1. Lemke P, Ren J, Alley RB, Allison I, Carrasco J, Flato G, Fujii Y, Kaser G, Mote P, Thomas RH, Zhang T (2007) Observations: changes in snow, ice and frozen ground. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Avery K, Tignor M, Miller H (eds) Climate change 2007: the physical science basis. Contribution of working group I to the fourth assessment report of the intergovenmental panel on climate change. Cambridge University Press, Cambridge, UK, pp 337–384
2. Fetterer F, Knowles K, Meier W, Savoie M (2002) Sea ice index. National Snow and Ice Data Center, Boulder, CO, USA. Digital Media, updated 2009
3. Budyko MI (1969) The effect of solar radiation variations on the climate of the earth. Tellus 21:611–619
4. Sellers WD (1969) A global climate model based on the energy balance of the earth-atmosphere system. J Appl Meteorol 8:392–400
5. Manabe S (1969) Climate and the ocean circulation I. The atmospheric circulation and the hydrology of the Earth’s surface. Mon Weather Rev 97:739–774