All the more reason for Catholics to get on board and propose ethical solutions.
Of course, it is not the number of people so much as the amount of GHGs (and other pollutants) they are emitting. Those favoring extreme pop control measures probably just want more goodies for themselves and their children, without having to actually reduce their own GHGs. My thinking is they are not really environmentalists (which I would define at a minimum as people who themselves are reducing their environmental harm).
Having said that, we can also look at Catholic ways of addressing “population,” such as more Catholics becoming celibate priests, nuns, monks, and hermits. And there is the rhythm method & “absinence makes the heart grow fonder.” I remember reading somewhere about how in the past married Catholics would practice abstinence for the whole of lent (then if a little one were to appear 9 months later after a month during lent, people would know they couldn’t quite keep up the penance

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The important point is that the children are NOT responsible for the environmental problems. We adults are. And each child conceived should be joyfully welcomed into this world. It is not only very evil, but is completely illogical to kill (unborn) children in order to save the world for the children. We will just have to find other ways to accomplish a sustainable environment for all.
Also, when people say they are against medical abortions, but don’t believe AGW is real, I have a very difficult time believing they are sincere about the abortion issue, that they must have some other ulterior motives and don’t really care about life issues. No one would risk life on earth, even if scientists were only 30% confidence AGW is real and dangerous – and first studies on AGW reached 95% confidence in 1995, and the science has just gone on to become more and more robust with proof from many different sources.
How many climate scientists can the denialist harass and threaten with death threats – there are 1000s of scientists and their studies they’d have to attack.
Better to be on the side of prudence (a good old Christian virture) and mitigate AGW, than waste so much time and energy attacking scientists and their studies with fallacious and slanderous claims and character assassination (unless one is connected to the fossil fuel industry, I suppose, and getting big bucks for doing so, and doesn’t believe in God or heaven & hell).