1) Intergovernmental Panel on Climate Change (IPCC) Working Group I: The Physical Science Basis, FAQ 3.1, How are Temperatures on Earth Changing? http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-3-1.html

2) National Center for Atmospheric Research (NCAR), et al http://www.ucar.edu/news/releases/2006/brightness.shtml

3) National Snow and Ice Data Centre http://nsidc.org/arcticseaicenews/

4) World Glacier Monitoring Service http://www.geo.unizh.ch/wgms/mbb/mbb9/sum06.html

5) National Oceanic and Atmospheric Administration (NOAA) http://www.arctic.noaa.gov/essay_romanovsky.html

6) Intergovernmental Panel on Climate Change (IPCC) Working Group I: The Physical Science Basis, FAQ 1.1, What Factors Determine Earth’s Climate? http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-1.html

7) Intergovernmental Panel on Climate Change (IPCC) Working Group I: The Physical Science Basis, 2.3 Chemically and Radiatively Important Gases, http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-3.html#2-3-1