(CN) — A crucial system of currents in the Atlantic Ocean is displaying early signs of collapse, according to a new study published Thursday in the journal Nature Climate Change. The study warns that the collapse “would have severe impacts on the global climate system.”
The Atlantic Meridional Overturning Circulation (AMOC) is responsible for moving warm water from the tropics into the Northern Hemisphere, making it a major contributor to global weather patterns. Research indicates the AMOC historically alternated between two modes of circulation — one strong, the other weak. But AMOC is currently estimated to be at its weakest point in 1,000 years.
“This decline may be associated with an almost complete loss of stability of the AMOC over the course of the last century,” wrote Niklas Boers, the author of the study.
This loss of stability could have global ramifications from the Amazon rainforest to the Antarctic ice sheet, affecting tropical monsoon systems and temperatures in Europe, according to the study. Other studies have also predicted troubling results as climate change destabilizes ocean currents. Without a strong ocean circulation system to redistribute heat and help moderate weather events, climate conditions would become increasingly intense.
The research used the temperature of the sea surface and the salinity, or amount of salt, to model the ocean’s circulatory system. The warming temperatures of the northern Atlantic and the infusion of freshwater from the melting Greenland ice sheet contribute to the weakening of AMOC. However, according to Boers, the study’s results show “the recently discovered AMOC decline is not just a fluctuation related to low-frequency climate variability or a linear response to increasing temperatures.”
Rather, Boers warned in the study that worsening instability might force the AMOC to make an “irreversible transition” to weak circulation. That finding is surprising, as climate scientists generally would expect much higher levels of global warming to trigger such a transition, according to a press release issued with the study.
The researchers indicate that neither the increasing sea temperatures nor the influx of meltwater are yet at the point where they are expected to trigger total collapse of the AMOC. However, the effects of climate change continue to threaten ocean circulatory stability. Boers urged for more research, which he said will be necessary to gain an in-depth understanding of the current dynamics of the AMOC.
The study was coordinated by the University of Copenhagen, Denmark and the Potsdam Institute for Climate Impact Research, Germany. It was part of the European TiPES project, which received funding from the European Horizon 2020 research and innovation program.
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