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[[Image:NASA-1024x933.jpg|thumb|right|A composite map of [[Antarctica]] showing areas of greatest warming in red. The Wilkins Ice Shelf lies off the peninsula in the top left corner, and shows extensive warming. Overall, Antarctica shows little warming, and many areas to the  East (right) are almost cooling.<ref>Roberts, Greg (April 18, 2009). [http://www.news.com.au/antarctic-ice-is-growing-not-melting-away/story-0-1225700043191 "Antarctic ice is growing, not melting away."]  News.com.au.  Retrieved on September 25, 2014.</ref>]]

[[Image:NASA-1024x933.jpg|thumb|right|A composite map of [[Antarctica]] showing areas of greatest warming in red. The Wilkins Ice Shelf lies off the peninsula in the top left corner, and shows extensive warming. Overall, Antarctica shows little warming, and many areas to the  East (right) are almost cooling.<ref>Roberts, Greg (April 18, 2009). [http://www.news.com.au/antarctic-ice-is-growing-not-melting-away/story-0-1225700043191 "Antarctic ice is growing, not melting away."]  News.com.au.  Retrieved on September 25, 2014.</ref>]]

'''Anthropogenic global warming''' (AGW) is a theory that suggests that human activity is causing the Earth to warm. The theory posits that greenhouse gases, including carbon dioxide, methane, nitrous oxide, and water vapor, trap solar warmth on the planet.<ref>Multiple references:

'''Anthropogenic global warming''' (AGW) is a theory that suggests that human activity is causing the Earth to warm. The theory posits that greenhouse gases, including carbon dioxide, methane, nitrous oxide, and water vapor, trap solar warmth on the planet. Industrial and vehicular emissions could therefore lead to catastrophic warming in the near future. Environmentalists use this theory as a basis to propose cuts in energy production and consumption.

*Taylor, James (November 23, 2011).  [http://www.forbes.com/sites/jamestaylor/2011/11/23/climategate-2-0-new-e-mails-rock-the-global-warming-debate/ "Climategate 2.0: New e-mails rock the global warming debate"]. Forbes website.  Retrieved on September 25, 2014.</ref> Industrial and vehicular emissions could therefore lead to catastrophic warming in the near future. Environmentalists use this theory as a basis to propose cuts in energy production and consumption.

Global temperatures are tracked by three different methods: satellites, weather balloons, and weather station data. All three methods confirm a modest amount of warming in recent decades.<ref>[http://www.euanmearns.com/wp-content/uploads/2016/01/ratpac850to300V.png Here] is a graph of the RATPAC radiosonde data, perhaps the most accurate measure of global warming. It shows 0.8 °C of warming between 1978 to 2014. (That corresponds to a warming rate of two degrees per century.) You can find a collection of global climate charts [https://wattsupwiththat.com/global-climate/ here].</ref> This trend can be explained by the interaction of several natural cycles, including the 11-year-sunspot cycle, the Pacific decadal oscillation, and the El Niño-Southern Oscillation (ENSO).<ref>72 percent of global temperature variation since 1958 reflects the influence of a Pacific Ocean weather cycle called the El Niño-Southern Oscillation (McLean, J. D., C. R. de Freitas, and R. M. Carter (2009-07-23). "Influence of the Southern Oscillation on tropospheric temperature". Journal of Geophysical Research)</ref> Although the recent warming trend is much discussed in the media, it is not what the AGW theory is about. AGW posits, based on computer modelling, that a period of rapid warming is imminent.<ref>Bailey, Ronald (December 26, 2012).  [http://reason.com/blog/2012/12/26/34-years-of-satellite-temperature-data-s "34 years of satellite temperature data show global warming is on a plateau"].  Hit & Run Blog/Reason.com.  Retrieved on September 25, 2014.</ref><ref>Cole, Steve and McCarthy, Leslie (January 12, 2011).  [http://www.nasa.gov/topics/earth/features/2010-warmest-year.html "NASA research finds 2010 tied for warmest year on record"].  NASA website.  Retrieved on September 25, 2014.</ref><ref>Tisdale, Bob (August 10, 2012).  [http://wattsupwiththat.com/2012/08/10/not-hot-ocean-sst-around-the-usa-not-anywhere-near-record-levels/ "Not so hot—ocean temperatures around the USA are not anywhere near record levels"].  Watts Up with That?  Retrieved on September 25, 2014.</ref>

Global temperatures are tracked by three different methods: satellites, weather balloons, and weather station data. All three methods confirm a modest amount of warming in recent decades.<ref>[http://www.euanmearns.com/wp-content/uploads/2016/01/ratpac850to300V.png Here] is a graph of the RATPAC radiosonde data, perhaps the most accurate measure of global warming. It shows 0.8 °C of warming between 1978 to 2014. (That corresponds to a warming rate of two degrees per century.) You can find a collection of global climate charts [https://wattsupwiththat.com/global-climate/ here].</ref> This trend can be explained by the interaction of several natural cycles, including the 11-year-sunspot cycle, the Pacific decadal oscillation, and the El Niño-Southern Oscillation (ENSO).<ref>72 percent of global temperature variation since 1958 reflects the influence of a Pacific Ocean weather cycle called the El Niño-Southern Oscillation (McLean, J. D., C. R. de Freitas, and R. M. Carter (2009-07-23). "Influence of the Southern Oscillation on tropospheric temperature". Journal of Geophysical Research)</ref> Although the recent warming trend is much discussed in the media, it is not what the AGW theory is about. AGW posits, based on computer modelling, that a period of rapid warming is imminent.

Difficulties with the theory:

Difficulties with the theory:<ref>Multiple references:

*'''Carbon dioxide is not a major greenhouse gas.''' Ninety to 95 percent of the greenhouse effect is due to water vapor.<ref>Friedenreich and Ramaswamy, "Solar Radiation Absorption by Carbon Dioxide, Overlap with Water, and a Parameterization for General Circulation Models," Journal of Geophysical Research 98 (1993):7255-7264)</ref> There are humidity measurements going back to 1948, and no upward trend.<ref>[https://wattsupwiththat.com/global-climate/ global climate]</ref>

*'''Carbon dioxide is not a major greenhouse gas.''' Ninety to 95 percent of the greenhouse effect is due to water vapor.<ref>Friedenreich and Ramaswamy, "Solar Radiation Absorption by Carbon Dioxide, Overlap with Water, and a Parameterization for General Circulation Models," Journal of Geophysical Research 98 (1993):7255-7264)</ref> There are humidity measurements going back to 1948, and no upward trend.<ref>[https://wattsupwiththat.com/global-climate/ global climate]</ref>

*'''The Earth has warmed or cooled many times. Historically, warm periods are associated with favorable climate.''' The [[Roman Warm Period]] of ancient times was followed by the Dark Ages Cold Period of the Early Middle Ages. In the Late Middle Ages, there was the Medieval Warm Period. From the 14th century to the early 19th century, there was a Little Ice Age.<ref>Bastasch, Michael, "[http://dailycaller.com/2013/12/13/study-earth-was-warmer-in-roman-medieval-times/ Study: Earth was warmer in Roman, Medieval times]", ''The Daily Caller''</ref>

*'''The Earth has warmed or cooled many times. Historically, warm periods are associated with favorable climate.''' The [[Roman Warm Period]] of ancient times was followed by the Dark Ages Cold Period of the Early Middle Ages. The Medieval Warm Period lasted from 900 to 1300. From the 14th century to the early 19th century, there was a Little Ice Age.<ref>Bastasch, Michael, "[http://dailycaller.com/2013/12/13/study-earth-was-warmer-in-roman-medieval-times/ Study: Earth was warmer in Roman, Medieval times]", ''The Daily Caller''</ref>

*'''The attraction of the theory is that supports a political agenda that believers are committed to.''' The environmentalist agenda of renewables, solar energy, conservation, and world government was put together in the 1970s in response to the energy crisis and to the overpopulation scare. At that time, most scientists thought the Earth was cooling. Steven Schneider, godfather of the AGW movement, was a global cooling believer in the early 1970s. AGW was an additional set of justifications for the cause. Scratch an AGW believer and there is an overpopulationist or world government socialist underneath.

*'''The attraction of the theory is that it supports a political agenda.''' The environmentalist agenda of renewables, solar energy, conservation, and world government was put together in the 1970s in response to the energy crisis and to the overpopulation scare. At that time, most scientists thought the Earth was cooling.<ref>[http://realclimatescience.com/the-corrupt-history-of-nasa-temperature-history/ The corrupt history of NASA temperature history.</ref> Steven Schneider, godfather of the AGW movement, was a global cooling believer in the early 1970s. If the carbon dioxide level in the atmosphere is too high, this can be addressed by promoting plant growth in the oceans.<ref>Carrington, Damian, "[https://www.theguardian.com/environment/2012/jul/18/iron-sea-carbon Dumping iron at sea can bury carbon for centuries, study shows]" ''The Guardian'', 18 July 2012</ref> Such technical fixes lack appeal because AGW is less about carbon dioxide than about creating an additional set of justifications for the anti-energy cause. Scratch an AGW believer and there is an overpopulationist or a world government socialist underneath.

Natural periods of global warming and global cooling are expected to occur regardless of human activity, and not long ago liberals were demanding more government control to combat an alleged cooling in temperatures, with some scientists warning of a possible ice age.<ref name="Time">"Science: Another Ice Age?" (June 24, 1974).  ''Time'' magazine.  Retrieved on September 25, 2014.</ref>  [[Global cooling]], a theory that predates global warming, obviously occurs naturally many times throughout [[Earth|Earth's]] geological history.<ref name="dissidents">"After any given warming phase begins, thousands of years later the cyclical [[Milankovitch]] decrease in the sun's heat kicks in. The warming stops, reverses and an [[ice age]] ensues."  Cockburn, Alexander (June 9–11, 2007).  [http://www.counterpunch.org/cockburn06092007.html "Dissidents against dogma"].  Counterpunch.  Retrieved on September 25, 2014.</ref> The ease of refutation of anthropogenic global cooling claims foretells the eventual fate of the current global warming hysteria.

Natural periods of global warming and global cooling are expected to occur regardless of human activity, and not long ago liberals were demanding more government control to combat an alleged cooling in temperatures, with some scientists warning of a possible ice age.<ref name="Time">"Science: Another Ice Age?" (June 24, 1974).  ''Time'' magazine.  Retrieved on September 25, 2014.</ref>  [[Global cooling]], a theory that predates global warming, obviously occurs naturally many times throughout [[Earth|Earth's]] geological history.<ref name="dissidents">"After any given warming phase begins, thousands of years later the cyclical [[Milankovitch]] decrease in the sun's heat kicks in. The warming stops, reverses and an [[ice age]] ensues."  Cockburn, Alexander (June 9–11, 2007).  [http://www.counterpunch.org/cockburn06092007.html "Dissidents against dogma"].  Counterpunch.  Retrieved on September 25, 2014.</ref> The ease of refutation of anthropogenic global cooling claims foretells the eventual fate of the current global warming hysteria.