And as absurd as my previous comment may have been to SpirituTuo, there is good reason to ask this. Given just how important this topic is to Francis and the fact that he found it necessary to point out how those who do not "preserve the environment" will be "called to judgment one day", it sure sounds like he considers it a mortal sin.
Now THAT is absurd.
And furthermore, what these popes have done to the Roman Catholic Church is a sin that cries out for vengeance. All since Pius XII get a one way ticket on the River Styx ferry.