Earth’s planetary-scale lake storage phenology

Lakes, Earth’s largest store of liquid surface freshwater, record upstream hydroclimatic variability while mediating downstream flows(ref.1-4). This dual role is encoded in lake storage phenology – the magnitude, timing, and shape of seasonal storage changes – whose planetary organization and human modification remain poorly understood(ref.4-6). Here, we use wide-swath satellite altimetry(ref.7) to unveil storage phenology across 5.1 million lakes ≥1 ha worldwide through a four-level framework: individual-lake variability, planetary-scale cycle, recurrent archetypes, and process interpretation via storage–flow coupling. Individual-lake variability, structured by landscape setting, totals 3,047.5–3,571.2 Gt (74.4–119.2% above previous estimates(ref.5,6)), with reservoirs contributing disproportionately and smaller lakes exhibiting greater volume-normalized variability. Phenological asynchrony attenuates these fluctuations to a planetary-scale seasonal cycle of 636.7–928.8 Gt, roughly tripling river-channel variability(ref.8). Seven archetypes organize this diversity into coherent seasonal patterns, including a high-variability monsoonal mode whose late-season filling opposes global storage recession, dampening planetary variability by 40.1%. While lake storage often retains the seasonal signature of naturalized upstream flow, phase delays of ≥6 weeks characterize nearly half of natural-lake and three-quarters of reservoir storage variability, revealing substantial mediation through hydrologic memory and human regulation. These findings establish lake storage phenology as a measurable dimension of the terrestrial water cycle, linking hydroclimate, storage mediation, and anthropogenic imprint across scales.