Yes, there are no definite studies however to say I want to spend X trillion dollars I need some evidence that what they said would happen is happening. If they want us to support them then they need to do something comprehensively enough to justify people believing them. Just saying it’s possible Polar bears might go extinct doesn’t cut it. Lots of things COULD happen.
The idea Polar Bears would die or any of the other Arctic creatures is not justified. The 1940s were hotter in the arctic than today. (TRUE — look it up — even with contentious adjustments) If you go back to the MWP or to other times over the last few million years there have been times where it was warmer and for most of the last 60 million years it was 4–10C (8–20F) warmer than today. Yet the polar bears survived.
It’s not believable that they really depend on sea ice to survive.