HadGEM1 (abbreviation for Hadley Centre Global Environmental Model, version 1) is a coupled climate model developed at the Met Office’s Hadley Centre in 2006 and used in IPCC Fourth Assessment Report on climate change.  It represents a significant advance on its predecessor, HadCM3, in terms of its science and is better at carrying out new climate experiments. HadGEM1 also provides a foundation for further modelling advances across a range of applications, particularly involving enhanced resolution and full Earth System modelling.
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