Fluid Security—Overcoming Water Shortfalls in the 21st Century
About 70 percent of Earth’s surface is covered with water, some 1.4 billion cubic kilometers of it. Too bad almost 96.5 percent of it’s salty, and another 2 percent is locked away as ice in remote places such as Greenland and Antarctica. All told, just a little more than 1 percent of our planet’s water is fresh and readily available for human uses such as drinking and irrigating crops. Even that small fraction, however, isn’t evenly distributed. Some regions are haves–think tropical rain forests–and others are Saharan have-nots.
New computer studies suggest that a number of nations will join the ranks of the water have-nots in the next few decades–not due to climate change, but mainly via population growth or the depletion of their groundwater resources. Despite technological innovations and improved farming practices that have made agriculture less water intensive, the models suggest that some nations’ water supply and therefore food production won’t keep up with demand. Results of the computer simulations may help policymakers in those countries, as well as international food agencies, plan for a thirsty and possibly hungry future.
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A growing demand
There’s a strong link between a country’s water resources and its ability to feed its citizens. That’s because, worldwide, about 70 percent of the water that people pump from rivers, lakes, and aquifers goes to irrigate crops. When countries don’t have an adequate supply of water, either due to a perpetually arid climate or a short-term drought, they typically compensate by importing food, says Hong Yang, a water-resources analyst at the Swiss Federal Institute for Environmental Science and Technology in Dübendorf. That’s especially true for cereals such as rice, wheat, corn, oats, and sorghum, she notes.
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Yang and her colleagues compared the availability of fresh water with recent cereal-import trends in countries of more than 1 million people in Asia and Africa, where most of the world’s water-scarce, cereal-importing countries are.
From 1980 to 2000 in all of the countries considered, rising populations caused per capita water availability to significantly decrease, says Yang. When a country’s supply of fresh water dropped below a certain threshold–about 1,500 cubic meters per person per year–that nation’s cereal imports started to climb. As of 2000, 21 African and Asian nations had freshwater resources below that threshold (see table, below). If population growth continues as expected, another 14 countries will join this club by 2030.
Three decades from now, those 35 countries will have a total water deficit of about 1,150 cubic kilometers per year–a volume roughly 13 times the annual discharge of the Nile River, says Yang. Pollution may increasingly affect water quality as well, thereby aggravating water shortfalls. The team’s analyses suggest that total cereal imports for those nations in 2030 will tip the scales at around 140 million tons, up from about 30 million tons in 2000. That’s a tall order, because the amount of cereals traded among nations would have to rise a whopping 50 percent above today’s tonnage to meet this demand.
Hope for the future?
One trend uncovered by the new analysis offers limited solace. The water supply threshold that seems to trigger increased cereal imports, now around 1,500 m3/person/yr, was about 2,000 m3/person/yr in the early 1980s. Part of that positive change stems from improved farming practices, which have decreased the amount of water needed to produce each ton of a crop. Also, increased fertilizer use has boosted corn, rice, and wheat yields in developing countries in the past 2 decades by 40 percent, 50 percent, and 70 percent, respectively.
But the threshold for a person’s annual water requirement can only drop so far, says Yang. Depending on a country’s living standards, the threshold could be trimmed to somewhere between 800 and 1,200 m3, but probably not much lower.
Between 1980 and 2000, the average cost of cereals–measured in constant U.S. dollars–dropped by about 50 percent. That trend, too, won’t last, says Yang. As international demand for cereals begins to accelerate, prices should eventually increase.
To date, most of the African and Asian countries with severe water shortages–such as Saudi Arabia, Libya, and the United Arab Emirates–have been oil-rich and therefore able to afford cereal imports. Also for example, Saudi Arabia supplements its meager 2.2 km3 yearly supply of fresh surface water by pumping about 13.5 km3 of water from deep underground–a resource that may run dry long before the country’s oil wells do. Saudi Arabia also desalinates about 700 million m3 of seawater each year, but at a cost of up to $1.50/m3, this technique certainly won’t help make food more affordable.
A better way for a country to tackle an impending water shortage might be to control its population growth, although Yang admits that this solution is difficult to implement. Countries often have neither the means nor the political will to stifle their burgeoning growth rates, she notes.
Many of the countries on tap to join the water have-nots by 2030 are poor and therefore may be unable to afford the cereal imports they’ll need, says Yang. Nevertheless, she’s optimistic that food crises can be avoided. In addition to further improvements to make agriculture more water-efficient, lower barriers for international trade and improved food-distribution networks could help alleviate future famines in water-starved nations.
Researchers predict that these African and Asian countries will have less than 1,500 cubic meters of fresh water per person per year by 2030.*
|Burundi||Korea Republic||South Africa|
|Eritrea||Morocco||United Arab Emirates|
|* Countries in bold letters fall below the
threshold after 2000 but before 2030.