“It has been predicted, basically, for decades that this circulation would weaken in response to global warming. And now we have the strongest evidence that this is already happening,” said Stefan Rahmstorf of the University of Potsdam, who contributed to this research.
The Atlantic South Circulation Circulation (AMOC) transports water through the planet’s oceans, including the Atlantic, Pacific and Indian Oceans. The region contributing to the slowdown is the North Atlantic, according to the research.
“The idea (of this movie), which is actually correct, is that if this tipping circulation of the Atlantic breaks down completely, this will lead to severe cooling around the North Atlantic, especially in Europe, in the kind of coastal areas (of) Britain and Scandinavia. But that’s only true if the capsize completely collapses, “Rahmstorf said.
“This indicates that the slowdown is probably not a natural change, but the result of human influence. The AMOC has a profound influence on global climate, and particularly in North America and Europe, so this evidence of continued weakening New evidence for the interpretation of future regional and global climate projections is critical new evidence for circulation, “said Andrew Meijers, deputy scientific director for polar oceans at the British Antarctic Survey.
“Both surface warming and increased water cycling, increased rainfall and melting ice are a consequence of global warming” in parts of the North Atlantic Ocean, he said.
As warm water currents move north, they generally return south as it gets colder and heavier. The addition of fresh water from the melting ice slows down this turn due to reduced salinity.
East Coast of the US To See Higher Sea Levels
One of the main impacts of the slowdown in ocean circulation is on sea levels, especially those on the east coast of the United States.
“The flow from the surface to the north of the AMOC leads to a deflection of the water masses to the right, away from the east coast of the US. This is due to the rotation of the Earth that deflects moving objects , like currents, to the right in the northern hemisphere and to the left in the southern hemisphere. As the current slows, this effect weakens and more water can accumulate on the east coast of the US. leading to a further rise in sea level, “said Levke Caesar, one of the report’s authors.
The rate at which these waters are rising has also increased in recent years.
“The rate of global sea level rise more than doubled from 1.4 mm per year for most of the 20th century to 3.6 mm per year between 2006 and 2015,” said NOAA.
A further slowdown in global ocean circulation, especially along the crucial Gulf Stream current off the east coast of the US, could combine with already accelerated sea level rise to make major Northeast cities are even more vulnerable to flooding.
Hotter heat waves, stronger hurricanes
“The seven warmest years in the world have occurred since 2014, and 10 of the warmest years have occurred since 2005,” NOAA said. Heat waves are already more and more frequent.
The ocean and currents also play a role in absorbing carbon dioxide, the most dominant greenhouse gas, from the atmosphere. The changing currents could decrease the amount of carbon that is removed from the atmosphere, according to NASA.
Marine organisms “are highly dependent on these ocean currents, which basically set the conditions for the entire ecosystem in terms of nutrient supply, temperature and salinity conditions,” Rahmstorf said.
When asked if the AMOC could slow further or even stop, Rahmstorf said that climate models suggest that currents will slow by between 34% and 45% by 2100.
“Despite a lot of research in the last decade on this, it is very difficult to quantitatively pinpoint how far this tipping point is. But the kind of model simulations that I am aware of suggest that if you weaken this circulation by about half, they are entering into a critical state. And then this could very well … happen by the end of the century, “Rahmstorf said.
“We should (strive to) stay well away from that tipping point because the consequences if circulation were to completely collapse would be really dramatic.”