Last year, a worrying study suggested that one of Earth’s major ocean currents is racing towards collapse. Unfortunately, there is now new data to support this.
“Changes in temperature, sea level and precipitation will seriously affect society, and Climate changes are unstoppable. on human time scales,” the authors of the latest study warn in an article for The Conversation.
It’s a terrifying prospect, and one of the most important parts of the new study is an 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 involving salinity transport at the southern edge of the Atlantic Ocean,” Van Westen and his team explain.
The southern circulation of the AtlanticI LOVE C) is a large system of ocean currents that transfers warm, salty water northward. This water cools on its winding journey north, making it denser. As cold water sinks, water from other oceans is absorbed to fill the surface.driving the circulatory system back to the south.
AMOC has been slowing significantly since the mid-20th century.
With increasing contributions of freshwater from melting glaciers and increased rainfall, salt concentrations in seawater decrease and salt water 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 AMOC “tipping point” is near: the decline in salinity will slow down at the southernmost edge of the Atlantic.
“Once a threshold is reached, the tipping point is likely to occur in one to four decades,” say the authors.
AMOC has only been monitored directly since 2004, so it has not been long enough to understand the full trajectory of the current slowdown trend. As a result, scientists have been using proxy indicators such as salinity levels to try to fill their knowledge gaps.
Van Westen and his team have yet to merge 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 suggest.
The new model explores the freshwater-induced tipping point itself, rather than trying to predict its timing. But the resulting data suggests that AMOC is much more sensitive to changes than most climate models have taken into account.
“The new study confirms past concerns that climate models systematically overestimate stability AMOC,” said University of Potsdam climatologist Stefan Rahmstorf, who was not involved in the study. explained for RealClimate.
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AMOC affects much of Earth’s climate, making it one of the decisive elements of Earth’s climate system that researchers are most concerned about. AMOC collapse happens cyclically On a million-year scale, and based on past events, we know that the Arctic should extend southwards during this time, causing temperatures in northwest Europe to drop by up to 15°C, disrupting the monsoons. tropical climates and further warming the southern hemisphere.
The chain of reactions that follows will seriously affect entire ecosystems and global food security.
“The new study significantly adds to the growing concern about an AMOC collapse in the not-too-distant future,” Rahmstorf said he Associated Press. “We will ignore this at our own peril.”
This research was published in Scientific advances.