Tokyo's heat island

A flock of bright green parakeets fly above hemp palm trees. This is not a tropical rain forest but central Tokyo. According to Meteorological Agency statistics quoted in the Japan Times, August 18, 2004 by Eriko Arita, Tokyo’s annual average temperature has risen 3 degrees in the last century. Tokyo is much hotter than the surrounding cities.

This phenomenon is attributed to the heat island effect which is characteristic of big cities. Arita's article suggests several reasons for this effect. Quite a few areas in big cities are covered with concrete and asphalt, which maintain the solar heat during the day and release it at night. On the other hand, only a few areas in those cities are covered with vegetation and big cities have less open water which can reduce temperatures through evaporation. Furthermore, a considerable amount of heat exhausts is produced by automobiles and air conditioners. In addition, the many tall buildings built along Tokyo Bay recently block the wind which might have swept the heat away from central Tokyo.

The heat island phenomenon has many adverse effects. One of the most significant concerns is a threat to the health of Tokyoites. A government study released in early August last year, quoted in the Japan Times, September 24, 2001 article by Nick Corlis, says, the number of victims of heat stroke in Tokyo is three times greater than in 1985. It has increased in proportion to the temperature and the number of tropical nights.

To alleviate the heat island effect, a variety of counter measures have been being taken. Eric Johnston writes in the March 31, 2005 Guardian, that Prime Minister Koizumi urged office workers to forgo wearing jackets and ties in order to set air conditioners at a higher temperature. As no ties and jackets might be revolutionary to Japanese workers, its success depends upon whether bosses are willing to follow the government guidelines.

The Tokyo government uses more practical methods. It has set up an ordinance requiring at least 20 percent of buildings’ roofs be covered with vegetation if they are on plots of 1,000 sq. meters or more, according to the article by Eriko Arita.The same article also suggests that the construction of buildings near Tokyo Bay should be restricted to ensure a wind path.

The article also eports that some citizen groups have turned to traditional methods such as “Uchimizu” pouring water on the road. The water helps lower temperatures by carrying away heat when it evaporates.

Tokyo’s high temperatures are our own affair as its increases are outpacing global warming. In the near future Tokyo's temperature will top 40 degrees. To avoid science fiction like images of a Tokyo jungle with prevailing malaria, all members of the society should tackle the problem.