Led by GAO Libao, the young scientist of the Ocean and Climate Research Center of FIO, the China-Australia Scientific Research Team has made significant progress in the study of the Southern Ocean Warming Mechanism with the findings named “Recent wind-driven change in Subantarctic Mode Water and its impact on ocean heat storage” published on the famous international academic journal Nature Climate Change. Recently, the warming trend in the Southern Ocean has attracted much attention. Since 2006, the Southern Ocean has absorbed more than 60% of the heat from Global Warming, making it a key element in the Global Warming Hiatus. However, the mechanism behind the Southern Ocean Warming is still mysterious.

As an important component of the Southern Ocean Meridional Circulation, Subantarctic Mode Water can greatly influence the global heat distribution, fresh water circulation, nutritive salt and carbon budget when it sinks or is transported. GAO’s team analyses the temporal and spatial variation of Subantarctic Mode Water meticulously and finds that between 2005 and 2015, Subantarctic Mode Water has thickened (3.6 ± 0.3 m yr−1), deepened (2.4 ± 0.2 m yr−1) and warmed (3.9 ± 0.3 W m−2). Wind forcing, rather than buoyancy forcing, is largely responsible for the observed trends in Subantarctic Mode Water. Most (84%) of the increase in its heat content is the result of changes in thickness; warming by buoyancy forcing (increased heat flux to the ocean) accounts for the remaining 16%. Based on estimated results from multi modes, it is predicted that the continuous increase of west wind and its curl in the Southern Ocean will further thicken the Subantarctic Mode Water, thus storing more heat from sea-air interface to the inside of the sea and slowing down the speed of global surface warming.

GAO Libao’s findings receive acceptance from international peers and gets high marks from an article named “Cold wind warms Southern Ocean” in Nature Climate Change.