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Ask the Conservationist: March 2013

Is There Really a Global Freshwater Shortage?

Nick Fetzer asks: "I'm curious about what issues you see on the horizon concerning the world's supply of freshwater. With only a fraction of the earth's water being fresh and the vast majority of that fraction locked in glaciers, how do you see the world's ever-expanding population handling any potential shortages?  Are shortages even an issue in your opinion?  If so, is desalination a realistic solution in the long-term? What are the most effective measures individuals can take to mitigate this issue?  Thanks!" 


Dr. Brian Richter, a Conservancy freshwater scientist, answers: 

Nick, the water shortages are real, and they definitely are an issue. 

The interesting fact about our water shortages is that today, there is just as much water on the Earth as there was when the first signs of life appeared. Of the 10,000 billion cubic meters of water that falls on the land surface of our planet as rain or snow, we consume less than 10 percent to grow our crops, supply our homes, keep our industries running, and generate electricity. 

So what’s the problem if we only use 10 percent of the water that falls to the Earth? The problem is that water that falls from the sky isn’t evenly distributed around the globe, and our needs for that water aren’t the same everywhere. 

For example, the competition for water between cities and farms is getting rather intense. If you’re living in an area where the available water is already heavily depleted, it makes it very difficult and expensive for a city to access additional water needed for its growth. That’s why cities are spending billions to import water from far-distant rivers or remove the salt from seawater. (I’ll get to desalination as a means to alleviate freshwater shortages in a minute.) 

By diverting rivers to provide irrigation and hydropower, or importing water from far-flung sources, we have caused fisheries in these once-bountiful rivers to crash. And as we suck water out of aquifers, the overlying soil and rock can compact or collapse into the dewatered void, causing tall buildings to teeter in Mexico City, automobiles to tumble into sinkholes in Florida, or swallowing tourists on the fringes of the shriveling Dead Sea in Israel and Jordan. 

A study that I co-authored last year shows that water scarcity impacts at least 2.7 billion people for at least one month each year – and 92 percent of this global depletion of water is tied to agriculture. 

We have to be smarter about how we use the water on the planet, especially as the global population only increases. 

Desalination can be a feasible option for creating additional water supply along coastlines, or in places where brackish aquifers can be readily tapped.  The great benefit of desalination is that it leaves rivers, lakes and freshwater aquifers untouched, adding freshwater deposits to a local water budget without tapping other freshwater accounts.  But there are considerable drawbacks: it is very costly – it remains the most expensive means for obtaining water supplies; the brine after the fresh water is extracted needs to be properly disposed; and the source of energy used to power desalination plants is also of considerable concern. (Until recently, Saudi Arabia used only oil and natural gas to generate the electricity needed to power its desalination plants, thereby contributing to carbon emissions that are driving global warming. The country is using 1.5 million barrels of oil each day to power its 30 plants!) 

Ironically, I’m optimistic about the global water shortage, because we already waste so much! In the near term, we could make huge progress in reducing water stress by using the technology and knowledge we already have to reduce our water use. We have to start investing deeply in improving water use in agriculture or we’re going to see cultures, economies and national security come apart in many regions of our world. 

The work that The Nature Conservancy is doing with farmers on the Flint River in Georgia or along Silver Creek in Idaho are great examples of how to reduce agricultural water consumption while still producing the same amount of crops. 

Also, we can reduce our own personal use to great effect by doing these three simple things:

  • Half of domestic water use goes to outdoor landscaping, so choose native and local plants, invest in drip irrigation and collect rainwater for outdoor use.
  • Invest in a water-efficient toilet.
  • Invest in water-efficient washing machines.

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