Industries are using pollution permits from governments, which means they buy rights of a certain amount of pollution.

Once the hash rate is determined to pass the threshold of creating environmental damage, companies as Bitmain will be asked to pay for this.

There are laws in every country that demand reduction of pollution and protection of the environment.

So to conclude, everything has a limit. If Bitcoin hash power becomes a problem that causes environmental damage, there are means, like the pollution permits, that won't allow it to happen.

And since you turned it into a POW argument, be certain that this would never happen.