Unravelling the uncertainties of predicting future heatwaves

Health Canal.com (UK): As the country swelters in the grip of a late September heat-wave researchers at The University of Nottingham have warned that while Indian summers could become more common, heat-waves in the future could become even hotter. Moreover, they could have important implications for human health. However, their research suggests that we are going to have to take a lot more notice of the things we don’t understand about the climate. In other words, we have up until now, been underestimating the uncertainties of climate change.

Dr Simon Gosling, in the School of Geography, said: “It is important that we represent this uncertainty when we try to understand future climate change. One way of understanding how heat-related mortality risk will change in the future is through the application of numerical models that simulate the effects of climate change on human health. Up until recently such models have typically produced projections of climate change impacts based upon only one or two possible future climates. However, great uncertainty is associated with the numerical models that simulate future climate, due in part to the limited understanding of the physical climate system. This means that this climate modelling uncertainty is often considerably under-estimated. A more complete treatment of this uncertainty is important for better informing risk-based decision-making.”

Using a technique called Perturbed Physics Ensemble (PPE) – Dr Gosling, in collaboration with experts from The University of Auckland and The Met Office Hadley Centre, ran 17 slightly different versions of a complex climate model to explore what the future climate might look like, and what it might mean for human health. The study, published in the journal Climatic Change provides the most complete treatment of climate modelling uncertainty in climate change health impacts assessment to date.

...By considering the different patterns of climate change projected by 17 climate models, the study gives an indication of the current level of scientific confidence in projected changes in heat-related mortality for six cities; Boston, Budapest, Dallas, Lisbon, London and Sydney. The cities were selected to represent a range of different climates.

.... Dr Gosling’s research demonstrates that relying on a single climate model for estimating future health impacts is not appropriate. The main finding is that although there is a lot of uncertainty...

In 1973, Dick Swanson took this picture of fountain by the Philadelphia Museum of Art during a heat wave