Rapid rise in Food prices driven up by global warming, study shows
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Perilous
Times and Climate Change
Rapid rise in Food prices driven up by global warming, study
shows
Scientists warn that farming practices must be adapted to a warmer
world and rises in global population
Damian Carrington guardian.co.uk, Thursday 5 May 2011 19.00 BST
Food prices have risen 20%, say scientists, as warmer temperatures
cause dehydration and prevent pollination in crop plants.
Photograph: David McNew/Getty Images
Global warming has already harmed the world's food production and
has driven up food prices by as much as 20% over recent decades,
new research has revealed.
The drop in the productivity of crop plants around the world was
not caused by changes in rainfall but was because higher
temperatures can cause dehydration, prevent pollination and lead
to slowed photosynthesis.
Lester Brown, president of the Earth Policy Institute, Washington
DC, said the findings indicate a turning point: "Agriculture as it
exists today evolved over 11,000 years of reasonably stable
climate, but that climate system is no more." Adaptation is
difficult because our knowledge of the future is not strong enough
to drive new investments, he said, "so we just keep going, hoping
for the best."
The scientists say their work shows how crucial it is to find ways
to adapt farming to a warmer world, to ensure that rises in global
population are matched by rising food production. "It is vital,"
said Wolfram Schlenker, at Columbia University in New York and one
of the research team. "If we continue to have the same seed
varieties and temperatures continue to rise, then food prices will
rise further. [Addressing] that is the big question."
The new research joins a small number of studies in which the
fingerprint of climate change has been separated from natural
variations in weather and other factors, demonstrating that the
effects of warming have already been felt in the world. Scientists
have shown that the chance of the severe heatwave that killed
thousands in Europe in 2003 was made twice as likely by global
warming, while other work showed that the floods that caused
£3.5bn of damage in England in 2000 were made two to three times
more likely.
Food prices have reached new record highs this year, and have been
implicated as a trigger for unrest in the Middle East and Africa.
A rising appetite for meat is a critical factor, said Wolfram. "We
actually have enough calories to feed the world quite comfortably,
the problem is meat is really inefficient," as many kilogrammes of
grain are needed to produce one kilogramme of meat, he said. "As
countries get richer and have a preference for meat, which is more
expensive, they price people in poorer countries out of the
market."
"The research provides evidence of big shifts in wheat and maize
production," commented Prof Tim Wheeler at the Walker Institute
for Climate System Research, Reading University, UK, who added it
had involved "heroic" statistical analysis. But he said that,
while long-term climate change impacts were another pressure on
food prices, short-term price spikes were linked to extreme
weather events, such as the Russian heatwaves and wildfires in
2010.
The study, published in the journal Science, examined how rising
temperatures affected the annual crop yields of all major producer
nations between 1980 and 2008. Computer models were used to show
how much grain would have been harvested in the absence of
warming. Overall, yields have been rising over the last decades
and the models took this into account. The scientists found that
global wheat production was 33m tonnes (5.5%) lower than it would
have been without warming and maize production was 23m tonnes
(3.8%) lower. Specific countries fared worse than the average,
with Russia losing 15% of its potential wheat crop, and Brazil,
Mexico and Italy suffering above average losses. Some countries
experienced lower production of rice and soybeans, although these
drops were offset by gains in other countries.
The losses drove up food prices by as much as 18.9%, the team
calculated, although the rise could be as low as 6.4% if the
increased carbon dioxide in the atmosphere strongly boosts plant
growth and yields - a factor that is not well understood by
scientists.
Global food prices have risen by about 200% in recent years, says
Schlenker. Other causes of the rise are the increased demand for
meat and the diversion of food into biofuels. Nonetheless, the
researchers conclude that the negative impact on crops overall is
"likely to be incurring large economic and health costs".
The US, which has the world's largest share of overall production,
stood out in the analysis because it appears to have lost no
production to climate change as yet. Schlenker said this was
because the rise in temperature there was very small compared to
other parts of the world. This was perhaps due simply to luck with
the weather, or the cooling influence of aerosol particles, such
as soot, that blocks warming.
"US farmers are having a good time in the sense that their yields
have not been impacted much and prices have been pretty high, so
for them it has been pretty profitable," he said. "But most
climate models predict that eventually the US will warm."
Adapting farming to climate change could involved moving to cooler
areas as existing areas warm, said Schlenker, but often soils are
poorer in the new locations. He highlighted the potential of
biotechnology - genetic engineering - to develop new crop
varieties that are more resistant to heat, but said the potential
remains unproven. "What happens over the next 20 years depends on
how optimistic you are about finding those extra ways of
adapting."