Interdecadal variability of terrestrial water storage since 2003

Earth’s water cycle is changing due to anthropogenic forcing and internal variations in the climate system. These changes are leading to an intensification of the water cycle that manifests as more frequent and stronger droughts in some areas, and pluvials in others. The resulting impacts on terrestrial water storage can be crucial for water availability. However, current understanding is hampered by limitations in observations and models, and the variety of processes that influence terrestrial water storage across temporal scales. Here, we leverage the now two-decades long satellite record from the Gravity Recovery and Climate Experiment and subsequent Follow-On missions to investigate persistent trends in the presence of internal variability. We use cyclostationary empirical orthogonal function analysis to uncover statistical modes of variability that help explain a shift in decadal terrestrial water storage trends that occurred around 2012. The dominant statistical mode suggests an interdecadal periodicity that is also found in the precipitation record. The second leading mode is highly correlated with the Pacific Decadal Oscillation. Isolating these modes points to regions where the magnitude of the terrestrial water storage trend may flatten or reverse in coming decades due to internal climate variability and reduces uncertainty in multidecadal linear trends.