I believe that these five Buddhist teachings of metta, karma, anicca, anatta and equanimity have a huge effect on the environment. Each of these teachings has a specific effect on the environment.
Metta teaches Buddhists to spread love and kindness around the world. This means that this love and kindness should also be extended towards the environment. Therefore Buddhists will try to help to keep the environment healthy, i.e. unpolluted and safe.
The law of karma states that actions have consequences. This means that if a Buddhist treats the environment badly (use CFC’s or cut down trees), then they will gain negative karma. If they continue to treat the environment in this way then they will accumulate a lot of negative karma. This may cause them to enter a lower realm on the cycle of samsara, once they are reborn. Therefore the teaching of karma prevents Buddhists from harming the environment.
Equanimity teaches Buddhists to treat all living beings as equal. This means that Buddhists should not cut down trees as this will mean killing a living being, a tree. If fewer trees are cut down, then the environment will be healthier and safer, as trees (and plants) absorb carbon dioxide in the atmosphere, which helps to reduce global warming.
Anicca is one of the three marks of existence. It states that everything is changing. Nothing lasts forever, i.e. the world is impermanent. This means that the environment is constantly changing and will never last forever. Eventually it will be destroyed.
Anatta is also one of the three marks of existence. It teaches Buddhists that there is no permanent self/identity. Nothing about you stays the same. This means that if someone else harms the environment, their actions will eventually affect you.
In conclusion I believe that these five Buddhist teachings all have a positive effect on the environment. They help to prevent Buddhists from harming the environment and therefore, making it both healthier and safer for us, humans, to live in.