Overpopulation is another problem and, IMO, more important.
I agree that over population is a growing problem. Especially with climate change causing more extreme weather, which will lead to crop failures, famines and food shortages. Clean water is already starting to be a problem.
However, the capitalist economy model is based on a model of perpetual growth. So, big money interests will oppose any efforts to slow down the population growth, because if the world changes the current economic model(s), it endangers their positions of power and influence.