What do you think making this a sin will mean?
Think about it, it will be a sin for you to drive your car unless you buy a carbon off-set. No you can’t give money to the poor, they may buy carbon causing heat sources which means you sinned.
Really, give me another interpretation of making this a sin, with sin there is no half way.
Really, I can’t wait to read the tortured logic of how this sin will be meted out and how he will see himself as not being in violation of this sin himself.
Maybe upon writing or attempting to write it, he will be overcome with the Holy Spirit and realize the failed path this teaching will lead the Church on.
It would spell trouble in the Roman Catholic theological system which is based on sin focus because yes, here would be a sin that can’t be wiped out by any conceivable human effort.
I think Francis wants to put emphasis, in a more evangelical manner, on positive directions to do good. Help your environment. You don’t have to restore it to Edenic pristine shape. That is not even possible.