A major system of currents in the Atlantic Ocean has weakened and is losing steam, which could have consequences for weather systems around the world, according to a new study published in the journal Nature Climate Change.
An unprecedented slowdown
The researchers found evidence that the Atlantic Southern Reversal Circulation (AMOC) is approaching collapse. The current system includes the Gulf Stream and circulates warm water to the surface of the ocean that contributes to the mild temperatures on the European continent.
The giant ocean circulation is relevant to weather patterns and its slowdown is also associated with a cold drop observed in the North Atlantic. Compared to a conveyor belt for the oceans, the circulation system plays an important role in the distribution of heat worldwide.
The study by climate scientist Niklas Boers of Freie Universität Berlin in Germany is neither the first nor will it be the last to point out how the AMOC appears to be slowly moving towards a major tipping point. The exact reason for this change is unknown, but there is growing evidence that increased runoff from melting ice is altering salinity and temperature in a way that significantly slows the entire system.
A threat to civilization
A possible collapse of this system of ocean currents could have serious consequences. If the current were to stop, there could be a great reorganization in the world climate. It would unduly disrupt the rains that billions of people depend on for food in India, South America and West Africa; there would be increasing storms and lower temperatures in Europe; sea level rise in eastern North America and, if that weren’t enough, would further endanger the Amazon rainforest and the Antarctic ice sheets. The most likely impact would be that Western Europe would fall into an indefinitely long cold snap. A similar situation is believed to have occurred when AMOC came to a halt near the end of the Ice Age, with a cold snap lasting around 1,000 years.
The complexity of this system and the uncertain levels of global warming for the future make it impossible to forecast the date of such collapse: it could be in a decade or two, or several centuries, but the impact of this event makes us see that we cannot allow that to happen, the scientists said.
“I would not have expected that the excessive amounts of freshwater added over the course of the last century would already produce such a response in the reversal of circulation. We urgently need to reconcile our models with the observational evidence presented to assess how far or how close to its The critical threshold is actually the AMOC. While the respective relevance of the different factors needs to be further investigated, they are all related to human-caused climate change, “says Boers.
Referencia: Niklas Boers. Observation-based early-warning signals for a collapse of the Atlantic Meridional Overturning Circulation. Nature Climate Change, 2021 DOI: 10.1038/s41558-021-01097-4
