It’s offcial - climate change is affecting food production
and driving up food prices. And the future looks even
worse.

Climate change cut
global wheat and corn output by more than 3% over the past three
decades compared to growth projections without a rise in
temperatures according to a study released on Friday.

The impacts translated into up to 20% higher average commodity
prices, before accounting for other factors, according to the paper
published in the journal Science.

Crop yields rose over the period as a result of improvements in
practices and plant breeding, and the isolated, negative impact of
climate change was equivalent to about one tenth of those
advances.

But that varied widely between countries with Russia, Turkey and
Mexico more affected for wheat, for example.

The isolated impact of climate change on wheat and corn was a
warning of the future food supply and price impact from an expected
acceleration in warming, the paper said.

“Climate changes are already exerting a considerable drag on
yield growth,” said the study, entitled href=”http://www.sciencemag.org/content/early/2011/05/04/science.1204531”
target=”_blank”>Climate Trends and Global Crop Production
Since 1980.

Climate change directly affects food
production by changing agro-ecological conditions. Increased
seasonal variations in rainfall are expected to further affect
water availability, making yield prediction more difficult.
Changing weather conditions are also expected to bring new crop
diseases and pests

The authors used crop yield models with and without changes in
temperature and rainfall to show global falls in wheat output of
5.5% and 3.8% for corn as a result of climate change from
1980-2008.

That was equivalent to the entire annual corn crop of Mexico, or
the wheat crop of France, the European Union’s biggest producer, it
said.

Nationally, among the worst affected was Russia, with a nearly
15% cull in wheat, while the United States was unaffected.

For soybeans and rice, climate change winners and losers
balanced each other out. For example, rice gained in cooler, higher
latitude countries.

CO2

The paper, written by scientists from US institutions including
Stanford University and Columbia University, noted that adaptation
responses, such as advances in crop breeding, could soften the blow
of future warming.

“Without successful adaptation, and given the persistent rise in
demand for maize and wheat, the sizable yield setback from climate
change is likely incurring large economic and health costs,” it
said.

The study did not account for the impact of higher atmospheric
levels of carbon dioxide (CO2), the main manmade greenhouse gas
which is also a raw ingredient of, and so spurs, crop growth -
called CO2 fertilisation.

Including that effect would likely see a net benefit from
climate change on soybeans and rice since 1980, it said.

Conversely, the paper did not account for extreme heatwaves or
rainfall, which means the findings could under-estimate the global
warming impact.

Climate change is expected to
introduce pronounced regional shifts in agricultural production. As
sea levels are expected to rise, a considerable increase in
suitable cropland at higher latitudes in most developed countries
is expected - matched with a corresponding decline of potential
cropland at lower latitudes, where most developing countries are
located.

The output losses since 1980 translated into 18.9% or 6.4%
higher average commodity prices, excluding and including the effect
of CO2 fertilisation respectively.

The models were based on actual data which showed rising
temperatures across nearly all the world’s main growing regions
with the exception of the United States, which saw a slight cooling
over the period. Rainfall trends were more muted.

Concerns have grown in the past few weeks for the impact of
droughts on wheat yields in parts of the United States and
Europe.