State of the Planet

News from the Columbia Climate School

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 the 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’s and China’s use of groundwater grew the most—today these countries use 10 times as much groundwater as they did in 1950.

Groundwater pumping accounts for as much as one-fifth of India's electricity consumption.

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 amount 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 be masking 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 power plants—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 power plant shutdowns.

What You Can Do

Think about diet. The amount of water it takes to produce different kinds of food varies tremendously. The water footprint of beef is particularly egregious, consuming anywhere from 2,500 to 5,000 gallons of water per pound. Consider cutting back, or switching to grass-fed beef, which has a significantly lower water footprint.

Please do turn off the tap when brushing your teeth! Leaving the water running while brushing your teeth uses 2-4 gallons, as opposed to only 1 gallon if you turn it off. On the other hand, according to the USGS, it takes 1,400 gallons of water to produce a burger, fries and soft drink—so maybe skipping a couple of fast food meals would help, too.

In some places, lawns use almost as much water per acre as agriculture does.

If you live in a water-stressed region, consider shrinking the size of your lawn.

Support sustainable, water-efficient agriculture, renewable energy and conservation. Wind and solar photovoltaic energy use considerably less water than conventional energy generation. Biofuels, however, are not water efficient.

Support policies that do not encourage excessive water consumption. Just a few days ago, Kansas passed a law ending the state’s “use it or lose it” policy on water rights—an important step in preserving the Midwest’s Ogallala aquifer. Policy changes such as this are important steps in supporting more efficient water use.

Support research and innovations that help conserve water. The Columbia Water Center is currently developing a crop optimization model for India that can inform a strategic shift of the cropping patterns across the nation toward a system that relies only on rainfall while maximizing national agricultural revenue and meeting national food security goals. At the same time, the tenisometer project is helping rice farmers reduce their irrigation by over 20 percent with a simple and inexpensive soil measuring device.

These projects are only one example of many innovations taking place around the globe to conserve water and promote food security. Supporting and promoting these kinds of innovations is the next step in moving the current water-food paradigm in a more sustainable direction.

Columbia campus skyline with text Columbia Climate School Class Day 2024 - Congratulations Graduates

Congratulations to our Columbia Climate School MA in Climate & Society Class of 2024! Learn about our May 10 Class Day celebration. #ColumbiaClimate2024

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