The world’s freshwater sources have been losing approximately 22 gigatonnes of freshwater annually for more than 30 years according to a new study.
The study published in the journal Science used three decades of satellite observations, climate data and hydrologic models and found significant storage declines in 53% of these freshwater bodies between 1992 and 2020.
The study team consisting of scientists analysed almost 2,000 of the world’s largest lakes for their research. Major freshwater sources, including the Caspian Sea and Lake Titicaca, collectively lost water at a rate of approximately 22 gigatonnes per year over nearly three decades.
The research team said this shrinking of lakes poses significant concerns about water supply for agriculture, hydropower and human consumption.
University of Virginia surface hydrologist and leader of the study team Fangfang Yao said 56% of the decline in natural lakes was driven by climate warming and human consumption. Climate warming formed “the larger share of that”, the scientist said.
What was surprising, however, was that even humid regions experienced significant water loss, challenging the assumption that wet areas would become wetter under the climate crisis. The researchers identified unsustainable human water usage, changes in rainfall and run-off patterns, sedimentation and rising temperatures as the primary drivers of declining lake levels.
The consequences of these shrinking water bodies are far-reaching, directly affecting nearly 2bn people globally, with many regions already facing water shortages in recent years. Unsustainable human water consumption led to the drying up of lakes such as the Aral Sea and the Dead Sea. Additionally, rising temperatures in Afghanistan, Egypt and Mongolia have intensified water loss to the atmosphere.
Researchers have estimated that roughly a quarter of the world’s population resides in a basin of a drying lake, underscoring the necessity of incorporating impacts from the climate crisis and sedimentation into sustainable water resources management. M