If you see someone behaving in a way which offends you, tolerate them . Imagine this magnified a billion times. Those who pollute, ruin, hate and kill are not evil, they are children who do not understand the consequences of their actions. If we help them, they will grow. The more we behave in a manner which heals Earth, the more this behaviour will filter throughout the world.
People learn by example.
If Earth's problems seem too large, sometimes, for you even to begin to do something, remember that even a tiny thing will have larger consequences. Do that thing.