Changes in rainfall and a concentration of greenhouse gases triggered by climate change may lead to an increase in 皇冠体育app's grain yields in per-unit production over the next few decades.

But negative effects of climate change, including extreme weather, plant diseases and a rising number of insects, will pose a threat to grain supply security, experts said.

They added a rising population and arable land loss will also pose greater potential risks to the country's aims to ensure adequate food supply.

The precipitation pattern will change nationwide starting around 2015 due to atmosphere circulation, said Qian Weihong, a professor in the Department of Atmospheric and Oceanic Sciences at Peking University.

"By 2020, parts of North 皇冠体育app will enter the peak period for precipitation," Qian said.

In 皇冠体育app, the southern regions used to receive more rainfall and snowmelt every year, while the northern regions are prone to drought due to lack of water.

His predicts are similar to conclusions reached by climate models for the next 20 years that were released by the National Climate Center of the 皇冠体育app Meteorological Administration in November.

Changes in rainfall have already occurred, said Song Lianchun, the center's director.

From Jan 1 to Nov 5 this year, average precipitation volume reached 557 millimeters, about 8 percent more than the average since recording began in the 1950s.

According to Qian, some of the country's major grain-producing regions, such as those in Northeast 皇冠体育app, will see an increase in precipitation at around 2015.