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Stratospheric water vapour and high climate sensitivity in a version of the HadSM3 climate model

Joshi, M. M., Webb, M. J., Maycock, A.C. and Collins, M. (2010) Stratospheric water vapour and high climate sensitivity in a version of the HadSM3 climate model. Atmospheric Chemistry and Physics, 10. pp. 7161-7167. ISSN 1680-7316

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To link to this item DOI: 10.5194/acp-10-7161-2010


It has been shown previously that one member of the Met Office Hadley Centre single-parameter perturbed physics ensemble – the so-called "low entrainment parameter" member – has a much higher climate sensitivity than other individual parameter perturbations. Here we show that the concentration of stratospheric water vapour in this member is over three times higher than observations, and, more importantly for climate sensitivity, increases significantly when climate warms. The large surface temperature response of this ensemble member is more consistent with stratospheric humidity change, rather than upper tropospheric clouds as has been previously suggested. The direct relationship between the bias in the control state (elevated stratospheric humidity) and the cause of the high climate sensitivity (a further increase in stratospheric humidity) lends further doubt as to the realism of this particular integration. This, together with other evidence, lowers the likelihood that the climate system's physical sensitivity is significantly higher than the likely upper range quoted in the Intergovernmental Panel on Climate Change's Fourth Assessment Report.

Item Type:Article
Divisions:Science > School of Mathematical, Physical and Computational Sciences > NCAS
ID Code:7239
Publisher:Copernicus Publications


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