Changes

<ref>Hansen's group at the Goddard Institute wrote, "Global warming is now 0.6&nbsp;°C [1.0&nbsp;°F] in the past three decades and 0.8&nbsp;°C [1.4&nbsp;°F]in the past century." http://data.giss.nasa.gov/gistemp/2005/</ref>

<ref>Hansen's group at the Goddard Institute wrote, "Global warming is now 0.6&nbsp;°C [1.0&nbsp;°F] in the past three decades and 0.8&nbsp;°C [1.4&nbsp;°F]in the past century." http://data.giss.nasa.gov/gistemp/2005/</ref>

A minority of scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), say that the patterns of global warming are naturally caused (see [[climate cycles]]).

Assessments by the [[United Nations]] promote the world view that most of the warming since around 1850 is mostly human-caused. In February, 2007, the [[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 world view that the warming since around 1850 is mostly human-caused.

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.  

In February, 2007, the [[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 recent global climate change was "very likely" caused by human activity, <ref>http://news.bbc.co.uk/2/hi/science/nature/6321351.stm</ref>.

 

Politicians who support the [[Kyoto Protocol]] have made the claim that there is a cause and effect relationship between increases in atmospheric concentrations of [[greenhouse gas]]es and air temperature.

==The Hockey Stick Reconstruction==

==The Hockey Stick Reconstruction==