Ecosystem /ˈiːkəʊsɪstəm/ - a community of living organisms and their environment interacting as a system. Example: The Amazon rainforest is an important ecosystem. Carbon footprint /ˈkɑːbən ˈfʊtprɪnt/ - the total amount of greenhouse gases emitted directly or indirectly by an individual, organization, event, or product. Example: Reducing your carbon footprint can help combat climate change. Renewable energy /rɪˈnjuːəbl ˈɛnədʒi/ - energy obtained from natural resources that are replenished constantly. Example: Solar power is a popular form of renewable energy.