Global agricultural expansion cut a wide swath through tropical forests during the 1980s and 1990s. More than half a million square miles of new farmland - an area roughly the size of Alaska - was created in the developing world between 1980 and 2000, of which over 80 percent was carved out of tropical forests, according to Stanford researcher Holly Gibbs.

"This has huge implications for global warming, if we continue to expand our farmland into tropical forests at that rate," said Gibbs, a postdoctoral researcher in the Department of Environmental Earth System Science and in the Program on Food Security and the Environment, who led the study.

Gibbs and colleagues at several other universities analyzed Landsat satellite data and images from the United Nations to reach their conclusions. Theirs is the first study to map and quantify what types of land have been replaced by the immense area of new farmland developed across the tropical forest belt during the 1980s and 1990s.

While this huge increase was happening within the tropics, agricultural land in the non-tropical countries actually decreased in area.

The study was published this week in the online Early Edition of the Proceedings of the National Academy of Sciences.

The United Nations Food and Agriculture Organization estimates that to keep pace with increasing demand, global agricultural production will have to keep increasing, possibly even doubling by 2050. That would likely lead to millions of additional acres of tropical forest being felled over the next 40 years.

Direct impact on carbon released into atmosphere

"Every million acres of forest that is cut releases the same amount of carbon into the atmosphere as 40 million cars do in a year," Gibbs said.

Most of the carbon released comes from burning the forests, but even if the trees are simply cast aside, the bulk of the carbon from the plants makes its way into the atmosphere during decomposition, she said.

Gibbs and her colleagues found that about 55 percent of the tropical forests that had been cut between 1980 and 2000 were intact forests and another 28 percent were forests that had experienced some degradation, such as some small-scale farming, logging or gathering of wood and brush for cooking or heating fuel.

"The tropical forests store more than 340 billion tons of carbon, which is 40 times the total current worldwide annual fossil fuel emissions," Gibbs said. "If we continue cutting down these forests, there is a huge potential to further contribute to climate change."

The increasing demand for agricultural production stems in part from the ever-growing number of people on the planet, who all want to eat. Additionally, members of the growing middle class in emerging economies such as China and India are showing interest in eating more meat, which further intensifies demand. And incentives to grow crops for biofuel production have increased.

But Gibbs and her colleagues also observed some encouraging signs. The patterns of change in the locations they analyzed made it clear that during the 1990s, less of the deforestation was done by small family farms than was the case in the 1980s and more was done by large, corporate-run farms. Big agribusiness tends to be more responsive to global economic signals as well as pressure campaigns from advocacy organizations and consumer groups than individual small farmers.

In Brazil, where a pattern had developed of expanding soy production by direct forest clearing and by pushing cattle ranching off pastureland and into forested areas, a campaign by Greenpeace and others resulted in agreements by key companies to rein in their expansion. Instead, they worked to increase production on land already in agricultural use.

'Seeing positive changes'

"These farmers effectively increased the yield of soy on existing lands and they have also increased the head of cattle per acre by a factor of five or six," Gibbs said. "It is exciting that we are starting to see how responsive industry can be to consumer demands. We really are seeing positive changes in this area."

Along with wiser use of land already cleared, Gibbs said, improvements in technology and advances in yield intensification also could slow the expansion of farming into the forests.

Other studies that analyzed land use changes between 2000 and 2007 have shown that the pace of cutting down the tropical forests has begun to slow in some regions.

But as long as the human population on the planet continues to grow, the pressure to put food on the table, feed in the barnyard and fuel in the gas tank will continue to grow, too.

"It is critical that we focus our efforts on reducing rates of deforestation while at the same time restoring degraded lands and improving land management across the tropics," Gibbs said. "The good news is that pressure from consumer groups and nongovernmental organizations combined with international climate agreements could provide a real opportunity to shift the tide in favor of forest conservation rather than farmland expansion."

In addition to her position at the Department of Environmental Earth System Science and the Program on Food Security and the Environment, Gibbs is affiliated with Stanford's Woods Institute for the Environment. Jon Foley, a professor of ecology, evolution and behavior, and director of the Institute on the Environment at the University of Minnesota, was Gibbs' PhD adviser when the research was begun. He is a coauthor of the paper.

Initial funding for the project was provided by NASA. Gibbs is currently funded by a David H. Smith Conservation Research Fellowship.

 

FSE Center Fellow David Lobell contributes a commentary to Climate Central on the recent heat wave in Russia, its impact on wheat production and global prices, and what rising temperatures mean in the larger context of climate change and food security.

The heat wave in Russia has captured international media attention, breaking temperature records left and right. It has also captured the attention of commodity traders. You see, in a typical year Russia produces about as much wheat as the United States, and is among the top exporters of wheat flour in the world. But this year, wheat has been decimated in the areas around Moscow, with yield expected to be 30 percent or so below normal. This week Russia announced they are banning all exports of wheat from August 15 through the end of the year. Since late June, wheat prices on the Chicago Board of Trade have risen by 50 percent, to more than $7 a bushel.

It is, and always will be, impossible to say whether a single event is caused by climate change. But we can ask, is this the type of thing we expect to be more common? In terms of warming, we can say with little doubt that heat waves like this will become more common with global warming. Exactly how much more common is tough to say, but it is likely that the average summer in 2050 will be as warm as the warmest summer in the 20th century. I am not aware of anyone who has done the calculation of exactly how common the type of heat experienced this year will be, but based on projections in the UN Intergovernmental Panel on Climate Change (IPCC) reports one can suspect this type of heat wave will be relatively common in Russia in a few decades.

Starting winter 2011, FSE will bring the world's leading policy experts in the fields of food and agricultural development to Stanford University to participate in an integrated seminar series on pro-poor growth and food security policy. The series, funded by a grant from the Bill & Melinda Gates Foundation, will consist of twelve lectures delivered on the Stanford campus over the course of two years.

"Providing food security for a world that will be warmer, more populous, and continually developing requires the implementation of sound policies that enhance agricultural production, incomes, and resource stewardship," said FSE director Rosamond L. Naylor.

"New ideas and exchanges are needed to meet this challenge and this seminar series intends to facilitate that process."

Participants will address the major themes of hunger and rural poverty, agricultural productivity, resource and climate constraints on agriculture, and food and agriculture policy. The series will draw heavily from economics, and will embrace polices related to demand, supply, price formation, marketing, trade and development.

"We focus this series on policy because it has proven to be extremely difficult to develop successful projects for hunger and poverty alleviation without first ensuring that sound policies are in play," noted Walter P. Falcon, FSE deputy director and project director. "Even the best-designed programs and projects at the local scale often fail due to counter-productive national policies."

The specific challenges will be to supply sufficient food at reasonable prices, to provide economic access to that food by all segments of society, and to do so without destroying the environment in the process, said Naylor.

In addition to lecturing, participants will write a significant paper that brings together new, relevant thinking about a particular topic area. At the end of the series, a volume of edited papers on international food security and food policy issues will be published. The volume will be designed for M.A. programs and mid-career professionals-individuals who later in their careers will have policy responsibilities. All the materials, including the videotaped lectures, will be freely available on the FSE website.

"We see an important opportunity to complement other efforts that have been funded by the Gates Foundation," said Naylor. "For example, the lecture series and educational volume are expected to contribute to the curriculum of the new Collaborative Master of Science in Agricultural and Applied Economics (CMAAE) program of the African Economic Research Consortium, partially funded by the foundation."

The lecture series will also target audiences in South Asia, and in particular India where there are more malnourished people than in all of sub-Saharan Africa.

The grant also provides funding to produce a specialized educational unit on food policy and food security for high school students. FSE will work closely with Stanford Program on International and Cross-Cultural Education (SPICE) to complete this project.

With the renewed interest in food, agriculture, and food security, it is important that the next generation have access to thoughtful commentary about global food issues, said Falcon.

This grant is part of the foundation's Agricultural Development initiative, which is working with a wide range of partners to provide millions of small farmers in the developing world with tools and opportunities to boost their yields, increase their incomes, and build better lives for themselves and their families. The Foundation is working to strengthen the entire agricultural value chain-from seeds and soil to farm management and market access-so that progress against hunger and poverty is sustainable over the long term.

Advances in high-yield agriculture achieved during the so-called Green Revolution have not only helped feed the planet, but also have helped slow the pace of global warming by cutting the amount of biomass burned - and the resulting greenhouse gas emissions - when forests or grasslands are cleared for farming. Stanford researchers estimate those emissions have been trimmed by over half a trillion tons of carbon dioxide. The paper is being released this week in the Proceedings of the National Academy of Sciences.

Advances in high-yield agriculture over the latter part of the 20th century have prevented massive amounts of greenhouse gases from entering the atmosphere - the equivalent of 590 billion metric tons of carbon dioxide - according to a new study led by two Stanford Earth scientists.

The yield improvements reduced the need to convert forests to farmland, a process that typically involves burning of trees and other plants, which generates carbon dioxide and other greenhouse gases.

The researchers estimate that if not for increased yields, additional greenhouse gas emissions from clearing land for farming would have been equal to as much as a third of the world's total output of greenhouse gases since the dawn of the Industrial Revolution in 1850.

The researchers also calculated that for every dollar spent on agricultural research and development since 1961, emissions of the three principal greenhouse gases - methane, nitrous oxide and carbon dioxide - were reduced by the equivalent of about a quarter of a ton of carbon dioxide - a high rate of financial return compared to other approaches to reducing the gases.

"Our results dispel the notion that modern intensive agriculture is inherently worse for the environment than a more 'old-fashioned' way of doing things," said Jennifer Burney, lead author of a paper describing the study that will be published online by the Proceedings of the National Academy of Sciences.

Adding up the impact

The researchers calculated emissions of carbon dioxide, methane and nitrous oxide, converting the amounts of the latter two gases into the quantities of carbon dioxide that would have an equivalent impact on the atmosphere, to facilitate comparison of total greenhouse gas outputs.

Burney, a postdoctoral researcher with the Program on Food Security and the Environment at Stanford, said agriculture currently accounts for about 12 percent of human-caused greenhouse gas emissions. Although greenhouse gas emissions from the production and use of fertilizer have increased with agricultural intensification, those emissions are far outstripped by the emissions that would have been generated in converting additional forest and grassland to farmland.

"Every time forest or shrub land is cleared for farming, the carbon that was tied up in the biomass is released and rapidly makes its way into the atmosphere - usually by being burned," she said. "Yield intensification has lessened the pressure to clear land and reduced emissions by up to 13 billion tons of carbon dioxide a year."

"When we look at the costs of the research and development that went into these improvements, we find that funding agricultural research ranks among the cheapest ways to prevent greenhouse gas emissions," said Steven Davis, a co-author of the paper and a postdoctoral researcher at the Carnegie Institution at Stanford.

To evaluate the impact of yield intensification on climate change, the researchers compared actual agricultural production between 1961 and 2005 with hypothetical scenarios in which the world's increasing food needs were met by expanding the amount of farmland rather than by the boost in yields produced by the Green Revolution.

"Even without higher yields, population and food demand would likely have climbed to levels close to what they are today," said David Lobell, also a coauthor and assistant professor of environmental Earth system science at Stanford.

"Lower yields per acre would likely have meant more starvation and death, but the population would still have increased because of much higher birth rates," he said. "People tend to have more children when survival of those children is less certain."

Avoiding the need for more farmland

The researchers found that without the advances in high-yield agriculture, several billion additional acres of cropland would have been needed.

Comparing emissions in the theoretical scenarios with real-world emissions from 1961 to 2005, the researchers estimated that the actual improvements in crop yields probably kept greenhouse gas emissions equivalent to at least 317 billion tons of carbon dioxide out of the atmosphere, and perhaps as much as 590 billion tons.

Without the emission reductions from yield improvements, the total amount of greenhouse gas pumped into the atmosphere over the preceding 155 years would have been between 18 and 34 percent greater than it has been, they said.

To calculate how much money was spent on research for each ton of avoided emissions, the researchers calculated the total amount of agricultural research funding related to yield improvements since 1961 through 2005. That produced a price between approximately $4 and $7.50 for each ton of carbon dioxide that was not emitted.

"The size and cost-effectiveness of this carbon reduction is striking when compared with proposed mitigation options in other sectors," said Lobell. "For example, strategies proposed to reduce emissions related to construction would cut emissions by a little less than half the amount that we estimate has been achieved by yield improvements and would cost close to $20 per ton."

The authors also note that raising yields alone won't guarantee lower emissions from land use change.

"It has been shown in several contexts that yield gains alone do not necessarily stop expansion of cropland," Lobell said. "That suggests that intensification must be coupled with conservation and development efforts.

"In certain cases, when yields go up in an area, it increases the profitability of farming there and gives people more incentive to expand their farm. But in general, high yields keep prices low, which reduces the incentive to expand."

The researchers concluded that improvement of crop yields should be prominent among a portfolio of strategies to reduce global greenhouse gases emissions.

"The striking thing is that all of these climate benefits were not the explicit intention of historical investments in agriculture. This was simply a side benefit of efforts to feed the world," Burney noted. "If climate policy intentionally rewarded these kinds of efforts, that could make an even bigger difference. The question going forward is how climate policy might be designed to achieve that."

David Lobell is a Center Fellow at the Freeman Spogli Institute for International Studies and at the Woods Institute for the Environment. The Program on Food Security and the Environment is a joint project of the Woods Institute and the Freeman Spogli Institute. The Precourt Institute for Energy and FSE provided funding for Jennifer Burney's research on agriculture and energy.

The impact of global warming on food prices and hunger could be large over the next 20 years, according to a new Stanford University study. Researchers say that higher temperatures could significantly reduce yields of wheat, rice and maize - dietary staples for tens of millions of poor people who subsist on less than $1 a day. The resulting crop shortages would likely cause food prices to rise and drive many into poverty.  

But even as some people are hurt, others would be helped out of poverty, says Stanford agricultural scientist David Lobell.

Lobell discussed the results of his research on Feb 19 at the annual meeting of the American Association for the Advancement of Science in San Diego.

"Poverty impacts depend not only on food prices but also on the earnings of the poor," said Lobell, a center fellow at Stanford's Program on Food Security and the Environment (FSE). "Most projections assume that if prices go up, the amount of poverty in the world also will go up, because poor people spend a lot of their money on food. But poor people are pretty diverse. There are those who farm their own land and would actually benefit from higher crop prices, and there are rural wage laborers and people that live in cities who definiztely will be hurt."

Lobell and his colleagues recently conducted the first in-depth study showing how different climate scenarios could affect incomes of farmers and laborers in developing countries.

Household incomes

In the study, Lobell, former FSE researcher Marshall Burke and Purdue University agricultural economist Thomas Hertel focused on 15 developing countries in Asia, Africa and Latin America. Hertel has developed a global trade model that closely tracks the consumption and production of rice, wheat and maize on a country-by-country basis. The model was used to project the effects of climate change on agriculture within 20 years and the resulting impact on prices and poverty.

Using a range of global warming forecasts, the researchers were able to project three different crop-yield scenarios by 2030:

• "Low-yield" - crop production is toward the low end of expectations.
• "Most likely" - projected yields are consistent with expectations.
• "High-yield" - production is higher than expected.

"One of the limitations of previous forecasts is that they don't consider the full range of uncertainties - that is, the chance that things could be better or worse than we expect," Lobell said. "We provided Tom those three scenarios of what climate change could mean for agricultural productivity. Then he used the trade model to project how each scenario would affect prices and poverty over the next 20 years.

"The impacts we're talking about are mainly driven by warmer temperatures, which dry up the soil, speed up crop development and shut down biological processes, like photosynthesis, that plants rely on," he added. "Plants in general don't like it hotter, and in many climate forecasts, the temperatures projected for 2030 would be outside the range that crops prefer."

Results

The study revealed a surprising mix of winners and losers depending on the projected global temperature. The "most likely" scenario projected by the International Panel on Climate Change is that global temperatures will rise 1.8 degrees Fahrenheit (1 degree Celsius) by 2030. In that scenario, the trade model projected relatively little change in crop yields, food prices and poverty rates

But under the "low-yield" scenario, in which temperatures increase by 2.7 F (1.5 C), the model projects a 10 to 20 percent drop in agricultural productivity, which results in a 10 to 60 percent rise in the price of rice, wheat and maize. Because of these higher prices, the overall poverty rate in the 15 countries surveyed was expected to rise by 3 percent.

However, an analysis of individual countries revealed a far more complicated picture. In 11 of the 15 countries, poor people who owned their own land and raised their own crops actually benefited from higher food prices, according to the model. In Thailand, for example, the poverty rate for people in the non-agricultural sector was projected to rise 5 percent, while the rate for self-employed farmers dropped more than 30 percent - in part because, as food supplies dwindled, the global demand for higher-priced crops increased.

"If prices go up and you're tied to international markets, you could be lifted out of poverty quite considerably," Lobell explained. "But there are a lot of countries, like Bangladesh, where poor people are either in urban areas or in rural areas but don't own their own land. Countries like that could be hurt quite a lot. Then there are semi-arid countries - like Zambia, Mozambique and Malawi - where even if prices go up and people own land, productivity will go down so much that it can't make up for those price increases. In the 'low-yield' scenario, those countries would see higher poverty rates across all sectors."

Under the "high-yield" scenario, in which global temperatures rise just 0.9 F (0.5 C), crop productivity increased. The resulting food surplus led to a 16 percent drop in prices, which could be detrimental to farm owners. In Thailand, the poverty rate among self-employed farmers was projected to rise 60 percent, while those in the non-agriculture sector saw a slight drop in poverty. In Zambia, Mozambique, Malawi and Uganda, poverty in the non-farming sector was projected to decline as much as 5 percent.

Risk management

Lobell said that, although the likelihood of the "low-yield" or "high-yield" scenario occurring is only 5 percent, it is important for policymakers to consider the full range of possibilities if they want to help countries adapt to climate change and ultimately prevent an increase in poverty and hunger. 

"It's like any sort of risk management or insurance program," he said. "You have to have some idea of the probability of events that have a big consequence. It's also important to keep in mind that any change, no matter how extreme, will benefit some households and hurt others."

The Program on Food Security and the Environment at Stanford is an interdisciplinary research and teaching program that generates policy solutions to the persistent problems of global hunger and environmental damage from agricultural practices worldwide. The program is jointly run by Stanford's Woods Institute for the Environment and the Freeman Spogli Institute for International Studies.

While Americans' appetite for seafood continues to grow, most of us know little about where our fish comes from or how it was produced. In California, more than half of our seafood comes from aquaculture, often imported from fish farms in other countries. Just as most chickens, pigs and cows are raised in tightly confined, intensive operations, so too are many farm-raised fish.

But raising fish in tight quarters carries some serious risks. Disease and parasites can be transmitted from farmed to wild fish. Effluents, antibiotics and other chemicals can be discharged into surrounding waters. Nonnative farmed fish can escape into wild fish habitat. And a reliance on wild-caught fish in aquaculture feed can deplete food supplies for other marine life.

These environmental impacts have been evident in many other countries with intensive marine fish farming. In Chile, where industry expansion was prioritized over environmental protection, salmon aquaculture has collapsed, causing a major blow to what had been one of Chile's leading exports. Tens of thousands of people are now jobless in southern Chile, where the salmon farming industry once boomed.

If aquaculture is to play a responsible role in the future of seafood here at home, we must ensure that the "blue revolution" in ocean fish farming does not cause harm to the oceans and the marine life they support.

In December, Rep. Lois Capps (D-Santa Barbara) introduced in the House the National Sustainable Offshore Aquaculture Act, a bill that addresses the potential threats of poorly regulated fish farming in U.S. ocean waters. Her bill shares many of the features of a California state law, the Sustainable Oceans Act, which was written by state Sen. Joe Simitian (D-Palo Alto) and signed by Gov. Arnold Schwarzenegger in 2006. That legislation regulates fish farming in state waters, which extend three miles off the California coast. At present, all aquaculture operations in California and the U.S. are located just a few miles offshore.

If the U.S. and other states follow California's lead, we may be able to reward innovation and responsibility in aquaculture and at the same time prevent the kind of boom-and-bust development that happened in Chile. Unlike previous attempts to legislate fish farming at the national level, the Capps bill would ensure that U.S. aquaculture in federal waters, which extend from three to 200 miles offshore, establishes as a priority the protection of wild fish and functional ecosystems. It would ensure that industry expansion occurs only under the oversight of strong, performance-based environmental, socioeconomic and liability standards.

The bill also would preempt ecologically risky, piecemeal regulation of ocean fish farming in different regions of the U.S. Indeed, regulation efforts are already underway in many states, with no consistent standards to govern the industry's environmental or social performance. If these piecemeal regional initiatives move forward, it will get much more difficult to create a sustainable national policy for open-ocean aquaculture.

Previous federal bills introduced in 2005 and 2007 were fundamentally flawed -- and ultimately did not pass -- because they put the goal of aquaculture expansion far above that of environmental protection. Now, for the first time, a bill has been introduced that would demonstrably protect marine ecosystems, fishing communities and seafood consumers from the risks of poorly regulated open-ocean aquaculture.

The Obama administration is currently developing a national policy to guide the development of U.S. aquaculture. The administration would do well to embrace the vision articulated by Capps and Simitian for a science-based and precautionary approach to help ensure a responsible future for U.S. ocean fish farming.

Rosamond L. Naylor is director of the program on food security and the environment at Stanford University. George H. Leonard is director of the aquaculture program at the Ocean Conservancy in Santa Cruz.

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