Step 3: Select Representative Concentration Pathways

Representative concentration pathways (RCPs) are forcing scenarios used in climate models to generate data about possible future climates.

Due to our inability to predict how the greenhouse gas and aerosol emissions and concentrations in the atmosphere will unfold, a range of RCPs should be considered when developing climate information.

It is recommended that the full range of RCPs (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) are used. If this is not possible, choose a higher and a lower RCP to capture this range for impact assessments.

The global climate implications of the forcing of the scenarios used can be seen in the projected changes in the global mean surface air temperature by 2100 as simulated by global climate models for two emissions scenarios, RCP2.6 (lower) and RCP8.5 (higher) compared to the historical period baseline (1986–2005).


CMIP5 multi-model simulated time series from 1950 to 2100 for change in global annual surface air temperature relative to 1986-2005. Shown is the time series of projections (bold lines) and uncertainty (shading) for RCP2.6 (blue) and RCP8.5 (red). Black (gray shading) is the modelled historical evolution of temperature using historical constructed forcings. The numbers of CMIP models used to calculate the multi-model mean is indicated (i.e. 42, 32, and 39 for the historical, RCP2.6, and RCP8.5, respectively).(Adapted from IPCC)



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