The Picture taken on April 22, 2008 of a crop duster plane spraying fungicide to protect the 7,000 hectare banana plantation of Tagum Agricultural Development Co. from destructive leaf virus in Tagum in Davao del Norte province, located in the southern Philippine island of Mindanao. Farm chiefs have a narrowing chance to diversify vital crops at rising threat from drought, flood and pests brought by climate change, food researchers warned on October 3, 2011. – AFP Photo

PARIS: Farm chiefs have a narrowing chance to diversify vital crops at rising threat from drought, flood and pests brought by climate change, food researchers warned on Monday.

The world’s nearly seven billion people are massively dependent on a dozen or so crops that, thanks to modern agriculture, are intensively cultivated in a tiny number of strains, they said.

When climate change gets into higher gear, many of these strains could be crippled by hotter and drier -- or conversely wetter -- weather and exposed to insects and microbial pests that advance into new habitats.

“Farmers have always adapted, but the pace of change under climate change is going to be much greater than in the past. There’s going to be a real need to move fast,” Bruce Campbell, head of a research programme called Climate Change, Agriculture and Food Security (CCAFS), told AFP.

In a series of studies, the experts highlighted the risk for staples such as wheat, corn, bananas and cassava.

They described the example of the potato, whose starch is a vital nutrient to hundreds of millions of people.

Although it is a hardy tuber, the potato is vulnerable to heat stress, which curbs growth and starch formation.

Warming will make potato-growing more hazardous in southern Africa and tropical highlands, and encourage the spread of an insect pest, the potato tuber moth, into more northerly latitudes. On the other hand, “late blight” -- the fungus that unleashed the Irish potato famine of the mid-19th century -- will be less of a threat.

At least $7 billion per year in extra funding will be needed for irrigation investments, agricultural research and rural infrastructure, according to the estimates.

To diversify crops, seed banks and genome libraries will play a key role.

Drawing on knowledge of DNA traits in wild plants will help breeders splice in genes to help cope with harsher conditions.

Genetic engineering, contested by many green groups, is also an option but using it “is a question that is left to society to answer,” said Campbell cautiously.

The UN’s Intergovernmental Panel for Climate Change (IPCC) estimates Earth’s surface will probably warm by between 1.8 and 4.0 degrees Celsius (3.24-7.24 degrees Fahrenheit) over the 21st century.

Campbell said many scientists suspect that climate change is already well on the march, as evidenced by shifts in rainfall patterns and growing seasons in many observed locations.