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The Caspian Sea shrinks to a third

According to new forecasts, the fall in the level of the Caspian Sea in the 21st century will be twice as large as estimates based on previous climate models. This means lowering the water table to 18 meters. Rising surface temperatures will increase evaporation from land and lakes in the 21st century. These changes help to lower water levels and reduce and increase lake area due to low rainfall in many parts of the world. Based on the Caspian Sea, the largest lake in the world, scientists call on “Nature” to participate in a joint campaign aimed at raising awareness of threats to humans, biodiversity and geopolitical stability.

Many countries are implementing or planning adaptation measures related to sea level rise, based on consistent and visible information from the International Committee on Climate Change (IPCC). On the other hand, very little attention is paid to the impact of global warming on lowering water levels in closed marine and lake systems. As the temperature of the Earth’s surface increases, evaporation increases. These changes are contributing to the reduction in the area of ​​the lake and the increase in precipitation in many parts of the world.

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Endoric lakes without flow are particularly vulnerable to climate change because their water level is determined by the delicate balance between rain and runoff to the lake and evaporation above the lake surface. Although the depletion of large climate-related inland areas in the context of freshwater scarcity is recognized as a significant problem, its impact on salt lake levels can be underestimated and have many far-reaching consequences. , affecting the economy and livelihoods. millions of people around the world.

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Scientists say in Nature that IPCC reports, the United Nations Sustainable Development Goals, internationally recognized policy and the International Platform on Biodiversity and Environmental Services (IPPES) are not sufficiently recognized. There are many places where water levels can drop in inland seas and lakes around the world. Meanwhile, the environmental, economic and political consequences of lower lake levels will be catastrophic. There is an urgent need for a global task force to develop and coordinate transnational mitigation and adaptation strategies, writes Nature.

Photo: magazine articles

Planned collapse of the Caspian Sea. Red areas that can become land at the end of the 21st century. Artwork from Nature.com

The Caspian disaster

The sea level in the Caspian Sea is expected to drop by 9-18m, which will be caused by a significant increase in evaporation from the lake, which will not be offset by an increase in river flow or precipitation. According to the new predictions, it will be twice as large as estimates based on previous climate models.

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The vast North Caspian Shelf, the Turkmenistan Shelf to the southeast, and all of the central and southern coastal areas of the Caspian Sea emerge from the seabed. In addition, the Gulf of Kara-Bokas-Kos, at the eastern end, will dry up completely. Overall, the Caspian Sea area will decrease by 23% with a 9m drop in sea level and 34% with an 18m drop in sea level.

One of the world’s largest salt lakes will disappear

The Caspian Sea is not the only country facing these problems. Lake Urmia in Iran is one of the largest salt lakes in the world, but climate change and poor water management are all but gone.

Almost thirty years ago, it was the sixth largest salt lake in the world and the largest in the Middle East. Tourists eagerly visited the coastal towns and locals made a living from agriculture as the land around the reservoir was fertile and the surrounding areas were home to flamingos, pelicans, deer and bighorn sheep.

Today, Lake Urmia in northwest Iran is unrecognizable: the shores are covered with a dense crust of salt, and rusty boats rest on abandoned boats. Tourists haven’t been here for a long time, which, as “Der Spiegel” points out, turns abandoned villages into ghost towns.

The reason is that the water level has dropped dramatically over the past 25 years and the lake is drying up. In 1995-2013, he lost about 60%. Over 5,000 in your area. Square kilometers and more than 90 percent. Volumes – Reports in “Nature”.

This significant change in size has a negative impact on the ecosystems of the lake with an increase in salinity and a significant reduction in aquatic habitats. Most of the more than 100 islands have disappeared, and the sand dunes and sediment on the dry bottom of the lake have formed a vast desert of salt.

The debate about the reasons for this continues among scientists. Many studies have blamed agriculture, after all, for the uncontrolled expansion of irrigated areas, which has been accompanied by increased construction of reservoirs and inefficient use of water in agriculture.

Other studies have shown that the main causes of the disaster are low rainfall and rising temperatures caused by climate change. Heat and drought In many places water evaporates and large areas disappear under a thick layer of salt. The salt is eventually blown into the fields, destroying farmland and hence the food sources for some animal species.

Nature also cites a 2016 study which found that climate and irrigation had an impact of 60%, respectively. And 40% in the state of the lake.

The best known salt lakes are the Dead Sea between Israel and Jordan, the largest salt lake in Utah in the United States, and Lake Iyer in Australia. The Caspian Sea is the largest salt lake in the world.

nature.com/PAP

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