A greenhouse captures heat from the sun and the glass wall traps it keeping the plants inside the greenhouse warm The 21_______. effect is a natural process that works the same way. 22_______. in the atmosphere like carbon dioxide trap heat that warms the Earth's surface. These gases that trap heat are called greenhouse gases. Too much of 23________. however are produced by human activities These includes carbon dioxide, methane, and chlorofluorocarbons that trap more and more heat causing the earth to warm up. This may lead to 24_________. greenhouse effect was first discovered by 25_________. in 1924.
