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As glaciers melt, the oceans supply fresh water and, due to heat and drought, our lakes and inland waters lose expensive fluids.
Earth’s largest inland body of water, the Caspian Sea, is particularly declining, according to a new study published in Communications Earth & Environment.
Scientists now warn that this body of saline water will run 9 to 18 meters by the end of the century if emissions continue to increase.
A recession of this magnitude would evaporate almost the entire northern Caspian shelf and part of the Turkmen shelf to the southeast. The eastern boundary would be “completely dry,” say the researchers.
Impact of −9 m and −18 m on Caspian Sea level projections in the late 21st century. The red regions are drying up.
© Prange et al., Communications, 2020
In the worst case, when the sea level drops 18 meters, the models show that 34 percent. these sea levels will drop, but society is still underestimating this huge crisis. Even the scientific community basically doesn’t know what is going on.
The International Commission on Climate Change has not considered the evaporation of lakes due to climate change in any of its reports, nor has it addressed the United Nations peace development goals.
“The impact of the imperceptible aspect of future sea level change – declining lakes and sea levels on continents globally – can be just as devastating when global sea levels rise and threaten the livelihoods of millions people around the world, “the authors write.
For its size, about 371,000 square kilometers and about 1.2 percent. Caspian salinity is considered a sea, not a lake.
Without immediate and concerted action, the Caspian Sea is in danger of extinction. Therefore, according to the authors, there is an urgent need for a global working group.
If we do nothing, the consequences for the environment will be enormous. The projected decline in sea level will severely affect this unique ecosystem, and the loss of shallow water in the south will result in the loss of invaluable habitat, spawning and food sources for endemic fish, birds and seals.
“The likely decline in the Caspian Sea level is likely to lead to a major transformation of ecosystems and threaten the unique Caspian biota that has evolved in the basin for millions of years,” the new study concludes.
Even those already protected areas of the Caspian Sea will be “unrecognizable transformed” as nutrient sediments bypass these rising shelves and drift directly to the central part of the basin.
Dead zones are likely to occur as temperatures rise and rivers carry less oxygen to the sea, affecting both the deeper and shallower inland waters, as is already the case in some parts of the world’s oceans.
© TASS / Scanpix
The geopolitical consequences are also worrying. The local economy, which depends on fishing and maritime trade, will be irreversibly affected, as will the coastal ports, which will “suddenly” find themselves much further from the water. The loss is also likely to exacerbate water scarcity problems in the arid region, which will undoubtedly lead to international disputes.
“As millions of people depend on the Caspian Sea for their livelihoods and food security, the loss of these ecosystem services will have drastic socio-economic consequences and could lead to local and regional conflict, in an ethnically diverse region where tensions already exist. they are frequent, “experts said.
And this is not just a Caspian problem. Several recent studies have shown that water levels are falling in closed marine and lake systems, largely due to the drying of the continent due to climate change.
Because the lakes do not have runoff, they are particularly vulnerable to rising temperatures. Its water level is determined almost exclusively by rainfall, river flows, and evaporation. The same is the case with the Caspian Sea, the inflow of which is based on the Volga River.
Accurate lake retreat models around the world are essential to preserving these precious ecosystems and the economies and societies they support.
Unfortunately, it is too late to save the Caspian simply by reducing emissions. The continental water mass is already shrinking by 6 to 7 centimeters each year.
Therefore, intensive regional adaptation and mitigation efforts are urgently needed. Public awareness would be a good starting point. For decades, the decline of the inland lakes has been misunderstood and even overlooked by experts.
“For example, the IPCC’s first assessment report (1990/92) proposes a rise in the level of the Caspian Sea since around 2010,” the authors write.
“None of the IPCC merger reports address this issue further.”
The lack of research alone is part of the problem. The risks and vulnerabilities of the Caspian Sea to water loss are generally poorly investigated.
Based on the Caspian Sea, the authors call for a global campaign to raise awareness and improve research on the world’s increasingly scarce lakes and inland waters. They were abandoned for too long.
“Many people don’t even know that the inland lake is drastically shrinking due to climate change, as our models show,” says Matthias Prange, who develops climate models at the University of Bremen in Germany.
“It just came to our attention then. We need more research and a better understanding of the consequences of global warming in the region.”
The study was published in Communications Earth & Environment.
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