Sources

 Global Warming - http://en.wikipedia.org/wiki/Global_warming

Microsoft Encarta Reference Library 2005

Microsoft Encarta kids, 2005

‘Air Quality for Kids’, produced by EPA Victoria
http://www.epa.vic.gov.au/air/aq4kids/pollution.asp

“Sources of Air Pollution’
http://www.infoplease.com/ce6/sci/A0856525.html

 
The Greenhouse Effect' - http://www.cmar.csiro.au/e-print/open/holper_2001b.html

Down to Earth Guide to Global Warming by Laurie David and Cambria Gordon, Ashton Scholastic Books

 
All photographs have been collected through copyright free public domain websites or creative commons. http://www.flickr.com/creativecommons/ 
The photographers in order that they appear on the header picture going left to right are: 

My Visita Iglesia, My Visita Iglesia, ZeNahla, ZeNahla, kaet44, flumpster, D'Arcy Norman, Michael (mx5tx), Stephen Barnett