A portion of the Atlantic meridional overturning circulation (AMOC) [image credit: R. Curry, Woods Hole Oceanographic Institution @ Wikipedia]

The article below links to another one which appears to contradict it. In ‘The threshold between natural Atlantic current system fluctuations and a climate change-driven evolution’ we’re told ‘natural variations are still dominant’ in the AMOC or “Gulf Stream System.” Then the key part:
‘According to the researchers, part of the North Atlantic is cooling—a striking contrast to the majority of ocean regions. All evaluations indicate that since the beginning of the 20th century, natural fluctuations have been the primary reason for this cooling. Nonetheless, the studies indicate that the AMOC has started to slow down in recent decades.’ If the slowdown occurred under cooling, why should future warming be likely to cause more of it?
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For decades, oceanographers have been measuring the Atlantic Meridional Overturning Circulation (AMOC), a large system of ocean currents that greatly influence Earth’s climate, says Phys.org.

In recent years, the data show it is weakening. But what does this mean?

“If this system of currents significantly slows down, this could change weather patterns in the tropics, with a detrimental effect on crop yields,” said Spencer Jones, a visiting assistant professor in the Department of Oceanography at Texas A&M University.

The AMOC is technically still within its natural normal range for speed, experts say, but as global warming continues, the AMOC could possibly slow dangerously.

Some scientists say that we are already seeing the effects of this slowing in recent abnormal weather patterns. One thing most scientists agree on, though, is the importance of the AMOC to the climate.

“Changes to the AMOC strength are likely to change the weather patterns in regions like Central America and Indonesia,” Jones said. “Even though the atmosphere compensates for some of the northward heat transport by the AMOC, the Northern Hemisphere still ends up being a bit warmer than the Southern Hemisphere. Most scientists agree that temperatures in northern Europe (particularly Norway) are warmer because of the additional heat transport of the AMOC.”

Because the AMOC is within its natural range as far as the speed of its currents, some might think there is nothing to worry about. Jones, however, disagrees.

“Whether or not it is true that the AMOC has been slowing down for a long time, most scientists expect that the AMOC will slow down quite a lot over the next few decades,” Jones explained.

“That’s because as the climate warms, the Greenland ice sheet will melt, and a lot of freshwaters will enter the Labrador, Greenland and Irminger seas. Fresh water is lighter than salty water, so the surface water in these areas will get lighter, and less water will sink into the deep ocean.”

Full article here.

via Tallbloke’s Talkshop

November 17, 2022, by oldbrew

Experts ‚explain slowing Atlantic ocean currents‘ – or do they? — Tallbloke’s Talkshop