This is EXCELLENT & worth reading in its entirety. It explains with the help of illustrations what global warming is, the consequences for our planet & its ecosystems & the potential threat to the human population. Most important, it says how each & everyone of us can help slow it down.
The Amazing Digital Art of a Disillusioned Idealist
Beautiful digital art you could display in your classroom to facilitate discussion about global warming. You could present one of images and ask the students what they think it's trying to convey, no text is needed to spark discussion. Great way to get students interested and engaged in the topic.