A 10C rise would put us in the Cretaceous, the hottest time in the past 300 million years. It would melt all ice on earth and the globe would be unrecognizable

A 10C rise would put us in the Cretaceous, the hottest time in the past 300 million years. It would melt all ice on earth and the globe would be unrecognizable due to sea rise. This has happened before. It hasn't happened in a couple centuries before. A 3C rise will kill a lot of plants. A 5C rise will kill most of the plants, and if they can survive the change in biodiversity, the release of methane and CO2 from everything rotting, starving predators, and extreme weather and fire, life on earth might survive and eventually recover after a few hundred thousand or million years. A 7-10C change over 300 years would, most likely, kill every single thing on the planet that was not transplanted by humans. There are only two ways to survive that without human intervention. 1: Be wide-ranging enough to spread very quickly to areas that become habitable as they open up. A few times a century the entire ecosphere will have to pack up and move to live in the changing climate as floods and deserts move things around. These plants would find it impossible to thrive over the long term and have very little chance of surviving. 2: Literally just tank the entire thing start to finish. For most plants, they will not be able to significantly change their range over this time. In ideal conditions yes, under the massively destabilized climate -disappearing coasts, halting ocean circulation, temperature swings from freezing to sweltering- no way. The plants in northern Canada would have to be able to survive in tropical heat as well as they currently do in ice and snow. Plants in the tropics would have to survive 100 meters underwater. As the permafrost melts, plants will spread northerly- but the climate will catch up. Ironically it would be better if we killed 99% of plants right now so they could beat the climate. As it stands in a hundred years tropical vines will not be winding their way between New England evergreens- they will be dust in a desert. The pines outside my window will be choking in 40C weather. Boabab trees wouldn't survive in the soil here and Redwoods won't survive in Greenland. NB: I don't mean to say I think the total collapse of life on earth is likely at this point in time. I think at present even humans are pretty likely to survive what's coming even if we stay our current course for 30 years. However I would give it better than 50% odds that a 7C+ warming would kill multicellular life. Most of the assumptions that you have to make to lead to warming that high necessarily kills everything, eg ice melting, circulation stopping, humans not giving a fuck, etc.