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tropical – adj. of, relating to, occurring in, or used in the part of the world that is near the equator where the weather is very warm
continent – n. one of the great divisions of land, such as North America, South America, Europe, Asia, Africa, Australia, or Antarctica, of the Earth
greenhouse gas(es) – n. pollution that causes the Earth's atmosphere to warm
desertification – n. the process by which an area becomes a desert
hydroelectric – adj. of or relating to the production of electricity by using machines that are powered by moving water
replace – v. to put someone or something new in the place or position of someone or something
log(ging) – v. to cut down trees in an area for wood
headache – n. a difficult or annoying situation or problem
cheaper – comparative adj. costing less money than something else
alternative – adj. offering or expressing a choice
