Global warming is caused by increased greenhouse gases from human use of fossil fuels and deforestation, trapping heat in the atmosphere. This is causing polar ice caps and glaciers to melt, raising sea levels and threatening wildlife. Other effects include more frequent and intense hurricanes, droughts, wildfires, and spread of diseases as climates change. To address global warming, alternatives to fossil fuels like solar, wind and water power must be adopted, and individual actions taken to reduce carbon footprints.