I like the design and the clean layout. The fruit photo you are using have a "healthy" and nice look. But - I think you should use a more dramatic approach to engage your visitors. For instance by using an un-healthy photo stating the seriousness of the environmental situation. Then lead your visitors to the next section "how to take action" then "why take action" and so on.
I also think the site should have a newsletter sigh up for the visitors who wants to do something. Its a great concept you can develop to infinity
Good luck.