Photo via Asbestos Bill via Flickr Creative Commons
Groundwater might as well be considered a non-renewable resource with the way we've been using it. Pumped from aquifers at a rate far exceeding its ability to be naturally replenished, groundwater is used for everything from households to agriculture. It represents somewhere around 20-30% of the planet's supply of fresh water -- surface water accounts for only 1% with the rest locked up in ice caps and glaciers -- and it's a resource we've doubled our use of it since 1960, says a new study from Utrecht University in Utrecht, the Netherlands. In fact, the researchers noted that worldwide, we're using groundwater at a rate that would suck the Great Lakes dry in just 80 years, and they liken our use of it to the way Americans use our credit cards. In other words, it's unsustainable and we're about to hit a very tall, very hard wall. According to the American Geophysical Union, the study by Marc Bierkens and his colleagues uses a database of global groundwater availability along with estimates of groundwater usage and recharge rates to model how quickly and in which locations groundwater stores are being depleted. It is difficult for the researchers to pinpoint when we'll use up all the groundwater because it is unknown exactly how much groundwater there is in the world. However, they can say with certainty that we're using much more than is sustainable.
"You're living on loaned money, in this case loaned water," says Bierkens. "It's a water debt you build up because these aquifers are not being recharged, but it allows you to raise your standard of living. I don't want to insult you, but it sounds a bit like how some people in the U.S. and Europe live when it comes to money."
Part of the reason for the sharp increase in groundwater use, says the researchers, is our improved efficiency at using water in one location to grow food or manufacture supplies that are shipped off to other locations. It's called "virtual water" or "embedded water." In fact, we heard earlier this year that the UK imports the bulk of its water in the form of goods purchased from other countries, including countries that are themselves feeling the pinch of reduced supplies.
The "virtual water" allows areas with low supplies to live as if they had the water themselves. However, should the water source in the place producing the goods dry up, not only does it impact the people living around the source, but also the people dependent on this virtual water.
"If you let the population grow by extending the irrigated areas using groundwater that is not being recharged, then you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it," says Bierkens. "That is something that you can see coming for miles."
The researchers state that highest rates of depletion are occurring in some of the world's major agricultural centers, including California's central valley, the US's midwest, northwest India, northeastern China, and northeast Pakistan -- all producers of agricultural exports and all places with pinched water supplies.
This video from the International Groundwater Resources Assessment Center explains how groundwater is such a vital resource:
Simply put, we can't get to the point where we run out of groundwater. Not only are people dependent upon it, but so too are whole ecosystems. Most rivers, lakes and wetlands are dependent upon groundwater, so overdrawing aquifers often means a drop in the water table, making it harder for every living thing to get at water supplies.
In some areas, groundwater mining is already being phased out for some uses, such as in Saudi Arabia where it is mined for wheat production, among other things. However, it will take a global change in water use and consumption habits to reduce groundwater use to a rate that matches replenishment.
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