Population is the root cause of all human suffering.
At first glance, that’s a ridiculous statement. Human suffering is caused by famine, by war, by disease, by bad government, and by depression. Not by population.
But what causes famine? The Earth is big enough to feed everyone on this planet—for now. However, not all people produce enough food to feed themselves. Those that don’t must buy food from other places. And if they don’t have money to buy food, then they’re screwed.
If there were fewer people on this planet, then by and large each individual person would have more land to produce food. That would allow each individual person to make a profit despite selling food at lower prices, and then market forces will bring food prices down. And in the end, more people will be able to afford food.
What causes war? War starts when people fight for limited resources, be it oil, minerals, arable land, or something else. Why are resources so limited? Naturally, they are limited because the population on Earth is too high. A lower population would be able to share the same resources, but with each person getting more of the pie. That will remove the single biggest justification for war.
What causes disease? When people are crammed into a small space, contagious diseases (and even not-very-contagious diseases) spread. With lower population density, diseases spread less easily, and everyone’s quality of life improves.
What causes bad government? With a large population, it’s difficult to get everyone to agree. The government then has a difficult job governing everyone fairly. When population density is too high, usually, a fair and democratic government will collapse and be replaced by a brutal dictatorship.
What causes depression? Depression is at least partially because today’s society lacks green spaces, is too polluted, and is too crowded. Humans are not built to live in a concrete building all day, but because of the lack of parks in cities, many have to. A smaller number of cities, and a smaller population per city, will both lead to enhanced green spaces.
So if we want a cleaner, richer, greener, happier, and overall better future, we must take steps to lower the world population, or at least stop it from growing so rapidly. Especially, high-fertility developing countries must start taking their baby booms as serious problems.