May 9, 2011

 

World climate change affects grain production

 

 

Climate change decreases global wheat and corn production by more than 3% over the last 30 years in contrast to growth forecasts without an increase in temperatures, according to a study published in the journal Science.

 

The impacts translated into up to 20% higher average commodity prices, before accounting for other factors, the paper stated.

 

For example, 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.

 

However, that varied widely between countries with Russia, Turkey and Mexico which are more affected by wheat.

 

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 titled "Climate Trends and Global Crop Production Since 1980".

 

The paper showed 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 EU biggest producer, it said.

 

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

 

For soy, climate change winners and losers balanced each other out. 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 corn and wheat, the sizable yield setback from climate change is likely to incur 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 that spurs crop growth. The process is called CO2 fertilisation.

 

Including that effect would likely see a net benefit from climate change on soy 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.

 

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 US, 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 US and Europe.