Our latest study, and an earlier report from our team, show that it is happening now. However, IPCC-predicted changes extend through the end of the 21st century. This pattern of wet getting wetter, dry getting drier, has long been predicted in a series of Intergovernmental Panel on Climate Change (IPCC) reports. Simultaneously, the mid-latitudes-the arid to semiarid belt sandwiched in between-are getting drier. These patterns aren’t seen in previous water maps, most of which were built from ground-based data.įor example, we found that the world’s high-latitude regions, including the northern half of the United States, as well as the global tropics, the low latitudes, are getting wetter. Perhaps the most concerning feature throughout the years of the map’s development has been persistent, distinct patterns that define emerging classes of water “haves” and “have-nots” around the world. We spent more than a decade studying the data and published our map and report in 2018.
And what the map shows is also simple to understand but deeply troubling: Water security-a phrase that simply means having access to sufficient quantities of safe water for our daily lives-is at a greater risk than most people realize. The data quantified the rates at which all regions on Earth are gaining or losing water, allowing my colleagues and me to produce the accompanying map. Unlike some satellite missions that rely on images, GRACE, which was launched in 2002 and decommissioned at the end of 2017, was more a “scale in the sky.” It measured the very tiny space-time variations in Earth’s gravity field, effectively weighing changes in water mass over large river basins and groundwater aquifers-those porous, subterranean rock and soil layers that store water that must be pumped to the surface.Īs complex as that sounds, the results are actually quite simple to understand. We know this thanks to 14 years’ worth of satellite data collected by a unique NASA Earth-observing mission called the Gravity Recovery and Climate Experiment-which has the gratifying acronym GRACE. The availability of fresh water is rapidly changing all over the world, creating a tenuous future that requires attention from policymakers and the public.
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