A multinational study involving researchers from the International Institute for Applied Systems Analysis (IIASA) has investigated the alignment of global water models and their consistency with observational data. Global water models play a crucial role in comprehending the water cycle and assessing the impacts of climate change, particularly in understanding phenomena like increased droughts and floods. However, variations among these models raise concerns about the reliability of model-based conclusions.

The study, featured in Nature Water, introduces a novel evaluation method to identify where global water models converge and diverge. It addresses the limitations of past evaluation methodologies, providing a comprehensive exploration of large-scale correlations between climatic and hydrological variables. By comparing model outcomes with observational data, the researchers aim to quantify discrepancies and enhance the models.

Sebastian Gnann, the lead author of the study associated with the University of Potsdam, highlighted the significance of understanding the realism of different model results. An example he provided was the correlation between precipitation and groundwater recharge over the African continent, emphasizing that not all models accurately represent such relationships.

Two researchers from the IIASA Water Security Research Group, Peter Burek and Yoshihide Wada, contributed to the study using the IIASA Community Water Model (CWatM). This open-source model assesses water supply, human, and environmental water demands globally and regionally. Burek emphasized the study’s role in not only comparing uncertainties among global water models but also advancing models by examining functional relationships through the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP).

The study marks a crucial step in addressing disparities within global water models, offering insights that could lead to improvements and increased reliability in understanding the intricate dynamics of the water cycle and its impacts on society and ecosystems.