Observed trends in high river flows strongly vary across regions but also with the considered time period  as influenced by climate oscillations such as the El Niño-Southern Oscillation . On the global scale, the spatial pattern of observed trends is largely explained by observed changes in climate conditions as demonstrated by multi- model hydrological simulations forced by observed weather, while the considered direct human influences play only a minor role on global scale . The annual total number of reported fatalities from flooding shows a positive trend  which appears to be primarily driven by changes in exposure dampened by a reduction in vulnerability, while climate-induced increases in affected areas show only a weak positive trend on the global scale. However, the signal of climate change in flood-induced fatalities may be lost in the regional aggregation, where effects of increasing and decreasing hazards may cancel out. Thus, a climate-driven increase in flood-induced damages becomes detectable in continental subregions with increasing discharge, while the signal of climate change may not be detectable without disaggregation . Compared with river floods, the analysis of impacts of long-term changes in the climate-related systems on the reduction in water availability is much more fragmented and reduced to individual case studies regarding associated societal impacts . At the same time, weather fluctuations have led to reductions in water availability with severe societal consequences and high numbers of drought-induced fatalities and damages in particular in Africa and Asia  and impacts on malnutrition . Although anthropogenic climate forcing has increased droughts' intensity or probability in many regions of the world ,  the existing knowledge has not yet been systematically linked to attribute long- term trends in malnutrition, fatalities and damages induced by reduced water availability to anthropogenic climate forcing or long-term climate change. For impacts of individual attributable drought events, see Table 4.5 and 'Water distribution-Reductions in water availability + induced damages and fatalities', Table SM16.23.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report