> Calling people 'deniers' is an ad hominen attack that doesn't prove anything, and most importantly doesn't help change people's minds.
This is true, but the people who are, in fact, deniers likely won't change their minds anyway and likely will not be alive long enough to see any undeniable evidence that could.
It's the same thing with discussing religion, I learned long ago to keep my mouth shut about it when talking to anyone who didn't express even a touch of an open mind about it.
I agree that the magnitude of the effect has not been demonstrably measured by anyone yet, but I don't see that as any reason to not take action to at least try to reduce whatever damage we might have done, are currently doing, and might do in the future.