(CN) — While much of the world frets over sea level rise as global temperatures spike from climate change, the largest lake in the world is quietly shrinking — and millions are in danger.
German and Dutch scientists say the water level of the Caspian Sea, a land-locked lake with very salty water straddling Europe and Asia, has been dropping several centimeters per year since the 1990s. But that decline is accelerating at a pace that puts the 100 million residents in countries ringing the Caspian Sea at risk, according to a study published in the journal Communications Earth & Environment.
“If the North Sea would drop two or three meters, access to ports like Rotterdam, Hamburg and London would be impeded,” warned Dutch geologist Frank Wesselingh of the Utrecht University. “Fishing boats and container giants alike would struggle, and all the countries on the North Sea would have a huge problem.”
Scientists estimate a decrease of 29.5 feet in the best-case scenario. However, the Caspian Sea could shrink as much as 59 feet — a loss of over a third of its surface area, Wesselingh and scientists from the German universities of Gießen and Bremen calculated.
Increased evaporation and the loss of winter sea ice due to rising temperatures will accelerate the drop, hurting ecosystems of migratory birds, beluga and the endemic Caspian seal, which raises its pups on the sea ice in the north of the Caspian Sea.
The effects of climate change vary. While rising global temperatures melt sea ice, which increases ocean levels, those same temperature hikes can promote evaporation, which causes levels of fresh water to drop.
Scientists say more media coverage is needed on shrinking freshwater supplies.
“The Caspian Sea can be viewed as representative of many other lakes in the world,” stated study co-author Matthias Prange of Justus Liebig University. “Many people are not even aware that an inland lake is dramatically shrinking due to climate change, as our models indicate.”
Even the report of the Intergovernmental Panel on Climate Change (IPCC) failed to mention lakes in its assessment, disregarding the social, political and economic consequences of global warming on the affected regions. "This has to change,” Prange said. “We need more studies and a better understanding of the consequences of global warming in this region.”
Prange and his fellow researchers say the goal must be to raise awareness of the consequences of climate change for inland seas and lakes so that appropriate strategies can be developed.
The Caspian Sea is an important regional water reservoir, as well as a biological and commercial center, despite its salt content. The body of water is bounded by Kazakhstan, Turkmenistan, Iran, Azerbaijan and Russia, and the politics of the Caspian Sea are tense as most regional adversaries would need to make new agreements on borders and fishing rights as their economies face impacts, including problems with harbors, fisheries and fish farming.
To mitigate the problem, scientists have called for an international task force, led by the United Nations Environmental Program, coupled with “international climate funds” to finance projects and adaptation measures.
“This aspect of climate change — falling levels of lakes — could be similarly devastating as global sea level rise,” researchers concluded. “Immediate and coordinated action is required to make up for valuable time lost.
“The shrinking Caspian Sea might serve as a poster child of the problem.”
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