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#Holocene

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Radical Anthropology

This comment on #archaeological analysis based in GINI coefficients (fundamentally house space across a 1000 sites) focuses on inequality (or not) in the #Holocene

livescience.com/archaeology/in

But do NOT imagine that there were no #Pleistocene #civilisations. We became Homo sapiens, the symbolic species, thanks to #egalitarianism
And don't anyone try telling me this isn't civilisation! Subsequent 'civilisations' were those which maintained egalitarianism, the most politically complex human societies. 'Civil' society promotes equality, sharing and cooperation with strangers, and investment in childcare not warfare -- the exact opposite tendencies of today's fascism.

c.im/@RadicalAnthro/1133239907

Live Science · Did every civilization have inequality? New 10,000-year study reveals a surprising answer.Von Ben Turner
Antwortete im Thread
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anlomedad

@rahmstorf

Did the wind-driven parts stop during deglaciation before the #Holocene?
#YoungerDryas
en.wikipedia.org/wiki/Younger_

I guess not.
Would Marotzke or Latif say, AMOC "collapsed" back then?

I heard oceanographer Mojib Latif say on German radio & TV, he doesn't see #AMOC having a tipping point at all. Is the wind thingy the semantic reason for such an opinion?

en.wikipedia.orgYounger Dryas - Wikipedia
Öffentlich *
anlomedad

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...

Map of the AMOC with its surface and deep water currents from Antarctica to the Norwegian Sea. At 5 latitudes, dashed white lines indicate installed monitoring arrays. Next to it are maps from the preprint for locations where Early Warning Signals were found in temperature trends. Shallow water depths on continental shelves are a corridor on 30°N near Africa, and some on Southern Africa's and South America's shelf.
Map of the AMOC with its surface and deep water currents from Antarctica to the Norwegian Sea. At 5 latitudes, dashed white lines indicate installed monitoring arrays. Next to it are maps from the preprint for locations where Early Warning Signals were found in salinity trends at various depths. Far fewer locations are suitable for observing salinity changes than for temperature changes. For using clams, locations are the area near Africa on 30°N and Argentina .
Figure from van Westen et al 2024 showing AMOC strength at 26°N in their freshwater experiment. Superimposed on it are reconstructions by Thornalley 2018 and Rahmstorf 2015. VanWesten's AMOC shows a gradual decline starting in experiment year 1500 and a serious decline from experiment year 1750. Thornalley's AMOC slows down slowly from year AD 1700 on and drops off a cliff in year 1830. Rahmstorf's AMOC reconstruction from the Cold Blob slides down 1850ff and drops off a cliff in 1970, recovering in 1994.
Antwortete im Thread
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anlomedad

@rahmstorf

Good read, and important to clarify the puzzling contradictions. Thank you. realclimate.org/index.php/arch

Was hoping for thoughts re team van Westen's finding that Cold Blob is no region for >Early Warning Signal<. Their preprint's suppl. figures show salinity and temperature at various depths where EWS were found in CMIP5 and also the reanalysis ORAS5.
For SST it's primarily almost all of the South Atlantic. For surface salinity, it's around 45°South. And both show other EWS locations at various depths.
Neither Cold Blob nor the heat jam at North America's coast is a pointer to pre-tipping behaviour of the #AMOC – according to the 2 map collections in their supplement.

I don't know to which depths the installed monitoring arrays go. But their locations, the dashed white lines in the AMOC schematic by Chidichimo et al 2023, do not look very promising compared to those preprint maps.

Are you aware of work underway to re-evaluate monitoring locations and also proxy locations for reconstructions accordingly, to see if #paleoclimate or #Holocene data shows interesting behaviour in the EWS locations ?
arxiv.org/pdf/2406.11738.

Map of the AMOC with its surface and deep water currents from Antarctica to the Norwegian Sea. At 5 latitudes, dashed white lines indicate installed monitoring arrays. Next to it are maps from the preprint for locations where Early Warning Signals were found in salinity trends at various depths. For surface salinity at 5m depth, only the RAPID array matches an EWS location.
Map of the AMOC with its surface and deep water currents from Antarctica to the Norwegian Sea. At 5 latitudes, dashed white lines indicate installed monitoring arrays. Next to it are maps from the preprint for locations where Early Warning Signals were found in temperature trends. For surface temperature in 5m depth, only the Eastern part of the RAPID array is valuable.
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💧🌏 Greg Cocks

Atop The Oregon Cascades, [Research] Team Finds A Huge Buried Aquifer
--
eurekalert.org/news-releases/1 <-- shared technical article
--
doi.org/10.1073/pnas.241515512 <-- shared paper
--
usgs.gov/centers/oregon-water- <-- shared USGS technical article, 2011, ‘McKenzie River Source Water Study’
--
youtu.be/6R8e5HwGMwU?si=sniW4b <-- shared media video overview
--
#GIS #spatial #mapping #model #modeling #water #hydrology #Oregon #Cascades #CascadeMountains #PNW #PacificNorthwest #volcanic #rocks #aquifer #waterresources #watermanagement #climatechange #snowpack #drought #spatialanalysis #CriticalZone #geohazards #geology #engineeringgeology #landscapes #weathering #bedrock #holocene #groundwater #structuralgeology #orogeny #remotesensing #geophysics #sampling #drilling #porosity #permability #tomography #lava #spring #seep #breccia #discharge #streams #runoff #precipitation #climate #rainfall #recharge

photo - Scientists examine a large-volume spring in young volcanic rocks of the McKenzie River watershed on the west side of the Cascade topographic crest that was monitored as part of this study. Credit: Benjamin Nash
map, photo and charts - (A) Electrical resistivity tomography of Olallie North Spring, which emerges along a flow contact of _25 ka Scott Mountain lava flows. Lateral variations correspond to spring discharge points along the lava flow basal breccia such as depicted in (B) (photo: Benjamin Nash). (C) Mean of total yearly range in discharge _Q divided by mean annual flow Qavg versus average upstream age for springs and streams. The horizontal line defines “spring-” versus “runoff-” dominated. (D) SD of yearly average summer discharge (June–September), normalized by Qavg, with CZ state shift labeled.
maps and chart - (A) Distribution of geothermal drill holes. Thin black circles’ radii scale with total logged length, and colors indicate the fraction of length for which dT=dz < 20_C/km (implying downward flux of meteoric water). Red circles are the fraction with inverted gradients (dT=dz < 0_C/km). The purple contour indicates bedrock ages <2 Ma, while stars mark Holocene age phreatomagmatic eruption vents. (B) Two example temperature-depth logs from deep wells in old and young bedrock. (C) Porosity (blue) and resistivity (orange) in the Santiam Pass drill hole SP 77-24. Dashed lines indicate low porosity at high measured resistivity. (D) Chemical weathering tracked by oxidation state of iron in the Santiam Pass drill hole. The green box indicates range of Quaternary High Cascades lavas (SI Appendix), indicating that much of the SP 77-24 hole has been oxidized.
maps and cross section - Oregon Cascades study site. (A) Topography, rivers (from USGS blue lines), stream gauges, lakes, and faults. Olallie North Spring (ONS) and HJ Andrews Experimental Forest (HJA) are labeled. (B) Surface bedrock ages (18), geothermal drill holes, and Quaternary volcanic vents (19). Labeled vents exhibited Holocene phreatomagmatic activity: Sand Mountain volcanic field (SMF), Blue Lake Crater (BLC), Twin Craters (TC). Gray areas are mapped as “Sedimentary deposits and rocks” in ref. 18. (C) Cross-section of swath topography and surface bedrock ages (N-S average of _4 km from Santiam Pass, pink box in panel A), with subsurface structures based on published geologic maps (SI Appendix). The proposed Critical Zone (CZ) state shift and physiographic “Western” and “High” Cascade provinces are labeled. (D) Temperature gradient versus depth in drill holes from panel (C). Near-isothermal or inverted temperature gradients define the “rain curtain.”
Öffentlich
anlomedad

The last time, today's warming rate happened was during deglaciation, see ice core from Greenland.
It was so fast that the AMOC stopped. Which also re-froze Scotland and Scandinavia for a while. Scotland was a wall of ice 800 m tall!

But the Earth's orbital cycles drove further warming, #AMOC restarted – and our stable #Holocene began.

The chart shows decadal average temperature in °C from Renland in East Greenland and a short contemporary time series from a weather station 600km further North at the coast in Danmarkshavn. To visualise the similar warming rates a little better, Danmarkshavn's data was copied in at the 2 previous periods of fast rising temperatures in Renland.
Noteworthy: the 2 steep warming periods took about 300 years each and covered first 10 and then 8 °C. Roughly 0.33°C per decade.
While Danmarkshavn saw a rise of 0.35 per decade since 1980.

Line chart with decadal average temperature in celsius from ice core at Renland, East Greenland and the decadal average temperature in celsius from Danmarkshavn, at the coast 600km North of Renland. Renland time series is shown from year -13,370 to 2000, common era. Danmarkshavn from 1950 to 2020 (December 2024). At -12,800, Renland's temperature rises from -31 to -19.6 by year -12530. Danmarkshavn's short temperature time series is plotted right next to this rise and shows the same amplitude: a rise of 1.4 degrees within 4 decades (preceded by a short drop). Renland's time series then shows a few downs and ups until year -10,960 when it drops from -23 to -29 in -10,680. The last, fast rise of 8 degrees celsius begins in -9,830 up to -9,610. Then the rise becomes more gradual and from -6990 stays at about -14 degrees celsius for 6 thousand years, after which a slow, gradual decline begins. The very end of the time series is a sharp increase of 1.4 degrees celsius within 3 decades. Source: Buizert et al 2018 GHCN weather station Danmarkshavn GL000004320
#Paleoclimate#Greenland
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anlomedad

@rahmstorf

Does anyone here know how or when AMOC is restarted after a shutdown?
How it used to get restarted in past climate changes. And how that restart would play out under our unusual changed factors?

I was thinking that maybe, a restart requires all Milankovic cycles to sufficiently favour Northern Hemisphere. And the process would be that sufficiently warmer summer temperatures over the Northern North Atlantic manage to evaporate enough ocean water for it to become saltier – and that would kickstart convection in place, with strictly local conditions as the first engine.

All 3 Milankovic cycles sufficiently favouring Northern Hemisphere, that's in about 120,000 years....

#AMOC#Ocean#AMOCShutdown
Antwortete im Thread
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anlomedad

@BenjaminHCCarr

You know what? Since I saw Fourteaux et al 2019 who have an incredible monthly resolution forcontinuous periods of hundreds of years in their Antarctica ice core, I am beginning to believe that
the rise 2020ff is not merely due to more CH4 production, but to a change in the OH sink.
Why?
Because monthly ±30pb and even ±50ppb year on year was quite common in the #Holocene .
It was the hiatus in CH4 growth in the early 2000s that was very unusual.

My thinking:
OH sink during the Holocene relied on NOx and ozone production from wood burning and wildfires, and lightening strikes. Today, it relies on fossil fuel burning – and the other things.
But we are regulating NOx emissions.

So while our #methane-producing landfills grow near our industrial centres, we deprive ourselves of NOx birthing the OH radicals who'd then bomb the methane where it emerges at the source.

How the hiatus could fit into this thinking I'm not sure yet. But I think it's an alley worth following.

Öffentlich
anlomedad

reuters.com/investigates/speci

Cool webstory by Reuters about future Iceland's and global volcanic eruptions to be triggered by retreating glaciers, when the weight of the ice is no longer keeping a lid on magma chambers.
Apart from neat writing, it's with video, lotsa photos, animated charts and everything one can think of to be included in #scicomm

tldr: yes, volcanic eruptions will increase with the retreat of glaciers. #Antarctica's volcanos too. #Earthquake activity has already been picking up in Iceland since 2021, also elsewhere in the #Arctic near glaciers, and around the globe.

It has happened before when Earth crawled out of the last #iceage into the #Holocene.

I might add: it happened not only at volcanos near glaciers. Rising #sealevel has triggered near-coastal volcanos, too, whether above or below the water. IIRC, a study on Stromboli proved it.

I personally think, #HungaTonga's eruption could have been one of the first submarine volcanos to have been triggered by #climateChange Another submarine volcano erupted near Japan in 2021 or 2022, forgot its name, starts with an O...
Not as huge an explosion like Hunga Tonga tho.

#paleoclimate#volcano#Iceland
Antwortete Dr Micha Campbell
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anlomedad

@michcampbell

Interesting.
From what I recall from a few papers I read, the Mediterranean, or #MENA, experienced droughts in the 4.2ky event.

But figure 4 in the new literature review by #McKay et al 2024 shows a decidedly wet excursion for MENA: nature.com/articles/s41467-024

They do mention the #Mediterranean and say, it were a complex and not at all clear case whether a drought was gripping the region or not.

So I pulled #d18O from cave #speleothem in the database " #Sisal3 " and plotted all those with okay resolution during the 4.2ky event.
The time span of the selection goes from 8.5ky to 2ky, like in McKay's paper.
My cave selection goes from longitude -9° to 85°E.
Locations are in the Google map, with the info whether it was dryer🔴 or wetter🌀 at 4.2ky.

A 3-colour-coded heatmap for the 50th percentile of d18O shows orange as drought and blue as wet.
More info in the ALT texts.

Conclusion: the mediterranean DID get dryer in the 4.2ky event. 🙂 🖖

Figure 4 from the literature review paper McKay et al 2024 shows global maps for temperature and moisture, top row for the 8.2Ka event and bottom row for the 4.2ka event. In the 4.2ka event, moisture went up in Europe and MENA, with the sole exception of Egypt which was a little dryer.
Location of the caves in the heatmap. Meaning of the colours : the difference between the average from 4250 to 4050 BP over the average in the whole individual speleothem series. Blue is if the 4.2ky period was higher than the alltime average, meaning, the speleothem received more rain during this period compared to its alltime average. Red is dryer than usual. The red dots are so big because otherwise, they'd hide behind the blue dots in cases where speleothems in a single cave/location show the opposite evolution. (This happens very often actually, d18O from stalagmites in the same cave not at all corresponding to each other. I don't know how to deal with this phenomenon. It's the reason why I usually don't look at stalagmites anymore. Very sad. They often have such high resolution. :( )
Heatmap for d18O in speleothems. Orange is dryer, blue is wetter. Visible in the top row is only a part of the coordinates of the caves, first longitude, then a part of the latitude. Red cells are caves below the equator. The selection is from -9 to 85°E. The leftmost column are the years before present. Red is the range 4250 to 4050 BP. The year 4200 is highlighted in green and also by an empty row above it. The visible range here is from year 4,254 to 4,016 BP. The whole selection goes from 8,500 to 2,000 BP. Only those caves are shown that have an okay resolution around the 4.2ky event. Source is Sisal v3.
#paleoclimate#holocene#drought
Öffentlich
Dr Micha Campbell

The first paper for our paper club is this recent one from McKay et al., presenting a thorough investigation of the (supposed?) 4.2 ka event. I'd read it when it was published, but just went through again in more detail, and what a good paper. Robust stats (of course, from this group), and they do a really nice job of building the case. I hope the group enjoys it!

#palaeoclimate #paleoclimate #Holocene #Quaternary

nature.com/articles/s41467-024

NatureThe 4.2 ka event is not remarkable in the context of Holocene climate variability - Nature CommunicationsA study of more than 1000 paleoclimate datasets reveals that the ”4.2 ka event” is not a globally significant climate excursion, unlike the prominent 8.2 ka event. In the Holocene, site-level excursions are common, but global-scale events are rare.
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Tino Eberl

Das tolle an Direct Air Capture mit unterirdischer Speicherung ist ja, dass das Gas ganz genau weiß, dass es dort unten bleiben muss und auf keinen Fall auf die Idee kommt, wieder zu entweichen.

#Google hat einen 10-Millionen-Dollar-Vertrag mit dem US-Unternehmen #Holocene abgeschlossen, um #CO2 aus der Luft zu filtern. Für 100 US-Dollar pro Tonne gilt dies als der bisher günstigste Preis für #DAC.

#CO2Abscheidung #Klimaschutz #Klimaneutralität #CCS

golem.de/news/direct-air-captu

Golem.de · Direct Air Capture (DAC): Google schließt Zehn-Millionen-Vertrag für CO2-Abscheidung - Golem.deVon Mike Faust
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anlomedad

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

2 charts with coloured areas for Milankovic cycles of eccentricity, obliquity, and precession favouring either Northern or Southern Hemisphere. CO2 and sea level are in sync in their ups and downs. d18O from U1308 is completely independent from the roughly 100 thousand year glacial cycle, and also doesn't seem to be disturbed by obliquity or precession. Instead long, more or less stable periods of 80 thousand years are followed by far more unstable periods of about 50 thousand years – but not triggered by Earth's orbital patterns.
Global map with the drilling site of the sediment core U1308 which is in a very deep part of the North Atlantic and on the same latitude as South Ireland but the same longitude as West Iceland.
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