In der neuen Folge erzählt @pikarl vom Eiszeitproblem: Im 19. Jahrhundert wurde klar, dass Europa und Nordamerika mehrmals unter dicken Eisschilden verschwunden waren. Nur warum hatten die Eiszeiten begonnen und warum endeten sie auch jedes Mal wieder?

➡️ https://astrogeo.de/von-gletschern-und-gestirnen-die-entdeckung-der-milankovic-zyklen/

Gelöst hat das Problem der serbische Mathematiker Milutin #Milanković - und zwar während seiner Gefangenschaft in Ungarn und dank einer kosmischen Eingebung. 🌞 🌏 🌨️

#podcast #astrodon #space #astronomie

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

Weird. Maybe, I've got a logical mistake in my thinking

Will #Steffen et al 2018 https://www.pnas.org/doi/10.1073/pnas.1810141115 warned in "Trajectories of the Earth System in the Anthropocene" of a "Hot House Earth" .
A term that got negative press all over and the paper is still discredited in public opinion among the non-scientific community, at least.
A Hot House Age is merely the term for an ice-less age in which the poles are not covered by kilometres of ice. That is called an Ice House Age.

#Talento et al 2021 https://esd.copernicus.org/articles/12/1275/2021/ modelled what happens to ice ages #glacial |s in several emission scenarios.
Today's CO2 concentration is already moving the next #iceage to later than what the #Milankovic cycles would dictate.
Scenarios for (in my opinion fictitious, unachievable) emissions of 1000 or 3000 Pg C move the next fullblown ice age to 600ky and 900ky from now.
Almost a million years. No ice age.

But the #AMOC is going to collapse: the convection in the Subpolar Gyre in the 2030s; the Northern branch of AMOC might tip before 2050 to later inevitably collapse, too.

Certainly that increases ice mass in Greenland, Europe, and Eurasia, and Arctic Sea Ice grows back, too. And all this AMOC-related ice grows and grows, each year puts more snow on the ever increasing ice layer.
I don't know how much ice is needed to meet criteria for a glacial definition.
But all that Eurasian ice also buries the boreal forests under it, ie removes their carbon from the cycle. And puts an ice plug on leaking methane from #permafrost in that area. (Tho not the permafrost in the far East. I gather, that area is not prone to ice sheets from Atlantic influences and needs other triggers to form? It wasn't covered by ice in #MIS11, 420ky ago. )

Weird isn't it, that ice mass models like Talento's don't factor in ever-increasing ice mass in low-to medium emission scenarios. Hm.

We need to save the coal. It's a good thing to reduce the carbon dioxide load in the atmosphere to limit global warming, but there is a far more important reason to reduce the use of fossil fuels. We need to save them. Check my post to see why.

#coal #ClimateChange #GreenhouseEffect #FossilFuels #Milankovic

https://greencomet.org/2023/06/28/save-the-coal/