Many people have heard about the disappearance of tropical rain forests, acid rain, ozone depletion, global warming, reduced biodiversity, poverty, refugee flows, food crisis and other issues.

• 许多人都听说过热带雨林的消失、酸雨、臭氧层破坏、全球变暖、生物多样性锐减、贫困、难民潮、食物危机等问题。