Thursday, 2 September 2010

Tokyo's heat island Part 1

Netaiya  or 'tropical nights' , defined as  nights above 25 degrees have been standard for the past  2 months - fifty  nights above 25 degrees so far this summer in Tokyo.   It's  forecast to be 28 over night tonight. That is like Sydney's average summer MAXIMUM.  !  eeewwww.... hot.... at least hot for a minimum.    I would guess that  that usually there are about 2, perhaps 3 weeks of the year that have netaiya.  It's been a really hot summer; hot more in terms of minimum temperatures, rather than that maximum. Yesterday it was announced as having been the hottest summer on record.  There are no doubt seasonal factors like  warm currents keeping high pressure systems rooted over the Japanese archipelago, and everywhere is hot, not just Tokyo,  but. the heat island effect is undeniable.

According to a Tokyo Metropolitan Government white paper (1) the average mean temperature in Tokyo has increased 3.5 degrees over the past hundred years - way ahead of international levels.  (0.6 degrees).  Furthermore,  between 1990 and 2003, Tokyo's energy use increased 12%. Of this only 3% has come from renewable energy.  (2)   I couldn't clear reasons  stated in the white paper, but as industry increasingly moves to China, and as the population growth is relatively static  I don't think either of these are likely to be major factors. In the absence of the white paper coming up with ideas for why, I decided to come up with my own list :)

Trends in Population in Tokyo
Tokyo's population

I don't have time to finish this now, will write part two after I get back from Noto next week. :)


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