Written by Nereus Fellow Tyler Eddy,

Models are an everyday part of our lives, including the weather forecasts that we check before we leave the house or make weekend plans. These models also form the basis of projections about how much our planet will warm with increasing carbon emissions and the associated impacts on natural systems that supply us with ecosystem services such as clean water and air and food from land and sea. Along with making projections of the future climate and natural systems, the modelling community spends a considerable amount of time improving model skill by comparing projections during past events to observations. This calibration process is used to improve the representation of processes within models so that future projections are more accurate. In this study titled ‘State-of-the-art global models underestimate impacts from climate extremes’ published in Nature Communications and led by Jacob Schewe from the Potsdam Institute for Climate Impact Research in Potsdam, Germany, we used the 2003 European heat wave that resulted in more than 70,000 human deaths as an extreme event to compare model projections to actual impacts.

The Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) was established to bring together modelling communities across a range of disciplines to standardize the way that climate change impacts are modelled. This multidisciplinary group addresses climate change impacts on agriculture, ground water, forests, human health, energy systems, terrestrial biodiversity, lakes, coastal infrastructure, and marine ecosystems and fisheries. Using the heat wave as a case study to see how models projected impacts compared to observations, we found that models underestimated observed impacts on agriculture, terrestrial ecosystems, and heat-related human mortality. For the European oceans, seas, and fisheries, the model projections were similar to observations of fisheries catches, however some locally observed mass mortalities of shallow nearshore species were too finely scaled to be represented by the more coarsely resolved models. Moving forward, this study is important not only for the modelling community, but also for policy makers as risks to society from future extreme events may be greater than previously thought.


Schewe J, Gosling SN, Reyer C, Zhao F, Ciais P, Elliott J, Francois L, Huber V, Lotze HK, Seneviratne SI, van Vliet MTH, Vautard R, Wada Y, Breuer L,Büchner M, Carozza DA, Chang J, Coll M, Deryng D, de Wit A, Eddy TD, Folberth C, Frieler K, Friend AD, Gerten D, GudmundssonL, Hanasaki N, Ito A, Khabarov N, Kim H, Lawrence P, Morfopoulos C, Müller C, Schmied HM, Orth R, Ostberg S, Pokhrel Y, Pugh TAM, Sakurai G, Satoh Y, Schmid E, Stacke T, Steenbeek J, Steinkamp J, Tang Q, Tian H, Tittensor D, Volkholz J, Wang X, Warszawski L. 2019. State-of-the-art global models underestimate impact from climate extremes. Nature Communications 10: 1005. Link

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