Climate changes featuring global warming will have more negative effects on human society, according to experts at an ongoing seminar on climate changes and ecological environment in Beijing.

In addition, the average global temperature will increase by 1.4 to 5.8 degrees Celsius by 2100 up from 1990, and the average sea level worldwide will increase by 0.09 to 0.88 m, according to the third assessment report issued in 2001 by the Intergovernmental Panel on Climate Changes.

Based on this report, the experts predicted the output changes of global wheat, corn and rice in years 2020, 2050 and 2080, only to find that crop output in most developing countries will shrink, while that in developed countries in the northern hemisphere will increase.

Owing to global warming, China's crop output will shrink, while farming costs will increase, said Qin Dahe, director of the China Meteorological Administration (CMA).

Climate changes will also affect river routes, the frequency of droughts and floods, and the quality of underground water, plunging many countries into water supply difficulties.

Global warming will also exacerbate the incidence of some infectious diseases carried by insects, food or water in less-developed areas.

However, some experts claimed that the expected climate changes may result in increased agricultural output in the middle- and high-latitude areas, a reduced death rate from cold, increased wood output and less energy consumption.

Edited by Li Guixiang.