High resolution temperature projections for the Barcelona Metropolitan Area (AMB)

The Barcelona Metropolitan Area (AMB), with nearly 3.5 million inhabitants, is one of the largest conurbations in Southern Europe. Furthermore, population growth is expected in the coming decades as a result of both internal and external migration. In the context of climate change, the projected increase in temperature is expected to have a profound impact on infrastructure management, urban design and ultimately in urban population.In this study, we present a set of high spatial resolution climate projections for temperature and derived climate indices. These projections have been obtained through statistical downscaling using the delta bias correction methodology applying Kernel Density Estimation (KDE) to compute the Cumulative Distribution Functions (CDF). Climatic data is  based on a set of Euro-CORDEX CMIP5 simulations and a high-resolution observational grid (1 km) derived from historical data provided by the Meteorological Service of Catalonia is used as a ground truth. Two subsets of Euro-CORDEX models were selected: one comprising models that best reproduce the observed temperature trends in Catalonia over the observational period 1971–2005, and another including models that perform worst in reproducing these trends. Results indicate a substantial spread in projected maximum and minimum temperatures across models. However, the spatial distribution of the warmest areas remains broadly consistent among simulations.Based on these projections, it is plausible that the threshold of 50 °C could be reached by the end of the century in several locations within the AMB. This threshold has not yet been recorded in the AMB, where absolute maximum temperatures reach 43–44 °C, nor in the warmest areas of Catalonia (44–45 °C) or across the Iberian Peninsula (47–48 °C), since the beginning of instrumental records (19th century). In addition, urban heat island effects are particularly evident in projections of minimum temperatures. Nevertheless, the intensification of night-time temperatures in urban areas should be better represented in future projections, as these processes may exhibit their own dynamics and are strongly dependent on urban design and development models currently being implemented.Finally, we emphasize the need to incorporate Euro-CORDEX CMIP6 simulations as soon as these datasets become available to the scientific community.