3 years ago

The World’s Largest Lakes are Dramatically Shrinking, Scientists Say

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Nicholas Vincent is a passionate environmentalist and freelance writer. He is deeply committed to promoting... Read More

Autumnal lake shore with forest under sky

If the Earth’s largest lakes could talk, they would share a sobering story of dramatic shrinkage. A recent scientific study has shed light on a striking pattern—more than half of our planet’s biggest lakes and reservoirs are losing considerable volumes of water, a concerning trend unfolding over the last thirty years.

Source: Environment and Climate Change Canada

Our planet is thirsty, and so are we. An estimated one-fourth of the global population makes their home in the basin of a drying lake. Though lakes cover a modest 3 percent of our globe, they act as life-giving arteries, storing nearly 90 percent of all the liquid surface freshwater on Earth. They quench our thirst, fuel our fields, power our cities, and are vibrant ecosystems teeming with life. But our lifeline is under threat.

The dipping water levels in these lakes are essentially a tale of two culprits—Climate change and excessive water use. Like a see-saw, lake levels typically fluctuate in response to natural variations in rain and snowfall, but human activities have disrupted this delicate balance. A significant example can be seen in the Colorado River’s Lake Mead in the US, where the vicious cycle of a megadrought and prolonged overuse have led to substantial recession. Similarly, the Caspian Sea, the world’s largest inland body of water sandwiched between Asia and Europe, is gradually succumbing to the pressures of climate change and overconsumption of water.

The study’s lead author, Fangfang Yao, highlighted that the shrinking of these lakes was expected, but the magnitude of this change and the reasons behind it were previously unexplored territories. The extensive study conducted by Yao and her team analyzed over 250,000 satellite images of approximately 2,000 of the world’s largest lakes and reservoirs from 1992 to 2020. The results were staggering; they found 53 percent of these water bodies had lost significant volumes of water, with a net annual decline of around 22 billion metric tons—equivalent to draining 17 Lake Meads each year!

Climate change and human activities shared the blame for over half of this loss, while the remaining were due to varying local factors. For instance, unsustainable water consumption plagued the Aral Sea in Uzbekistan and California’s Salton Sea. Changes in rainfall and runoff were the culprits behind the Great Salt Lake’s decline. In the Arctic, warming temperatures and changes in precipitation, evaporation, and runoff were shrinking the lakes.

As lakes recede, they induce aridification in their surrounding regions, which escalates evaporation rates and exacerbates their decline. This vicious cycle harms water quality and aquatic biodiversity, impacting communities dependent on these resources.

A special mention must be made of sedimentation, a creeping disaster choking our reservoirs, like Lake Powell, the second-largest man-made reservoir in the US. As wildfires, exacerbated by Climate change, burn through forests, they destabilize the soil, increasing sediment flow into lakes and reservoirs, clogging and reducing storage capacity.

However, there’s a silver lining. While many lakes are shrinking, others are growing, especially those in less populated regions, including North America’s Northern Great Plains and the inner Tibetan Plateau. These gains, though, bear the fingerprints of Climate change, as melting glaciers fill lakes and pose potential risks for communities downstream.

As we tread further into a world growing hotter and drier, managing our lakes responsibly is crucial. Let’s heed this clarion call to action. Let’s step up to advocate for and practice sustainability and environmentalism!