Monday, March 19, 2012

Water and Food Facts for World Water Day

March 22 is World Water Day, and its theme this year—water and food security—couldn’t be more pressing. But what do we really know about water—where it goes, what it’s used for, and how to preserve it? Here are a few water facts to get people thinking about what the “food and water crisis” really means, and how we can begin to change things.


India, China and the United States together account for about one-third of the water extracted each year globally.

Over 90 percent of the water consumed globally by humans is used for agriculture.

Irrigation and Groundwater

Only 16 percent of world’s cropland is irrigated. But because irrigated land is more than twice as productive, that land accounts for 36 percent of the food we harvest.

To meet the constant demand for irrigation, countries are increasingly using more and more non-renewable groundwater. According to the United Nations, groundwater extraction has tripled in the last half century. India and China’s use of groundwater grew the most – today these countries use ten times as much groundwater as they did in 1950.

The amount of groundwater the world uses is so huge, it’s contributing to rising sea levels – as much as 25 percent of the observed amount in recent years. That means that an enormous amounts of water drawn from underground aquifers is never replaced. Or as Duke University’s Bill Chameides puts it, “Mankind is moving buckets and buckets of water from land to the ocean.”

The amount of groundwater the world uses is so huge that it’s also changing local climates, and it may bemasking the effects of global warming, according to research published in Climate Dynamics. This masking effect is most striking over North America, India, the Middle East and East Asia.

Pumping groundwater consumes enormous amounts of energy. In India, approximately one-fifth of the nation’s total electricity consumption goes toward pumping groundwater for irrigation. In the most important food producing areas, that number is much higher.

Virtual Water

Almost everything we do—from growing food, to making clothes and computers and automobiles, to generating electricity requires water. “Virtual water” refers to the amount of water it takes to produce and transport a commodity. Check your own water footprint here.

Many water-stressed nations are today virtual water exporters. India is the largest net exporter of virtual water.

Climate Change and the Future

According to the OECD, by 2030 almost half of the world’s population will be living under severe water stress.

Globally, heat waves and extreme drought could increase under climate change. The impact will be worse in some areas. According to research by Lamont-Doherty scientists at the Earth Institute, by mid-century dustbowl conditions seen in the 1930s will become the new norm for the southwestern United States.

Water stress threatens the grid. Conventional powerplants – hydroelectric, coal-fired, gas fired and nuclear—require tremendous volumes of water to run, accounting for 50 percent of water withdrawals in the United States. According to a study for the Columbia Journal of Environmental Law, the convergence of population growth, rising demand and drought could cause huge water shortages and force powerplant shutdowns.

What You Can Do

Think about diet. The amount of water it takes to produce different kinds of food various tremendously. The water footprint of beef is particularly egregious, consuming anywhere from 2500 to 5000 gallons of water per pound. Consider cutting back, or switching to grass-fed beef, which has a significantly lower water footprint. More