The US Geological Survey stated that freshwater makes up just 2.5 percent of the Earth’s water and humans may be consuming it at an alarming rate.
Scientists are now trying to figure out the actual size of the global freshwater footprint. Data collected from basins all over the world showed that irrigating crops and damming waterways may in fact increase freshwater consumption.
In the study – published December 3 in the journal Science – scientists analysed the amount of water that is released back into Earth’s atmosphere through evapotranspiration (ET). In this process, which is the sum of plant transpiration and evaporation, liquid water on our planet is released into the atmosphere as vapour.
The liquid water evaporated from irrigated fields and dammed waterways accounts for human consumption of freshwater. According to scientists, through the water vapour the global human freshwater footprint is raised by 18 percent.
Dr. Fernando Jaramillo, author of the study and a postdoc at the Department of Physical Geography at Stockholm University, said that all the water that is consumed on Earth is sent back to the atmosphere.
In the water cycle, water turns from liquid to vapour and it moves from the planet’s surface to the atmosphere. Then it freezes into snowflakes or condenses into liquid drops, and falls back to Earth via precipitations.
However, we cannot control where that water falls on the planet. It could end up in lakes or rivers, on land, on the top of mountains, or in salty water like the ocean, where it stops being freshwater.
Between 1955 and 2008, humans consumed freshwater at a rate of approximately 1,048 cubic miles (about 4,370 cubic kilometres) per year, according to scientists.
Georgia Destouni, Professor of Hydrology at Stockholm University and General Secretary for the Swedish Research Council FORMAS, and Dr. Jaramillo proposed a planetary boundary – that is meant to limit how much sustainable resources humans can use – of 4,000 cubic kilometres each year. However, that boundary has already been passed, as the data shows.
According to Dr. Jaramillo, more studies need to be conducted on other types of water use developments. Humans are made out of water, so it is only normal that they need water to survive, he added.
People are unaware of how much water is being consumed globally, which is why further research regarding the freshwater footprint could help us manage our natural resources a lot better, Dr. Jaramillo said.
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