Meteorologists warned that global warming will bring changes to
surface runoff, the frequency of droughts and floods and the water
quality in some areas of China, and exacerbate the uncertainty of
the country's water resources and contradictions between demand and
supply.
Many Chinese and overseas meteorologists have expressed their
concern over "Our future climate" -- the theme of World
Meteorological Day (WMD) 2003, held annually on March 23.
They said further global warming will influence the earth's water
cycle by increasing evaporation and changing the quantity and
distribution of regional rainfall, which would make disasters like
floods and droughts more prevalent and serious.
China, the northern areas in particular, has witnessed a sustained
drop in precipitation since the rainfall in the country reached its
maximum in the 1950s, revealed the China Meteorological
Administration's (CMA) statistics.
Meteorologists estimated that the western regions of China will
lack about 20 billion cubic meters of water from 2010 to 2030,
andin 2050 the regions would still need 10 billion more cubic
meters of water.
The absence of adequate water conservation facilities in the west
could make the water resources system more fragile in the face of
the climate changes, they said.
China will face a tougher challenge in its water security as global
warming will further increase the evaporation of its seven major
valleys, of which the annual natural runoff has kept falling as a
whole during recent years, according to the CMA.
"The aridity caused by climate changes in drought seasons will
further deteriorate the already short water supply in the northern
and northwestern parts of China," said Professor Ding Yihui,
CMA'sspecial adviser on climate changes.
Ding said more evaporation and less flow of water due to climate
warming in certain areas would probably intensify the pollution of
rivers and lower the water quality.
The CMA's statistics show the temperature in China has risen 0.4 to
0.5 degree Celsius during the past century, slightly lower than the
global average increase of 0.6 degree.
"Global warming will have a more profound effect on the water cycle
in China's fragile arid and semiarid areas," said Zhu Changhan,
chief research fellow on climate effects with the National Climate
Center, adding that the northern China area would turn warmer and
drier.
Zhu said global warming would bring also about serious consequences
to the agriculture and hydropower in those drought-affected
areas.
However, some experts also said global warming might enhance the
earth's hydrological cycle and bring more rainfall worldwide on the
average.
"Precipitation is projected to intensity during the 21st century.
At low latitudes, there would be decreases in some regions and
increases in others while in middle to high latitudes,
precipitation would be intensified," said Godwin O.P. Obasi,
secretary-general of the World Meteorological Organization in his
address to the WMD 2003.
Some meteorologists said global warming would closely affect
China's security in sectors like food, water resources and
energy.
"The real risk is that the consequences caused by climate changes
are usually irreversible," cautioned CMA director Qin Dahe.
(Xinhua News Agency March 24, 2003)