Cross-posted from Cool Green Science, a Nature Conservancy blog.

You’re probably doing your part to conserve water, especially if you live in a drought-stricken area. But water is in short supply across the globe because of people’s increasing demands for it — a huge problem for cities, agriculture, and industry that will only get worse with climate change.

Getting an accurate handle on what’s causing the problem has been missing — until now. A new study in the journal PLoS ONE, coauthored by Nature Conservancy scientist Brian Richter, provides fresh insight into the factors behind water shortages in the world’s most important river basins.

The study provides the most comprehensive picture of the global water problem to date, looking at monthly rather than annual changes and digging into the actual causes of water depletion — agricultural, industrial, and domestic — in our ecosystems. While the findings aren’t rosy — more than 2 billion people are affected by water shortages each year — coauthor Richter says there are still reasons to be hopeful … read on to the end of this Q&A with him to find out what they are.

Q. Why is this study so important? Your numbers seem to corroborate previous findings — water is scarce and getting more so, affecting billions of people worldwide.

Brian Richter.

A. Previous studies only looked at the amount of water withdrawn from freshwater sources, not taking into account the fact that much water is returned after use. For example, cities use a lot of water, but 80-90 percent of that water is returned to the original water source after use. If it’s returned in good quality, it doesn’t deplete the water source and the water is available for others to use and to sustain aquatic life.

Even with this distinction between water consumption and depletion, our study shows that it’s getting very difficult to meet water needs in more than half of the river basins in the world — potentially affecting some 2.7 billion people.

And we found that 92 percent of this water depletion globally is tied to agriculture.

Q. So it sounds like ag is the place to start in order to solve the water problem. Can we change our farming practices? 

A. Unlike cities, most water used to irrigate farms is not returned to the ecosystem. On average, more than half of that water is lost to the atmosphere — it either passes through the plant during growth or evaporates from the soil. So cities use more water than crops on a per-area basis, but it’s important to note that irrigated agriculture occupies four times as much land as cities do.

We need to help farmers implement state-of-the-science irrigation methods and improve the productivity of rain-fed farms as soon as possible. We are going to have to produce more food with less water. If we can’t do that, we can’t add another 3 billion people to our planet. No way. And we will kill our rivers and lakes in the process.

Q. Tell us more about the impacts of water shortages — who or what will be hit the hardest?

A. We would expect that places with scarcity at some time during the year are already experiencing ecological degradation in rivers or lakes, perhaps with recurrent fish die-offs. In places with multiple months of scarcity, they are likely experiencing serious competition for water, and during droughts they’ll have economic impacts in agriculture, power production, or other industries.

For example, during the 2007-8 drought in Georgia, a severe reduction in hydropower generation cost the Southern Company electricity provider more than $33 million. Water shortages in California in 2009 devastated the state’s agricultural industry, leading to an estimated loss of 21,000 jobs and more than $1 billion in revenue.

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 being 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.

Q. There’s been lots of talk about companies labeling their products — from food to wine to clothing — with information about the “water footprints” of those products. Do you see this as a beneficial step? How close are we to it?

A. Labels could be very misleading and not very useful if they aren’t done right. The reality is that it takes different amounts of water to produce the same consumer item in different parts of the world, so just telling the consumer how much water was used in the product is not very useful.

What is far more important is whether the company producing that good is using water as efficiently as possible, and whether they are contributing to sustainable management of the shared water resources wherever they operate. That’s what the Alliance for Water Stewardship (AWS) will be seeking to certify beginning in 2013; if they decide to put out a label, it would be extremely useful because consumers could have confidence that the certified company they’re buying from is a good water steward.

Q. You also suggest that trade for agricultural products can help by importing water-intensive products from more water-rich areas — are locavores going to be up in arms over this?

A. When you know where your food is being grown and who’s growing it, you have a better chance of understanding any problems that might be caused by agriculture and you can help resolve those problems. So it’s good to try to buy our food from the closest-possible sources.

But buying everything locally simply isn’t possible for everyone. When you’re buying a food product from some distant part of the world, you want to ensure that the water used to produce it is being used sustainably — that’s what an AWS label could communicate.

Q. In your study you note that  an increasing demand for biofuels is a factor worsening water scarcity — how big of a deal are biofuels?

A. It takes 10,000 gallons of water to produce one gallon of biofuel. That’s the most water-intensive way to produce energy. In the process, you’re trading off the use of a lot of water and land that could be used for producing food or supplying water to cities. We need to take a much harder look at those trade-offs.

Q. Tell us about some of the river basins seeing the highest amount of scarcity — what impacts are already being felt by people and ecosystems? How will those impacts intensify in the future?

A. Texas is the place to watch at the moment. That state’s rivers and aquifers are among the most heavily depleted in the world. When you put a drought on top of already-stressed water sources you can expect catastrophes.

Last year, the state lost more than $5 billion in agricultural production, and now they’re facing serious electricity shortages if they don’t get a lot of rain soon. Water depletion is seriously impacting tourism, aquatic life, and coastal fisheries.

To Texas’ credit, they have some of the best water policies and institutions found anywhere in the world. For example, the state updates its 50-year water plan every five years, and it does so with a great deal of citizen input. They have invested heavily in computer models that track how much water is being used, and for what purpose. They have policies that require that adequate water remain in their rivers to support aquatic life.

Let’s hope those plans and policies can get them through this crisis.

Q. What about climate change — how will variations in rainfall, flood, and drought patterns hurt the water situation?

A. We’re quite certain that things are going to look considerably worse in coming decades because of multiple factors (population growth, changing diets in India and China, etc.), including climate change.

Take rain-fed farmland, for example — 60 percent of food is grown with “green water” or direct rainfall. Even if the average annual rainfall stays the same, we expect that it will be distributed across the year in different ways, coming in different seasons or in more intense rainstorms. That could be catastrophic for agricultural production. I expect to see a lot of adjustments in the types of crops being grown in many regions.

Q. Speaking of the future: As an expert on global water issues, the future must seem pretty bleak to you. What keeps you hopeful that we can get this water problem under control?

A. Ironically, I’m optimistic because we 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.

Recent global population growth estimates (10 billion by 2100, anyone?) plus slowing annual increases in agricultural yields have a lot of analysts worried that many of those new people will suffer from chronic hunger — and that much of the land that hasn’t been converted to agriculture will be plowed under to grow crops.

But a new study in the journal Nature argues that we can feed the world’s growing population without destroying the planet … if we make major adjustments now in agricultural and consumption practices and patterns. (Hey, if it were easy, we’d already be there, right?)

Based on new data about the Earth’s agricultural lands and crop yields, the study offers some core strategies to meet future food production needs and environmental challenges. Those strategies include:

• Stop farming in places like tropical rainforests, which have high ecological value and low food output;

• Improve crop yields in regions of Africa, Latin America, and Eastern Europe where farmland isn’t meeting its potential;

• Change farming practices to better manage water, nutrients, and chemicals;

• Shift diets away from meat; and

• Stop wasting food (up to one-third of all food grown is wasted either in production, transport, or after purchase).

Taken together, these strategies could lead to 100 to 180 percent more food available for consumption, and sustain the lakes, rivers, forests, and soil that food production depends on.

I talked with Jonathan Foley — lead author of the study and director of the University of Minnesota’s Institute on the Environment, as well as a member of The Nature Conservancy’s Science Council advisory board — to find out what it would take to make these recommendations a reality.

Jonathan Foley

Your study’s findings are very promising. But the money question is, how do we do this? Roughly 1 billion people don’t have enough food right now, so it’s clearly a difficult challenge.

A. In this paper we’re looking at, “What does the science say?” A lot of people talk about the issue of food, but don’t have much data or science to back up the claims. So we wanted to find out which ideas can actually solve the problem.

We found that there is no silver bullet — we need to incorporate the best of what we know now into solving the world’s food problems and protecting our natural resources.

Can we do it? We have to — it’s absolutely necessary. It’s up to us to decide what’s politically feasible. We can change how we govern, tax, ship, produce, etc. What we can’t change are the laws of physics.

The problem of feeding the world and not wrecking the planet is a huge challenge and it’s going to shape a lot of the 21st century. Solving it will require huge cooperation, innovation, and hard work. What our study does is lay out the data.

Q. One focus of the article is how much land is given over to meat and dairy production, especially for growing fodder crops for these animals. Are you recommending that everyone should be vegetarian?

A. No, we’re not saying that — and that’s not realistic. People are going to eat meat. But it matters how meat is produced.

Thirty-five percent of our agricultural lands go to producing animal feed, and cattle and dairy farming take up 3.38 billion hectares. Grain-fed beef is a huge drain on the planet — it takes 30 kilos [66 pounds of grain] to produce one kilo [two pounds] of boneless beef. It’s just not efficient. We’re better off producing grass-fed beef or more chicken and pork, which requires far less grain feed. And we’re clearing rainforests to produce this meat! It’s not necessary.

Q. Speaking of rainforests — agriculture in tropical areas is increasing rapidly, yet your study says we could stop this growth altogether with little to no loss in food production. Can you explain that?

A. We found that agriculture in tropical areas yields limited food calories — most of it is going to crops like sugarcane, palm oil, and soybeans for animal feed or biofuel. Ceasing agricultural expansion into the tropics would have an impact on global food crops, but it would be small and we could offset those losses elsewhere.

It’s about the trade-offs. We lose rainforests, with huge impacts to climate change, but we don’t feed many people. Instead, we’re better off improving production in places where we currently farm than clearing more rainforests.

Q. Improving crop production and yields aren’t new ideas — what makes your approach different?

A. Yes, these things are already happening. But our study looks at it from a new perspective. Instead of trying to get high-performing farmlands to perform even better, we found that improving the lower-performing farmlands could dramatically increase the amount of food produced.

For instance, if we close the “yield gaps” in underperforming regions of Latin America, Africa, and Eastern Europe, food production could be increased by 60 percent. Closing “yield gaps” means helping poor farming regions meet their potential with basic improvements, like better use of crop varieties, irrigation, and fertilizer. Giving them access to these things, and helping them manage their land better.

Our idea is to focus on lifting the people near the bottom of the floor up closer to the ceiling, rather than lifting the ceiling higher. We need to change our approach to agriculture. Instead of sitting back and waiting for famine to strike, let’s ask: How can we prevent the next big famine?

Read more on population. Check out our series 7 Billion: What to expect when you're expanding

Q. What about organic farming — does it have a role to play in solving the global food problem?

A. Organics make up less than 1 percent of the world’s food supply right now. So, organic broccoli is not going to solve the problem of feeding the world and saving the planet’s natural resources.

But our current farming practices use a lot of water and chemicals. We need to ask, how can we improve that? Our research found that nearly half the fertilizer applied runs off rather than nourishes crops — and some places, like China and the central United States, could substantially reduce fertilizer use with little to no impact on food production.

Ultimately, it’s not abo
ut either organic or conventional; it’s about using the best from all our options. Organic farming practices blended with conventional ones — when brought to large scales — could have big impacts.

That goes for local food, too. What’s appealing about local food is that it’s grown in a competent manner, with more transparency — you know who grew it and where. Same with organic; it includes more scrutiny. But local food isn’t necessarily better for the planet on an environmental level, and it’s not practical for all the various food products we use.

The question is, could we take that same degree of competency and put it to work on the global food system? Let’s take the best from organic, local, and conventional farming practices and global trade and use all these tools.

Q. What’s an ecologist like you doing looking at agriculture and food security issues anyway?

A. Agriculture is the biggest thing we do to the planet — it covers 38 percent of the planet’s land surface — and it’s the biggest thing we do for humanity. So it makes sense for ecologists to be looking at these issues.

I’m a climatologist as well, and I was originally looking at climate change issues in my research but noticed how agriculture has such a big impact on water, climate, and land use. And the role of agriculture was not being looked at enough — remarkably very little science has been done to figure out the role of agriculture in climate change. And vice versa. Our understanding of the role that climate change plays on agriculture is still in the early stages. No doubt it will have an effect on crops — some people focus on temperature change, some focus on water. Personally, I think water will be the bigger issue.

It’s a big, messy, complicated problem.

Q. Now that the study is out, what kinds of reactions are you hoping for?

A. So far the reception to our research has been mostly positive, because we’re laying the facts out on the table and saying, “This is the science,” rather than pointing fingers or advocating for certain changes.

I hope we’ll see more collaboration — we need everyone to work together on this problem, from Big Ag companies to organic farmers. It’s time to have a sensible, grown-up conversation about these issues.

The good news is: We can feed the world and not wreck the planet.

The bad news: It’s going to take a lot of work, and right now we’re not headed in the right direction. There’s no room for error, because the pressures on our natural system are tremendous.

Read more about Jonathan Foley at the New Security Beat blog.