From advocacy to action: Projecting the health impacts of climate change

Even when the long term is relevant, as, for example, in the case of large infrastructure developments, the uncertainties involved in climate prediction on local scales are so large that they can exceed the magnitude of the projected change [7]. [...]with many relevant non-climate factors, it is difficult to disentangle the role that climate change projections may have played in the development of an adaptation plan. Differences in projections among models are examined closely, but the ensemble of available models is ad hoc and cannot be expected to provide a reliable estimate of the range of futures that might plausibly occur. [...]without past test cases over which to calibrate the ensemble projections, it is impossible to know whether probabilistic climate change projections are reliable [8]. Nor can we use climate projections to infer anything about the future climate over periods shorter than 30 years. Because projections do not capture the timing of interannual and decadal variations, statistics should always be calculated over at least three decades. [...]we cannot set too much store by probabilistic projections because the ensemble of models used in the projections is not an accurate representation of the full range of possible futures [9].