@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: https://www.nature.com/articles/s41467-024-50886-w

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. 🙂 🖖

#paleoclimate #holocene #drought

@arthurgessler

Cool! What do you think, can I correlate annual rain sum in mm of near-by weather stations with the annual #d18O found in those #treerings? Several tree location have a near-by station in NOAA's GHCN network. The German tree is close to the Göttingen station 01691 in DWD opendata.dwd.de and reports since 1927 while the annual / summer tree d18O goes from 1776 to 1999.
Would just be nice to get a feel for d18O – for when I see #paleoclimate data from #stalagmites or other land-bound proxies.
There are intriguing papers on Mediterranean #drought in the Bronze age which use d18O from several caves all around the region. If I know which treering d18O in Spain means how much annual rain, I can translate the bronze age d18O from caves to rain sum, as well – what do you think?

I use this chart as template for when I want to see a particular proxy for #paleoclimate in the bigger context of Earth's #climate factors. Because I add many and varying #proxy records to this template, they need to fit either y-axes. So all records get re-scaled. The individual formula is given in brackets () in the legend, eg., (*10000, /20, +2).
The x-axis is kiloyear ky before present BP (BP is 1950), data resolution is in centuries.

The background of the chart is always the #Milankovic cycles: #Eccentricity as black area, #obliquity / tilt in pink and climatic #precession favoring North in gold and favoring South in darker rosé.
Standard curves are CO2 (gray), CH4 (dark magenta), and sealevel (light blue). CO2 and CH4 are at home on the left y-axis, by the way. Virtually all other proxies end up to be at home on the right hand y-axis.

When I add a proxy from the Southern hemisphere, I usually choose a red-ish colour, and gold-ish for proxies from the NH. Exception to the rule is the tropical South American glacier index "TEG" in white.

Sources for the standard items in this chart are:
- #Milankovic cycles from Laskar 2004 / 2010 http://vo.imcce.fr/insola/earth/online/earth/online/index.php
- #SeaLevel (light blue) from Miller 2020 https://www.science.org/doi/full/10.1126/sciadv.aaz1346
- #CH4 #methane (dark magenta) from Loulergue 2008 https://www.ncei.noaa.gov/access/paleo-search/study/6093
- #CO2 (gray) from M. Yamamoto 2020 https://www.ncei.noaa.gov/access/paleo-search/study/34052

Non-standard proxies in this version for the #tegtmeier thread on modern humans :
- #d18O (magenta) for sea surface temperature in the South Atlantic from Starr 2020 (published January 2021) https://www.nature.com/articles/s41586-020-03094-7
- #Glacier index TEG (white) from Rodbell 2020 https://www.nature.com/articles/s41586-022-04873-0
- ºC in subtropical Africa from Chevalier 2021 https://pubs.geoscienceworld.org/gsa/geology/article/49/1/71/590736/Temperature-change-in-subtropical-southeastern

I use #LibreOffice #Calc.

#TegtmeierBasics