===== HadCRUT =====

http://www.cru.uea.ac.uk/cru/data/temperature/

==== CRUTEM4 ====

http://www.metoffice.gov.uk/hadobs/crutem4/data/download.html
http://www.cru.uea.ac.uk/cru/data/temperature/crutem4/station-data.htm


http://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/tree-ring

http://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/climate-reconstruction

http://en.wikipedia.org/wiki/Temperature_record