Scientists are making progress in helping millions of wheat farmers adapt to hotter conditions, but the gains have been uneven, reports a new study led by Stanford University. New approaches to breeding are needed to withstand increasingly common heat waves and keep pace with growing global food demand.

Wheat is the most widely grown crop in the world; unfortunately it is also one of the most sensitive to future global warming. Scientists around the world strive to develop new wheat varieties each year that incorporate improved features, much like car companies release new models each year. Different strategies are commonly used; some target fully irrigated conditions that favor very high yields, while others focus on dry and hot conditions where yield maintenance under stress is a priority.

The team, which includes scientists from Stanford and the International Maize and Wheat Improvement Center (known as CIMMYT), evaluated 25 years of data from historical trials around the globe and analyzed the outcome of different past breeding approaches to help prioritize future strategies. The fully irrigated nursery, known as the elite spring wheat yield trials, produces varieties that are released for the majority of wheat farmers in countries like India and Egypt each year. While cultivars selected under stressed conditions showed significant yield progress at higher temperatures, the elite trials did not.

“There has been very impressive progress in improving yields for the elite varieties at the cooler temperatures that wheat prefers,” explains lead author Sharon Gourdji, a post-doctoral scholar in Stanford’s department of Environmental Earth System Science and Center on Food Security and the Environment (FSE).

“However, to date, our analysis shows a lack of yield gains for these varieties in hot environments over the past 25 years. Along with the gains in cool conditions, this means that the yield difference between cool and hot conditions is getting larger.”

A CIMMYT researcher plants wheat seed in pots in the center's greenhouse facilities. Photo credit: X. Fonseca/CIMMYT

"I think we have learned that the current main approach to breeding won't quite cut it in terms of adapting wheat to climate change,” said co-author David Lobell, assistant professor in Environmental Earth System Science and FSE center fellow. “That is useful information as breeding centers try to raise their game to contend with long-term warming."

Lobell notes that there are good reasons why improved heat tolerance for the elite varieties has not happened naturally.

“Breeding is tough since scientists are aiming for so many traits at once – for example, disease resistance, high yields, and good quality for bread making. Adding heat tolerance is like telling a scout looking for a superstar athlete, ‘by the way, make sure he’s a straight A student’,” said Lobell.

One important lesson from the study is that sifting through historical data can help identify what works and what does not.

“It can often be a hard sell to have breeders take the time to send their data back once they have selected their varieties and moved on,” explains CIMMYT wheat physiologist and co-author Matthew Reynolds. “This study clearly demonstrates the advantage of having these data to assess progress. It shows the genetic potential of wheat to adapt to warmer-than-usual conditions, and reinforces the value of screening under stress as a strategy for adaptation to climate change.”

The progress in the nursery targeted towards stress conditions shows that it is possible to make sizable gains in improving heat tolerance. But whether this can be combined with continued high performance under cooler conditions remains to be seen.

“It is critically important for farmers that they not only survive the bad or hot years, but that they can take full advantage of the favorable years” says Gourdji. “What is needed is a breeding strategy that can successfully achieve both.”

This work was supported by a grant from the Rockefeller Foundation. Additional co-authors of the study include CIMMYT’s Ky Mathews and Jose Crossa.

Wheat is a staple crop throughout much of India, but in many areas it is commonly sown past the optimum yield window. A study led by FSE associate director David Lobell uses satellite measurements to estimate a decade’s worth of sow dates in wheat-growing areas of India.

The study finds, among other developments, that wheat was sown one week earlier by 2010 than it was at the beginning of the decade, a change that explains 5% in country-wide yield gains. It also predicts that yield benefits from sow date shifts will likely diminish in the next decade.

"There's an important, one time boost farmers have gotten recently from moving into the optimum sowing window, but the data suggest this effect will run out of steam in the coming years," says Lobell.

Without coordinated global action on climate change, it will be increasingly hard to reduce poverty in the world's poorest countries, said UN Development Program Administrator Helen Clark. Clark's visit to campus comes a few weeks before global climate negotiations are set to begin in Doha, Qatar. 

She highlighted ways in which climate change will, and is already, impacting food security in the world's most vulnerable regions: 

Outside of China, the world now has more food insecure and nutrient deficient people than it had a decade ago, and the prevalence of obesity-related diabetes, high blood pressure and cardio-vascular diseases is increasing at very rapid rates. Expanded food production has done little to address the fact that between one-third and one-half of all deaths in children under five in developing countries are still related to malnutrition.

“With only three years away from the Millennium Development Goals deadline, this is a terrible track record,” said food and nutrition policy expert Per Pinstrup-Andersen at FSE's Global Food Policy and Food Security Symposium Series last week.  

Pinstrup-Andersen, the only economist to win the World Food Prize (the ultimate award in the food security field), has dedicated his career to understanding the linkages between food, nutrition, and agriculture. What is driving persistent food insecurity and malnutrition in a food abundant world?

Poor food supply management is part of the problem. According to the United Nations Food and Agricultural Organization (FAO), 20-30% of food produced globally is lost every year. That’s enough to feed an additional 3-3.5 billion people.

Jatropha in Africa. Photo credit: Ton Rulkens/flickr.

Biofuels production, such as jatropha in Africa, now competes with food for land, and climate change is already negatively impacting crop yields in regions straddling the equator—with major implications for food supply.

For low-income consumers in both the U.S. and developing countries increasing and more volatile food prices, such as those seen in 2007, are also driving food insecurity. Poor consumers respond by purchasing cheaper, less nutrient food, and less of it.

Nutritional value chain

Consensus is developing—at least rhetorically—among national policymakers and international organizations that investments in agricultural development must be accelerated. Members of the G8 and G20 have committed $20 billion in international economic support for such investments and some developing countries such as Ethiopia and Ghana are planning large new investments.

While most of these recent initiatives focus on expanded food supplies, there is an increasing understanding that merely making more food available will not assure better food security, nutrition, and health at the household and individual levels.

“It matters for health and nutrition how increasing food supplies are brought about and of what it consists,” said Pinstrup-Andersen. “We need to turn the food supply chain into a nutritional value chain.”

Diet diversity is incredibly important for good nutrition. Agricultural researchers and food production companies need to look at a number of different commodities, not just the major food staples, said Pinstrup-Andersen.

“The Green Revolution successfully increased the production of corn, rice, and wheat, increasing incomes for farmers, and lowering prices for consumers, but now it is time to invest in fruits, vegetables and biofortification to deal with micronutrient deficiency,” said Pintrup-Andersen.

Biofortification, the breeding of crops to increase their nutritional value, offers tremendous opportunity for dealing with malnutrition in the developing world, but is not widely available.

This is particularly important for areas in sub-Saharan Africa where between one and three and one and four people are short in calories, protein, and micronutrients. Obesity is actually going up in these countries with the introduction of cheap, processed, energy-dense foods (those high in sugar and fat) contributing to the diabetes epidemic.

Pathways to better health

Women hauling water to their gardens in Benin.

The path to better health and nutrition must look beyond the availability of food at affordable prices, clean water, and good sanitation, and consider behavioral factors such as time constraints for women in low-income households.

“Field studies have shown time and time again that one of the main factors preventing women from providing themselves and their families with good nutrition is time,” explained Pinstrup-Andersen.

He told the story of a woman in Bolivia too burdened with farm and household responsibilities to take the time to breastfeed her six-month old daughter. Enhancing productivity in activities traditionally undertaken by women could be a key intervention to improving good health and nutrition at the household level.

Access is another issue. A household may be considered food secure, in that sufficient food may be available, but food may not be equally allocated in the household.

“If we focus on the most limiting constraint we can be successful,” said Pinstrup-Anderen. “But we must tailor our response to each case.”

For sub-Saharan Africa, this includes investments in rural infrastructure, roads, irrigation systems, micronutrient fertilizer, climate adaptation strategies, and other barriers holding back small farmers.

Fortunately, there has been a renewed attention to the importance of guiding food system activities towards improved health and nutrition. The Global Agriculture and Food Security Program (GAFSP), which facilitates the distribution of some of the G8 and G20 $20 billion commitments, prescribes that country proposals for funding of agricultural development projects must show a clear pathway from the proposed agricultural change to human nutrition.

“But it’s not going to be easy to implement good policies,” warned Pinstrup-Andersen. “There are few incentives in government for multidisciplinary problem solving. The economy is set up around silos and people are loyal to their silos. Agricultural and health sectors are largely disconnected in their priorities, policy, and analysis."

Incentives must change to encourage working across ministries and disciplines to identify the most important health and nutrition-related drivers of food systems, impact pathways, and policy and program interventions to find win-wins for positive health and nutrition.

In advance of the third presidential debate, Freeman Spogli Institute center directors thought about key international policy issues that need addressing by presidential candidates Barak Obama and Mitt Romney. FSE center director Rosamond L. Naylor posed the question below among a list of other suggested FSI foreign policy questions to debate:

Should our government help American farmers cope with climate impacts on food production, and should this assistance be extended to other countries – particularly poor countries – whose food production is also threatened by climate variability and climate change?

What to listen for: Most representatives in Congress would like to eliminate government handouts, and many would also like to turn away from any discussion of climate change. Yet this year, U.S. taxpayers are set to pay up to $20 billion to farmers for crop insurance after extreme drought and heat conditions damaged yields in the Midwest.

With the 2012 farm bill stalled in Congress, the candidates need to be clear about whether they support government subsidized crop insurance for American farmers. They should also articulate their views on climate threats to food production in the U.S. and abroad.

Without a substantial crop insurance program, American farmers will face serious risks of income losses and loan defaults. And without foreign assistance for climate adaptation, the number of people going hungry could well exceed 15 percent of the world's population. 

~Rosamond L. Naylor, director of the Center on Food Security and the Environment 

Inspired by the spirit of debate, FSE fellows took the opportunity to pose a few additional questions for the candidates. 

Questions from FSE deputy director Walter P. Falcon:

The US now uses more that 40% of its corn crop for biofuel. While some argue this contributes to long-term energy independence, others note that ethanol mandates, along with unfavorable weather, can contribute to higher and more volatile food prices like those seen in recent years. Do you regard the US policy emphasis on biofuels, especially corn-based ethanol, as being a successful program to date? Have the benefits from biofuels outweighed the negative impacts on higher food costs around the world, and do you believe that mandates continue to be the most appropriate policy going forward?

One of the largest agricultural programs in the US is in the form of food stamps to poor consumers. Would you prefer to cap, perhaps even eliminate, the food stamp (SNAP) program? Would you prefer to replace it with a direct cash transfer system? Whom do you think generally should qualify either for food stamps or cash transfers?

Questions from FSE associate director David Lobell:

A major initiative of the Obama Administration has been Feed the Future, which aims at improving food security in other countries. Is the U.S. focused sufficiently on hunger in other parts of the world? Have actions matched rhetoric? Is a $3 billion expenditure on this initiative the right sum in an era of large fiscal deficits in the U.S.?

Question from research scholar Bill Burke:

The United States is viewed by many as a world leader, but its role in foreign assistance is contentious. In dollar terms, the United States consistently gives more foreign assistance than any other donor nation. In 2012, for example, the U.S. provided nearly 34 billion dollars, or more than twice as much as any other country. On the other hand, many criticize the U.S. for contributing relatively little in comparison to other countries when donations are measured as a share of GDP. Some also point out that much of what is labeled foreign assistance is actually military or security assistance, and does not contribute directly towards economic development. Does the U.S. spend too little or too much on foreign assistance, and should a greater proportion of U.S. funding go directly towards poverty reduction and food security?