A comprehensive new study performed by a team of scientists from six countries has found that the world's natural landlocked water storage is in sharp, widespread decline, reports Phys.org.
The alarming report utilized data from gravity observations collected from NASA/German Aerospace Center's Gravity Recovery and Climate Experiment, or GRACE, satellites, which can measure the amount of water mass loss by looking at how Earth's gravitational field has shifted over time. The research found that a water mass equivalent to five Great Salt Lakes or three Lake Meads is gone every year from the planet's endorheic regions, or regions where water flows inland rather than into the oceans.
"Over the past few decades, we have seen increasing evidence of perturbations to the endorheic water balance," explained Jida Wang, lead author on the study. "This includes, for example, the desiccating Aral Sea, the depleting Arabian aquifer and the retreating Eurasian glaciers."
The Aral Sea is perhaps the most visually compelling representation of the intensifying crisis. It was the world's fourth largest lake in the 1960s. Today, it's largely a windswept sand plain, most of which has been renamed the Aralkum Desert. Since 1960, the Aral Sea has lost about 90 percent of its volume.
Water is moving in all the wrong directions
The study concluded that a combination of factors, including human activities and climate change, have contributed to the problem. For instance, unsustainable human water management, such as river diversion, damming and groundwater withdrawal, have sucked some of these regions beyond their limits. Of course, anthropogenic global warming has also altered climate systems and increased evaporation in many of these regions as well.
Worse yet, the water we're losing in our endorheic regions is essentially being transplanted into the oceans. This contributes to sea level rise, another global environmental concern which also threatens freshwater coastal regions.
"We are not saying the recent endorheic water loss has completely ended up in the ocean," said Yoshihide Wada, co-author of the study. "Instead, we are showing a perspective of how substantial the recent endorheic water loss has been. If it persists, such as beyond the decadal timescale, the water surplus added to the [ocean-linked] system may signify an important source of sea level rise."
In other words, endorheic water loss is not an isolated problem. It can lead to feedbacks that intensify a larger global environmental crisis, of which endorheic water loss is a mere symptom.
"These messages highlight the underrated importance of endorheic basins in the water cycle and the need for an improved understanding of water storage changes in the global hinterlands," said Wang.