Making robust decisions

Making Robust Decisions in the Face of Uncertainty: Using Climate Models

Traditionally, adaptation planning has been achieved through so-called ‘top down’ or ‘scenario-led’ methods which focus on developing fine scale climate data from coarse scale Global Climate Models (GCMs). The resulting local-scale scenarios are fed into impact models or mapped against the locations of people or infrastructure assets to determine vulnerability.

Figure 1: Robust adaptation to climate change, from Wilby and Dessai (2010)
Although climate models are constantly being improved, they are not able to predict future climate conditions with a degree of confidence allowing precise adaptation decisions to be made. In addition, outputs from different climate models often differ, presenting users with a range of possible climate futures to consider, and ultimately a wide range of possible adaptation options (see Figure). The user will be faced with the problem of deciding which model they should use. Even with improvements in climate modelling, uncertainties will remain.  Downscaling climate projections to a higher resolution should not be seen as increasing confidence in data, and can be misinterpreted as providing more accurate data.

Given these uncertainties, the focus should be on identifying and implementing adaptation actions which perform well both under current and possible future climatic conditions. A policy or project should have the effect of improving the ‘adaptive capacity’ or reducing the ‘sensitivity’ of residents and communities – this is the cornerstone of climate resilience.

A ‘bottom up’ approach to adaptation planning is an effective way of planning projects in the Caribbean and elsewhere (Wilby and Dessai, 2010; Pielke et al., 2012). The method focuses initially on finding adaptation options which reduce vulnerability to past and present climate variability (as well as ‘non-climatic pressures’). It begins with an assessment of vulnerability to observed climate variability and change. Robust adaptation measures are then identified that would reduce vulnerability under current climate conditions, whilst being acceptable in other terms (e.g. technically, financially, economically, socially, environmentally).

Climate models have a major role in decision making. If the lifetime of a project spans several decades, they can be used to establish upper and lower bounds for testing of possible adaptation options. The aim is to identify adaptation options which perform well (though not necessarily optimally) over a wide range of conditions experienced now and potentially in the future- a shift in emphasis from identifying optimal actions to finding robust ones.  A further important principle for decision-making in the face of uncertainty is to apply ‘adaptive management’ i.e. a strategy which can evolve and adjust as circumstances change (e.g. Wilby, 2011).

Further reading

Wilby, R. L. and Dessai, S. 2010. Robust adaptation to climate change. Weather, 65(7), pp. 180-185.
Pielke, R. A., Sr., R. Wilby, D. Niyogi, F. Hossain, K. Dairuku, J. Adegoke, G. Kallos, T. Seastedt, and K. Suding (2012), Dealing with complexity and extreme events using a bottom-up, resource-based vulnerability perspective, in Extreme Events and Natural Hazards: The Complexity Perspective, Geophys. Monogr. Ser., vol. 196, edited by A. S. Sharma et al. 345–359, AGU, Washington, D. C.
Wilby, R.L. 2011. Adaptation: Wells of wisdom. Nature Climate Change, 1, 302-303.

CCORAL Version: V 1.7 Last updated: 09/04/2014