Global freshwater levels falling since 2014, NASA-German satellites reveal

Earth’s fresh water reserves experienced a sudden decline starting in May 2014 and remained persistently low, according to the findings of an international team of scientists using German NASA satellites. Observations from the Gravity Recovery and Climate Experiment (GRACE) mission have revealed a significant reduction in fresh water stored on earth, including in lakes, rivers and underground aquifers. The study, published in Surveys in Geophysics, suggests that this change could indicate a transition to drier conditions across continents.

Quantified reduction of fresh water

Between 2015 and 2023, terrestrial freshwater levels were find or 290 cubic miles below the average recorded from 2002 to 2014, according to Matthew Rodell, a hydrologist at NASA’s Goddard Space Flight Center. This is more than twice the volume of Lake Erie. Contributing factors include droughts and increased reliance on groundwater for agricultural and urban needs, which deplete reserves faster than they can be replenished. A 2024 United Nations report on water stress highlighted the societal risks of dwindling water supplies, including famine, poverty and dependence on unsafe water sources.

Impact of global warming on water cycles

Research indicates that rising global temperatures could exacerbate freshwater loss. Michael Bosilovich, a meteorologist at NASA Goddard, explained that warming intensifies evaporation and increases the atmosphere’s ability to hold moisture, leading to extreme precipitation. Even if total annual precipitation remains stable, prolonged dry periods between these events reduce soil absorption, thereby worsening drought conditions.

Persistent trends raise concerns

Satellite data showed that global fresh water failed to recover after a significant El Niño event between 2014 and 2016, which caused changes in atmospheric patterns and widespread droughts. Rodell noted that 13 of the 30 most severe droughts since 2002 occurred after 2015. Although the link to climate change is not definitive, the coincidence with record global temperatures has raised concerns about future resource stability. in fresh water.

Hydrologist Susanna Werth of Virginia Tech, not affiliated with the study, noted the challenges of predicting long-term outcomes due to uncertainties in climate models. However, current trends are being closely monitored for other implications.