Important ocean currents that redistribute heat, cold and rain between the tropics and the northernmost part of the Atlantic region will close around the year 2060 if current greenhouse gas emissions continue. This is the conclusion based on new calculations from the University of Copenhagen which contradicts the latest report from the IPCC.
Contrary to what we might think about the impact of climate change in Europe, a colder future may be in store. In a new study, published in Communication in Natureresearchers from the Niels Bohr Institute at the University of Copenhagen and Department of Mathematical Sciences predict that the ocean current system that currently distributes cold and heat between the North Atlantic region and the tropics will completely stop if we continue to emit the same level of greenhouse gases as we do now.
Using advanced statistical tools and ocean temperature data from the last 150 years, the researchers calculated that the ocean current, known as the Thermohaline Circulation or the Atlantic Meridional Overturning Circulation (AMOC), will collapse—with 95% certainty—between 2025 and 2095. This is likely to happen in 34 years, and in 2057 which could result in a major tropical storm, and in 205 7. North Atlantic Region.
“The closure of the AMOC can have serious consequences for the Earth’s climate, for example, by changing how heat and rain are distributed around the world. While a cooling in Europe seems less severe as the whole world becomes warmer and heat waves occur more often, this closure will contribute to a further warming of the tropics, where the temperature rise in the tropics, where the rise in Nihrlev temperature has already given life conditions in Ni hrlev,” said Peter.
“Our results highlight the importance of reducing global greenhouse gas emissions as soon as possible,” says the researcher.
The calculations contradict the message of the latest IPCC report, which, based on climate model simulations, considers a sudden change in the thermohaline circulation to be very unlikely in this century.
The early warning signals are there
The researchers’ prediction is based on observations of early warning signals displayed by ocean currents as they become unstable. These early warning signals for the Thermohaline Circulation have been reported before, but it is only now that the development of advanced statistical methods has made it possible to predict when a collapse will occur.
The researchers examined sea surface temperatures in a specific area of the North Atlantic from 1870 to the present. These sea surface temperatures are the “fingerprints” that confirm the strength of the AMOC, which have been directly measured over the past 15 years.
“Using new and improved statistical tools, we have made calculations that provide a more robust estimate of when the collapse of the Thermohaline Circulation is likely to occur, something we have never done before,” explained Professor Susanne Ditlevsen of UCPH’s Department of Mathematics.
The thermohaline circulation has been operating in its present way since the last ice age, where the circulation actually collapsed. The abrupt jump in climate between the current AMOC state and the collapsed state has occurred 25 times in relation to ice age climates. These are the famous Dansgaard-Oeschger phenomena that were first observed in ice cores from the Greenlandic ice sheet. In the event, climate change is severe, with 10 to 15° change per decade, while current climate change is 1.5° warming per century.
The Atlantic Meridional Overturning Circulation (AMOC) is part of the global ocean current system. Currently, it is responsible for the most significant redistribution of heat from the tropics to the northernmost region of the Atlantic region—not least to Western Europe. At the northernmost latitudes, the circulation ensures that surface water is transformed into deep, southward ocean currents. The change creates space for more surface water to be moved northward from the equatorial regions. As such, the thermohaline circulation is important for maintaining the relatively mild climate of the North Atlantic region.
Peter Ditlevsen, Warning of the impending collapse of the Atlantic meridional overturning circulation, Communication in Nature (2023). DOI: 10.1038/s41467-023-39810-w. www.nature.com/articles/s41467-023-39810-w
Provided by the University of Copenhagen
Citation: Gloomy climate calculations: Scientists predict collapse of Atlantic ocean to occur by mid-century (2023, July 25) retrieved on 25 July 2023 from https://phys.org/news/2023-07-gloomy-climate-scientists-collapse-atlantic.html
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