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Posted by wglb 7 hours ago

Snowball Earth may hide a far stranger climate cycle than anyone expected(sciencex.com)
63 points | 9 comments
chasil 2 hours ago|
Most people do not know that we are in an icehouse phase, which is rare.

Earth spends most of its time in greenhouse phases.

"A "greenhouse Earth" is a period during which no continental glaciers exist anywhere on the planet... Earth has been in a greenhouse state for about 85% of its history.

"Earth is now in an icehouse state, and ice sheets are present in both poles simultaneously... Earth's current icehouse state is known as the Quaternary Ice Age and began approximately 2.58 million years ago... Earth is expected to continue to transition between glacial and interglacial periods until the cessation of the Quaternary Ice Age and will then enter another greenhouse state."

https://en.wikipedia.org/wiki/Greenhouse_and_icehouse_Earth

AlotOfReading 1 minute ago|
We'll be much closer to a greenhouse earth than a glacial earth if we get that 4°C warming, so the distinction is more academic than practical in most contexts. What's a century here or there in geologic time?
jtwaleson 27 minutes ago||
Just as a thought experiment, what would be worse for humanity. Global warming or global cooling by the same amount of degrees C?

I'm in western Europe and really hope the AMOC will not collapse.

timschmidt 17 minutes ago|
Global cooling could be worse. But the danger from either comes from the speed with which it happens, and inflexible sociopolitical structures, more than the absolute difference in temperature. Rapid change doesn't permit gradual adaptation like relocation to more habitable areas. The danger from the current global warming trend comes from it's incredible rapidity compared to historical trends.

Given time, humans and other animals will move toward the poles or toward the equator to find habitable zones. Put that on a rush schedule and everyone suffers.

wglb 7 hours ago||
Paper in Proceedings of the National Academy of Sciences: https://www.pnas.org/doi/10.1073/pnas.2525919123
dmix 5 hours ago|
TIL about silicate weathering https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc...

silicate rocks basically traps co2 over millions of years and causes temperatures to fall

prawn 4 hours ago||
There are various companies/projects set up around that idea:

https://www.lithoscarbon.com/

https://en.wikipedia.org/wiki/Carbfix

https://co2crc.com.au/

https://sgeas.unimelb.edu.au/research/carbon-trap-lab

fred_is_fred 3 hours ago||
The Lithos Carbon idea is interesting. The mine they show looks like they can just scrape it rather than needing to mine it with explosives. Unfortunately the site's blog has 1 post and it is 3.5 years old. Is it still a going concern?
chris_va 4 hours ago||
It's really the alkalinity (e.g. the Mg++ or Ca++), which silicate rocks often have (but technically not limited to silicates).

As an aside, we need to dissolve roughly one large mountain into the mix layer (top ~50m) of the ocean to have it fully take up atmospheric CO2. Without dissolving, the reaction is very slow (co2 in atmosphere => slightly lower pH rain => reaction with mostly passivated rock + erosion).

russearyus 2 hours ago||
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