By Kirye (in Tokyo)
On March 13, Japan’s Honmaddeka TV spoke about THE SANKEI NEWS, which reported there is a possibility that people will become less able to see cherry blossoms in full bloom in the near future. Readers may surmise the culprit for this themselves.
Biologist Dr. Kiyohiko Ikeda tells audience on Honmaddeka TV that warming in Tokyo is due to urban heat island effect, not global warming. (Image: Honmaddeka TV).
Urban heat island effect responsible for Tokyo’s warming
However well-known Japanese biologist Dr. Kiyohiko Ikeda poured some cold water on that claim, commenting on Honmaddeka TV last Wednesday: “They said that it’s global warming’s fault, but actually it is because of heat island effect. Most of the cherry trees are in cities, for example in the neighborhood of Tokyo or surroundings. The urban areas are getting warmer. Tokyo has gotten warmer by 3.2℃ over the last one hundred years and Hukuoka by 3.1℃.”
Rural locations not warming
Dr. Ikeda then noted: “However in Hachijojima and Miyakejima [islands of Tokyo], the temperature did not change in the period. So only cities are getting warmer. Urban cherry blossoms are getting worse. Cherry trees […] get a real wake-up after being exposed to cold winter temperatures for a long spell. There are people who worry that the cherry tree period of dormancy won’t work if the weather warms earlier and so they will not blossom in a normal way.”
No warming in 90 years
Unadjusted data from the NASA and the JMA for island of Hachijojima (Tokyo) and Tokyo city back up his statement. In fact, Hachijojima has not seen any temperature increase since 1926, i.e. 90 years (NASA data begin in December):
Comparing the rural (island) Hachijojima’s trend to Tokyo’s since 1980:
Tokyo’s mean annual temperature has been rising, while nearby rural island Hachijojima has not seen any warming this century. Chart: KiryeNet.
Tokyo cherry trees haven’t been blossoming earlier
Though historical observations for cherry blossoms in Tokyo show they have been appearing earlier over the long-term, they have not been occurring earlier since the start of the current century:
Chart by Kirye; data from the Japan Meteorology Agency (JMA). 2019 data will be available soon.
That should not be a surprise because although Tokyo long-term annual temperature has risen, its winters have not warmed up since 1985:
Chart: Kirye; data from JMA.
In summary, mean annual temperatures in Japan’s urban areas are being impacted hugely by urban heat island effect. Yet in the countryside – away from all the asphalt, steel and concrete – this is not quite the case at all. In the media we are seeing more hysteria than fact when it comes to aspects such as cherry blossoms and warming.
P. Gosselin (Germany) contributed to this article.