Criteria for Selecting Climate Scenarios
Five criteria that should be met by climate scenarios if they are to be useful for impact
researchers and policy makers are suggested:
- Criterion 1: Consistency with global projections. They should be consistent with a broad range
of global warming projections based on increased concentrations of greenhouse gases. This range
is variously cited as 1.4°C to 5.8°C by 2100, or 1.5°C to 4.5°C for a doubling of atmospheric CO2
concentration (otherwise known as the "equilibrium climate sensitivity").
- Criterion 2: Physical plausibility. They should be physically plausible; that is, they should
not violate the basic laws of physics. Hence, changes in one region should be physically
consistent with those in another region and globally. In addition, the combination of changes in
different variables (which are often correlated with each other) should be physically
- Criterion 3: Applicability in impact assessments. They should describe changes in a sufficient
number of variables on a spatial and temporal scale that allows for impact assessment. For
example, impact models may require input data on variables such as precipitation, solar
radiation, temperature, humidity and windspeed at spatial scales ranging from global to site
and at temporal scales ranging from annual means to daily or hourly values.
- Criterion 4: Representative. They should be representative of the potential range of future
regional climate change. Only in this way can a realistic range of possible impacts be
- Criterion 5: Accessibility. They should be straightforward to obtain, interpret and apply for
impact assessment. Many impact assessment projects include a separate scenario development
component which specifically aims to address this last point. The DDC and this guidance
document are also designed to help meet this need.
Page last modified: 28 November 2011