The theme of the World Meteorological Day this year was "our future climate", which drew people's consideration about the deep influences of the warming climate on humanity.

The changes in climate have the most sensitive affects in agriculture, taking all the aspects of the human social and economic development as a whole, said Qin Dahe, director of the State Meteorological Administration.

Qin added that China is a major agricultural producer, and its sensitivity to the climate changes will be embodied in the fluctuation of agricultural output.

The scientific estimates jointly made by the state meteorological and agricultural departments indicated that by 2030 China's farming output may reduce by five percent to 10 percent ingeneral, with the reduction focusing mainly on the outputs of wheat, rice and corn.

The dioxide existing in the atmosphere constitutes the main factor leading to the output drop, as when its density and temperature rise, the dioxide may quicken the growth of crops and shorten their reproduction, said Ding Yihui, professor with the State Meteorological Administration.

Ding held that if counter-measures such as readjusting the agricultural planting system and reverse-resistant seed selection are taken, the changes in climate may not exert a negative impact on the country's grain output in the coming 30 to 50 years.

In contrast to the farming output reduction in general in the country, the warming climate may increase crop outputs in some areas located in the middle or high latitudes.

The study shows that by 2050, the warming climate may remove the northern boundary of the three-crop pattern areas from the Yangtze River delta to the Yellow River delta. The two-crop pattern areas will move northward to the middle part of the one-crop pattern area, and the plantation area of the one-crop patternwill reduce by 23.1 percent.

In addition, the changes will take place in the layout of the main crop varieties. The research shows that the winter wheat species currently produced in northern China may not adapt to the warming climate. And the rice species which are resistant to high temperatures may dominate southern China and move further northward.

Moreover, the early-maturing corn varieties in northeast China will be gradually replaced by the medium- and late-maturing varieties.

Research still shows that if there is no dramatic increase in rainfall, the warming climate will move the country's farming and pastoral cross belts southward. And the cross belts in the northern part of north China will move more than 150 kilometers southward.

Ding Yihui mentioned that the cross belt moving southward may increase the grassland area, but the newly-emerged transition areas may become deserted if no proper protection measures are taken.

He indicated that after the climate gets warmer, the decomposition in the soil may be quickened which may lead to the prevalence of pests and diseases and an overgrowth of weeds. And the increasing usage of the fertilizers, pesticides and weed killer may increase the farm production cost.

Experts here stressed that climate is an important environment for agricultural production. Only by bringing it in line with the general agricultural plan, can it bring benefits instead of damages to agricultural production.

(Xinhua News Agency March 24, 2003)