Beijing has hotter summers due to urban "heat island" effect
(Xinhua)
Updated: 2004-06-25 09:30

The urban "heat island" effect is bringing Beijingers more scorching summer days, as the "heat island" now covers about 20 percent of the 1,040-sq-km downtown area of China's capital, according to the latest scientific research findings.

Studies using remote sensing technology discovered that the urban "heat island" effect was a major factor behind the air temperature rise in Beijing, said Li Yanming, a senior engineer with the Beijing Research Institute of Garden, at an internationalurban "heat island" effect symposium held Wednesday in the city.

Beijing's downtown area under the unified design by the municipal government had its land area used for construction purposes almost double the level 15 years ago, whereas the area ofnatural plants, including farm land, reduced from 645 sq. km to 279 sq. km, according to Li Yanming. This made the capital look like a huge "heat island", Li added.

The term "heat island" comes from the fact that in an air temperature distribution graph, the high temperature part has a shape of an "island".

Originating in the early 19th century, "heat island" studies focus on the manmade effect on temperature gap between a city's downtown and suburban areas and the ensuing impact on the urban ecological environment.

A research team headed by Li Yanming found that Beijing's "heatisland" featured low green patch coverage but high concentration of buildings. It is also densely populated, with a great deal of artificial heating resources.

To allay the urban "heat island" effect, it is imperative to increase the areas of water surface and green patches, Li said. Research shows that when a city's green coverage surpasses 40 percent, the "heat island" effect will be lowered notably.

In this regard, Beijing has cultivated 81 vast green patches since 1999. Another seven patches of large wedge-shaped green lotswill be arranged with a combined area of 175 square kilometers between the downtown and suburban areas of Beijing to raise the city's green coverage to 43 percent by the time the city hosts theOlympic Games in 2008.

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