Extinction is wildly unlikely. Humans occupy a wide range of climates, from very cold to very hot, and even the most extreme predictions don't make the earth completely unlivable.
Complete collapse of the current civilization and population drops of 90% or even 99% aren't impossible. But there's an enormous difference between a 99% loss and a 100% loss.
Complete collapse of the current civilization and population drops of 90% or even 99% aren't impossible. But there's an enormous difference between a 99% loss and a 100% loss.