I'm not saying we don't know whether climate change poses a tail risk or not (it obviously does). I'm just saying that claiming uncertainty isn't a good reason to avoid action.

In general, if there's a poorly understood but potentially very bad risk, then (a) more research to understand the risk is really high priority (b) if that research doesn't rule out the really bad scenario, we should try to do something to prevent it.

With AI, unfortunately waiting until the evidence that it's harmful is well established is not possible, because then it could be too late.

What AI risk research could involve is laid out in detail in the link.