Yup, but NOBODY wants to hear it.
Take all the major problems that face the human race or, indeed, the planet today.
Polluted oceans, polluted air, global warming, deforestation, species extinction, energy and food shortages- ect.... (You get the point)
All of these problems are caused by overpopulation. Through technology, we have been able to feed many more people than the earth could otherwise support.
We are at the top of the food chain. We have no natural predators to thin our herd. In the past, wars, plague, famine, ect. have served this function.
Think of the hundreds of millions of people that died in wars just in the last 100 years.
Now think of their children, grandchildren and great grandchildren that were never born.
So the ultimate solution has to be less people. The obvious and civilized answer has to be through birth control - globally. How about each couple has only one child. It's harsh I know, but if we don't limit the population, war, famine and plague will surely come and will certainly be less humane.
We can choose our poison, but the longer we wait the more the planet will suffer.
Earth First!!! we'll screw up the other planets later....