According to a new study co-authored by Stanford professor David Lobell, the chance of a worldwide slowdown in agricultural yield growth in the next two decades is significantly higher due to global warming.

Lobell and co-author Claudia Tebaldi, a senior researcher at the National Center for Atmospheric Research, set out to estimate the odds of a steep drop in global wheat and corn yield progress under several climate scenarios. The study, “Getting caught with our plants down: the risks of a global crop yield slowdown from climate trends in the next two decades” appeared in Environmental Research Letters.

Lobell said he was motivated to pursue the study based on questions posed by stakeholders and decision makers in governments and the private sector.

“I’m often asked whether climate change will threaten food supply, as if it’s a simple yes or no answer,” Lobell said. “The truth is that over a 10 or 20 year period, it depends largely on how fast the Earth warms, and we can’t predict that very precisely. So the best we can do is try to determine the odds.”

Lobell and Tebaldi calculated the chance of a 10 percent global yield loss from climate change over the next 20 years, which would represent a severe impact on food supply, enough to roughly halve the rate of yield growth.

The short time frame of the study was deliberate, Lobell said. “Many studies have looked at climate and agriculture trends over the coming 50 or 100 years. But the next two decades are when most of the global population growth, and dietary shifts driven by a growing middle class, will occur. The growth rate of food demand will be higher during this time than at any other time in the next century.”

Without human-induced global warming – in other words, in a world with only natural climate variability – the likelihood of a yield drop that large is only 1 in 200. But when the team accounted for global warming, they saw the odds jump to 1 in 10 for corn and 1 in 20 for wheat. “In this study, we did not try to estimate the most likely impacts of climate change on crops,” Lobell said. “Rather, we estimated the likelihood of a really major impact, not because we want to scare people, but because there are many people who want to be prepared for all contingencies.”

“The point of the paper is to move from hand-waving about scenarios of what could go wrong, to specific and transparent estimates of the actual odds,” Lobell said. “The odds are not very high, but they are significant and a lot bigger than they used to be. The people asking these questions are accustomed to planning for scenarios with much less than a 10 percent chance of happening, so it will be interesting to see whether this study has any effect on how they operate.”

Lobell adds that organizations working toward global food security, and related issues such as conflict prevention, are most interested in the next 20 years because their decisions rarely consider the more distant future.  “As scientists, we might prefer to work on time scales in which the answers are clearer, but we also want to be responsive to the actual concerns and questions that decision makers have.”

Lobell is associate professor of Environmental Earth System Science at Stanford and associate director of the Center on Food Security and the Environment. He is also a senior fellow at the Stanford Woods Institute for the Environment and the Freeman Spogli Institute for International Studies.

Contact:

David Lobell: dlobell@stanford.edu

Laura Seaman, Communications and External Relations Manager, Center on Food Security and the Environment: lseaman@stanford.edu

Has the global food price bubble  burst, and if so, does it matter? In the first installment of FSE's new Food and Nutrition Policy Symposium Series, Professor Thomas Hertel of Purdue University and Professor Johann Swinnen of Leuven University outlined global trends in the cost of food, and explained how a drop in prices after the food price shocks of 2007-2008 might affect global politics and economics.

What drives food prices?

As population growth and rising incomes put pressure on the global food supply, many scholars consider high food costs to be the "new normal," especially following the food price shocks of 2007-2008. Professor Thomas Hertel challenged this view, saying that "To look forward 45 years, you have to look back 45 years" at what factors actually impact food prices.

Prices for many food commodities fell between 1961 and 2006, despite strong population and income growth, because the world was able to triple crop production during the same period. Since the recent price spikes, the "food price bubble" seems to have burst, with prices falling steadily since 2009.

Although population will continue to grow over the next several decades, the rate of growth is slowing worldwide and is mostly concentrated in developing countries, where per capita purchasing power is relatively low. This minimizes the pressure that population growth puts on the global food supply.

Economic factors may be more influential. "For the first time in history," Hertel said, "income will surpass population as a driver of global food demand." As countries move up the income scale, they consume richer diets of input-intensive products like meat, dairy and processed foods.

Energy prices also influence global food costs. As oil and gas prices rise, demand grows for alternative fuels like ethanol. Half of the increase in corn production over the past several decades came from the growing demand for ethanol, which was fueled by government mandates and which drove up the global price of corn. These mandates have been rolled back in recent years, however, and demand growth for biofuels has waned.

Hertel added that issues around climate change, urbanization, water supply, food waste and deforestation may also impact global food prices in the future.

Many scholars point to crop yields as a way to close the gap between food supply and demand and keep prices low. But Hertel cautioned that scientists and policymakers may be constrained by technical and economic limits.

To further increase yields "is a bigger job than simply doing some more science in the lab," Hertel said. But he noted with optimism that new investments in research and development have risen sharply from both the public and private sector, particularly in countries like China, India and Brazil where food security is a pressing issue. 

Impacts of the food price bubble

Professor Johann Swinnen explained that if the food price bubble has in fact burst, the next several years are likely to bring a shift in the politics and economics of global food issues.

The recent bubble coincided with an increase in both policy attention and donor funding to combat food insecurity - a focus that has benefitted both farmers and consumers, but that could wane as prices fall.

While the high prices of 2007-2008 benefited farmers, they in turn hurt low-income consumers in urban areas. And because people in high-density areas find it easier to organize and voice their concerns over government policies, they are more likely to capture media attention.

This "urban bias," as Swinnen described it, influenced policymakers to respond to the heavy media coverage. His team found that after 2007, agricultural funding from the World Bank, United Nations Food and Agriculture Organization (FAO) and the International Maize and Wheat Improvement Center (CIMMYT) all rose sharply. The percentage of global development aid targeted toward agriculture also grew.

Swinnen described the social and political conditions of 2007-2008 as a "perfect storm" that shifted the attention of policymakers toward global food security investments. Paradoxically, Swinnen explained, this policy response to urban unrest over food prices ultimately benefitted both rural and urban populations, by boosting agricultural investments for food producers while also helping lower costs for consumers.

 The Food and Nutrition Policy Symposium Series will run for three years and will consist of a total of ten lectures spanning a wide range of issues around global food and nutrition policy. It is funded by Zachary Nelson, '84 and Elizabeth Horn. The series follows on the successful two-year Global Food Policy and Food Security Symposium Series which concluded in May 2013 and was funded by the Bill and Melinda Gates Foundation.

Corn yields in the central United States have become more sensitive to drought conditions in the past two decades, according to a new study in the journal Science from a team led FSE associate director David Lobell.

"The Corn Belt is phenomenally productive," Lobell said, referring to the region of Midwestern states where much of the country's corn is grown. "But in the past two decades we saw very small yield gains in non-irrigated corn under the hottest conditions. This suggests farmers may be pushing the limits of what's possible under these conditions."

He predicted that at current levels of temperature sensitivity, crops could lose 15 percent of their yield within 50 years, or as much as 30 percent if crops continue the trend of becoming more sensitive over time.

As Lobell explained, the quest to maximize crop yields has been a driving force behind agricultural research as the world's population grows and climate change puts pressure on global food production. One big challenge for climate science is whether crops can adapt to climate change by becoming less sensitive to hotter and drier weather.

"The data clearly indicate that drought stress for corn and soy comes partly from low rain, but even more so from hot and dry air. Plants have to trade water to get carbon from the air to grow, and the terms of that trade become much less favorable when it's hot," said Lobell, also the lead author for a chapter in the U.N. Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report, which details a consensus view on the current state and fate of the world's climate.

Rain, temperature, humidity

The United States produces 40 percent of the world's corn, mostly in Iowa, Illinois, and Indiana. As more than 80 percent of U.S. agricultural land relies on natural rainfall rather than irrigation, corn farmers in these regions depend on precipitation, air temperature and humidity for optimal plant growth.

According to the research, over the last few decades, corn in the United States has been modified with new traits, like more effective roots that better access water and built-in pest resistance to protect against soil insects. These traits allow farmers to plant seeds closer together in a field, and have helped farmers steadily raise yields in typical years.

But in drought conditions, densely planted corn can suffer higher stress and produce lower yields. In contrast, soybeans have not been planted more densely in recent decades and show no signs of increased sensitivity to drought, the report noted.

Drought conditions are expected to become even more challenging as temperatures continue to rise throughout the 21st century, the researchers said.

Lobell said, "Recent yield progress is overall a good news story. But because farm yields are improving fastest in favorable weather, the stakes for having such weather are rising. In other words, the negative impacts of hot and dry weather are rising at the same time that climate change is expected to bring more such weather."

Extensive data

Lobell's team examined an unprecedented amount of detailed field data from more than 1 million USDA crop insurance records between 1995 and 2012.

"The idea was pretty simple," he said. "We determined which conditions really matter for corn and soy yields, and then tracked how farmers were doing at different levels of these conditions over time. But to do that well, you really need a lot of data, and this dataset was a beauty."

Lobell said he hopes that the research can help inform researchers and policymakers so they can make better decisions.

"I think it's exciting that data like this now exist to see what's actually happening in fields. By taking advantage of this data, we can learn a lot fairly quickly," he said. "Of course, our hope is to improve the situation. But these results challenge the idea that U.S. agriculture will just easily adapt to climate changes because we invest a lot and are really high-tech."

Lobell and colleagues are also looking at ways crops may perform better under increasingly hot conditions. "But I wouldn't expect any miracles," he said. "It will take targeted efforts, and even then gains could be modest. There's only so much a plant can do when it is hot and dry."

This animation shows the increasing sensitivity of U.S. corn to drought over time. Animation by Carlo Di Bonito.

Growing agave and other carefully chosen plants amid photovoltaic panels could allow solar farms not only to collect sunlight for electricity but also to produce crops for biofuels, according to new computer models by Stanford scientists.

This colocation approach could prove especially useful in sunny, arid regions such as the southwestern United States where water is scarce, said Sujith Ravi, who is conducting postdoctoral research with professors David Lobell and Chris Field, both on faculty in environmental Earth system science and senior fellows at the Stanford Woods Institute for the Environment. David Lobell is associate director and Chris Field is a core faculty affiliate at the Center on Food Security and the Environment.

“Colocated solar-biofuel systems could be a novel strategy for generating two forms of energy from uncultivable lands: electricity from solar infrastructure and easily transportable liquid fuel from biofuel cultivation,” said Ravi, lead author of a new study published in a recent issue of the journal Environmental Science & Technology that details the idea.

Photovoltaic (PV) solar farms run on sunlight, but water is required to remove dust and dirt from the panels to ensure they operate at maximum efficiency. Water is also used to dampen the ground to prevent the buildup and spread of dust. Crops planted beneath the solar panels would capture the runoff water used for cleaning the PV panels, thus helping to optimize the land. The plants’ roots would also help anchor the soil, and their foliage would help reduce the ability of wind to kick up dust.

Computer simulations of a hypothetical colocation solar farm in California’s San Bernardino County by Ravi and colleagues suggest that these two factors together could lead to a reduction in the overall amount of water solar farms need to operate. "It could be a win-win situation," Ravi said. “Water is already limited in many areas and could be a major constraint in the future. This approach could allow us to produce energy and agriculture with the same water.”

But which crops to use? Many solar farms operate in sunny but arid regions that are very not hospitable to most food crops. But there is one valuable plant that thrives at high temperatures and in poor soil: agave. Native to North and South America, the prickly plant can be used to produce liquid ethanol, a biofuel that can be mixed with gasoline or used to power ethanol vehicles. "Unlike corn or other grains, most of the agave plant can be converted to ethanol," Ravi said.

The team plans to test the colocation approach around the world to determine the ideal plants to use and to gather realistic estimates for crop yield and economic incentives.

“Sujith’s work is a great example of how thinking beyond a single challenge like water or food or energy sometimes leads to creative solutions,” said Lobell, who is a coauthor on the new study. “Of course, creative solutions don’t always work in the real world, but this one at least seems worthy of much more exploration.”

Ker Than is associate director of communications for the School of Earth Sciences.

Contact: Sujith Ravi, 703-581-8186, sujith@stanford.edu; Ker Than, 646-673-4558, kerthan@stanford.edu 

FSE’s David Lobell finds that an increase of more than two degrees Celsius in average global temperature is likely to cause yields of wheat, rice and maize to fall throughout the 21st century. Early adaptation could increase projected yields by up to 15 percent.

If global temperatures continue to rise, the amount of crops farmers can harvest will sharply decline during the next 100 years.

Stanford professor David Lobell and an international team of climate scientists modeled future crop yields under several global climate scenarios throughout the 21^st century. They found that if average global temperatures rise by more than two degrees Celsius, farmers are likely to get less wheat, rice and maize out of each plot of land. Yields are expected to fall by an average of 4.9 percent for every one degree Celsius rise in average temperature. Year-to-year variability of harvests is also expected to rise, as drought and flooding become more frequent. Crop yield losses will speed up throughout the century, with declines in yield beginning around 2030 and with the fastest drop happening in the second half of the century.

Lobell, an associate professor of Environmental Earth System Science and the associate director of the Center on Food Security and the Environment at Stanford, reviewed over 1,700 published studies with a team of climate scientists from the United States, United Kingdom and Australia. The team found that if farmers adapt to climate change within the next few years, they have a better chance of avoiding or even reversing the predicted decline of wheat and rice yields in some regions. Agricultural adaptation strategies like irrigating fields and developing new crop breeds could increase projected yields between 7 percent and 15 percent.

The new study also highlights the need for better data on the potential future impacts of other factors that affect crop yields, like the prevalence of pests and plant diseases, and the availability of water supply. A full version of the study can be found online at Nature Climate Change.

By Terry Nagel, Stanford Woods Institute for the Environment

David Lobell, an associate professor of environmental Earth system science and a senior fellow at the Freeman Spogli Institute for International Studies, has been named a 2013 MacArthur Fellow and one of Foreign Policy Magazine's 100 Leading Global Thinkers of 2013.

MacArthur "Genius Grant"

Lobell, who is also the associate director of FSI’s Center on Food Security and the Environment, was cited "for unearthing richly informative, but often underutilized sources of data to investigate the impact of climate change on crop production and global food security." He received his doctorate degree from Stanford in 2005 and was appointed to the faculty in 2009.

A pioneer of the emerging field of crop informatics, Lobell is revolutionizing the understanding of the environmental factors controlling crop yields, with a particular emphasis on adaptation to climate change.

His work provides decision makers, for the first time, with critical information about how to adapt agricultural development to climate change.

"I was completely surprised by this recognition, but am really excited by the opportunity it presents," said Lobell, who is also a senior fellow at Stanford Woods Institute for the Environment. "To have the MacArthur Foundation recognize the value of taking new approaches and the importance of the topics of hunger and food production is deeply gratifying."

Lobell's research focuses on identifying opportunities to increase yields of crops including wheat and corn in major agricultural regions, with projects currently underway in Africa, South Asia, Mexico and the United States. 

"I'm interested in how to feed the world and protect the environment at the same time," he said. "While there are many theories about how to do that, my work tries to test these theories, often using data that were collected for completely different reasons."

The citation emphasized Lobell's work on understanding the risks of climate change, and options for adaptation. "Climate change is one of the reasons for concern about feeding people in the future, but it's not insurmountable if good decisions are made," he said. 

When asked how he would use the funding, Lobell said he would not rush the decision. He said that some of the award would likely relieve him of writing grant proposals. In addition, he said he would consider using some toward more travel.

"A lot of my better ideas in the past have started with travel and interactions with international collaborations," he said.  "And there's always a tradeoff between my work travel and family.  I now might take my wife and young sons with me on some extended trips."

Foreign Policy's Leading Global Thinkers

In December, Foreign Policy named Lobell one of the 100 Leading Global Thinkers of 2013. The recognition comes for his work "helping farmers feed the world" in a changing climate. Lobell is joined on the magazine's list by fellow researchers working on climate issues, along with prominent public figures like German Chancellor Angela Merkel, U.S. Secretary of State John Kerry, and Pope Francis.

Widely sought throughout the world to provide expert advice, Lobell is a lead author for the Intergovernmental Panel on Climate Change Fifth Assessment Report chapter on food security, to be published in 2014. The IPCC, which won the Nobel Prize in 2007, also made Foreign Policy's 2013 Leading Global Thinkers list alongside Lobell, "for showing that humanity is on the brink of catastrophe" if climate change is not addressed quickly and aggressively.

Lobell studied applied mathematics at Brown University, and before receiving his bachelor's degree in 2000, he spent the summer of 1999 as a research intern at Stanford, developing remote sensing algorithms. He then pursued graduate studies at Stanford, receiving his doctorate in geological and environmental sciences in 2005.

He was a postdoctoral fellow at Lawrence Livermore National Laboratory from 2005-2007, and returned to Stanford as a senior research scholar in the Program on Food Security and the Environment in 2008-2009.  He accepted an appointment as assistant professor in the Stanford School of Earth Sciences in 2009. 

In addition to his research, Lobell teaches several courses open to both undergraduates and graduate students, including "Feeding Nine Billion," "Climate and Agriculture," and "Global Land Use to 2050," as well as modeling and statistical methods classes.

Lobell received a NASA New Investigator Program Award for 2008-2011. He received the James B. Macelwane Medal from the American Geophysical Union in 2010, awarded for significant contributions to the geophysical sciences by an outstanding scientist under the age of 36.

Nancy Peterson is the chief communications officer for Stanford's School of Earth Sciences. Laura Seaman, communications manager for the Center on Food Security and the Environment, contributed to this article.

America may have legitimate competitive reasons to worry about the number of computer science and engineering graduates from elite Chinese and Indian universities – the figure dwarfs that of U.S. students with similar degrees.

But a new book by Stanford researchers and others says that the concern that these countries will develop their own centers of high-tech production and innovation and draw research, development and scholarship away from American shores is still premature.

The research, a multidisciplinary look at the growth of higher education in the world's four largest developing economies – Brazil, Russia, India and China (known collectively as the BRICs) – analyzes the quality of institutions, the quantity of people getting degrees and equal access to education.

The book, University Expansion in a Changing Global Economy: Triumph of the BRICS?, is published by Stanford University Press.

"In the past 20 years, university systems in these big countries have just exploded," said Martin Carnoy, a Stanford professor of education and one of the authors. Carnoy is also an affilate of the Center on Democracy, Development, and the Rule of Law at the Freeman Spogli Institute for International Studies.

"So the questions are why did it happen and what are the implications? And specifically, what are the implications for the U.S. if the market is flooded with new scientists and engineers? Are we going to be overwhelmed? What happens to their societies if all the energy is focused on elite institutions," Carnoy said.

The researchers approached their questions with the belief that societies, and governments, can be judged by the way they invest in and organize their public higher education systems.

For example, how well these countries create a labor force that is competitive in the information age depends on the quality of higher education. Whether people have equal chances to succeed relies on having colleges that are accessible to even the poorest students. And how effectively a country expands its university system may determine how successful it is at growing a robust economy and competing with the United States and Europe, the scholars argue.

"If you have economic growth and provide educational opportunities, you're perceived as a legitimate, successful government," Carnoy said. "So our theory was, if you can pull this off, if you can successfully expand your university systems, you are likely a pretty efficient government."

BRIC undergraduate education increased from about 19 million students in 2000 to more than 40 million students in 2010. The largest increase was in China, which went from less than 3 million to almost 12 million bachelor's degree students during that period, the study says.

Financing elite schools

The study found that BRIC countries are pouring money into their elite colleges in an effort to create world-class institutions and have their graduates compete with the United States and Europe.

Researchers say the elite colleges are much better for the focused investment, and the engineers and computer scientists are graduating with similar competency and training as those from developed countries.

But the mass institutions are receiving fewer resources, the study says, and that's where most of the students go. In 2009, 2.1 million of the 2.5 million total bachelor's graduates in China matriculated from mass institutions, not elite ones. In India, it was 2.2 million of 2.3 million.

This widening funding gap between top schools and mass institutions has broad implications, the scholars argue. The gap has the potential to slow economic growth domestically, deepen income inequality and create less social mobility.

Students who go to the mass institutions aren't getting high quality, competitive educational experiences, the study says, and many of the students also get stuck with big bills as funding assistance is directed toward the elite universities.

"What happens, then, is they are doing a good job of educating students at the elite levels, but they are not doing a good job of educating students at the non-elite levels who are also fundamental for the economy," said Prashant Loyalka, a research fellow at FSI and one of the study's authors.

In absolute terms, the sheer numbers of students graduating from elite institutions in computer science and engineering majors in these countries is also high. In China, for example, the total number of computer science and engineering graduates from elite universities is more than the total number of such graduates from the United States.

But sustaining and building innovation hubs requires more than the elite, the researchers said. The engine of these new economies is the rest of the population – those that attend mass institutions.

"In the United States, we have relied on competent second-tier engineers. They are the guts of our system. We need good students in all fields in these second-tier universities because the top-tier universities just don't produce that many graduates. They simply don't," Carnoy said.

He warned that this redistribution of funds away from second-tier institutions is a concern in the United States as well. "To an extent the BRICs have to do it, because they don't have enough resources to go around. But do we have to do it? The answer is probably no. It certainly should be no," Carnoy said.

The research is one of the first empirical and comparative looks at the higher education systems across these countries, and relied on in-country interviews, surveys, data analysis and classroom observation.

Report card

Overall, the researchers found that significant challenges remain as these countries march toward creating universities that can rank alongside those in the United States and Europe.

China, the scholars said, is doing pretty well, but Russia and Brazil are question marks.

"Russia has provided the vast majority of its people with a high level of education, but it has lagged in terms of putting money into research," Loyalka said. "Brazil has a high-level of graduate education and research at its top-tier public institutions, and these institutions are receiving a lot of support. However, the vast majority of students attend private institutions, which are, on average, of dubious quality."

India, Loyalka noted, was surprising. Despite its very good technical universities, he said, "you have a small proportion of Indians going to those, and the mass institutions are of really poor quality."

"The higher education system in India does not appear to be well organized," Loyalka said.

Among other recommendations, the researchers said India should increase its graduate education and, along with Russia, increase spending on research.

The project began in 2007 as an interdisciplinary venture supported by FSI, and incorporated scholars in economics and international comparative education at Stanford Graduate School of Education, FSI and universities in Moscow and Beijing.

Several articles focusing on different aspects of the review also have been published over the past year. The most recent, which appears in the July/August issue of the journal Change, highlights the research on quality and quantity of graduates in engineering and computer science from the four countries.

Besides Carnoy and Loyalka, the scholars involved in the project include Maria Dobryakova, a research associate and the director for portals at the Center for Monitoring Quality Education at the Higher School of Economics in Moscow; Rafiq Dossani, a senior economist at RAND Corp. and former senior research scholar at Stanford's Shorenstein Asia-Pacific Research Center at the Freeman Spogli Institute; Isak Froumin, a mathematician and director of the Institute for Educational Studies at the National Research University Higher School of Economics in Moscow; Katherine Kuhns, who received her PhD in the International and Comparative Education Program at Stanford Graduate School of Education; Jandhyala B. G. Tilak, a professor at the National University of Educational Planning and Administration in New Delhi, India; and Rong Wang, director and professor of the China Institute for Educational Finance Research at Peking University.

Brooke Donald is the social sciences writer at the Stanford News Service.