- I hugely recommend reading Peter Brannen's The Story of CO2 Is the Story of Everything. I picked it up thinking it'd be a good book about climate change—it is—but it's so much more. It's an excellent journey through our planet's (bio)geochemistry, and really gives you a sense for the power and scope of CO2 over millions and billions of years. Snowball earth features prominently, and there are some really fascinating history and consequences of them.
- 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."
- Yeah, this is also why the "the climate has changed before and will always change" comments are so misleading - indeed it does, and currently, it's in a cold phase, so if we're seeing rapid warming right now, then something is seriously off.
- It is worth pointing out that there is evidence of warming on Mars just now. I don't doubt anthropogenic warming is a thing, but it appears there is a solar factor too.
- 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?
- The Cambrian and Eocene reached around +14C compared to today[1]. Two of the warmest periods in Earth's history, granted. But life thrived. Governments, private property ownership, civilization, not as battle tested.
1: https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...
- Hmm. I do like civilization. How about humans, would human life thrive?
- No reason not. It would push human habitable zones into the high mid-latitudes and subpolar regions though. 55–65° N/S would be closest to comfortable temperatures. So, northern Canada and Russia, Greenland, Antarctica.
The mad rush to get there would likely extract a heavy toll.
- The main problem is agriculture. If rain patterns get severely disrupted in most of world's current breadbaskets, it takes time to increase production in areas that may now have more favourable climate. During that time lots of people would starve.
Rain patterns and extreme weather events are the things to really worry about. Temperature changes alone can be mostly dealt with by planting different crops.
- Oh, yeah, like even if it's survivable for humanity in general, it's going to kill billions of humans.
- No doubt the transition period would likely involve more death than most catastrophes in history. In part because there are simply more people. Available sunlight is also less nearer the poles, which already affects agriculture in places like Greenland. Crops would shift. We'd be more dependent on energy and supplemental light for certain crops. Adjustment would be difficult. But quite a bit of land would still be habitable.
- > The mad rush to get there would likely extract a heavy toll.
Climate refugee situation will dwarf any war refugee issues. They claim "invasion" now, but this one will be an actual invasion.
- Interesting. Paying close attention to geopolitics lately, it kind of seems like we're already in a slow-motion mad rush to own these places. Remember when Trump almost invaded Greenland?
- Certain investment firms purchased cold-weather ports which were iced in 8 months a year, 20 years ago, which now operate nearly year-round.
- Sounds like a good long term investment. And maybe not that long term!
- I know civilization sounds appealing but have you considered giant dragonflies?
- From what I read recently (and I don't remember where it was), the current thinking is that it wasn't oxygen levels or temperatures, but the lack of predators that let dragonflies grow that big. A big dragonfly is much slower and an easier target. So unless you get rid of birds, you won't have giant dragonflies.
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- Assume that there will be a mass extinction event somewhere in the next 1000 years - meteor, WW3, whatever. If you'd then play a timelapse of earth, you'd see it on fire, cooling down, oceans forming, greenery forming, continental drift, north/south poles icing over and clearing, snowball (?) earth a few times, then in a short blip the rise and fall of humanity, then uh. more of the same. Geological (and universal) time scales are mind blowing.
- Paper in Proceedings of the National Academy of Sciences: https://www.pnas.org/doi/10.1073/pnas.2525919123
- 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
- There are various companies/projects set up around that idea:
- 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?
- 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).
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- 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.
- 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.
- How does growing crops work when it's dark 6 months a year?
- > How does growing crops work when it's dark 6 months a year?
Have you noticed that all broadleaved trees and shrubs lose their leaves for half the year in temperate zones already?
Did you not wonder why that is?
They'll be fine. Annual crops are fine. Wildlife is fine if it's got somewhere to migrate to.
Tough for wildlife when there's nowhere to migrate to, though. But what's burning desert in summer might be just about tolerable hot tropics in winter.
The problem is that current tropical species can't handle the alternation of the seasons. You don't get seasons at the equator. Spring/summer/autumn/winter is a temperate-zones thing. Near the equator the sun rises and sets at the same time every day, and there are at best 2 seasons: the dry season, when it never rains, and the wet season, when it rains a lot all the time.
- there are no guarantees in life, can look up any random day and see a meteor streaking across the sky and realize that this is the end regardless of "sociopolitical structures".
All that matters is sociotechnological progress to be able to progress further enough to overcome these tests of existence.
- > look up any random day and see a meteor streaking across the sky
That's happened rather more times in Earth's history than most folks are comfortable admitting. Tunguska would have leveled any major metropolitan city on the planet. I still think an impact is one of the more likely initiators of the Younger Dryas abrupt cooling and worldwide ~100M sealevel rise ~12,000 years ago. Conspicuously aligned with the oldest surviving traces of city living, agriculture, etc. It's increasingly accepted that a large portion of human history is 100M underwater on the continental shelves, estuaries, and other coastal areas where humans would have liked to live.
- The impact hypothesis for Younger Dryas isn’t really tenable. Among other things, the climate effects of a large bolide impact would be global, whereas Antarctica actually warmed during YD. This “Polar See-saw” pattern is easily explained by a northerly meltwater pulse hypothesis, but not a bolide.
- Sea level rise was much faster before the cooling of the Younger Dryas.
- You're right, and here's a graph: https://en.wikipedia.org/wiki/Past_sea_level#/media/File:Pos...
It's possible the sea level rise could have initiated the cooling. But there is much disagreement as to what exactly initiated the de-glaciation which caused the sealevel rise.
- > I'm in western Europe
Me too.
> and really hope the AMOC will not collapse.
It absolutely categorically will, probably in a decade or two.
However, as the rest of the planet rapidly warms, for a decade or so western Europe gets cooler and wetter. I only have 2 or 3 decades to live at best, so it's swings and roundabouts: some you lose, some you win.
- Having followed every bit of info, data, and discussion(that I can find) on climate, geology, etc, since I was a child in the 1970's, I can point to the fact that earth climate science is ferociously complex, but that almost all of the variables are pushing towards a much warmer planet, and that there is NO big offset. Like it or lump it, we have whatever passes for a global civilisation, where we are so intertwined that we cut special "deals" with the people we are bombing and bieng bombed by, for certain trade items, ie: gasses for chip production, "humantarian exemptions", etfuckingcetera, and so the real threat to All That™, is ocean rise, as it can wipe out shipping fast under some realistic scenarios , which if fact, are playing out there preliminary set points.
https://www.ospo.noaa.gov/products/ocean/sst/contour/
- Short term (low single-digit decades): rapid sealevel rise. When (not "if") the Thwaites Glacier goes and the West Antartic Ice Sheet floats (not melts, just gets seawater underneath it) then we're looking at circa 5 metres, stabilising globally in about 12 days.
Goodbye every single coastal city, air or sea port, industrial area, power plant, transport infrastructure in the world.
Medium term (high single-digit decades): rapid global warming pushing the habitable zones to the poles and sub-polar regions. Note, critically, that means agriculture, as there are no established ecosystems to hunt/gather from at the poles.
We are heading for ~7º C by the end of the 21st century. Never mind 4º, double it.
Long term (millennia): another mass extinction event, much as the previous ones. We're 75-80% of the way through already, though.
Geological terms...
Hundreds of thousands of years: if humans go extinct, the planet will recover in 100K years or so, with plentiful but severely species-impoverished ecosystems.
Tens of millions of years: lots of new species, new rich ecosystems form.
Hundreds: if another sentient species evolves, it will have a hard time bootstrapping an technological civilisation, as we've extracted most of the the easy-to-access resources.
93 points by wglb 13 hours ago | 39 comments
