Ding Yihui: Urbanization affects climate

World Expo 2010 Shanghai will be another landmark event for China to present itself to the world after the 2008 Beijing Olympic Games. As a Shanghainese working in Beijing, I would like to extend my best wishes for the success of this great event.

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We all know that a World Expo lasts much longer than the Olympic Games, so the meteorological services for the former pose even greater challenges. The most critical services our administration provided for the Olympic Games were focused on the opening and closing ceremonies.

By contrast, the six-month World Expo requires not only forecasts on meteorological trends but also climatic and weather forecasts for each month, each week and each day to facilitate the scheduling of visits and activities.

The Shanghai World Expo provides a golden opportunity for increasing public awareness about climate. We can use this platform to educate visitors to Expo about the importance of climate and environmental protection. I know the organizers are preparing a climate pavilion, which will be an important venue.

China has recorded rapid economic growth over the past 30 years. As a result, the pace of urbanization has quickened, too. Although urbanization has contributed positively to Chinaís growth, it has also produced considerable negative side-effects in terms of climate and ecology.

Climatic changes resulting from urbanization create:

Ding Yihui, born in 1938, is an international climate scientist. He is deputy director-general of Climate Change Experts Committee andexecutive director of the scientific committee of World Climate Research Program. [en.expo2010.cn]

1. Greater risk of flooding and waterlogging due to strong, convective weather resulting from urban expansion and increases in the ìurban heat island effect.? At the same time, widespread drought resulting from climatic changes may also seriously affect water supplies to urban areas.

2. High temperatures and heat waves. With climatic warming, cities are suffering more from excessive temperature. The duration of sultry weather has become abnormally long, producing record-breaking high temperatures.

3. Low temperatures, sleet and snowy weather.

4. Strong winds. Crowded skyscrapers in a city often produce funneling effects that increase wind velocity.

5. Urban heat island effects. According to the latest statistics from the China Meteorological Administration, about one-fourth of the temperature rise caused by climate warming can be blamed on the "urban heat island effect." Other phenomena resulting from urbanization include dry islands, wet islands, dark islands and rain islands in cities.

6. The atmospheric effect of aerosols. These substances influence cities in many ways: polluting the air and consequently endangering public health, as well as reducing visibility and increasing the frequency of hazy days.

As the first World Expo to embody "city" and "life" in its theme, World Expo 2010 Shanghai will imprint some long-lasting "Shanghai memories" in the history of World Expos if we can take this opportunity to enhance the public awareness of climate change and environmental protection.