LAKE POOPÓ The dry, salt-crusted Bolivian lake bed unfurls into the distance. Boats are stranded; the fish and waterfowl are gone. Fishermen who depended on the lake are moving else - where. It’s a diaspora born of drought.
PHOTOGRAPH BY MAURICIO LIMA
Excerpt:
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.
Similar scenarios are playing out in terminal lakes on nearly every continent, a combination of overuse and worsening drought. Side-by-side satellite images reveal the shocking toll. Lake Chad in Africa has shrunk to a sliver of its former self since the 1960s, heightening shortages of fish and irrigation water. Displaced people and refugees who now depend on the lake put an additional strain on resources. Shortages as well as tensions in the hot, dry Sahel are driving conflict and mass migration. Utah’s Great Salt Lake and California’s Salton Sea and Mono Lake have undergone periods of recession too, diminishing critical breeding and nesting areas for birds as well as playgrounds for recreational boaters.
