“Atlantic meridional overturning circulation” = AMOC
A 2018 write-up:
GREENLAND IS RAPIDLY GAINING ICE AND DISRUPTING THE AMOC
JULY 12, 2018 CAP ALLON
For decades Greenland has been losing ice, but not anymore. It’s building again — due to our naturally cooling planet.
It’s the middle of July and the Greenland Ice Sheet is gaining so much ice that the blue line, indicating the accumulated surface mass balance, has pushed above the 1981-2010 mean.
As seen on the below chart, courtesy of the Danish Meteorological Institute.
I went off into the strange world of AMOC “studies”. Seems we have actual data from about 2007, so it is almost entirely models, proxies, and speculation. A bit of a dry hole. However, there was lots of ability to claim that a faster AMOC was running during the last Ice Age Glacial, and it was faster during the Little Ice Age, and that just proves that as we warm up the globe by eating beef and driving cars, WE are the cause of the AMOC slowing down and it will inevitably cause us all to die in massive snow and freezing Global Warming… or something like that.
Like this crap:
Gulf Stream weakest in 1,000 years, US East Coast may see more flooding if climate change worsens: Study
Scientists warn that if global warming continues unabated, it will weaken further, and could reduce by about 34% to 45% by the end of this century, bringing it closer to a ‘tipping point’
By Mihika Basu
Updated On : 03:58 PST, Feb 27, 2021
No data? No problem, it just means the “crisis” is worse than we thought /sarc;
OTOH, other folks find no change overall. (And I must remind folks of that paper from a decade or so back about Florida showing that during the Glacial the water there was warmer and the winter climate more like current summers with more rain and oaks, fewer pines, and other pollen markers, caused by a very slow Gulf Stream).
WRITTEN BY MULTIPLE ON FEB 26, 2021. POSTED IN LATEST NEWS
Atlantic ‘Conveyer Belt’ Shows No Sign Of Slowing, Scientists Find
A decline in Atlantic meridional overturning circulation (AMOC) strength has been observed between 2004 and 2012 by the RAPID-MOCHA-WBTS (RAPID – Meridional Overturning Circulation and Heatflux Array – Western Boundary Time Series, hereafter RAPID array) with this weakened state of the AMOC persisting until 2017.
Climate model and paleo-oceanographic research suggest that the AMOC may have been declining for decades or even centuries before this; however direct observations are sparse prior to 2004, giving only “snapshots” of the overturning circulation.
Previous studies have used linear models based on upper-layer temperature anomalies to extend AMOC estimates back in time; however, these ignore changes in the deep circulation that are beginning to emerge in the observations of AMOC decline.
Here we develop a higher-fidelity empirical model of AMOC variability based on RAPID data and associated physically with changes in the thickness of the persistent upper, intermediate, and deep water masses at 26∘ N and associated transports.
We applied historical hydrographic data to the empirical model to create an AMOC time series extending from 1981 to 2016.
Increasing the resolution of the observed AMOC to approximately annual shows multi-annual variability in agreement with RAPID observations and shows that the downturn between 2008 and 2012 was the weakest AMOC since the mid-1980s.
However, the time series shows no overall AMOC decline as indicated by other proxies and high-resolution climate models.
Our results reinforce that adequately capturing changes to the deep circulation is key to detecting any anthropogenic climate-change-related AMOC decline.
So I became a bit disenchanted with the whole notion that anyone really knows what is happening with the Gulf Stream, Atlantic Drift, etc.
Also, every paper repeats the notion that it is salt and cold that drives the circulation. They all implicitly assume the sun is a constant and plays no role. BUT, we know that when the sun went quiet, there was a big increase in IR and huge decrease in UV / Blue. So much more solar energy goes into prompt water vapor at the surface and much less penetrates to depth warming those waters and causing them to rise. Without SOME rise in the tropics, the water would just end up staying 4 C at depth.
I think it is pretty obvious that the Heat Engine driving this circulation pump has both a Hot zone and a Cold zone and it is the differential between them that runs it. BOTH matter. But whatever. They do what they do.
On the plus side, it send me off to the Danes for a look at the Greenland Ice Gain. Yup, still gaining ice!
The map illustrates how the surface of the Greenland Ice Sheet gains and loses mass on a daily basis. This is known as the surface mass balance. It does not include the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.
By holding the mouse over the black circles, you can see the day’s weather observations from meteorological stations that are used to monitor the melting processes. By clicking on the magenta circle, measurements of runoff from Watson river close to Kangerlussuaq is shown. The river drains about 12000 km2 of the inland ice.
The graph below the map shows the total daily contribution from all points on the ice sheet.
The blue curve shows the current season’s surface mass balance measured in gigatonnes (1 Gt is 1 billion tonnes and corresponds to 1 cubic kilometre of water).
The dark grey curve traces the mean value from the period 1981-2010.
The light grey band shows differences from year to year. For any calendar day, the band shows the range over the 30 years (in the period 1981-2010), however with the lowest and highest values for each day omitted.
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