Some of the World’s Biggest Lakes Are Drying Up. Here’s Why.

By Kenneth R. Weiss | National Geographic

Photographs by Mauricio Lima, Newsha Tavakolian, Carolyn Drake, and Michael Christopher Brown

Tire tracks stretched across the flat lake bed to the horizon. We followed them in a Suzuki 4×4, looking for clues about what’s happened to Poopó, once Bolivia’s second largest lake, which has vanished into the thin air of the Andean highlands.

We were driving on the lake bottom, yet we were more than 12,000 feet above sea level. The spring air was lip-chapping dry. Many of the fishing villages that have relied on Lake Poopó for thousands of years have emptied too, and we drove past clusters of abandoned adobe homes. Dust devils danced around them, spinning in warm winds. In the distance we spotted several small aluminum boats that seemed to be floating on water. As we drove closer, the mirage receded, and we found the boats sitting abandoned in the silt. I stepped out of the vehicle. My shoes cracked the salty crust that had formed jagged lumps, like ice cream in a freezer that has melted and recrystallized.

My guide, Ramiro Pillco Zolá, crunched across the salt pan to reach one of the dilapidated, half-buried boats. Boyhood memories of paddling across the lake flooded back to him from long before he left his village of San Pedro de Condo to study hydrology and eventually earn a Ph.D. in hydrology and climate change at Lund University in Sweden. “We’re not talking about a small thing,” Pillco Zolá told me. “Three decades ago this lake covered 3,000 square kilometers. It’s going to be hard to recover.”

Water that once spread across an expanse about the size of Rhode Island was gone. A pair of black rubber boots lay discarded near the boat. A fish skull bleached brilliant white flashed under the blinding sun. The wind suddenly stopped, cloaking the post-apocalyptic scene in silence. If water is life, this was the absence of both.

Round the globe, climate change is warming many lakes faster than it’s warming the oceans and the air. This heat accelerates evaporation, conspiring with human mismanagement to intensify water shortages, pollution, and loss of habitat for birds and fish. But while “the fingerprints of climate change are everywhere, they don’t look the same in every lake,” says Catherine O’Reilly, an aquatic ecologist at Illinois State University and co-leader of a worldwide lake survey by 64 scientists.

In eastern China’s Lake Tai, for example, farm runoff and sewage stimulate cyanobacterial blooms, and warm water encourages growth. The organisms threaten drinking-water supplies for two million people. East Africa’s Lake Tanganyika has warmed so much that fish catches that feed millions of poor people in four surrounding countries are at risk. The water behind Venezuela’s massive Guri hydroelectric dam has reached such critically low levels in recent years that the government has had to cancel classes for schoolchildren in an effort to ration electricity. Even the Panama Canal, with its locks recently widened and deepened to accommodate supersize cargo vessels, is troubled by El Niño–related rainfall shortages affecting man-made Gatun Lake, which supplies not only water to run the locks but also fresh drinking water for much of the country. Low water levels have also forced limits on the draft of ships so the ships don’t run aground in the lake.

Of all the challenges lakes face in a warming world, the starkest examples are in closed drainage basins where waters flow into lakes but don’t exit into rivers or a sea. These terminal, or endorheic, lakes tend to be shallow, salty, and hypersensitive to disturbance. The vanishing act of the Aral Sea in Central Asia is a disastrous example of what can happen to such inland waters. In its case the main culprits were ambitious Soviet irrigation projects that diverted its nourishing rivers.

Read full, original story and view high quality images: https://www.nationalgeographic.com/magazine/2018/03/drying-lakes-climate-change-global-warming-drought/