50% of species would be considered an extinction event, and that is absolutely on the table. We're already in the 6th largest mass extinction event in the hist

50% of species would be considered an extinction event, and that is absolutely on the table. We're already in the 6th largest mass extinction event in the history of life on this planet. I would strongly recommend reading Peter Ward's "Under a Green Sky" (or his academic papers if that's more your style). He makes a very compelling argument about the relationship between rising CO2 and many of the previous major (and minor) extinction events. To be clear, I'm not saying "extinction is certain!" but in "the worst case scenario" mass extinction is absolutely a real possibility. If we reach the neighborhood of 5+C (which is in the realm of possibility, especially when talking about 'worst case') we're looking at a planet that is very hostile to human and most other current life. A few books I would recommend (all in the popular non-fiction category but backed up with plenty of academic sources): - Peter Ward "Under a Green Sky" - Elizabeth Kolbert "The Sixth Extinction" - Mark Lynas "Our Final Warning: Six Degrees of Climate Emergency" (update of his earlier "Six Degrees") Ward is an academic, and Kolbert and Lynas are science journalists, but both have plentiful, credible citations. Again, there are so many big unknowns that very little can be said for sure, but saying that a mass extinction (and more specifically human extinction) event is not possible is simply wrong given our current understanding of the situation.