First crucial thing is education. All people should learn (and apply this knowledge to their life) that future generations will depend on what we leave on earth.
Thus people should consume responsibly:
A minority of the world's population (17%) consume most of the world's resources (80%), leaving almost 5 billion people to live on the remaining 20%; thus, billions are living without the basic necessities of life - food, water, housing and sanitation (Source: worldcentric.org).
Second thing, all countries should find a way to cooperate on the sustainable use of the resources. If we can find the way with which all countries behave in harmony, precautions will be more effective.
Question is: can people achieve this?
One example, why some countries do not sign the Kyoto protocol which is designed to reduce the effect of global warming?