Would this be a good book idea?

So this story takes place WAY in the future, so far that the Earth is practically destroyed because of pollution. It's gotten so bad that the usual way of life could no longer be sustained and people were once again hunting and gathering, but it's not enough to turn back the damage that's been done. THen comes in the Elementalist, a powerful being who came to Earth at it's worst to help retore the land to it's former glory. But he can't do it alone. A special place is set up for students who may have the ability to manipulate the elements and help the planet. Then comes in Sydney, a girl who can manipulate water. It isn't the greatest of powers, beisdes cleaning it there really isn't another purpose. She befriends Arabella, a rare plantlife manipulator. She can grow and bring back the forests and grow food. Sydney hopes she can use her friend as an advantage to get the apprenticship. After the two pull a prank, they accidentally release the worst enemy of all on their beloved planet: the selfish ways of mankind. Now they have to use their elemental powers to stop history from repeating itself and the Earth from being destroyed for good.