[continued from previous message]

To find out how it had changed over centuries, they used sediment cores that had been drilled out of layers of mud and sand on the bottom of the Labrador Sea. The team measured the sediment grains – bigger grains meant a faster current. “A fast-
flowing mountain stream has a rocky boulder bed, whereas a slow meandering river has sediments at the bottom,” says Thornalley. In this way, the sediments offered direct evidence of what was happening in the deep-sea currents. They found that the DWBC
began weakening around 1750. By 1870, it was significantly weaker than at any point in the previous 1500 years. It has slowed ever since.

Total collapse

Put all the evidence together, and the case that the AMOC is getting weaker starts to look quite strong. “From a whole range of different types of evidence, we get the same answer,” says Thornalley.

“If I had to guess, I would say the AMOC is decreasing and it’s not just an
internal variability that is occurring,” says Giovanni Sgubin at the University of Bordeaux in France.

So a weak AMOC could already be affecting weather patterns, but what about the more extreme possibility: a collapse, with the more violent climatic impacts that would follow? The core problem with predicting that eventuality, says Rahmstorf, is that even
after decades of study, it is unclear how big a “push” is needed for collapse. As the AMOC slows down, it comes closer and closer to a theoretical tipping point that would lead to its collapse, but “we still don’t know how
close to that threshold
we are”.

“Although we think it’s very unlikely that you would get a sudden collapse of the AMOC, obviously the impacts from that would be huge,” says Jackson. She calls it “a low-probability, high-impact event” – like a financial crash. Only with far
worse consequences.

***

This is the kind of shit we're playing with by continuing to
burn a lot of fossil fuels. And yet Trump says full steam ahead.

.

--- SoupGate-Win32 v1.05
* Origin: www.darkrealms.ca (1:229/2)