A combine harvester reaps, threshes and winnows its way through a field of corn at harvest time. Yields in the US, Canada and northern Mexico have yet to feel the impact of global warming. Credit: UDSA/Bruce Fitz
Researchers propose ‘whole-system redesign’ of U.S. agriculture
changes in markets, policy and science, rather than just incremental
changes in farming practices and technology, will be critical if the
United States is to achieve long-term sustainability in agriculture,
according to a nationwide team of agriculturists that includes a
University of California, Davis, animal scientist.
team’s recommendations, first published as a 2010 report by the U.S.
National Research Council, appear as a Policy Forum piece in the May 6
issue of the journal Science.
The lead author of the paper is John Reganold, regents professor of
soil science and agroecology at Washington State University, Pullman.
decades, the agricultural industry, research community and government,
have looked to incremental improvements in agricultural procedures and
technologies for achieving advances in productivity,” said Deanne Meyer,
a Cooperative Extension livestock waste management specialist in the UC
Davis Department of Animal Science and a member of the research team.
noted that such incremental improvements have included adoption of
two-year crop rotations, precision agriculture technologies, classically
bred and genetically engineered crops, and reduced- or no-tillage
all of these have resulted in important improvements, it’s become
apparent that as modern agriculture also grapples with important issues
such as global climate change, biodiversity, resource conservation and
public health problems, a more transformative approach is needed,” she
an approach would balance production goals with long-term
sustainability concerns involving the environmental, social and economic
impacts of agriculture. It would focus on a “whole-system redesign”
that would address policy and market issues, as well as technological
issues, the researchers recommend in their report.
approach would incorporate innovative agricultural systems such as
organic farming, grass-fed and other alternative livestock production
systems, mixed crop and livestock systems, and perennial grains. And it
would require significant changes in market structures, policy
incentives and public funding for agricultural science, according to the
research team suggests that with a new version of the U.S. Farm Bill
due in 2012, the time is now ripe to begin reforming U.S. agriculture.
The team’s 598-page 2010 National Research Council report, “Toward Sustainable Agricultural Systems in the 21st Century.”
U.S. farmers dodge the impacts of global warming — at least for now
warming is likely already taking a toll on world wheat and corn
production, according to a new study led by Stanford University
researchers. But the United States, Canada and northern Mexico have
largely escaped the trend.
appears as if farmers in North America got a pass on the first round of
global warming,” said David Lobell, an assistant professor of
environmental Earth system science at Stanford University. “That was
surprising, given how fast we see weather has been changing in
agricultural areas around the world as a whole.”
and his colleagues examined temperature and precipitation records since
1980 for major crop-growing countries in the places and times of year
when crops are grown. They then used crop models to estimate what
worldwide crop yields would have been had temperature and precipitation
had typical fluctuations around 1980 levels.
The researchers found that global wheat production was 5.5 percent lower than it would have been had the climate remained stable. Credit: USDA/Stephen Ausmus
researchers found that global wheat production was 5.5 percent lower
than it would have been had the climate remained stable, and global corn
production was lower by almost 4 percent. Global rice and soybean
production were not significantly affected.
United States, which is the world’s largest producer of soybeans and
corn, accounting for roughly 40 percent of global production,
experienced a very slight cooling trend and no significant production
of North America, most major producing countries were found to have
experienced some decline in wheat and corn (or maize) yields related to
the rise in global temperature. “Yields in most countries are still
going up, but not as fast as we estimate they would be without climate
trends,” Lobell said.
Lobell is the lead author of a paper about the research to be published May 5 online in Science Express.
India and France suffered the greatest drops in wheat production
relative to what might have been with no global warming. The largest
comparative losses in corn production were seen in China and Brazil.
worldwide relative losses of the two crops equal the annual production
of corn in Mexico and wheat in France. Together, the four crops in the
study constitute approximately 75 percent of the calories that humans
worldwide consume, directly or indirectly through livestock, according
to research cited in the study.
the relatively small temperature trends in the U.S. Corn Belt, it
shouldn’t be surprising if complacency or even skepticism about global
warming has set in, but this study suggests that would be misguided,”
1950, the average global temperature has increased at a rate of roughly
0.13 degrees Celsius per decade. But over the next two to three decades
average global temperature is expected to rise approximately 50 percent
faster than that, according to the report of the Intergovernmental
Panel on Climate Change. With that rate of temperature change, it is
unlikely that the crop-growing regions of the United States will
continue to escape the rising temperatures, Lobell said.
climate science is still unclear about why summers in the Corn Belt
haven’t been warming. But most explanations suggest that warming in the
future is just as likely there as elsewhere in the world,” Lobell said.
“In other words, farmers in the Corn Belt seem to have been lucky so far.”
This is the first study to come up with a global estimate for the past 30 years of what has been happening, Lobell said.
develop their estimates, the researchers used publicly available global
data sets from the United Nations Food and Agriculture Organization and
from the University of Delaware, University of Wisconsin, and McGill
The researchers also estimated the economic effects of the changes in crop yield using models of commodity markets.
found that since 1980, the effects of climate change on crop yields
have caused an increase of approximately 20 percent in global market
prices,” said Wolfram Schlenker, an economist at Columbia University and
a coauthor of the paper in Science.
said if the beneficial effects of higher carbon dioxide levels on crop
growth are factored into the calculation, the increase drops down to 5
percent sounds small until you realize that at current prices world
production of these four crops are together worth nearly $1 trillion per
year,” Schlenker said. “So a price increase of 5 percent implies
roughly $50 billion per year more spent on food.”
commodity prices have so far benefited American farmers, Lobell and
Schlenker said, because they haven’t suffered the relative declines in
crop yield that the rest of the world has been experiencing.
will be interesting to see what happens over the next decade in North
America,” Lobell said. “But to me the key message is not necessarily the
specifics of each country. I think the real take-home message is that
climate change is not just about the future, but that it is affecting
agriculture now. Accordingly, efforts to adapt agriculture such as by
developing more heat- and drought-tolerant crops will have big payoffs,
even today. “
Justin Costa-Roberts, an undergraduate student at Stanford, is also a coauthor of the Science paper.
David Lobell is a researcher in Stanford’s Program on Food Security and
the Environment, a joint program of Stanford’s Woods Institute for the
Environment and Freeman Spogli Institute for International Studies.
Schlenker is an assistant professor at the School of International and
Public Affairs and at the Department of Economics at Columbia.