on edit: fixed typo.
https://co2coalition.org/wp-content/uploads/2021/11/2015-Coh...
It states in summary that:
"doubling atmospheric CO2 from the current level of 400 ppm to 800 ppm only decreases the pH of ocean water from about 8.2 to 7.9. This is well within the day-night fluctuations that already occur because of photosynthesis by plankton"
"doubling atmospheric CO2 from the current level of 400 ppm to 800 ppm only decreases the carbonate-ion concentration, [CO2−3], by about 30%. Ocean surface waters are already supersaturated by several hundred per cent for formation of CaCO3 crystals from Ca2+ and CO2−3. So scare stories about dissolving carbonate shells are nonsense."
"Over most of the Phanerozoic, the past 550 million years, CO2 concentrations in the atmosphere have been measured in thousands of parts per million, and life flourished in both the oceans and on land. This is hardly surprising, given the relative insensitivity of ocean pH to large changes in CO2 concentrations that we have discussed above, and given the fact that the pH changes that do occur are small compared to the natural variations of ocean pH in space and time"
"This minimalist discussion already shows how hard it is to scare informed people with ocean acidification, but, alas, many people are not informed."
If you or anyone else thinks this paper's calculations are wrong, then that would be interesting to learn why.
Wikipedia claims, "[the] trigger for these mass extinctions appears to be a warming of the ocean caused by a rise of carbon dioxide levels to about 1000 parts per million":
https://en.wikipedia.org/wiki/Anoxic_event#Atmospheric_effec...
Here's the Scientific American article they cited:
https://www.scientificamerican.com/article/impact-from-the-d...
The most likely final outcome of full-flowered climate catastrophe is global thermonuclear war. Before that happens, we will probably have two billion people starve. After, another five billion. The ocean will cease to be a reliable source of protein, and whatever sea life survives acidification will be fished out at an increasingly frantic pace.
https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extin...
>The Permian–Triassic extinction event, also known as the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras, approximately 251.9 million years ago. It is the Earth's most severe known extinction event, with the extinction of 57% of biological families, 83% of genera, 81% of marine species and 70% of terrestrial vertebrate species.
>Possible causes supported by strong evidence appear to describe a sequence of catastrophes, each worse than the last: the Siberian Traps eruptions were bad enough alone, but because they occurred near coal beds and the continental shelf, they also triggered very large releases of carbon dioxide and methane. The resultant global warming may have caused perhaps the most severe anoxic event in the oceans' history: according to this theory, the oceans became so anoxic, anaerobic sulfur-reducing organisms dominated the chemistry of the oceans and caused massive emissions of toxic hydrogen sulfide.
According to this hypothesis which is well-supported by the archaeological evidence, it took Earth's atmosphere between hundreds of thousands to millions of years to return to conditions capable of supporting much life. That's a long time for biodomes, bunkers, and orbital stations not to break in irreparable ways.
Arguably that’d at least be a “human society extinction” event.
I find cities of less than about 5 million people uninteresting in terms of having enough of the entertainment and eating out options I enjoy.
A planet with a few million people scattered here and there would be incapable of much more than early industrial revolution technology I suspect. I can imagine people building steam engines, but making transistors is beyond that capability of pretty much everyone I know. Perhaps a few million people would get by scavenging electronics left behind by the 5 billion dead, but they’re not going to be running semiconductor fabs and buying new cpu or ram chips. And they’re not going to be mining rare elements and smelting alloys like modern metallurgy.
I’m not sure what small and distantly distributed bands/villages of humans trying to find habitable places with productively farmable land would look like, but it doesn’t sound fun to me…
I’m old, and _maybe_ I could justify my existence in post climate apocalypse society by being “that guy” who gets other people to carefully remove the wiring harness and everything plugged into it from every abandoned car they come across, and re purposing engine management and entertainment system components into useful computing devices and electrical gadgets, or perhaps by building carburettors and magneto ignition systems to make efi vehicles run on home grown biofuel. But I’d say I’m Rob ably way more likely be killed (and eaten?) as an old person with no useful contribution to the clan.
My personal fear though is more the model of large parts of earth's surface unlivable by humans, humanity down to a few million living near the poles.
Although both of the two you mention of course also strike me as potential catastrophic scenarios.
Would you be okay with the effort to go to Mars if the main person advocating for it were also simultaneously personally doing more than anyone else alive to reduce the human consumption of fossil fuels on Earth?
>That is to say that I don't think he means we need to fix every problem
in short, my post was really describing what I think Robinson was getting at and I am not really wedded to the argument that we shouldn't do both at the same time, especially as the stuff we do to make one planet habitable might give spark to scientific/technological advancement that could help save the one we have.