Crops are feeling the heat
Warming temperatures over the past quarter-century have cut production of cereal crops worldwide by millions of tons and caused annual losses of roughly $5 billion, according to a study released Friday.
Laboratory also said the damage has been offset by production gains from
genetically modified crops and better farming techniques.
Researchers also
said they did not account for farmers making their own adjustments to cope with
the rising temperatures.
Impact of climate change
“The warming
we’ve already experienced since 1980 (about 0.7 degrees Fahrenheit) is having a
major impact on the production of crops,” according to lead author, David
Lobell. “It is true that the impacts of climate change have been relatively
small compared to the overall increase because of technology.”
The study
from the Livermore-based lab is the first to examine how much global food
production has been harmed by climate change, Lobell said. The study estimated
that the global temperature increase from 1980 to 2002 means 40 million fewer
metric tons of barley, corn, rice, sorghum, soybeans and wheat are produced
around the world each year, leading to an annual loss of $5 billion.
The
report does not include national or regional breakdowns. California officials
said there would be little effect on the nation’s top agricultural state, which
is not a major producer of grains other than rice.
Farmers are
sceptical
Farm researchers were sceptical of the study’s findings. Terry
Francl, a senior economist with the Washington, D.C.-based American Farm Bureau
Federation said: “The reality is we’ve had improved trends in yields during all
of that time. It’s hard to see how you would calculate global warming’s effect
on that.”
Longer growing seasons and an increase in carbon dioxide also
encourage plant growth. Yields have improved due largely to genetic modification
of grain crops, and farmers have adjusted to changing conditions by planting
crops where they grow best, Francl said. Lobell said changes in growing seasons
and carbon dioxide levels have tended to cancel each other out when it comes to
crop yields. He said researchers did not attempt to account for farmers’ crop
adaptation. “Farmers have the ability to adjust,” Lobell said. “But over
the last 20 years, there has been little evidence that farmers are adjusting.”
Related website:
Lawrence Livermore National Laboratory
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