11-member RCM: Uncertainties

• Modelling uncertainty

This arises from incomplete understanding of Earth system processes and incomplete representation in climate models:

• An estimation of modelling uncertainty is quantified through running 11 variants of the regional climate model.
• This is a significant advance from UKCIP02, which had no estimation of modelling uncertainty. However, it does not include as complete an estimate of uncertainty as that available in the PDFs in UKCP09, which also used other models to estimate structural uncertainty and account for uncertainties in carbon cycle feedbacks.

• Natural climate variability

This arisies from both external influences on the climate and internal chaotic climate processes.

• The effects of natural climate variability are quantified to a limited extent through the use of 11 variants of the regional climate model.
• This is a significant advance from UKCIP02, which explored natural climate variability in a more limited way.

• Emissions uncertainty

This arises from not knowing the amount of future global greenhouse gas emissions:

• As only one emissions scenario was explored in this data source the emissions uncertainty was not addressed.