A selected number of extremes were selected as case-study specific climate indicators, and these were constructed for both the present day and future periods (up to the year 2050). Increases in very hot summer days and nights are projected by the CIRCE climate models. However, the intermodal spread is very large. Projections for other extreme weather events, such as heavy precipitation and flooding, are highly uncertain, but any increase in such events would further increase vulnerability in the case-study regions.
1. Present day
Indices of temperature extremes from E-OBS and ERA-40 gridded temperature datasets have been calculated for the period 1950-2010, for each of the CIRCE case studies. These data can be downloaded as a single text file, and the data, method of analysis and long-term trends are described in an accompanying project report:
Climate extremes indicators have been constructed using output from the CIRCE climate models using a single grid box for the urban case studies, and the average of land-based grid boxes for the rural and coastal case studies. Plots of key extremes indices are available to download as a Word document.
Key temperature extremes indices for the case studies include: very hot summer days (Tx95), very hot summer nights (Tn95), and very cold nights (Tn5). While key precipitation extremes indices for case studies include: the maximum dry spell length (consecutive dry days - CDD); heavy precipitation (the 90th percentile of daily precipitation - pq90) and maximum three-day precipitation (px3d).
A project report on future changes in temperature extremes in the Mediterranean region is available to download. Future changes are assessed using output from four of the CIRCE climate model simulations and 15 indices of extremes. These indices include the number of very hot days and nights and very cold days and nights, together with warm and cold spell duration. Changes are presented for 2021-2050 with respect to 1961-1990 and for the A1B emissions scenario. The general picture of more warm/hot extremes and fewer cold extremes is consistent with the changes observed over the Mediterranean over the last few decades and with other projections for the end of the 21st century. While the direction of the projected changes is robust, there is, however, uncertainty in the magnitude of change.