GHP cross-cutting project proposal Short time-scale precipitation extremes Proposers/Contacts Jason Evans Climate Change Research Centre, University of New South Wales, Sydney, Australia. Jason.evans@unsw.edu.au Lisa Alexander Climate Change Research Centre, University of New South Wales, Sydney, Australia. l.alexander@unsw.edu.au Motivation Flood causing precipitation extremes are an important societal hazard. The potential for these precipitation extremes to change due to increasing greenhouse gases presents a significant risk to life and property if current flood management strategies prove to be inadequate in a future climate. At daily and longer time scales the Expert Team on Climate Change Detection and Indices (ETCCDI - http://cccma.seos.uvic.ca/ETCCDI/ ) defined 11 indices derived from daily data related to precipitation extremes. Gridded global datasets were developed from these indices (Alexander et al. 2006) although efforts are now underway through the CLIMDEX project (http://www.climdex.org/ ) to update these datasets using various global meteorological station networks. Currently many parts of the world are poorly represented in this global database. In recent years a number of studies have investigated trends in sub-daily precipitation extremes (e.g. Hardwick Jones et al. 2010; Lenderink and Van Meijgaard 2008; Dai et al. 2007), and there relationship with atmospheric warming. Results vary geographically but in some cases show large increases in very short (hourly or less) precipitation extremes without similar changes in daily extremes. Few regions of the world have investigated these changes to date. This project aims to better characterize the global distribution and temporal trends in precipitation extremes at daily and shorter time-scales. It will also examine future changes in these extremes as projected by climate models (CMIP5 & CORDEX). This will provide more robust knowledge of the global state of precipitation extremes, the relationship between daily and shorter time-scale extremes, and the potential changes due to global warming. 1