World’s population susceptible to water risks is concentrated in two of the 58 IPCC reference regions

The use of climate reference regions is a common practice in climate change research and impact assessment studies 1 , 2 , 3 , 4 , having been utilized especially within the context of the Intergovernmental Panel on Climate Change (IPCC)’s Assessment Reports (ARs) over the past 25 years. They have been developed and used for synthesizing the regional properties and historical trends of climate, and for climate change projections for the future 4 . Climate reference regions have shown their value and usefulness in providing consistent geographic delineation for showing a high number of interrelated and intricate natural phenomena with complex societal implications in climate change impact assessments 4 , 5 , 6 .