But even a smaller percentage deals with significant issues due to climate change, today. The changes thus far have been excessively inflated, and may be net-positive so far.
You're right about the worst case scenario, GHG emissions could in theory lead to Earth becoming like Venus or somewhere in between the two where the atmosphere is bad enough to cause the end of humanity. But this is extremely unlikely and might not even be possible with the sum of our economically accessible fossil fuel reserves.
In reality, it seems there is still a threat of huge increase in poverty due to some WW3 type event, or a superbug global plague, or something like that.
I think it's unfair to weigh climate change above poverty at the moment, even for the overall prosperity of the human race.
In fact, I think climate change will end up being much worse for the rest of life on Earth than humanity. We have the advantage of being able to plan and react in advance, so we will probably be fine for a long time to come, but most plants and animals might go extinct.