final_program_abstracts[1]

11 IMSC Session Program
Detection of human influence on extreme precipitation
Thursday - Parallel Session 7
Seung-Ki Min 1 , Xuebin Zhang 1 , Francis W. Zwiers 1 and Gabriele C. Hegerl 2
1 Climate Research Division, Environment Canada, Toronto, Canada
2 School of GeoSciences, University of Edinburgh, Edinburgh, UK
Heavy precipitation events have become more intense over a large part of the
Northern Hemisphere (NH) land area. It has been suggested that human influence
may be partly responsible for the intensification of extreme precipitation in line with
the increased water holding capacity of atmosphere due to global warming. However,
because of the limited availability of daily observations, most previous studies have
examined only the potential detectability of extreme precipitation through modelmodel
comparisons. Here we compare observed and multi-model simulated extreme
precipitation using an optimal fingerprinting method, and provide the first evidence
that human-induced increase in greenhouse gases and sulphate aerosols have
contributed to the observed intensification of heavy precipitation events during the
latter half of the 20th century. The anthropogenic signal is found to be detectable over
large NH land areas. Models, however, under-simulate the observed increase in heavy
precipitation trend, indicating that model projected changes in extreme precipitation
and their impacts may also be underestimated.
Abstracts 256