Across
- 4. the introduction of harmful materials into the environment
- 7. removal of forest and trees for human activities
- 8. the plant or animal material used as fuel to produce electricity
- 9. convert waste material into reusable material
Down
- 1. the long term heating of earth's climate system
- 2. power obtained by harnessing the energy of the sun rays
- 3. _________ can be used to generate electricity.
- 5. resources which exist without the action of human beings
- 6. extraction of valuable minerals from the earth