Topline
According to a new study published in Science on Thursday, over half of the world’s largest lakes have seen a decline in lake water storage due to climate change and unsustainable human consumption, putting the world’s already low amount of available freshwater at risk.
Key Facts
The study examined about 2,000 lakes and reservoirs from 1992 to 2000 and found 53% have experienced “significant water losses” at a rate of about 22 gigatonnes per year.
The authors estimate around two billion people live in the basins of a drying lake, accounting for around one-quarter of the world’s population.
Key Background
Freshwater lakes and reservoirs store 87% of the Earth’s water, the study notes, making them key resources. According to NASA, due to climate change, Earth’s surface temperature has risen about two degrees Fahrenheit since the late 19th century, with most of the warming happening within the last 40 years and the last seven accounting for the warmest. The ocean is also getting warmer, as it’s absorbed most of this heat—Earth stores 90% of its extra energy in the ocean. The top 328 feet of the ocean has shown warming of around 0.67 degrees Fahrenheit since 1969. Although 3% of earth’s water is freshwater, 2.5% of that is unusable as it’s either locked up in glaciers, polar ice caps, the soil or the atmosphere, very polluted or buried too far down into the earth’s surface that extracting would be too expensive, according to the U.S. Bureau of Reclamation. However, humans are overconsuming water at a large rate. The U.S. Environmental Protection Agency reports the average American family uses 300 gallons of water per day at home, with the toilet and shower accounting for 24% and 20% of usage respectively. When water reservoir levels drop, human health, water supplies and the environment face serious risk. Lower water levels can increase concentrations of human and natural pollutants, the EPA also notes.
Surprising Fact
Although most lakes are experiencing a decline in water, 24% are seeing a significant increase, according to the study. The underpopulated areas around the Northern Great Plains in North America and areas in the inner Tibetan Plateau and places with new reservoirs like Mekong, Yangtze and Nile river basin are seeing substantial growth.
Lakes Experiencing Droughts
Lake Mead (Nevada and Arizona)
The Dead Sea (Jordan and Israel)
Lake Poopó (Bolivia)
Lake Urmia (Iran)
The Aral Sea (Kazakhstan and Uzbekistan)
Lake Eyre (Australia)
Keban Dam Lake (Turkey)
Lake Powell (Arizona)