Last year, an alarming study suggested that one of Earth's major ocean currents is headed toward collapse. Unfortunately, new data now supports this.
“Changes in temperature, sea level and precipitation will severely impact society, and the world Climate shifts cannot be stopped On human time scales,” the authors of the latest study said Warning in the article For conversation.
This is a terrifying prospect, and one of the most important parts of the new study is the early warning system, identified by Utrecht University oceanographer René van Westen and his colleagues.
This glimpse into the future could provide the world with at least some ability to prepare for what is to come.
“We were able to develop an observable physics-based early warning signal that includes salinity transport at the southern boundary of the Atlantic Ocean,” said van Westen and his team. He explains.
Atlantic overturning cycle (Amok) is a large system of ocean currents that transport warm, salty water northward. This water cools as it winds its way north, making it denser. As cold water sinks, water is drawn from other oceans to fill the surfacewhich pushes the circulatory system south again.
AMOC has slowed significantly since the mid-20th century.
As freshwater contributions increase due to melting glaciers and increased rainfall, salt concentrations in seawater decrease, and the saltwater becomes less dense, disrupting the sinking process and weakening the entire physical cycle.
Now, by modeling these ocean systems, van Westen and his colleagues have found a way to detect when the “tipping point” in the AMOC is near: the decline in salinity will slow at the southernmost limits of the Atlantic Ocean.
“Once this threshold is reached, the tipping point will likely come within one to four decades.” He says Authors.
The AMOC has only been directly observed since 2004, so it is not long enough to understand the full path of the current slowing trend. As a result, scientists have used indirect indicators such as salinity levels to try to fill their knowledge gaps.
Van Westen and his team have not yet combined all the factors to accurately predict when the AMOC collapse will occur, but they believe the catastrophic moment is much closer than many current simulations indicate.
The new modeling explores the freshwater tipping point itself, rather than trying to predict its timing. But the resulting data suggest that AMOC is more sensitive to changes than most climate models have taken into account.
“The new study systematically confirms previous concerns about climate models Stability is overrated AMOC,” University of Potsdam climate scientist Stefan Rahmstorf, who was not involved in the study, said. Explained to RealClimate.
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The AMOC influences a large portion of Earth's climate, so it is one of the pivotal elements of the Earth's climate system that researchers are most interested in. AMOC collapse It happens periodically Over a million years, and based on past events, we know that the Arctic should have extended southward during this time, dropping temperatures in northwestern Europe by up to 15°C, disrupting the tropical monsoons and further warming the Southern Hemisphere.
The following chain reactions will severely affect entire ecosystems Global food security.
“The new study adds significantly to the growing concern about the collapse of the AMOC in the not-too-distant future,” Rahmstorf said Tell the News agency. “We will ignore this at our peril.”
This research was published in Advancement of science.
