The world will be warmer than today in 2050; the patterns of rainfall and drought across the world will be different. If we pursue "business as usual",
CO2 concentration levels will reach twice the pre-industrial level by around 2050. The higher its concentration, the greater the warming - and, more important still, the greater the chance of triggering something grave and irreversible: rising sea levels due to the melting of Greenland's icecap; runaway release of methane in the tundra.
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http://www.guardian.co.uk/science/2009/may/26/future-planet-earth