640,000 years ago the co2 levels were higher than they are today
Co2 has been higher in the past yes, but you also have to take in to account the, explosively high
rate of Co2, and other greenhouse gases (such as methane), that are being currently dumped into the atmosphere. Compared to the PETM (a rate of extreme warming about 56 million years ago), humans are releasing 10 times more carbon. Every. Single. Year. The Permian-Triassic extinction event however, (or Great Dying, as it's sometimes referred to) puts the PETM to shame. The P-Tr exterminated 97% of all life and is the only known extinction event to have wiped out almost all insects. How did this happen you might ask? Well, believe it or not, but the P-Tr, the worst known extinction event in Earth's planetary history, was, in fact, caused by a runaway greenhouse effect, almost exactly similar to the kind that's happening today. In the P-Tr's case, the Siberian Traps (a long chain of ancient volcanoes) erupted, putting out trillions of tons of Co2. There is also a lot of evidence that their flood basalts managed to hit huge coal deposits, causing them to burn up as well. The eruptions also promoted the growth of methane-producing bacteria by fertilizing the oceans with nickel. Ocean ecosystems were disrupted by the dramatic climate change and ocean acidification kicked off by all that extra Co2 in the air and then the toxic volcanic gases and coal ash coming from the Siberian Traps just made things worse. The oceans reached a tipping point where the methane-producing bacteria found an increasingly fertile environment, leading to a huge population boom. This lead to more methane going into the air & water, which led to more warming / ecosystem disruption and MORE methane going into the air & water which eventually made the oceans a hot, soupy mess of archae mostly devoid of oxygen. And here we are
SURPASSING every single factor that led to the P-Tr happening in the first place. Keep in mind as well that the P-Tr took place over a course of tens of thousands of years. We've long overtaken it in only a couple hundred years of industrial activity. If that statement alone doesn't knock you right over onto your ass then I don't know what will. To say that hell on Earth is coming is a massive understatement. The reality will be much, much worse. Just another reason for one to kill themselves, I suppose. Get out while the getting's good, so to speak. Or, if you can, just sit back and enjoy the show. What a privilege it will be to see the curtain finally come down on all this horror.
These Extinction events happen, yes we are causing our own demise by burning carbon based fuels and by all scientific accounts even if we stopped all carbon burning now the acidity in the ocean will rise and most plankton will die.
Ocean acidification has already sealed the fate of the world's oceans. The last time the oceans got this acidic, this fast (P-Tr) 96% of all marine life went extinct. And again, we're doing it AT A RATE ONE THOUSAND TIMES FASTER THAN THE P-Tr FUCKING DID! To say the oceans will be an anoxic soup of toxic sludge before the end of this century is pretty much like saying the sun will rise tomorrow. Over half of the ocean's marine biodiversity has already vanished. Corral reefs the world over, one of the richest sources of marine biodiversity, are critically bleached turning them into barren underwater graveyards. Extinction rates overall are happening at 1000 times the natural background rate. Amphibians in particular are experiencing extinction rates at
45,000 times their natural speed. The fact of the matter is we, as a species, have committed suicide. Our greed & myopia led us off the cliff a long time ago. Pathetic yes, but at least we're sterilizing the planet before we go.
But eventually the ocean will absorb the co2 over 10's of thousands of years.
Do you really know what that means, though? Do you have any idea of the nightmarish wasteland that this will look like? On a world 5C above pre-industrial levels, the oceans will be effectively dead and we'll be seeing "dead zones" (areas devoid of oxygen everywhere). Also, oxygen producing phytoplankton (the main lung of the Earth) will be extinct (thanks to all that carbonic acid having been absorbed by the oceans). Afterwards comes a total collapse of ocean circulation, and a two thousand year interval for the ocean basins to go completely anoxic and stew with sulfur-loving organisms. Then, allow another 500 years for the photosynthetic zone to fill with green & purple sulfur bacteria. This will, again, essentially all lead to a repeat of the "P-Tr" (Great Dying). The Earth will basically become a toxic soup of ionizing radiation from nuclear reactors gone into meltdown due to the lack of maintenance given the absence of any sort of organized human life and hydrogen sulfide being spewed from the now dead oceans. That's what 5C, or higher, really means.
I forgot to mention, that there's also the "Clathrate Gun" element in play here. Methane hydrates, aka clathrates, which tend to become unstable during periods of rapid climate warming. They store trillions of tons of methane, and when they start to disintegrate, they become a HUGE positive feedback in the climate system, causing more warming and more methane release. If the climate warming is slow, then the methane doesn't have a chance to build up in the atmosphere all that much. But if the climate changes too fast for the biosphere to adapt, then you're in deep fucking shit. Like throwing a tanker full of gasoline on an already towering inferno.
A lot of people don't realize that natural selection isn't something that works by ensuring the universe will eventually create the perfect beings when it comes to strength, intelligence, beauty etc... But merely, software programmed to ensure the universe keeps creating whatever shit that can survive and pass on it's DNA.
Yep. Evolution is an unconscious engine of pain that isn't going in any direction whatsoever. If it's "perfecting" anything, it's the many tools that each organism has to inflict pain, whether it be on one another or even on the creature itself just by its mere survival. Your comfort as an organism is simply not a requirement for DNA replication. This world won't be missed. Good fucking riddance.