Changes

==The modern warm period==

==The modern warm period==

[[Image:Artic 1979.jpg‎|left|thumb|250px|A computer projection comparing the Polar Ice Mass in 1979 (left) and 2000 {right).]]

[[Image:Artic 1979.jpg‎|left|thumb|275px|A computer projection comparing the Polar Ice Mass in 1979 (left) and 2000 (right).]]

Average [[Earth]] surface air temperature has risen about 1° F since 1850.  

Average [[Earth]] surface air temperature has risen about 1° F since 1850.  

<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> How much of this is due to contamination of the temperature record from the [[urban heat island]] effect is hard to assess. Spurious warming trends that might be considered as global warming can occur almost anywhere. [http://climatesci.colorado.edu/2006/01/29/do-urban-areas-have-larger-long-term-temperature-trends-than-other-locations/feed/]

<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> How much of this is due to contamination of the temperature record from the [[urban heat island]] effect is hard to assess. Spurious warming trends that might be considered as global warming can occur almost anywhere. [http://climatesci.colorado.edu/2006/01/29/do-urban-areas-have-larger-long-term-temperature-trends-than-other-locations/feed/]