How do precipitation trends propagate through the terrestrial water cycle?

Climate Change involves changes in precipitation. The propagation of precipitation changes into the water cycle is complex and dependent on e.g. aridity and land cover which are themselves affected by climate change. As a result, estimating effects on water fluxes such as evaporation and runoff as well as water resources such as soil moisture is not straightforward. This study maps future changes in the seasonal cycle of precipitation across the globe, as projected by Earth system models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Additionally, we analyse the propagation of the detected seasonal precipitation surpluses and deficits into the water cycle, and determine the main underlying controls. For this purpose we determine and compare seasonal changes in precipitation, evapotranspiration, runoff and soil moisture across the next decades. While this yields a first indication of the propagation of increasing or decreasing precipitation, we furthermore calculate correlations between the considered variables in each decade as an independent measure of the relation between precipitation and the water cycle components. In this context we use partial correlations to better separate water cycle couplings from the impact of other meteorological forcings such as radiation. A particular focus of our analysis will be on uncertainties of (i) precipitation trends and (ii) their projected propagation into the water cycle across the CMIP6 model ensemble to distinguish robust patterns from areas with high uncertainties. Our analysis helps to understand changes in future water fluxes and resources and the underlying robustness, which can inform the development of Earth system models as well as water resources management.