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Over half of the world’s lakes are shrinking

According to a new study, climate change’s hotter temperatures and society’s diversion of water have been shrinking the world’s lakes by trillions of gallons of water a year since the early 1990s.

In the past 30 years, more than half of the world’s large lakes and reservoirs have shrunk due to the climate crisis and human consumption.

This is according to a new study, which has intensified concerns about water supply for agriculture, hydropower, and our future survival.

Published in the journal Science, the research analysed almost 2,000 of the world’s most important freshwater sources, from the Caspian Sea between Europe and Asia to South America’s Lake Titicaca.

It found them to have lost water at a cumulative rate of about 22 gigatonnes a year for nearly three decades, which is equivalent to the total water use in the US for the entire year of 2015.

Using satellite observations (namely images from Landsat, the world’s longest-running Earth observation programme) climate data, and hydrologic models, it uncovered significant storage declines in 53 per cent of these water bodies between 1992 and 2020.

As it states, unsustainable human use, changes in rainfall and run-off, sedimentation, and rising temperatures are primarily to blame.

Fangfang Yao, a surface hydrologist at the University of Virginia who led the study, said that 56 per cent of the decline was driven by global heating and human consumption, with warming ‘the larger share of that.’

The diversion of water from lakes – a direct human cause of shrinkage – is probably larger and more noticeable because it is ‘very acute, very local, and it has the capability of really changing the landscape,’ said co-author Ben Livneh, a University of Colorado hydrologist.

What was surprising, however, was that even humid regions experienced noteworthy water loss, challenging the assumption that arid areas will become drier and wet areas wetter under the environmental emergency.

‘This should not be overlooked,’ Yao said, explaining that this is a result of both a thirstier atmosphere from warmer air sucking up more water in evaporation, and a thirsty society that is diverting water from lakes to agriculture, power plants, and drinking supplies.

The consequences of these shrinking water bodies are far-reaching, directly affecting close to two billion people across the globe, with many regions already facing water shortages in recent years.

The findings underscore the urgent need to address the impacts of climate change on freshwater sources. If greenhouse gas emissions are not curtailed, the world is on a trajectory of reaching 3C warming by the end of the century, which would have devastating repercussions for humanity.

Researchers of the report estimated that roughly a quarter of the Earth’s population resides in a basin of a drying lake, bringing to the forefront the demand for sustainable resource management.

‘The complete quantification of water storage variations for large lakes that Yao and colleagues provide is new and it creates a much more complete picture’ than past research has,’ said University of North Carolina hydrology professor Tamlin Pavelsky, who was not a part of the study.

‘I’m generally most worried about lakes that are ecologically important and in populated areas without a lot of other good sources of water. It’s all extremely worrisome.’