Global food supplies at risk

2006-06-30 11:09

Washington - Global food supplies may be at risk without new production methods because rising carbon dioxide (CO2) levels fail to compensate for drier conditions associated with global warming, a study said on Thursday.

Researchers used landmark open-field tests to study how the world's main staples - such as corn, rice, sorghum, soybeans and wheat - would grow under conditions projected for 2050.

The study, published in Science magazine, found that crop yields were about 50% below those drawn from similar, earlier experiments conducted in enclosed test conditions.

It assumed that CO2 rates in 2050 would be 1.5 times greater than now, while ozone levels were projected to rise by about a quarter.

Earlier studies had presumed that higher CO2 rates - which increase photosynthesis and decreases crop water use - would compensate for the drier conditions associated with global warming as well for larger amounts of ozone, which is toxic to plants.

The Free-Air Concentration Enrichment technology experiments, said the researchers, "clearly show that much lower CO2 fertilisation factors should be used in model projections of future yields".

The landmark open-air study was conducted at the University of Illinois at Urbana-Champaign.

- AFP