The Japan Meteorological Agency maintains official records of the flowering of trees across the country, which has been done by tracking the flowers on a series of “reference” trees since 1953. This year’s peak flowering in Kyoto on 26 March, is the earliest recorded and is 10 days ahead of the average of the last 30 years.
But data on trees in the form of historical documents, diaries, poems and other imperial records goes back to the early 800s (yes, it is a three-digit date). Yasuyuki Aono, an environmental scientist at Osaka Prefecture University, has combed through these records and made them available online as a dataset. The blossoming of cherry trees is a culturally significant time of year in Japan – historically, there are celebrations and festivals for the arrival of flowers – making it possible to consistently follow your high season in historical documents.
Aono’s records are not entirely complete – he said some years’ worth of information is missing, which is understandable given the long period to be covered. But, according to these historical records, the first previous record was set in 1409 – the flowers peaked on March 27 of that year.
It is no coincidence that Kyoto’s cherry blossomed so early this year, or that historical data suggests that these events are gradually becoming increasingly early. The average temperature in the city in March last year reached 10.6 degrees Celsius, a big increase from the average of 8.6 Celsius in 1953. Cherry blossoms are especially sensitive to changes in temperature – the trees bloom only for about two weeks each year – which means they provide a valuable barometer of how even minimal changes in the weather can affect them.
This year’s extremely early flowering was not limited to Kyoto. Across Japan, cherry trees blossom earlier and earlier. Of the 58 “reference” trees that the Japan Meteorological Agency registers each year, 40 have already reached their peak of flowering, and 14 of them have reached their peak in record time.
“We can say that the most likely explanation is the impact of global warming,” Shunji Anbe, from the Japan Meteorological Agency’s observation division, told the news agency. AP.
Cherry cousins in Washington, DC – planted in March 1912 after Japan sent over 3,000 trees as a gesture of friendship to the United States – are also in full bloom now. And they also tend to flourish earlier, as temperatures rise in the city. A 2011 study predicted that sensitive trees could bloom five days before the historical average in 2050 and 10 days in 2080 in a medium-sized emissions scenario. In the case of higher emissions, this anticipation could be 13 and 28 days, respectively.
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