More than half of the world’s lakes and reservoirs are dwindling and placing humanity’s future water security at risk, with climate change and unsustainable consumption tagged as the main culprits in a paper which appeared in the publication Science.
“Lakes are in trouble globally, and it has implications far and wide,” said Balaji Rajagopalan, a professor at the University of Colorado Boulder and co-author of the paper.
Unlike rivers, which have tended to hog scientific attention, lakes aren’t well monitored, despite their critical importance for security,” said Rajagopalan. However, high profile environmental disasters in large bodies of water like the Caspian Sea and the Aral Sea, signaled researchers to a wider crisis.
The scientists looked at 1,972 of the Earth’s biggest lakes and reservoirs, using observations from satellites from 1992-2020, to determine how lake volumes varied over nearly 30 years.
They found that 53 percent of lakes and reservoirs saw a decline in water storage, at a rate of approximately 22 gigatons a year. Over the whole period, 603 cubic kilometers of water was lost.
For natural lakes, much of the net loss was attributed to climate warming, as well as human water consumption. Increased temperatures from climate change drive evaporation, but can also decrease precipitation in some places.
One surprising aspect was that lakes in both dry and wet regions of the world are losing volume, suggesting the “dry gets drier, wet gets wetter” paradigm that is frequently used to summarize how climate change affects regions, doesn’t always hold. Losses were found in humid tropical lakes in the Amazon as well as Arctic lakes, demonstrating a trend more widely spread than predicted.
Globally, freshwater lakes and reservoirs store 87 percent of the planet’s liquid freshwater, underscoring the urgency of new strategies for sustainable consumption and climate mitigation.
The world’s dwindling lakes and reservoirs, freshwater sources that many of us have a tendency to take for granted, emphasizes the need for better stewardship on our part. As these essential bodies of water will continue to lose volume due to human activity and climate warming, it is entirely up to the humans living near and around them to be more responsible and sustainable when it comes to the way we use water, a resource that all our communities will need in order to survive and thrive.*
