The warming of the Southern Ocean and its significance

The Southern Ocean encircles Antarctica and extends north to abut the subtropics at ~30-35°S. The Southern Ocean is a difficult place to collect measurements because it is far from many major ports, and only a limited number of nations have the research infrastructure and expertise to mount campaigns to the Southern Ocean. Measurement difficulties are confounded by the fact that the Southern Ocean has some of the stormiest conditions on the planet, it is covered by seasonal and in some places, perennial sea ice, and it contains icebergs. Expanded observing campaigns since the early 2000s have taken advantage of autonomous measurement systems to show that the Southern Ocean is gaining heat faster than the rest of the global ocean, with detectable heat gain extending from the ocean surface to depths of 1000-2000 m or more. Warming of the Southern Ocean has implications for the climate system as a whole. This is because the presence of warmer water at the periphery of the Antarctic continent can contribute to ice sheet melt and consequent sea level rise, and also because transfer of heat from the atmosphere to the ocean has long-term consequences for ocean circulation and for the climate system as a whole.

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