http://www.ipcc.ch/ - Web site of the IPCC.
http://www.onr.navy.mil/focus/ocean/default.htm - General site about the ocean.
http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification - Köppen classification of the different climate on Earth.
http://nsidc.org/data/atlas/ - Atlas of the Cryosphere, National Snow and Ice Data Center (NSIDC).
http://www.geo.arizona.edu/Antevs/biomes/ - Description of the different biomes with nice photographs.