{"id":113854,"date":"2026-04-08T10:29:09","date_gmt":"2026-04-08T08:29:09","guid":{"rendered":"https:\/\/www.sonnenseite.com\/?p=113854"},"modified":"2026-04-08T10:29:09","modified_gmt":"2026-04-08T08:29:09","slug":"amoc-collapse-could-turn-southern-ocean-into-carbon-source-adding-0-2c-to-global-warming","status":"publish","type":"post","link":"https:\/\/www.sonnenseite.com\/en\/science\/amoc-collapse-could-turn-southern-ocean-into-carbon-source-adding-0-2c-to-global-warming\/","title":{"rendered":"AMOC collapse could turn Southern Ocean into carbon source, adding 0.2\u00b0C to global warming"},"content":{"rendered":"\n

A shutdown of the Atlantic Meridional Overturning Circulation (AMOC) could trigger a substantial release of stored ocean carbon into the atmosphere over hundreds of years, according to a new study that simulated such a collapse under stable climate conditions. <\/p>\n\n\n\n

This would add 0.2\u00b0C of extra global warming. The new paper from researchers at the Potsdam Institute for Climate Impact Research (PIK), published in Nature\u2019s Communications Earth & Environment, highlights the AMOC\u2019s role as a key regulator of the global climate.<\/p>\n\n\n\n

To assess how a collapse of the AMOC \u2013 a major Atlantic Ocean circulation system that transports warm water north and cold water south \u2013 would affect the carbon cycle and global temperatures, the authors simulated Earth\u2019s climate stabilising at different atmospheric CO\u2082 levels and subsequently applied fresh water input to the Atlantic surface to induce an AMOC shutdown.<\/p>\n\n\n\n

At pre-industrial atmospheric CO\u2082 concentrations, 280 ppm, even if the AMOC collapses under freshwater forcing, it fully recovers once the forcing ends. However, at CO\u2082 levels of 350ppm or higher \u2013 well below today\u2019s level of around 430ppm \u2013 once the AMOC collapses it stays in the \u201coff\u201d state.<\/p>\n\n\n\n

\u201cHigher CO\u2082 concentrations fundamentally alter the AMOC’s stability, pushing the system into a bistable regime where the AMOC could weaken over hundreds of years before shifting to, and remaining in, a collapsed state. Once shutdown, we see it does not recover in the long run,\u201d says lead author Da Nian of PIK.<\/p>\n\n\n\n

In all scenarios analysed in the paper, a shift of the AMOC into an off state would see additional warming of 0.17\u00b0C to 0.27\u00b0C.<\/p>\n\n\n\n

\u201cThis change in temperatures is driven by a large release of carbon from the Southern Ocean, due to enhanced mixing that brings carbon-rich deep waters to the surface,\u201d explains co-author Matteo Willeit of PIK.<\/p>\n\n\n\n

Regional temperature changes would be even more pronounced than global mean temperature change. In one scenario at CO\u2082 concentrations of 450ppm \u2013 last experienced by the Earth several million years ago, when polar ice was significantly reduced \u2013 Antarctic temperatures rise by 6\u00b0C while Arctic temperatures drop by 7\u00b0C due to AMOC collapse.<\/p>\n\n\n\n

\u201cThe ocean has been our greatest ally, absorbing a quarter of human-made CO\u2082 emissions. Our study shows how an AMOC collapse could flip the Southern Ocean from a carbon sink into a carbon source, releasing vast amounts of CO\u2082 and fueling further global warming. The more CO\u2082 in our atmosphere at the stage of shutdown, the higher the likelihood of additional warming. Put simply, rising emissions today increase the risk of a stronger climate response down the line,\u201d says PIK Director and co-author Johan Rockstr\u00f6m.<\/p>\n\n\n\n