Scientists Predict a Collapse of the Atlantic Ocean Current

Important ocean currents that redistribute warmth, chilly, and precipitation between the tropics and the northernmost components of the Atlantic area will shut down across the yr 2060 if present greenhouse fuel emissions persist. This is the conclusion primarily based on new calculations from the University of Copenhagen that contradict the most recent report from the IPCC.

Contrary to what we might think about in regards to the affect of local weather change in Europe, a colder future could also be in retailer. In a brand new examine, researchers from the University of Copenhagen’s Niels Bohr Institute and Department of Mathematical Sciences predict that the system of ocean currents that at the moment distributes chilly and warmth between the North Atlantic area and tropics will utterly cease if we proceed to emit the identical ranges of greenhouse gases as we do right now.

Using superior statistical instruments and ocean temperature information from the final 150 years, the researchers calculated that the ocean present, often called the Thermohaline Circulation or the Atlantic Meridional Overturning Circulation (AMOC), will collapse – with 95 % certainty – between 2025 and 2095. This will almost certainly happen in 34 years, in 2057, and will end in main challenges, notably warming within the tropics and elevated storminess within the North Atlantic area.

“Shutting down the AMOC can have very serious consequences for Earth’s climate, for example, by changing how heat and precipitation are distributed globally. While a cooling of Europe may seem less severe as the globe as a whole becomes warmer and heat waves occur more frequently, this shutdown will contribute to increased warming of the tropics, where rising temperatures have already given rise to challenging living conditions,” says Professor Peter Ditlevsen from the Niels Bohr Institute.

“Our result underscores the importance of reducing global greenhouse gas emissions as soon as possible,” says the researcher.

The calculations, simply revealed within the famend scientific journal, Nature Communications, contradict the message of the latest IPCC report, which, based on climate model simulations, considers an abrupt change in the thermohaline circulation very unlikely during this century.

Early warning signals present

The researchers’ prediction is based on observations of early warning signals that ocean currents exhibit as they become unstable. These Early Warning Signals for the Thermohaline Circulation have been reported previously, but only now has the development of advanced statistical methods made it possible to predict just when a collapse will occur.

The researchers analyzed sea surface temperatures in a specific area of the North Atlantic from 1870 to the present day. These sea surface temperatures are “fingerprints” testifying to the strength of the AMOC, which has only been measured directly for the past 15 years.

“Using new and improved statistical tools, we’ve made calculations that provide a more robust estimate of when a collapse of the Thermohaline Circulation is most likely to occur, something we had not been able to do before,” explains Professor Susanne Ditlevsen of UCPH’s Department of Mathematical Sciences.

The thermohaline circulation has operated in its present mode since the last ice age, where the circulation was indeed collapsed. Abrupt climate jumps between the present state of the AMOC and the collapsed state has been observed to happen 25 times in connection with ice-age climate. These are the famed Dansgaard-Oeschger events first observed in ice cores from the Greenlandic ice sheet. At those events, climate changes were extreme with 10-15 degrees changes over a decade, while present day climate change is 1.5 degrees warming over a century.

Facts:

• The Atlantic Meridional Overturning Circulation (AMOC) is part of a global system of ocean currents. By far, it accounts for the most significant part of heat redistribution from the tropics to the northernmost regions of the Atlantic region – not least to Western Europe.
• At the northernmost latitudes, circulation ensures that surface water is converted into deep, southbound ocean currents. The transformation creates space for additional surface water to be moved northward from equatorial regions. As such, thermohaline circulation is critical for maintaining the relatively mild climate of the North Atlantic region.
• The work is supported by TiPES, a joint-European research collaboration focused on tipping points of the climate system. The TiPES project is an EU Horizon 2020 interdisciplinary climate research project focused on tipping points in the climate system.

Reference: “Warning of a forthcoming collapse of the Atlantic meridional overturning circulation” by Peter Ditlevsen and Susanne Ditlevsen, 25 July 2023, Nature Communications.
DOI: 10.1038/s41467-023-39810-w

The work is supported by TiPES, a joint-European research collaboration focused on tipping points of the climate system. The TiPES project is an EU Horizon 2020 interdisciplinary climate research project focused on tipping points in the climate system.

Furthermore, funding was provided by Novo Nordisk Foundation; and European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement, “Economic Policy in Complex Environments (EPOC).