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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.
Various natural and anthropogenic (human-caused) factors contribute to global warming. This graphic shows the percentage contribution of solar variability to global warming for 2 time periods, the past 100-150 years (left) and the past 50-65 years (right), from various peer-reviewed studies (colors). The studies find a relatively small solar contribution to global warming, less than 40% (0.3°C) of the observed warming over the past century, and less than 15% (0.1°C) over the past 50 years.