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#coldblob

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@DoomsdaysCW @hanscees @rahmstorf

Yeah. But first the heatwaves. 19°C and muggy at 6.30am here on 54°N in Germany.

The North Atlantic #ocean is back to "normal" global heating climatereanalyzer.org/clim/sst

simply because ...the #ColdBlob reappeared, indicator of a slowing #AMOC and heralding #heatwaves with deaths & crop loss in Europe
climatereanalyzer.org/clim/dai

To laugh, to weep, to scream?

climatereanalyzer.orgClimate ReanalyzerSea surface temperature (SST) data visualizations

More on Bananas from North Atlantic in 2023, here by #MattEngland, Stefan #Rahmstorf et al
nature.com/articles/s41586-025

They also wrote prose on the Conversation theconversation.com/unpreceden

Low surface wind speed led to shallower-than-normal ocean mixing which enabled heating the surface more.
Less clouds from shipping SO2 were only marginally responsible and only in small pockets.

Okay. But where did the wind go?
Surface wind is impacted by jetstream. And I think, the jetstream got diverted in June and July 2023 to Northern Greenland. Due to low spring snow cover in Eastern Canada which led to dry soil – which in turn gets hotter than wet soil.
And according to
"Summer atmospheric circulation over Greenland in response to Arctic amplification and diminished spring snow cover over Canada" by
Preece et al 2023
nature.com/articles/s41467-023
that hot soil in Eastern Canada leads to a High over Greenland – and a low over the #ColdBlob
East Canada was ablaze in June July 2023 suggesting dry and hence hot soil =perfect conditions for a North Greenland High, diverting the jetstream.

edit: added another image.
aslopubs.onlinelibrary.wiley.c

Amazing!
And #openaccess °
Also, the references in the paper are a treasure trove.

20,000 days in the life of a clam shell 10 mio years ago in the Indonesian Throughway shows heavy rain events, seasons and what the authors say is a proto- #ENSO cyclicality, dominated by #LaNina .
sciencedirect.com/science/arti

When you hear "dominated by La Nina", is your mind jumping to AMOC slowdown and tipping? Mine does.

The longterm climate records stored in this clam species can indeed show early warning signals for AMOC's tipping behaviour. In this paper, Arellano-Nava and D.J. Reynolds et al 2024 look at up to 500 year old (!) clams from the Northern Atlantic, document the approach for finding Early Warning Signals, and see a slowdown since 1750 aslopubs.onlinelibrary.wiley.c

Light slowdown since 1750 was already visible in Thornalley's #AMOC reconstruction from 2018. He used sortable silt grain sizes near Iceland and near the Canadian coast .
So a different proxy showing the same slowdown.
I took the liberty to superimpose Thornalley's and also Rahmstorf's AMOC reconstruction over vanWesten's AMOC in their freshwater experiment to show the striking similarity, see picture 3.

But a gradual, even slowdown isn't an actual Early Warning Signal for tipping behaviour where
"...it flickers, then it tips...".

For AMOC's tipping behaviour, van Westen's team last year identified various Atlantic locations in various depths, none are in the classical research locations in the Northern North Atlantic ! Particularly not in the #ColdBlob... See the two map images from the supplement with the AMOC schematic by Chidichimo et al 2023.
It's still only a preprint tho, first author Emma Smolders arxiv.org/pdf/2406.11738

If I understand it correctly, the clam species lives on continental shelves in shallow-ish waters, not in the ocean abyss. So most locations Smolders et al identified are probably not good for using clams in reconstructing AMOC during the late #Holocene or in #paleoclimate. But some are, eg around the Canary Islands near Africa on 30°N, and many on the shelf along South America.
Especially important because the monitoring arrays (dashed lines in Chidichimo's schematic) have only been installed very recently. But clams can provide a continuous, annual to daily climate record everywhere – in shallow-ish waters.

I'm feeling actual excitement in the hope that researchers are now combing the ocean floor for these shells in the identified locations...

Guter Podcast zum Cold Blob und AMOC ardaudiothek.de/episode/iq-wis

Mit #Rahmstorf, eh klar, aber noch eine Forscherin ist dabei, die speziell Interessantes erzählt.

Hab wieder was dazu gelernt.
Zum Beispiel ziemlich am Anfang, zum Subpolaren Wirbel, wie der überhaupt entsteht.
Durch Wind!
Der treibt das warme Golfstromwasser auf der Höhe New Yorks nach Osten. Und dort gibt es dann irgendwo so eine Art Kreuzung, wo der Wind nach Norden oder weiter nach Osten geht.
Wenn er nach Norden geht, treibt er damit auch den Wirbel an.
Und dann weht er auch mal vo Ost nach West... im Winter wohl..

Im Filmchen sieht man die v-Wind Komponente in den Wintermonaten. V-Wind ist rot, wenn der Wind nach Norden weht. Und blau, wenn er nach Süden weht. Daten: climatereanalyzer.org/research

Der Subpolar Gyre / Cold Blob ist auch nich immer an derselben Stelle, fest eingemauert oder so. Nee! Das wabert alles so fuzzy rum, mal mehr rechts und mal mehr links.
Und je nachdem ob mehr rechts oder mehr links, gibt es in Zentraleuropa starke Hitze.

Muss auch gucken, dass ich ein paper von ihr finde. Vll steht ja in der "Introduction" noch mehr Interessantes um Subpolar Gyre drin.

#AMOC#ColdBlob#SPG

My girlie chart with 490ky years of #Milankovic cycles, CO2, sea level, and the top line is d18O of a sediment core from within the #ColdBlob, see map. I think, it records AMOC shutdowns in the past.

Would be intriguing to know why it shut down. Eg, 427ka, "just" before the interglacial MIS11.
And why it not shut down during that very long interglacial which was ~as warm as the Holocene,
and had an ice-free West #Greenland (with a leaf found just 2 years ago at rock-bottom of an ice core from there),

and why AMOC instead collapsed in the middle of the following #iceage.

The very long interglacial MIS11 with its ice-free West Greenland and stable AMOC throughout tells me that the amount of freshwater input from melting ice on its own isn't the trigger for a collapse. But instead, the speed at which freshwater is added: very slowly like during #MIS11 won't do it.

Also intriguing: why the stuttering motor during the last glacial before the #Holocene?

#d18O from sediment cores at other locations strictly follow the ups and downs of #sealevel and #CO2. This one site #IODP #U1308 is exceptional.
#paleoclimate #AMOC

Rahmstorf's talk at #EGU about his life's work, or rather, about one of the topics of his life's work and what others and him contributed to what is known of #AMOC today
youtu.be/HX7wAsdSE60

At 14:30min or so, he mentions that his Bachelor student just worked out (or maybe repeated the results successfully) what happens at the #ColdBlob. Why is it colder there, what's the mechanism?
So the AMOC slows down and brings less and less warm water into that subarctic gyre South of Greenland. But the cold blob doesn't look cold due to warm water getting released more than compared with the rest of the North #Atlantic . It looks colder because it releases less heat to the atmosphere, precisely bc less warm water manages to enter the gyre.

And near the American coast, the opposite is observed: more heat is released there, so it looks orange. Also due to AMOC slowdown. * End of his short mentioning of this explanation.

This next part is my processing the info.

I had read this also in his recent paper. And stared at it for minutes but didn't get it. It took listening & watching to comprehend what he meant.

Still unclear: obviously, lotsa warm water is around the gyre, just waiting to be pulled into the roundabout. "I bought the ticket, now let me in!"
Why No Entry? Or why very limited entry?
Hm. Gotta think some more about it.

Maybe all that warm water abhores the cold blob. A no-go zone, maybe.

Or the access is limited bc it's full already... and ... oh, and the queue exists bc South of Iceland, the AMOC is too slow in pushing warm salty water down into the abyss.
If it were faster, it would manage to pull in water from within the gyre as well.

So the gyre and its cold blob isn't really part of what drives AMOC.
It just swivels happily around itself?
And whether its cold-er than its surrounding waters or of the same salinity and warmth doesn't matter, it'll go round and round anyway.
AMOC also doesn't need the gyre. When AMOC is faster, the blob disappears. When it's slower, the blob happens.

Ah. Due to it being cold-er, it attracts clouds bursting overhead. So it rains there more often than elsewhere bc it's cold-er, and it's cold-er bc there's only limited entry for warm water, depending on how fast the region North of the gyre can push the salty water into the abyss.

Okay. That might be it. But Rahmstorf's explanations ended at *. The rest is only me, doing a #Tegtmeier , a working theory. Written down so it sticks and can later be compared to newly learned stuff.

Germany has a warning for tonight, a storm coming from the South West. I thought, SouthWest is unusual for winter, hence I checked the broader conditions @ #EarthNullschool earth.nullschool.net/#current/
Top left:
So there's this #PolarVortex #SSW split still ongoing, as seen in windspeeds at 10hPa.

Top right: the normal #jetstream at 250hPa races from North America straight to Europe because, I reckon, there's the hard border between the Azores High pressure system and the Iceland Low. (not in picture). Where the jet "hits" Spain, it gets driven North East. Dunno why. (And creates that storm in Germany. #weather )

Bottom left: sea surface temperature anomaly in the #Atlantic with a location in the #ColdBlob highlighted. It's currently 0.1°C colder than its longterm average. Yay. And for real it's 2.1°C warm there. #AMOC

And now the eyeopener🥁
the bottom right pic shows "significant wave height". The cold blob sees 9-10m waves = ocean mixing, bigly.
Are waves 1 of the 🌡️ reasons that blob forms where it does?

Antwortete im Thread

@rustoleumlove
And it's everywhere... except for a few locations. Like in the North Atlantic, that #ColdBlob and as an extension to the blob, off the US coast, where it's cooler than the base line 1979-2000.

The daily SST anomaly since January 1st as maps with a slider:
climatereanalyzer.org/clim/dai
While January 2023 saw only a hint of the ColdBlob and off the US coast it was much warmer, not cooler like this year climatereanalyzer.org/clim/dai
:(

climatereanalyzer.orgClimate Reanalyzer