Southern Indian Ocean Freshening Rapidly

A study published in Nature Climate Change by researchers from the University of Colorado Boulder, including Weiqing Han and Gengxin Chen, reveals that the Southern Indian Ocean is freshening at an unprecedented rate. Over the past 60 years, the area of high salinity surface water has shrunk by about 30%, representing the fastest freshening signal in the Southern Hemisphere. This change is attributed to anthropogenic warming altering surface winds over the Indian Ocean and Pacific Ocean, which redirects freshwater from the Indo Pacific freshwater pool into the Southern Indian Ocean. The influx of freshwater is equivalent to about 60% of United States===Lake Tahoe's volume annually. This freshening decreases seawater density, enhancing layering and suppressing vertical mixing, which limits the exchange of heat and nutrients. This could impact marine ecosystems by reducing food supplies for phytoplankton and seagrass, and intensifying thermal stress on organisms. It also adds another potential influence on the global thermohaline circulation, alongside freshwater input from melting Greenland===Greenland ice sheet and Arctic ice pack.