| ▲ | Snowball Earth may hide a far stranger climate cycle than anyone expected(sciencex.com) |
| 77 points by wglb 10 hours ago | 21 comments |
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| ▲ | chasil 5 hours ago | parent | next [-] |
| 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 |
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| ▲ | AlotOfReading 3 hours ago | parent [-] | | 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? | | |
| ▲ | timschmidt 2 hours ago | parent [-] | | 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... | | |
| ▲ | reverius42 44 minutes ago | parent [-] | | Hmm. I do like civilization. How about humans, would human life thrive? | | |
| ▲ | timschmidt 38 minutes ago | parent [-] | | 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. | | |
| ▲ | rwyinuse 29 minutes ago | parent | next [-] | | 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. | | |
| ▲ | reverius42 23 minutes ago | parent | next [-] | | Oh, yeah, like even if it's survivable for humanity in general, it's going to kill billions of humans. | |
| ▲ | timschmidt 23 minutes ago | parent | prev [-] | | 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. |
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| ▲ | reverius42 23 minutes ago | parent | prev [-] | | 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? | | |
| ▲ | timschmidt 21 minutes ago | parent [-] | | Certain investment firms purchased cold-weather ports which were iced in 8 months a year, 20 years ago, which now operate nearly year-round. |
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| ▲ | wglb 10 hours ago | parent | prev | next [-] |
| Paper in Proceedings of the National Academy of Sciences: https://www.pnas.org/doi/10.1073/pnas.2525919123 |
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| ▲ | jtwaleson 3 hours ago | parent | prev | next [-] |
| 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. |
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| ▲ | timschmidt 3 hours ago | parent [-] | | 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. | | |
| ▲ | arjunchint 3 hours ago | parent [-] | | 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. | | |
| ▲ | timschmidt 2 hours ago | parent [-] | | > 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. | | |
| ▲ | vkou 2 hours ago | parent [-] | | Sea level rise was much faster before the cooling of the Younger Dryas. | | |
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| ▲ | dmix 8 hours ago | parent | prev [-] |
| 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 |
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