Dynamical Constraints on regional Projections of Extreme Precipitation Events

Extreme precipitation events cause major ecological and societal hazards (e.g. river flooding and landslides). Aggravatingly, climate change will likely exacerbate extreme precipitation events on a global scale. Scientifically even more concerning, however, are remaining major uncertainties in projections of regional extreme precipitation events, which hamper and complicate local adaptation measurements around the globe. The arguably largest source of these remaining uncertainties stems from climate models feuding about the dynamic evolution of atmospheric circulation; atmospheric circulation governs moisture transport and profoundly affects the location of extreme precipitation events as well as their severity around the globe. We exploit this feud among climate models to narrow down the arguably largest source of uncertainttiesin projections of extreme precipitation events through a storyline approach. For a given location, the approach: (i) unravels the properties of driving weather systems that repeatedly gave rise to extreme precipitation events in the past, (ii) assesses the fidelity of a large suite of models, participating in the Coupled Model Intercomparison Project 6 (CMIP6), in representing these driving weather systems in historical simulations (1950-2015), and (iii) constrains regional projections of extreme precipitation events based on the ascertained fidelity of models.

Here, we present such a storyline approach that dynamically constrains regional projections of extreme precipitation events. Accompanying the outline of the approach, we identify regions that are particularly plagued by uncertain projections of extreme precipitation events and showcase for a subset of these regions how to track down weather systems that repeatedly gave rise to extreme precipitation events in the past.