The country's grain harvest is likely to fall considerably because of global warming and it will need an additional 10 million hectares of arable land to feed the people by 2030, a top climate official said yesterday.

"Global warming may cause the grain harvest to fall by 5 to 10 percent, that is by 30-50 million tons, by 2030," said Zheng Guoguang, head of the State Meteorological Administration.

And since the population is expected to peak at 1.5 billion in 2030, 200 million more than now, the country would need to produce an additional 100 million tons of food to feed them.

Factoring in the two elements, the country will need more than 10 million hectares of arable land by 2030 to ensure food security, Zheng said at the first Ecological Well-off Forum in Hohhot, capital of north China's Inner Mongolia Autonomous Region.

Global warming has a negative impact on agricultural products, changing both the life pattern of principal grains and increasing the cost of production because more money would be needed to fight new insects and diseases, he said.

"Warmer weather will shorten the growth period of some grains and their seeds won't have enough time to ripen."

The swarm of insects will increase, too, because warmer winters will enable them to be active in spring, Zheng said.

Also, a 1 C rise in temperature would hasten the speed of ground water evaporation by 7 percent and that would greatly affect grain production, he said.

Global warming will cause more drought in the already dry low-lying and mid-altitude areas, reducing rainfall by 10 to 30 percent by 2030, Zheng said. On the other hand, wet high-altitude areas will experience more drastic floods, making agricultural production a hostage to more weather-related disasters.

"Climate change will cause corn and rice production both to fall. It could have little impact or even help wheat production in some areas, though."

There are places in Northeast China where grain production has gone up because rice could be grown there owing to warmer winters, he said. But in most of the regions, grain production has fallen because of global warming.

Zheng said his administration and the Ministry of Agriculture have been carrying out researches to minimize the effects of global warming on agriculture.

The country should change the pattern of the major types of grains, and adjust agricultural production to tackle global warming to ensure food security.

An expert with Chinese Agriculture University, surnamed Li, however, said technological breakthroughs in agriculture, including increasing the yield, could ease the tension.

Attention nevertheless has to be paid to "shrinking arable land because of excessive urbanization," Li said. China has set a bottomline of 12 million hectares of arable land by 2010, but the country is already approaching that target.

Also, Zheng said global warming will cause the country's forest resources to shift northward and trees will grow at higher altitudes, Zheng said. "This could increase the country's forest products."

(China Daily August 23, 2007)