There is a very popular narrative that asserts that the Catholic Church, due to her restrictive, antiquated, anti-scientific, anti-feminist teachings on birth control and abortion, is contributing to the demise of Mother Earth.
"The planet is bursting with people! It's unsustainable! Our children and our grandchildren will be starving in the near future! And the Catholic Church is oppressing not only women, but the planet, but denying her members the right to use birth control and abortion. Stop making more people!" (This presupposes that abortions stop "making" people; in actuality abortion kills an already-made person, but more on that later.)
It turns out that this is, frankly, just nonsense. Not just the overpopulation part, but also the restrictive part, and the antiquated part, and the anti-scientific part, and the anti-feminist/oppression of women part. :)
The earth is well able to support a growing population.
There is plenty of room--one estimate maintains that every family on earth could have a house with a yard and all live together on a land mass the size of Texas. source: https://overpopulationisamyth.com/
There is also plenty of food--according to the World Food Programme, "There is enough food in the world today for everyone to have the nourishment necessary for a healthy and productive life."
So where did the idea of this ominous, dangerous, "the sky is falling" concept of overpopulation come from? I think the credit goes to a 19th century British cleric named Thomas Malthus, who observed that while population was growing exponentially, food production increased only incrementally. He predicted that the world world would not be able to sustain and feed its population by 1890.
It turns out Mathus was wrong. He failed to account for human ingenuity and resourcefulness.
In the 1970's a biologist named Paul Ehrlich announced that by 1985 65 million Americans would die of starvation. Because of his prediction he advocated unlimited access to birth control and abortion.
It turns out Ehrlich was wrong, too.
Planned Parenthood also joined the alarmist bandwagon in the 1980s and distributed a pamphlet entitled, ""The Human Race Has 35 Years Left: After that, People will Start Eating Plankton. Or People."
However, let's disregard the idea of overpopulation being a myth. Let's say that it's actually a reality that the planet is overpopulated and is indeed the biggest menace to society....
shouldn't we consider moral ways to deal with overpopulation?
As Pope John Paul II so eloquently said, regarding population growth: "But such interventions must always take into account and respect the primary and inalienable responsibility of married couples and families, and cannot employ methods which fail to respect the person and fundamental human rights, beginning with the right to life of every innocent human being. It is therefore morally unacceptable to encourage, let alone impose, the use of methods such as contraception, sterilization and abortion in order to regulate births."--The Gospel of Life
Thus, abortion as a solution to the threat of an overpopulated world is indefensible.
We wouldn't embrace the idea of killing a bunch of born people because, hey, we need the room on the planet, right?
Similarly, we shouldn't embrace the idea of killing a bunch of un-born people either, as a means of addressing the alleged overpopulation of the earth.
I think the best answer to the question of what to do with an overpopulated world (if it even is a fact) was asserted by GK Chesterton: "The answer to anyone who talks about the surplus population is to ask him, whether he is part of the surplus population; or if not, how he knows he is not" (Introduction to A Christmas Carol).