Science Writing (EFE).- The Atlantic Circular Current (AMOC, its acronym in English) could collapse by mid-century, or potentially at any time since 2025, if greenhouse gas emissions continue, which would have serious repercussions on the climate of the North Atlantic and the world.
Researchers at the University of Copenhagen publish in Nature Communications a study on estimates of the future of the AMOC, a large system of ocean currents that carry warm water from the tropics north to the North Atlantic.
The AMOC “will collapse, with 95% certainty, between 2025 and 2095. This will most likely happen in 34 years, in 2057,” which could bring big challenges, particularly warming in the tropics and increased storms in the North Atlantic region, he told the University of Copenhagen.
Serious consequences for the climate
Recent assessments by the International Panel on Climate Change (IPCC), however, suggest that a complete collapse of the AMOC in the 21st century is unlikely, and some experts have conflicting views on the new Danish study.
The AMOC shutdown, which does not rule out that it may be partial, “could have very serious consequences for the Earth’s climate, for example, by changing the way heat and precipitation are distributed globally,” said Peter Ditlevsen, one of the authors.
The expert noted that “while Europa’s cooling may appear less severe as the planet as a whole warms and heat waves become more frequent, this disruption will contribute to further warming of the tropics, where rising temperatures have already led to difficult living conditions.”
These results underline, for Ditlevsen, “the importance of reducing global greenhouse gas emissions as soon as possible.”
The authors do not make hypotheses about the drivers of AMOC change, but note that the logarithm of atmospheric CO2 concentrations has increased almost linearly over the period studied. However, it cannot be excluded that there are other mechanisms at play, according to the publication.
abrupt climate change
The team made their calculations using advanced statistical tools and data on sea surface temperatures in the North Atlantic between 1870 and 2020 as a proxy for AMOC.
These records go back much further than the AMOC’s direct measurements, which have been tracked continuously since 2004, and can provide more robust information on temperature trends.
This type of abrupt climate change was last experienced during the Dansgaard-Oeschger phenomena in the last glacial period, caused by the collapse and restoration of the AMOC.
That period caused fluctuations in the average temperature of the northern hemisphere of 10-15 degrees in a decade, much greater than the current changes of 1.5 degrees in a century.
Analyzing the details of the study, in which he has not participated, Stefan Rahmstorf, from the University of Potsdam (Germany), considered that this work adds to previous studies that analyze early warning signs and reaches similar conclusions.
A single study provides limited evidence, but when multiple approaches lead to similar conclusions this must be taken very seriously. “Especially when we talk about a risk that we really want to rule out with 99.9% certainty,” he stressed.
conflicting opinions
The scientist, quoted by the Science Media Center (a platform that offers expert scientific sources), added that “the current scientific evidence is that we cannot even rule out that a tipping point will be crossed already in the next decade or two.”
In contrast, Niklas Boers of the Technical University of Munich (Germany) indicated his disagreement with the results of the study.
Although the qualitative statement that the AMOC has been losing stability in the last century is true, the uncertainties are too high to reliably estimate the moment of inflection. “In particular, the uncertainties in the model assumptions—very simplified by the authors—are too high,” according to Boers.