Global warming refers to the long-term rise in Earth's average temperature due to human activities like burning fossil fuels. Since pre-industrial times, human activities have increased Earth's average temperature by about 1 degree Celsius. It is unequivocal that human influence has warmed the atmosphere, ocean and land. The greenhouse effect occurs naturally and makes Earth habitable, but human emissions of greenhouse gases like carbon dioxide are enhancing the effect and causing global warming. Continued emissions will lead to more extreme weather, higher sea levels, and other damaging impacts. Addressing global warming will require international cooperation on clean energy and adaptation efforts.