The phrase Global Warming refers to the increasing of the average temerature of the Earths near-surface air and oceans in recent decades and its temperature. The average global air temperature near the earths surface rose 1.33°C during the past century. The Intergovernmental Panel on Climate Chnage (IPCC) concludes "most of the observed increase globally averages temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations", which leads to the warming of the surface and lower atmosphere by increasing the greenhouse effect.
Natural phenomena such as solar variation combined with volcanoes have probably had a small warming effect since the pre-industral times of 1950. These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the nation academies of science of the major industralised countries. The American Association of Petroleum Geologists is the only scientific society that rejects these conclusions. A few individual scientists disagree with some of the main conclusions of the IPCC.
Remaining scientific uncertainties include the exact degree of climate change expected in the future, and how changes will vary from region to region around the globe.