Extreme future rainfall in Bologna: exploring climate scenarios depicted by CMIP6 models

Inferring the statistical behaviours of future rainfall extremes is a topical issue for the mitigation of pluvial and flood risk. There is increasing evidence that extreme short-duration rainfall is intensifying, but the quantification of such increase is still a challenging issue. By banking on the availability of one of the longest daily rainfall series today available, continuously recorded in Bologna from Jan 1st, 1850, we test the performances of up-to-date CMIP6 climate models in the reproduction of historical rainfall statistics and assess the projections for the XXIst century, with different emission scenarios. We refer to the extreme rainfall indexes given by the annual and 10-year maximum 1-day rainfall (Rx1day), the annual and 10-year number of heavy (>10 mm) and very heavy (>20 mm) rainfall days (R10mm and R20mm) and the annual and 10-year number of days with rainfall greater than the 99th percentile of daily amounts (R99p). The results confirm the expectation of a potential increase of heavy rainfall during the next decades.