Atlantic Meridional Overturning Circulation, aka Gulf Stream

[rcjordan]

^{Debbie: UK, Scandinavia screwed if this progresses.}

Concern grows over Atlantic Ocean 'conveyor belt' shutdown
https://www.aljazeera.com/news/2021/11/12/concern-grows-over-atlantic-ocean-conveyor-belt-shutdown

[creative666]

A guilty pleasure, I actually really love this film:
https://www.businessinsider.com/day-after-tomorrow-was-right-and-wrong-about-climate-shifts-2019-3

[rcjordan]

Debbie says that she's been seeing Atlantic storm formation shift slightly north over the last 3 or 4 years.  She's not seen this shift confirmed by any weather services, but this year was particularly off the usual pattern. If this shift IS occurring the heavily populated Maryland-Massachusetts coastal corridor and even the UK could be hit.  This year, the US Atlantic coast was repeatedly saved by unusual offshore winds and -maybe- the Saharan dust storms.  The question is whether the changes in the Gulf Stream are behind some of this shifting?

Atlantic hurricanes slightly below normal in 2021 | AccuWeather  ^{(But total storm activity was the 3rd highest)}
https://www.accuweather.com/en/hurricane/atlantic-hurricanes-slightly-below-normal-in-2021/1053374

2021 the 3rd most active hurricane season, but that's not complete picture
https://www.news4jax.com/weather/2021/11/30/2021-the-third-most-active-hurricane-season-but-thats-not-complete-picture/

[rcjordan]

>Debbie says that she's been seeing Atlantic storm formation shift slightly north over the last 3 or 4 years.  She's not seen this shift confirmed by any weather services

Bingo!

'been observed that the latitude at which hurricanes reach their maximum intensity has moved northward so that that is a shift'

CT Will be More Susceptible to Hurricanes in The Future – NBC Connecticut
https://www.nbcconnecticut.com/news/local/ct-will-be-more-susceptible-to-hurricanes-in-the-future-study/2681834/

[rcjordan]

>Concern grows over Atlantic Ocean 'conveyor belt' shutdown

Uh-oh. This has happened before and....

Winter is coming: Researchers uncover a surprising cause of the Little Ice Age | NSF - National Science Foundation
https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=304203&WT.mc_id=USNSF_1

[ergophobe]

I was curious what the data sources for that are... unfortunately, I only vaguely understand phrases like

Stable oxygen isotope (d18O) measurements of two speleothems, collected from Huagapo Cave in the central Peruvian Andes and with overlapping age from 1.1 to 1.4 ka, characterize tropical South American climate variability over the last 7150 years.

It is interesting though. There have been a lot of theories including that the depopulation of the Americas as a result of massive die-off due to introduction of European diseases resulted in massive reforestation and carbon sequestration. AFAIK the current opinion is that that is not a cause or not a significant cause.

[Torben]

You'd think that we can fix this with global warming 

[rcjordan]

>Little Ice Age > fresh water in the oceans

A68: 'Megaberg' dumped huge volume of fresh water - BBC News
https://www.bbc.com/news/science-environment-60060299

[rcjordan]

A Major Ocean Current Is at Its Weakest Point in 1,000 Years - Scientific American
https://www.scientificamerican.com/article/a-major-ocean-current-is-at-its-weakest-point-in-1-000-years/

[rcjordan]

sorta-kinda good news update:

https://yaleclimateconnections.org/2024/12/atlantic-circulation-collapse-new-clues-on-the-fate-of-a-crucial-conveyor-belt/

Atlantic circulation collapse? New clues on the fate of a crucial conveyor belt » Yale Climate Connections

[ergophobe]

It's better news than finding out they've been wrong in the other direction and collapse is imminent. That is good news.

It's also one of the clearest overviews of the whole issue. That article is really well-done.

I hope above all to run out the clock. My dad is already there. One of the things he says pretty often is, "Well, I won't be around to see it. That'll be your problem to deal with."

[rcjordan]

Rainy Tropics Could Face Unprecedented Droughts as an Atlantic Current Slows | UC Davis

https://www.ucdavis.edu/news/rainy-tropics-could-face-unprecedented-droughts-atlantic-current-slows

==========

‪Sang-Ki Lee‬ - ‪@sklee621.bsky.social‬

Another important consequence of the projected (relative) cooling and drying of the tropical North Atlantic (driven by the weakening AMOC) is a suppression of Atlantic hurricane activity

Future Impact of Differential Interbasin Ocean Warming on Atlantic Hurricanes in: Journal of Climate Volume 24 Issue 4 (2011)
https://journals.ametsoc.org/view/journals/clim/24/4/2010jcli3883.1.xml

[rcjordan]

New Findings on Crucial Atlantic Current a Huge 'Wake-Up Call'

Scientists say collapse of AMOC currents system is no longer just a remote possibility

https://www.newser.com/story/374320/atlantic-ocean-current-collapse-now-a-real-risk.html


^Debbie: If it collapses UK, IE, NL, DK, NO, FI, SE won't have to worry about rising temperatures for a while.

[rcjordan]

+
But a *LOT* of their other past climate norms could go to hell.

The Effects of the Little Ice Age (c. 1300-1850) - Climate in Arts and History
https://www.science.smith.edu/climatelit/the-effects-of-the-little-ice-age/


The original climate crisis – how the little ice age devastated early modern Europe
https://theconversation.com/the-original-climate-crisis-how-the-little-ice-age-devastated-early-modern-europe-178187

[ergophobe]

Notice the bumps in the charts in both articles around the 1530s or 1540?

My first academic paper had quotes from people who attributed the bad weather in Geneva to the fact that the city had turned away from the Roman Church and gone Reformed in 1536. Things like, "Back when we had the Mass, it wasn't so cold."

Later, the cold threatened the city's defenses. The lake side of the town had no walls, just pickets and chains to stop attack by boats. But then it turned cold and the lake froze enough to walk on.

Later still, as the glaciers grew, the town of Argentiere, just up the road from Chamonix, sent the priest out every spring (or was it fall?) to exorcise the glacier demons as the advance of the glacier was threatening to wipe the town away.

Later still, I would go to Argentiere in the 1990s and it was a short hike to the glacier to practice ice climbing in the summer. Now it is... I don't know... multiple kms further away.

Also, all the glaciers in the Sierra Nevada, the ones that John Muir studied to show that many of the Sierra Valleys were glacier-carved, were the product of the Little Ice Age. If Muir had come 400 years earlier, there would have been no glaciers to see. The great geologist Josiah Whitney (from whence Mount Whitney) heard Muir's theories and rejected them, calling Muir "a mere sheepherder" and "an ignoramus."

Our MAGA US Rep loves to say, "Temperatures on earth have been changing for 4 billion years" and then use that to dismiss any concerns with climate change.

What he seems to fail to realize is that human civilization has existed only within a very narrow band and changes smaller than what we have experienced have extinguished civilizations.

As both of those articles mention, the LIA was preceded by the Medieval Warm Period, which was great for Europe, but which probably led to the collapse of the civilizations of the Southwest US.

One of the articles mentions the Black Death, but doesn't say why it was connected to the LIA. The thing was that during the Medieval Warm Period, people expanded agriculture faster than population and famine all but disappeared. As the climate cooled and high altitude and high latitude lands became untenable, famine returned by the early 14thC. So when the Black Death arrived in Europe in 1348, it fell upon a weakened and somewhat malnourished population.

But notice from the charts that the magnitude of both the MWP and the LIA were much much smaller than the current warming.