BEIJING-- Rising temperatures will expose China's Yangtze River basin to extreme weather such as severe floods, drought and storms that could threaten cities such as Shanghai, a new report has said.

In the coming decades, global warming will increase glacier melt in the Himalayan reaches of the Yangtze, diminish food production in the basin and lead to rising waters in coastal regions, said the World Wide Fund for Nature, which co-authored the report with Chinese research institutes.

"Extreme climate events such as storms and drought disasters will increase as climate change continues to alter our planet," Xu Ming, lead researcher on the report, said in a statement released Tuesday.

"If we take the right steps now, adaptation measures will pay for themselves."

Up to 400 million people live in the Yangtze River basin, which cuts a swathe through the middle of China and includes some of the nation's most productive agricultural lands.

Over the next 50 years, temperatures in the basin will climb by an average of 1.5-2.0 degrees Celsius (2.7-4.0 degrees Fahrenheit), leading to an increased number of natural disasters, the report said.

The basin has already seen a spike in flooding, heat waves and drought over the past two decades as temperatures rose by an average of 1.04 degrees Celsius between 1990 and 2005, it said.

Meanwhile, sea levels at Shanghai rose 11.5 centimeters (4.6 inches) over the last 30 years and will rise by an additional 18 centimeters by 2050, threatening the city's water supply, it said.

"Climate change will make coastal cities like Shanghai more vulnerable to sea level rises, extreme climate events, as well as natural and human-induced disasters," the report warned.

The production of crops in the basin such as corn, winter wheat and rice will fall considerably, the report said.

The rice harvest alone could fall by between nine and 41 percent by the end of the century, the group warned.

The report, jointly produced by researchers from the China Academy of Sciences and other institutes, along with the WWF, was issued ahead of key climate change talks in Copenhagen next month that will seek to reach a new international accord to replace the Kyoto Protocol, which expires in 2012.

China and the United States are the world's leading producers of greenhouse gases that lead to global warming.