Production and use of regional climate model projections – A Swedish perspective on building climate services

Abstract

We describe the process of building a climate service centred on regional climate model results from the Rossby Centre regional climate model RCA4. The climate service has as its central facility a web service provided by the Swedish Meteorological and Hydrological Institute where users can get an idea of various aspects of climate change from a suite of maps, diagrams, explaining texts and user guides. Here we present the contents of the web service and how this has been designed and developed in collaboration with users of the service in a dialogue reaching over more than a decade. We also present the ensemble of climate projections with RCA4 that provides the fundamental climate information presented at the web service. In this context, RCA4 has been used to downscale nine different coupled atmosphere-ocean general circulation models (AOGCMs) from the 5th Coupled Model Intercomparison Project (CMIP5) to 0.44° (c. 50 km) horizontal resolution over Europe. Further, we investigate how this ensemble relates to the CMIP5 ensemble.We find that the iterative approach involving the users of the climate service has been successful as the service is widely used and is an important source of information for work on climate adaptation in Sweden. The RCA4 ensemble samples a large degree of the spread in the CMIP5 ensemble implying that it can be used to illustrate uncertainties and robustness in future climate change in Sweden. The results also show that RCA4 changes results compared to the underlying AOGCMs, sometimes in a systematic way.

European climate change at global mean temperature increases of 1.5 and 2 °C above pre-industrial conditions as simulated by the EURO-CORDEX regional climate models

“…In the latter case it is even the question of changing sign in the precipitation signal; from a decrease in HadGEM2-ES to an increase in the RCMs. A similar discrepancy between HadGEM2-ES and RCA4 was found also in a RCA4 simulation at 50 km 20 horizontal resolution by Kjellström et al (2016). They also found wetter conditions in RCA4 compared to a range of other GCMs it has downscaled indicating that the hydrological cycle is more sensitive to the increasing temperatures in this regional climate model.…”

European climate change at global mean temperature increases of 1.5 and 2 °C above pre-industrial conditions as simulated by the EURO-CORDEX regional climate models

“…In the latter case it is even the question of changing sign in the precipitation signal: from a decrease in HadGEM2-ES to an increase in the RCMs. A similar discrepancy between HadGEM2-ES and RCA4 was also found in an RCA4 simulation at 50 km horizontal resolution by Kjellström et al (2016). They also found wetter condi- (Table 2), (ii) the nine-member GCM ensemble that has been downscaled and (iii) the 18-member RCM ensemble (Table 1).…”

Bias patterns and climate change signals in GCM-RCM model chains

“…The model version RCA4 is used at 0.44 • (50 km) horizontal resolution, with 40 vertical levels. Details about the simulations can be found in Kjellström et al (2016) and Strandberg et al (2014).…”

“…On an institutional level, the need for regional climate change information is reflected in the formation of climate services, which have a strongly national and regional orientation (Fischer * Deceased. et al 2012a, Goddard 2016, Kjellström et al 2016, Adams et al 2015. The importance of an adequate assessment of the associated uncertainties has been emphasized in a number of studies (Déqué et al 2012, Hawkins andSutton 2009).…”