Rising surface salinity and declining sea ice: A new Southern Ocean state revealed satellites

• 成果类型: Article
• 署名作者: Silvano, Alessandro; Narayanan, Aditya; Catany, Rafael; Olmedo, Estrella; Gonzalez-Gambau, Veronica; Turiel, Antonio; Sabia, Roberto; Mazloff, Matthew R.; Spira, Theo; Haumann, F. Alexander; Garabato, Alberto C. Naveira
• 署名单位: NERC National Oceanography Centre; University of Southampton; Consejo Superior de Investigaciones Cientificas (CSIC); CSIC - Centro Mediterraneo de Investigaciones Marinas y Ambientales (CMIMA); CSIC - Instituto de Ciencias del Mar (ICM); European Space Agency; European Space Research Institute; University of California System; University of California San Diego; Scripps Institution of Oceanography; University of Gothenburg; Helmholtz Association; Alfred Wegener Institute, Helmholtz Centre for Polar & Marine Research; University of Munich
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10330
• DOI: 10.1073/pnas.2500440122
• 发表日期: 2025-07-08

摘要

For decades, the surface of the polar Southern Ocean (south of 50 degrees S) has been freshening-an expected response to a warming climate. This freshening enhanced upper-ocean stratification, reducing the upward transport of subsurface heat and possibly contributing to sea ice expansion. It also limited the formation of open-ocean polynyas. Using satellite observations, we reveal a marked increase in surface salinity across the circumpolar Southern Ocean since 2015. This shift has weakened upper-ocean stratification, coinciding with a dramatic decline in Antarctic sea ice coverage. Additionally, rising salinity facilitated the reemergence of the Maud Rise polynya in the Weddell Sea, a phenomenon last observed in the mid-1970s. Crucially, we demonstrate that satellites can now monitor these changes in real time, providing essential evidence of the Southern Ocean's potential transition toward persistently reduced sea ice coverage.