Urban climate change-related effects on extreme heat events in Rostock, Germany

The urban heat island effect poses a challenge in several cities, and may affect human and ecosystem health. It was proven that relatively small urban conglomerations in mid-latitudes, such as the case study region of Rostock, have undergone a considerable effect recently, noticeable particularly in the warm season. Due to climatic changes, these effects are expected to alter in intensity and/or frequency. This was investigated using a model that focuses on interactions between land use and surface temperatures and on specific air conditions in cities. The model enables urban surface temperature differences to be projected with regard to different assumptions of (future or planned) land use/land cover and its specific characteristics. In addition, 99th percentile summer days from the period 1961-1990 and scenario runs from regional climate models (RCMs) were used as an example of extreme heat events. The frequency of occurrence of extreme heat events resembling those occurring in the present day will be up to four (2041-2070) and six (2071-2100) times higher, respectively. Furthermore, the average temperature on defined extreme heat days will rise by 1.6 to 3.4 degrees C (2041-2070) and 2.2 to 4.4 degrees C (2071-2100), respectively. The model calculated no significant effects for differences in maximum surface temperatures between land use classes. Some parts of land use change scenarios constructed during scenario workshops in Rostock were integrated into the surface temperature model with regard to climate change adaptation. The results revealed a range of outcomes, from an enlargement of vulnerable areas to the near eradication of climate change-related heat effects in several areas.