The Atlantic Ocean could start well on the other side of the world

In recent years, climatologists have posed the question of whether the main circulation system of the Atlantic Ocean is slowing down, a development that could have dramatic consequences for Europe and other parts of the Atlantic coast. But a new study suggests that help could come from an unexpected source, the Indian Ocean.

Think of it as an altruism ocean to ocean in the era of climate change.

The new study, conducted by Shineng Hu of the Scripps Institution of Oceanography at the University of California at San Diego and Alexey Fedorov of Yale University, appears on Sept. 16 in the newspaper Nature Climate change. This is the latest in a burgeoning body of research examining how global warming could alter climate components such as the Atlantic Meridional Rollover Circulation (AMOC).

AMOC is one of the largest water circulation systems on the planet. It works as a liquid escalator, providing warm water to the North Atlantic via a higher limb and sending colder water south via a deeper limb.

Although AMOC has been stable for thousands of years, data from the past 15 years, as well as computer model projections, have worried some scientists. AMOC has shown signs of slowing down during this period, but it is unclear whether it is global warming or just a short-term anomaly related to variability. natural of the ocean.

"There is no consensus yet," said Fedorov, "but I think the question of the stability of AMOC should not be ignored.The mere possibility that AMOC will Falling should be a major cause for concern at a time when human activity is imposing significant changes to the Earth's systems.

"We know that AMOC has substantially weakened for the last time 15,000 to 17,000 years ago and that it has had a global impact," added Fedorov. "We would be talking about harsh winters in Europe, with more storms or a drier Sahel in Africa due to the downward shift of the tropical rain belt, for example."

Fedorov and Hu devote much of their work to specific climate mechanisms and features that are likely to change due to global warming. With the help of a combination of observation data and sophisticated computer modeling, they explain the effects that such changes might have over time. For example, Fedorov has already examined the role that melting of Arctic sea ice could have in AMOC.

For the new study, they examined the warming of the Indian Ocean.

"The Indian Ocean is one of the fingerprints of global warming," said Hu, the first author of the new work. "The warming of the Indian Ocean is considered one of the most robust aspects of global warming."

The researchers said their modeling indicated a series of cascading effects extending from the Indian Ocean to the Atlantic: as the Indian Ocean warms up faster and faster it generates additional rainfall. This, in turn, draws more air from other parts of the world, including the Atlantic, to the Indian Ocean.

With so much rainfall in the Indian Ocean, there will be less rainfall in the Atlantic Ocean, researchers said. Less rainfall will result in higher salinity in the waters of the tropical part of the Atlantic, as there will not be as much rainwater to dilute it. This more salty water from the Atlantic, when heading north via AMOC, will cool much faster than usual and will sink faster.

"This would serve as a starting point for AMOC, by increasing traffic," Fedorov said. "On the other hand, we do not know how long this increased warming of the Indian Ocean will continue.If the warming of other tropical oceans, especially the Pacific, catches up with the Indian Ocean, the benefit of AMOC will cease. "

The researchers said this latest discovery illustrates the complex and interconnected nature of the global climate. While scientists are trying to understand the effects of climate change, they must try to identify all climate variables and mechanisms that may play a role, they added.

"There are definitely many other relationships that we are not aware of," Fedorov said. "What are the most dominant mechanisms? We are interested in this interaction."