Teaching climate change can be seen by students as controversial (although it is generally not seen this way in the scientific community). Students have been "doomed and gloomed" about the future of the Earth since they were in elementary school. My approach to climate change education is to move from describing catastrophe to a more pragmatic approach -- balancing human need and use of natural resources.
I start the climate change unit with an engagement activity -- what if humans needed to find a new planet to sustain life, like in the movie Interstellar? What makes the Earth just the right temperature? How is does the atmosphere work and how are humans influencing it?