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The Potential Impacts of Climate Change on U.S. Agriculture: What Can Farmers Do About it? - September 29, 2003
- Go To:
- Introduction
- Agenda
- White Paper
- Press Release
- Lecture Videos
White Paper - Download Printable PDF
Introduction
Eric Chivian M.D., Director, Center for Health and the Global
Environment
Recent Climate Variability and Future
Climate Change: What They Mean for the Nation’s Farmers
William Easterling Ph.D., Professor of Agronomy and Director
of the Institutes of the Environment, Penn State University
Climate Change Effects on Crop Diseases and Pests
X.B. Yang Ph.D., Associate Professor of Plant Pathology, Iowa
State University
Carbon Sequestration on Farms
Charles W. Rice Ph.D., Professor of Soil Microbiology, Kansas
State University; Director, Consortium for Agricultural Soils Mitigation
of Greenhouse Gases
Wind Energy and the Production of Biofuels
Dan McGuire, CEO, American Corn Growers Foundation
Heat waves and drought this summer in Europe and in parts of the
U.S. farm belt have resulted in marked losses in crop productivity
and have raised the question about whether these extreme weather
events are a preview of things to come in a world warmed by increasing
concentrations of greenhouse gases generated by human activity. In
Europe, record-setting temperatures withered crops in virtually every
country, with the greatest damage occurring in Eastern Europe. For
example, the Ukraine, long a leading wheat exporter, has been forced
this year to import wheat, as its harvest plummeted from 21 million
tons in 2002 to 5 million this year. In the U.S., for the second
straight year in Kansas, and in parts of Missouri and Nebraska, severe
drought and temperatures of 100 degrees Fahrenheit or more for days
on end have destroyed crops on millions of acres and brought back
memories of the 1930s Dust Bowl.
This briefing will examine some of the impacts that climate change,
with warmer and more variable weather, has had, and is projected
to have, on U.S. agriculture. It will also cover what farmers can
do to mitigate climate change – through such practices as carbon
sequestration in soils, the production of biofuels, and the use of
wind energy on their farms.
Since the 1970s, U.S. agriculture has achieved enhanced productivity,
but it has also experienced greater variability that has been, in
part, climate related. The most recent climate models predict that
the nation’s grain producing regions will warm on average more
than the rest of the world and that, despite receiving more precipitation
(with an increase in high-intensity rainfall events), they will also
experience more droughts. While some farmers in the U.S. growing
some crops in some years may prosper because of warmer temperatures,
more precipitation, and CO2 fertilization, U.S. agriculture in general
is likely to become increasingly unstable, and farmers may find it
hard to plan what crops to plant and when.
Scientists project that this instability will come in the form of
more intense and frequent extreme weather events (very high temperatures,
torrential rains and flooding, and droughts) linked to global climate
change. Such events have already taken a heavy toll on U.S. crop
yields. The drought of 2003, for example, was in large part responsible
for a 94 million bushel decrease in end season U.S. wheat stocks,
and, based on figures as of September 1, 2003, national average soy
bean yields are estimated at 36.4 bushels per acre, the lowest levels
since 1996. Some farmers in Kansas have reported corn harvests of
30 to 40 bushels per acre, rather than their typical averages of
around 150 bushels per acre.
Based upon historic trends and current research, warmer temperatures
and extreme weather events will also augment crop losses from pests
(i.e., insects, infections, and weeds). In three growing seasons
between 1988 and 1990, pests destroyed approximately 37% (amounting
to $22 billion) of total North American crop value. Climate change
triggers an increased pest burden upon crop yields in several ways.
For one, warming allows for more breeding cycles per season for some
insects that destroy crops, as well for as an expansion of their
ranges. In addition, warmer winters in northern production regions
have increased winter pest survival and outbreaks of the insect-borne
viral diseases associated with them. There has also been an increase
in the number of pests affecting certain crops. Soybeans are now
under threat from twice the number of diseases that they were in
the mid 1980s.
The increase in pest numbers and distribution has made the task
of containing them costly. New diseases in particular pose significant
control problems, as they may not respond to established pest control
measures. Moreover, efforts to develop disease- or insect-resistant
crops can take several years while disease problems can emerge in
one or two seasons.
The continued build-up of CO2 in the Earth’s atmosphere, now
at a rate of over 1500 million metric tons per year, thus poses a
clear threat to sustainable agriculture in this country. Farmers
can do much on their own to lessen the amount of greenhouse gas accumulation
and can benefit financially in the process.
Conservation tillage, a practice that limits the extent to which
soil is plowed, has been shown to reduce soil erosion and improve
soil moisture retention, particularly in times of drought. While
conventional soil tilling can deplete soil carbon stores, conservation
tillage can increase soil carbon by 0.1-0.2 metric tons per acre
per year. Replanting with grasses can likewise sequester atmospheric
carbon in farmland soils. By current estimates, carbon sequestration
practices in agricultural lands, combining all known strategies,
could reduce total U.S. carbon emissions by 200 million metric tons
or 15% of the total carbon emissions in the U.S. per year. Private
carbon emissions trading markets, which have begun to be implemented
in the U.S., could provide farmers with a significant economic incentive
to engage in these practices. Early estimates indicate that the potential
for “carbon credits” for U.S. agriculture could reach
$1-$5 billion per year for the next 20-40 years.
Carbon emissions may also be reduced via a transition to non-fossil
fuel based energy sources. Wind turbines provide clean energy to
society and a steady cash flow to farmers who put them on their land.
They also relieve some pressure on the demand for natural gas, which
helps hold down its price as well as that of its derivatives, which
include ammonia-based fertilizers. Farmers can produce other non-fossil
fuel based energy sources as well, including corn for ethanol and
the raw materials (such as soy) for biodiesel fuel. There is also
great potential for the use of anaerobic digesters on farms, where
crop and animal wastes can be turned into methane. Taken together,
these clean, renewable energy sources can boost farm income while
having a positive effect on farm-based emissions of carbon, as well
as on air pollutants such as SOx and NOx.
References for More Information:
- The Potential Consequences of Climate Variability and Change
for the United States 2002. Report of the Agriculture Assessment
Team, U.S. National Assessment. Cambridge University Press, New
York
- Crop diseases and pests (pdf)
- Carbon sequestration www.casmgs.colostate.edu/
- Biodiesel www.biodiesel.org/resources/fuelfactsheets
- Ethanol The Energy Balance of Corn Ethanol: An Update www.usda.gov/oce/oepnu/aer-814.pdf (PDF)
- Wind Energy www.awea.org/pubs/factsheets/WindEnergyAnUntappedResource.pdf (PDF)
- Anaerobic digestion www.earthpledge.org/foodwaste.html
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