Global warming

For past climate change, see Paleoclimatology and Geologic temperature record.
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Global mean surface temperature difference relative to the 1961–1990 average
Comparison of ground based (blue) and satellite based (red: UAH; green: RSS) records of temperature variations since 1979. Trends plotted since January 1982.
Mean surface temperature change for the period 2000 to 2009 relative to the average temperatures from 1951 to 1980.[1]

Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to a report by the Intergovernmental Panel on Climate Change (IPCC) global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) between the start and the end of the 20th century.[2][A] The global scientific community agrees that most of the observed temperature increase since the middle of the 20th century was caused by increasing concentrations of greenhouse gases, which results from human activity such as fossil fuel burning and deforestation.

Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.[2] The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.[3] Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects include changes in the frequency and intensity of extreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain.[4]

Political and public debate continues, regarding the legitimacy of global warming, in part due to the fact that multinational oil and coal corporations have funded public relations campaigns to attack and/or deny scientific evidence in order to protect their industries/investments [5]. There is no debate amongst the scientific community as to whether or not human-made global warming is real.[6]


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