ocean temperature increases. The observed ocean changes are initially driven by atmospheric warming and reduced sea ice production, creating positive feedbacks that amplify ongoing climate change. The adjacent ocean has seen a >1 °C rise in summer surface temperatures, increased upper‑layer salinity, and these changes—driven by warming and reduced sea ice—create positive feedbacks that threaten marine ecosystems, especially krill.

Abstract

The climate of the Western Antarctic Peninsula (WAP) is the most rapidly changing in the Southern Hemisphere, with a rise in atmospheric temperature of nearly 3°C since 1951 and associated cryospheric impacts. We demonstrate here, for the first time, that the adjacent ocean showed profound coincident changes, with surface summer temperatures rising more than 1°C and a strong upper‐layer salinification. Initially driven by atmospheric warming and reduced rates of sea ice production, these changes constitute positive feedbacks that will contribute significantly to the continued climate change. Marine species in this region have extreme sensitivities to their environment, with population and species removal predicted in response to very small increases in ocean temperature. The WAP region is an important breeding and nursery ground for Antarctic krill, a key species in the Southern Ocean foodweb with a known dependence on the physical environment. The changes observed thus have significant ecological implications.