From China Daily report:
“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.
…
“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.