Changes in very heavy and extreme precipitation events: what do we know?

The presentation will review the evidence for the hypothesis: As the climate warms, many areas will experience increases in the frequency of very heavy and extreme precipitation events and these changes will be disproportionately large compared with changes in the mean. Virtually all climate model simulations with enhanced greenhouse gas forcing find a much stronger and more consistent signal of increasing very heavy precipitation events compared with changes in the mean as the climate warms due to greenhouse gas forcing. We will assess the observational data and theoretical information that support or contradict this hypothesis. Numerous analyses have now been undertaken with the purpose of detecting changes in precipitation rate in the observed record. None of the analyses are global in scope as there are serious data limitations related to spatial coverage and the length of the observed record. Although substantial difficulties still remain in our ability to comprehensively link observed changes to climate model simulations, there is substantial evidence to support the hypothesis.