Global climate change is causing falling water levels in many of the world’s freshwater lakes systems, with devastating impacts for regional economies and ecosystems, according to research by scientists in Germany and the Netherlands.
They say rising surface temperatures have intensified evaporation from inland lakes, and lack of rainfall has added to the problem.
In a paper published in the open access journal Communications Earth & Environment, the researchers have called for “a global awareness campaign concerning future climate-driven lake level changes”. They also want a global task force set up to develop and lead climate adaptation strategies.
“The environmental, economic, and political impacts of falling lake levels will be devastating. A global task force is urgently needed to develop and coordinate transboundary mitigation and adaptation strategies,” the paper says.
Lead author Matthias Prange, from the University of Bremen, says the impact of climate change on the world’s freshwater lakes systems has received less attention than rising sea levels in developing global policy responses. The paper focuses on falling water levels for the Caspian Sea – the world’s largest inland body of water with borders in five countries, including Russia and Iran.
“The Caspian Sea can be viewed as representative of many other lakes in the world. Many people are not even aware that an inland lake is dramatically shrinking due to climate change, as our models indicate,” says Prange.
He says a recent report by the Intergovernmental Panel on Climate Change failed to mention inland lakes and the potential social, political and economic consequences of falling water levels for countries bordering the Caspian Sea.
“This has to change. We need more studies and a better understanding of the consequences of global warming in this region.”
The research paper says that while “climate-driven drying of continental interiors is recognized as an important problem in terms of fresh water scarcity, its impact on lake levels will have many other far-reaching consequences that are underappreciated, but affect the livelihoods and economies of millions of people all over the world”.
Prange and his co-researchers Thomas Wilke (Justus Liebig University) and Frank Wesselingh (Utrecht University), argue that “not enough space has been devoted to the issue of falling water levels in inland seas and lakes worldwide” by international organisations and programs such as the IPCC, the United Nations sustainable development goals and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.
“The environmental, economic, and political impacts of falling lake levels will be devastating. A global task force is urgently needed to develop and coordinate transboundary mitigation and adaptation strategies,” their research paper says.
“Sea level in the Caspian Sea is projected to fall by 9–18 metres in medium to high emissions scenarios… caused by a substantial increase in lake evaporation that is not balanced by increasing river discharge or precipitation. According to these new projections, twenty-first century Caspian sea level decline will be about twice as large as estimates based on earlier climate models.”
The researchers suggest the Caspian Sea is a “poster child” example of the impacts that will affect freshwater lakes systems across the world.
“A growing number of scientific studies predict climate-driven drying in many regions of the world, which will inevitably entail substantial lake level drops in Asian, African, and American basins,” the paper says.
“Lake levels are also affected by human water withdrawals, river damming and diversions… which often mask climate impacts.”
The paper doesn’t mention Australia but the impact of drought on many of the country’s lakes has been well documented by scientists and state water management agencies. Systems such as the Gippsland Lakes in eastern Victoria and Lake Eppalock in the state’s central farming region, have recorded falling water levels in recent years.
Even the nation’s capital – and its 11k long ornamental lake in the city’s centre – has been affected. In January 2020, the Australian Capital Territory government in Canberra announced the water level for Lake Burley Griffin had “dropped down to approximately 300mm below normal lake level over the last 8 weeks”
“This is primarily due to low flows into the lake combined with evaporation and abstraction from the lake for irrigation,” a government statement said.
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