Global warming refers to the increase of the Earth's temperature due to higher levels of greenhouse gases trapping heat in the atmosphere from the sun. The main cause is the influx of greenhouse gases like carbon dioxide released from burning fossil fuels. Effects of global warming include a projected rise in average global temperatures of 2.5-10 degrees Fahrenheit by 2100, rising sea levels, and more extreme weather. Melting polar ice caps and glaciers will impact ocean currents and cause sea level rise, threatening coastal communities and wildlife.