BEIJING, Jan. 3 (Xinhua) -- Rising temperatures may pose a challenge to the long-term food security of China, the world's most populous country, according to an official report evaluating climate change.

    China's output of major crops, including rice, wheat and corn, could fall by up to 37 percent in the second half of this century if no effective measures are taken to curb greenhouse gases in the coming 20 to 50 years, according to the report.

    Global warming will negatively impact China's ecological, social and economic systems, especially farming, animal husbandry and water supply, and some damage will be irreversible, said the report.

    The average temperature in China has risen by 0.5 to 0.8 degree centigrade in the past century and is expected to go up another two to three degrees centigrade in the coming 50 to 80 years, it said.

    Most areas in China, especially northern areas, will get drier, even though annual rainfall may increase 7 to 10 percent, it said.

    The greater demand for water for agriculture will impact the cost of farm produce, it reasoned.