ENVIRONMENT: Japan Swelters Under Urban Heat Island Effect

By Suvendrini Kakuchi Reprint | | Print |

Suvendrini Kakuchi

TOKYO, Aug 31 2006 (IPS) - The gleaming high rise buildings that crowd the cityscape may symbolize Japan’s economic recovery but they have also converted this priciest of human habitats into vast heat-trapping canyons in what is known as the urban heat island (UHI) effect.

Heat churned out by air-conditioners, automobiles and human activity finds no escape, causing ambient temperatures, especially in the summer months, to rise by several degrees and forcing authorities to constantly look for newer ways to cool down a city on the boil.

For some years now a favoured method has been the nurturing of rooftop gardens. There are laws stipulating that high rises reserve some of their precious surfaces for plants and shrubs – but the concrete jungle has been growing faster.

”Tokyo has turned into a nightmare caused by government policy that prioritises the economy over environmental protection,” said Komichi Ikeda, deputy director of the Environmental Research Institute Inc. a private organization comprising environmental scientists.

Ikeda, a leading expert on UHI, says Japan’s building boom is rooted in boosting real estate value and fetch massive profits for land owners and developers at the expense of the environment and the health of residents.

A report released by the Tokyo Metropolitan government this year shows that average temperature rise in the capital over the course of the 20th century has been 3 degrees C.

‘’Accompanying this temperature rise,” says Takako Yamaguchi, official in charge of monitoring the UHI effect, ‘’is the city’s electricity consumption that has grown four times more than the five million kw recorded in 1975, mostly due to air-conditioning.”

Yamaguchi also told IPS that the number of days recording temperatures of over 35 degrees C has gone up to more than 35 days a year, concentrated around the three summer months between July and September. That contrasts with the 14 days recorded in 1975.

With humidity hovering around 70 percent on average, the summers have become steamy and uncomfortable for the 12.5 million residents. The city’s population nearly doubles during the day as office goers and workers pour in.

According to surveys conducted by the health and welfare ministry, the reported number of deaths related to serious heat exhaustion in central Tokyo has grown to 23 in 2005, compared to 17 in 2003.

Tokyo has an estimated 600,000 asthma patients, a condition aggravated by automobile exhaust, representing the largest single largest concentration of the total three million sufferers in the country.

This summer as urban Japanese swelter under high humidity, UHI seems to be on everybody’s lips.

The media now point to data showing how the summer nights that traditionally brought relief to Tokyoites, are not effective any more, having been blocked out by the tall structures that wall off Tokyo bay. The much admired neon glitter of the Shinagawa seafront actually obstructs the cool breeze that once flowed into the city after dark.

Shinagawa, a former warehouse district, brims with posh shopping malls and a new bullet train station. In 2003, the area had 89 buildings higher than 13 floors, compared to five in 1997.

Data released from the metropolitan administration show parts of Tokyo that are close to the sea hotter in the evening compared to inland areas. Researchers have also found from tests that temperatures are significantly lower close to green areas such as the parks of Tokyo.

Yamaguchi says that, besides regulations requiring new high rise buildings to have rooftop gardens, roads are to be constructed with a lattice of pipes beneath the surface to circulate cool sea water pumped in from Tokyo bay.

Other costly solutions now being considered including a mind boggling plan to ship snow collected from Hokkaido, Japan’s northern island, to be stored in basements for a cooling effect.

‘’For the first time in history,” she explained, ‘’we are also providing subsidies of up to 20 million dollars for the 2006 fiscal year, to support one-third of the budget needed to include these facilities.”

But Ikeda is not impressed. ”All these steps are important but, as usual, the government refuses to deal with the root causes of the heat island effect such as taking steps to curtail high rise buildings or reducing the number of cars,” she said.