How can we stop over-population in our society?

if you notice that the tolerance level at personal and national level has been decreasing gradually in past few decades. After last world war, all the countries had enough of war and they worked together for peace which they achieved but since then we are heading towards the same again.

I am not an expert on this topic but i think one of the following 2 things will happen in not so distant future which will have a major impact on our planet's population.

1. A global war will errupt and consider the advancement of weapons in last century its safe to say that in such a scenario population will be reduced.

2. Nature will have its own correction. this one is already started we are seeing glimpses of unusual floods, extreme heat waves , huge earth quakes and its just the beginning as nature gets upset it will restore its balance.

I would love to mention the optimism here that we will learn from our mistakes and we will stop growth in population we will control population and we will learn to live peacefully and respect each other but that would not be what i think.