#tegtmeier — Public Fediverse posts

"Forests moderate local climate by keeping their local environments cool. They do this partly by shading the land, but also by releasing moisture from their leaves. This process, called transpiration, requires energy, which is extracted from the surrounding air, thus cooling it. A single tree can transpire hundreds of liters of water in a day. Each hundred liters has a cooling effect equivalent to two domestic air conditioners for a day, calculates Ellison."

https://e360.yale.edu/features/how-deforestation-affecting-global-water-cycles-climate-change

It's now part of my new #Tegtmeier project: figure out how much eg. European and American land use change has impacted local, regional and continental weather. See above posting where I asked this question, too.

So I plot #treering widths alongside d18O from #speleothem (eg. stalagmite). Both proxies are precisely dated and (can) have annual resolution.

I would expect to see a warming =
trees grow more when, at locations from where "their weather comes", other forests are felled .
And a drying =
d18O increase in speleothems.

I use #GoogleEarth and my rudimentary history knowledge to determine certain locations in Australia, New Zealand, USA and Europe. tbc.🍿

#paleoclimate #ECS #climateModel

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
https://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.