Decadal-scale projections of climate variability and change must integrate projections of externally forced century-scale climate change with natural modes of climate variability. In addition to the CMIP5 decadal climate model simulations, CFAN uses a network-based dynamic climatology based on multidecadal teleconnection indices.
Providing a range of possible scenarios, rather than focusing only on a mean or most likely scenario, enables decisions that are robust across a range of possible outcomes. Extreme event scenarios consist of frequency distribution of regional extreme events over the target time interval, as well as worst-case scenarios of individual events. CFAN’s possibility distributions and likelihood analysis distinguish what is plausible versus the most likely versus surprising versus impossible. Providing a range of possible scenarios allows the user to assign more or less confidence to different assumptions used in constructing the scenarios in assessing the likelihood of the future scenarios. For a particular application, consideration of the full range of scenarios may be less relevant than the likelihood of scenarios in the vicinity of the user’s vulnerability threshold.
Further information about CFAN’s climate change scenario development can be found [here].