Meteorologists have attributed the once-in-a-century drought parching southwest China to climate change.

The drought has left more than 18 million residents and 11.7 million head of livestock suffering drinking-water shortages over a region encompassing the southwestern provinces of Yunnan, Guizhou, Sichuan, the Guangxi Zhuang Autonomous Region and the municipality of Chongqing, data from the Ministry of Civil Affairs showed.

"The direct reason for the drought is light rain and high temperatures," Ren Fuming, a leading expert at China's National Climate Center, told the latest edition of Outlook Weekly, a well-known magazine in China.

Ren's opinion was echoed by Zhang Peiqun, also a meteorologist with the center.

Zhang said the rainfall in worst-hit Yunnan since September last year is the lowest in about 50 years while the average temperature since the beginning of winter is the highest.

"The decreased rainfall during the rainy season led to less water in store and high temperatures resulted in greater evaporation, directly causing the severe drought," Zhang said.

Zhang said the reasons underlying it were the complicated ocean currents and anomalous atmospheric circulation.

Zhang said the lingering cold air mass that formed last September in the Qinghai-Tibet Plateau had fenced off the warm and moist currents from the Indian Ocean and the Bay of Bengal, and at the same time the cold air from the north has had difficulty reaching the Yunnan-Guizhou plateau hinterland.

"The cold and warm currents can't converge to produce rain, so there is little rain," Zhang said.

Sun Honglie, director of the national expert committee on climate change, told the magazine that he was inclined to believe that the drought was a result of anomalous atmospheric currents.

"It is not an environmental or ecological problem," he said. "But the drought is bound to have an impact on the ecological system."

Another expert, Chen Yiyu, an academic at the Chinese Academy of Sciences, also said the year has seen anomalous climate conditions globally and that the drought in China is part of the phenomenon.

Globally, climate-related natural disasters have climbed from less than 50 a year in the 1950s to between 350 and 450 a year in the 2000s. In 2009, extreme weather events affected 55 million people around the world, according to figures released by the UN International Strategy for Disaster Reduction (UNISDR).