How do the storm projections for UKCIP02 and UKCP09 compare? Does UKCP09 show an increase in the frequency, intensity and severity of storms?
There is little change in the frequency in winter storms in UKCP09.
In HadAM3H (the climate model used in UKCIP02) there is an increase in the future number of UK winter depressions because there are more depressions overall and not because the probability of the most intense storms increases. This is attributed to a southward shift in the north east end of the North Atlantic storm track in this model giving more UK storms.
In HadCM3 (the climate model used in UKCP09) there is little change in the frequency of storms over the UK in winter. Although there is a southward shift in the North Atlantic storm track in this model the increase in frequency occurs to the southwest of the UK giving little change over the UK. There is also little change in the intensity of UK storms in this model.
There are errors associated with both the position and strength of the present day storm tracks and these contribute to the large uncertainties in the future predictions of storms.
The different results between the two models illustrate the lack of any robust changes in UK storms, hence the Annex 6.4 summary of the Climate change projections report states:
"There is no consistent signal of change in either storms or blocking near the UK in either ensemble of Met Office models or the ensemble of alternative models. Such changes as are seen are relatively modest, and the potential for substantial changes appears to be small."