Uncertainty refers to a state of having limited knowledge. Uncertainty can result from lack of information or from disagreement over what is known or even knowable. Uncertainty may arise from many sources, such as quantifiable errors in data, or uncertain projections of human behaviour. Uncertainty can be represented by quantitative measures or by qualitative statements.
Uncertainty in climate change projections is a major problem for those planning to adapt to a changing climate. Uncertainty in projections of future climate change arises from three principal causes:
- natural climate variability;
- modelling uncertainty, referring to an incomplete understanding of Earth system processes and their imperfect representation in climate models; and
- uncertainty in future emissions.
UKCP09 is an advance from previous UK climate scenarios in that it attempts to quantify uncertainties in a more comprehensive way, using probabilistic projections.
- An overview of the uncertainties associated with climate modelling is described in Section 3.1 of the UKCP09 Briefing report.
Find out more
- IPCC Fourth Assessment Report, Working Group 1 report The Physical Science Basis , Chapter 10