It goes without say that movies have great power and are an influential tool that can be used to spread important messages. They can convey values as well as beliefs of the culture within which and for which it is made. One impressive environmental movie of all time is : An Inconvenient Truth (2006).
Some would say it was the most important film while others would say it was the most damaging film for the environmental movement. This is because It presented the scientific case for global warming in no uncertain terms, but it seemed to polarize the nation on the subject. Nevertheless, it's hard to imagine what the climate advocacy movement would be without Al Gore at the podium.