Newspaper article The Christian Science Monitor

Are Humans Using Too Much Water?

Newspaper article The Christian Science Monitor

Are Humans Using Too Much Water?

Article excerpt

Water is essential for life as we know it. But freshwater, the stuff we drink and use to grow crops, makes up just 2.5 percent of the Earth's water, according to the US Geological Survey.

Is that enough? How are humans manipulating this vital natural resource? And just how much are we using?

Scientists set out to figure just how big the global freshwater footprint really is. That footprint could be more significant than previously thought, and it might just be because we're trying to control it.

According to data gathered from water basins across the globe, human attempts to control freshwater by damming waterways and irrigating crops could actually increase water consumption.

The scientists specifically looked at how much water is released back into the atmosphere through evapotranspiration, the process through which liquid water on Earth is released as vapor into the atmosphere, in and around human created reservoirs and irrigation systems, categorizing this as human consumption of water.

The liquid water lost to the atmosphere as water vapor from these dammed waterways and irrigated fields raises the global human freshwater footprint by about 18 percent, according to a paper published Thursday in the journal Science.

"As you have a lot of consumption, and you're sending this water back to the atmosphere, it's less water that's available on the rivers, in the streams, so it's actually well linked to water availability on Earth," study author Fernando Jaramillo tells The Christian Science Monitor in an interview. "We are doing something big to the water cycle."

How does it all work?

Think back to elementary school science. You likely learned about the water cycle, a process in which water changes states.

In the water cycle, water changes from liquid to vapor via evaporation or transpiration, the process by which plants turn liquid water into vapor, moving the water from the surface of Earth to the atmosphere. Then, that water vapor condenses into liquid drops or freezes into snowflakes, precipitation, and falls back down to Earth.

But here's the catch, that water could fall anywhere on the planet. …

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