A recent analysis of 150 years of temperature data reveals the Atlantic Ocean current is slowing and becoming less resilient, raising concerns of potential collapse within a few decades. As per The Washington Post, the Atlantic Meridional Overturning Circulation (AMOC) is considered a vulnerable "tipping element," with significant global consequences.
Earth's current climate allows this aquatic conveyor belt to carry saline warm water from the tropics to the North Atlantic and subsequently return colder water south along the ocean floor. That means the influx of cold freshwater from melting Arctic ice disrupts the system, risking its shutdown.
Atlantic Meridional Overturning Circulation (AMOC) Explained
According to the National Ocean Service of the National Oceanic and Atmospheric Administration (NOAA), ocean currents are continuously circulating, influenced by tidal currents near the shore due to the sun and moon and surface currents driven by the wind.
However, slower currents from the surface to the seafloor are powered by changes in ocean temperature and saltiness, known as thermohaline circulation, and play a crucial role in the global conveyor belt, which includes the AMOC.
The Atlantic Meridional Overturning Circulation (AMOC) moves water in a cycle from north to south within the Atlantic Ocean, distributing warmth to various regions and essential nutrients for marine life.
Warm surface water travels towards the poles, cools, and forms sea ice, leaving behind salt that increases the water's density and makes it sink to the depths, flowing southwards. Eventually, the water rises to the surface, warming up in a process called upwelling, completing the cycle.
The AMOC's entire circulation process, along with the global conveyor belt, operates slowly, taking about 1,000 years for a parcel of water to complete its journey along the belt. However, there are indications that the AMOC is slowing down further, prompting research funded by NOAA to understand its potential slowdown, its impact on coastal sea levels, and its connection to extreme events.
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Climate Change Weakening the AMOC
The new study, titled "Warning of a Forthcoming Collapse of the Atlantic Meridional Overturning Circulation" published in Nature Communications, warns that the ocean climate system is at the brink of an irreversible tipping point due to climate change. However, not everyone is convinced of the accuracy of the projections.
New Scientist reported that climate experts have issued warnings about climate change weakening the AMOC, raising concerns of a potential collapse in the future. However, due to the limited consistent monitoring of AMOC strength since 2004, precise estimates of the collapse timing remain elusive.
The Intergovernmental Panel on Climate Change (IPCC) suggests that a full AMOC collapse is improbable in this century based on climate models.
To estimate AMOC stability, researchers Peter and Susanne Ditlevsen utilized sea surface temperature data from the sub-polar North Atlantic dating back to 1870. Other experts, like Niklas Boers and Jon Robson, point out the increasing instability of the AMOC in the past century but highlight uncertainties in relying solely on sea surface temperatures for precise predictions.
Peter Ditlevsen responded to criticisms and acknowledged that calculations are founded on the assumption that sea surface temperatures accurately reflect AMOC behavior, expressing confidence in their predictions but acknowledging the underlying premise.
RELATED ARTICLE: Major Atlantic Ocean Current System at Its Weakest in Over 1,000 Years, Poses Risks of Collapse Due to Climate Change
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