If we bumped to 1000ppm carbon, would the earth warm 5C? That’s a technical question. We don’t know exactly how sensitive the climate is or what feedback mechanisms are at play. I don’t lose sleep over it. But I’m just trying to give my perspective to counter some of the doom, since the doomers are very active online.
Humans have already caused many mass die offs. Go into a forest today and try to catch dinner with your bare hands and you'll find it is near impossible. Yet it used to be possible - that's how our ancestors lived.
Us inventing aids like the bow and arrow has depleted the wild animal population enough that we now couldn't survive without such aids.
FWIW, quoting https://en.wikipedia.org/wiki/English_longbow : "The trade of yew wood to England for longbows was such that it depleted the stocks of yew over a huge area."
My proof is that they're the oldest surviving civilization on earth and lived mostly a hunter gatherer lifestyle without running out of food and requiring mass scale agriculture to survive.
Did you know that just a couple of thousand of years ago there were more elephants than humans in sub Saharan Africa? Feeding yourself with hunting then is really easy, there are meat giants to eat everywhere, that is what earth was like when humans were still hunters. Then humans hunted most of the largest animals to extinction and the remaining got turned to cattle.
This does not appear surprising. Elephants were perfectly adapted to that environment and able to fend off dangerous predators. Humans - several thousand years ago - were not as dangerous. And thus used to be the prey of necessity for older, limping lions in the past. The old big cats could no longer catch a fleeting gazelle but the slow, clumsy humans made an acceptable substitute - even if the meat tasted like bad pig. Even in the last millennium, thousands of humans were devoured by man-eating cats.
The humans that made thorn bush corrals and teamed up with spears when one yelled lion?
They're not as easy for big cats as many might think, even today you can see barefoot humans with spears facing down cats and cats shying away from the sound of humans.
Only old slightly mad cats gave humans a go, and they rarely lasted long until people teamed up and took out the man eaters.
https://www.youtube.com/watch?v=RJZR68KSIgY
> Even in the last millennium, thousands of humans were devoured by man-eating cats.
That's, like, one or two a year ... comparable to drowning and other accidental fatalities.
In reality, outside the drama of Rudyard Kipling story, it's a rare bit of drama for big game hunters to have an actual man eater to go after.
Big cats don't face groups - they are ambush predators. Some man-eaters have murder counts reaching several hundred just by their lone selves. Even late as the early 1900's, a tigress in India stalked and killed 436 people. https://en.wikipedia.org/wiki/Tiger_attack#The_Champawat_Tig...
It might be two degrees warmer this century. Life will go on just fine. Possibly better in some ways and places. No problem, relatively speaking, compared to the hazards our ancestors face.
If it warms 5C, we might have a real problem on our hands. I don’t think we can predict that, and I don’t think it will happen over 100-200 year timescales.
Many people seem to think there will be mass die offs, the ocean will become unsurvivable acidic, and crops won’t grow. I don’t think any of that will happen anytime soon. I think there is a very strong “doom” instinct in humans to think this is the last generation, the end of times. This is just the latest manifestation.