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#IODP

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anlomedad

Learned today:
Cement -making, which involves high heat, incurs 9% of the annual global CO2 emissions.
Roman #cement endured 2000 years, and counting.
"Ours" lasts merely 50-150 years.
Why is that?
Ours crumbles because little fissures are widened by rain water.
The Roman mix contains lotsa tiny calcium lumps. When fissures occur and rain enters them, it dissolves the calcium crumbs and this "dough" smears across the gaps. Case closed.

Heard in a curious podcast episode by a Noam Hassenfeld.

Also learned: when scientists drilled for sediment cores in 2022/2023 around Santorini and the submarine #volcano , the drill got stuck often, and 3 times, they had to use explosives to get it free. One reason: a Roman cement structure on the sea floor !
Thomas Ronge, cli-sci on this #IODP expedition, posted it yesterday on Bluesky.

Public
Or M. Bialik

We really need to talk more about what's going on with #IODP. After more than 60 years of (near) continuous activity, the program is now in its most precarious and fractured state.
There is a new program (#IODP3) in the works, but it's a much smaller dream.

nytimes.com/2024/08/26/science

The New York Times · Dismantling the Ship That Drilled for the Ocean’s Deepest SecretsBy Maya Wei-Haas
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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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