Global Warming: Also known as the Greenhouse Effect most scientists believe global warming is happening right now. When too many greenhouse gasses such as carbon dioxide and methane are trapped in the atmosphere, the temperature on the Earth rises causing the ice at the north and south poles to melt. This raises the water level in the oceans and different places on the earth slowly get hotter or colder. If it goes on long enough, global warming could change rainforest’s to deserts and dry areas to wet ones.