Changes

Assessments by the [[United Nations]] promote the view that most of the warming since around 1850 is likely human-caused. In February, 2007, the [[IPCC|Intergovernmental Panel on Climate Change]], a body of scientists<ref>http://www.chicagotribune.com/news/nationworld/chi-0704280477apr29,1,4275902.story?coll=chi-newsnationworld-hed</ref> established by the [[United Nations]], released their fourth assessment report on climate change. That report concluded that most of recent global warming was "very likely" caused by human activity<ref>http://news.bbc.co.uk/2/hi/science/nature/6321351.stm</ref>. It says that increases in atmospheric concentrations of [[greenhouse gas]]es cause warming.

Assessments by the [[United Nations]] promote the view that most of the warming since around 1850 is likely human-caused. In February, 2007, the [[IPCC|Intergovernmental Panel on Climate Change]], a body of scientists<ref>http://www.chicagotribune.com/news/nationworld/chi-0704280477apr29,1,4275902.story?coll=chi-newsnationworld-hed</ref> established by the [[United Nations]], released their fourth assessment report on climate change. That report concluded that most of recent global warming was "very likely" caused by human activity<ref>http://news.bbc.co.uk/2/hi/science/nature/6321351.stm</ref>. It says that increases in atmospheric concentrations of [[greenhouse gas]]es cause warming.

According to evolutionary scientists, there have been many cycles of naturally-caused global warming and cooling over many millions of years (see [[climate cycles]]). However, this particular cycle has been much more rapid and sudden than any associated with natural climate cycles. Although some scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), claim that the recent warming could be part of another natural cycle or random fluctuations in the atmosphere, the consensus of opinion favours the idea of anthropogenic (human-induced) climate change.

According to evolutionary scientists, there have been many cycles of naturally-caused global warming and cooling over many millions of years (see [[climate cycles]]). Some scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), say that the recent warming could be part of another natural cycle or random fluctuations in the atmosphere.

==The Hockey Stick Temperature Reconstruction==

==The Hockey Stick Temperature Reconstruction==

==Natural variability of the climate system==

==Natural variability of the climate system==

Evolutionary scientists who believe in global warming think that the Earth has experienced numerous [[Ice Age|ice age]]s over two million years, during which global temperatures dropped approximately 6 degrees Celsius and then returned to normal. The frigid temperatures allowed ice sheets to expand southward, covering much of [[Asia]], [[Europe]], and [[North America]]. The cooling associated with ice ages is gradual, while the terminations are relatively rapid. However, even the rapid terminations of ice ages take centuries to millennia, as opposed to the recent warming.

Evolutionary scientists who believe in global warming think that the Earth has experienced numerous [[Ice Age|ice age]]s over two million years, during which global temperatures dropped approximately 6 degrees Celsius and then returned to normal. The frigid temperatures allowed ice sheets to expand southward, covering much of [[Asia]], [[Europe]], and [[North America]]. The cooling associated with ice ages is gradual, while the terminations are relatively rapid. However, even the rapid terminations of ice ages take centuries to millennia.

==Global Warming on other Planets==

==Global Warming on other Planets==

*[http://www.magma.ca/~hurleyp/FightingTheHoax.htm Fighting the Hoax]

*[http://www.magma.ca/~hurleyp/FightingTheHoax.htm Fighting the Hoax]

*[http://www.climateaudit.org Climate Audit], Steve McIntyre's blog

*[http://www.climateaudit.org Climate Audit], Steve McIntyre's blog

*[http://www.realclimate.org Real Climate], scientific blog by climatologists, addressing concerns such as the queries about the 'Hockey Stick' reconstruction.

*[http://www.realclimate.org Real Climate], blog by a group of climatologists including Michael Mann

==Critique of the Hokey Stick Reconstruction==

==Critique of the Hokey Stick Reconstruction==