I've never really been convinced that the AMOC was slowing or weakening. The system as a whole is very variable and changes cyclically, but the waters north of the GIS gap and south of Labrador have both been unusually warm for several years, indicating that the Greenland cold spot is an unrelated phenomena and that the conveyance of oceanic heat to the far north is continuing unabated.
The much hyped putative driver behind a percieved slow-down doesn't really exist in geologically modern times: No glacier is big enough, close enough, and melting fast enough, or draining suffiiciently into the Arctic to cause a fresh-water induced slowdown - which is a popular theory to explain big swings in the AMOC in the geological past.
And a quick google on "amoc strengthening" finds plenty of evidence to support Hefaistos' post, including this one in Science Direct from 2016: There is no real evidence for a diminishing trend of the Atlantic meridional overturning circulation
here is another interesting paper, On freshwater fluxes and the Atlantic meridional overturning circulation. From the Abstract:
While the role of freshwater forcing in the AMOC has received much attention, this question remains unresolved ... Our results robustly suggest that for the equilibrium state of the modern ocean, freshwater fluxes strengthen the AMOC
Recent research is pointing to a link between the Indian Ocean and the AMOC, with a warmer
IO causing a stronger AMOC. There are plenty of papers to be found online, including this one:
PC23A-03 - The Strengthening of the Atlantic Ocean Meridional Overturning Circulation Caused by Enhanced Indian Ocean Warming, from the Abstract:
Here, we describe how a salient feature of anthropogenic climate change – enhanced warming of the tropical Indian ocean (TIO) – can strengthen the Atlantic meridional overturning circulation (AMOC) by modulating salinity distribution in the Atlantic
Here is what Stefan Rahmstorf (who wrote the oft-quoted paper about a 15% AMOC slowdown, and who probably eats AMOC Sverdrup data for breakfast every morning) said about it on September 17 at
http://www.realclimate.org/?comments_popup=18180#comment-626528New studies confirm weakening of the Gulf Stream circulation (AMOC) "[T]here is growing evidence that another climate forecast is already coming true: the Gulf Stream system in the Atlantic is apparently weakening, with consequences for Europe too."
"The Intergovernmental Panel on Climate Change (IPCC) stated for the first time a year ago in the Summary for Policy Makers of its Special Report on the Oceans:
“Observations, both in situ (2004–2017) and based on sea surface temperature reconstructions, indicate that the Atlantic Meridional Overturning Circulation (AMOC) has weakened relative to 1850–1900.” "
"Two new studies now provide further independent evidence of this weakening."
1. "The result: the Florida current has weakened significantly since 1909 and in the last twenty years has probably been as weak as never before. Piecuch’s calculations also show that the resulting reduction of heat transport is sufficient to explain the ‘cold blob’ in the northern Atlantic."
2. "Model simulations show that a weakening of the AMOC leads to an accumulation of salt in the subtropical South Atlantic."
"This is exactly what the measured data show, in accordance with computer simulations. The authors speak of a “salinity fingerprint” of the weakening Atlantic circulation."
"In addition to these oceanographic measurements, a number of studies with sediment data indicate that the Gulf Stream circulation is now weaker than it has been for at least a millennium."
"[T]he latest generation (CMIP6) of climate models shows one thing: if we continue to heat up our planet, the AMOC will weaken further – by 34 to 45% by 2100. This could bring us dangerously close to the tipping point at which the flow becomes unstable.
This article appeared originally in German in Der Spiegel: Das Golfstromsystem macht schlapp"
