The Washington Post article:
Quote:The new research, based on ocean measurements off the coast of East Antarctica, shows that melting Antarctic glaciers are indeed freshening the ocean around them. And this, in turn, is blocking a process in which cold and salty ocean water sinks below the sea surface in winter, forming “the densest water on the Earth,” in the words of study lead author Alessandro Silvano, a researcher with the University of Tasmania in Hobart.
This Antarctic bottom water has stopped forming in two key regions of Antarctica, the research shows — the West Antarctic coast and the coast around the enormous Totten glacier in East Antarctica.
These are two of Antarctica’s fastest-melting regions, and no wonder: When cold surface water no longer sinks into the depths, a deeper layer of warm ocean water can travel across the continental shelf and reach the bases of glaciers, retaining its heat as the cold waters remain above. This warmer water then rapidly melts the glaciers and the large floating ice shelves connected to them.
In other words, the melting of Antarctica’s glaciers appears to be triggering a “feedback” loop in which that melting, through its effect on the oceans, triggers still more melting. The melting water stratifies the ocean column, with cold fresh water trapped at the surface and warmer water sitting below. Then, the lower layer melts glaciers and creates still more melt water — not to mention rising seas as glaciers lose mass.
“What we found is not only a modeling study but is something that we observed in the real ocean,” said Silvano, who conducted the research in Science Advances with colleagues from several other institutions in Australia and Japan. “Our study shows for the first time actual evidence of this mechanism. Our study shows that it is already happening.”
Hansen said that “this study provides a nice small-scale example of processes that we talk about in our paper.”
So, this is something that was observed.
Quote:Rahmstorf pointed to additional studies that also suggest Antarctic bottom water formation is changing. In one case, a 2017 study relying on measurements from the Southern Indian Ocean, where Antarctic bottom water travels after leaving the Southern Ocean, found that this deep water has been growing fresher over time, especially in the past decade.
One limitation with the current study, however, is that although the researchers have found that deep water is not forming in two key Antarctic regions, they cannot say when a change in these regions occurred. Measurements do not go back far enough for that, study author Silvano said. Thus, it’s possible that deep water formation in these regions shut off a long time ago, well before the modern period of intense climate warming. That would make it harder to pin current events on human-caused climate change.
Still, the mechanism detected by the study, in which freshening water from glaciers inhibits the sinking of colder waters at the surface, would presumably continue to apply.
https://www.washingtonpost.com/news/energy-environment/wp/2018/04/23/one-of-the-...Yeah, it will continue and continue to weaken that oceanic overturning. At some time it could well be possible to find out how long this has been happening.
The globe is warming and severe consequences are beginning to become apparent. The Beast from the East and the three North Easters that hit the New England coast this year are minor. Stopping or significantly slowing the overturning circulation is going to cause a lot more damage. The circulation and bringing up of nutrients forms the basis of the pyramid of life in the oceans, something to think about. Save the wales, yeah.