Peak bloom was reached on March 26 in the ancient capital of Kyoto, the earliest date since the country's meteorological agency started collecting official data in 1953 and 10 days ahead of the 30-year average.
Researchers at Osaka University, who have compiled historical data on the issue using the diaries of emperors, aristocrats, governors and monks, said it was the earliest peak bloom in more than 1,200 years.
Yasuyuki Aono, an environmental scientist who leads the Osaka University team, said unusual weather fluctuations had caused the cherry trees to bloom more quickly this year.
“In Japan, the winter in January this year was very cold, and the springtime after the latter half of February was very warm,” Aono said. “I think it accelerated the development of the cherry blossoms.”
Aono’s team had previously identified March 27, 1409 as the earliest date of the peak bloom in Kyoto — one day later than this year.
Shunji Anbe, an official at the observations division at the Japan Meteorological Agency, told the Associated Press that climate change was likely responsible for the early blooming.
“We can say it’s most likely because of the impact of global warming,” he said.
Cherry blossoms signify impermanence and are one of the most important motifs in Japanese art and popular culture.
Cherry blossom season is usually greeted by crowds of locals and tourists taking part in Hanami, or flower viewing, a tradition dating back more than 1,000 years in Japan.
Japanese companies and groups often hold parties on blankets under the cherry trees, though that was thwarted last year by the coronavirus pandemic.
Given how sensitive cherry trees are to temperature changes, the timing of their blooming can provide valuable data for climate change studies.
The meteorological agency tracks 58 “benchmark” cherry trees across the country. This year 40 of those have already reached their peak bloom and 14 have done so in record time. The trees normally bloom for about two weeks each year from first bud to all the blossoms falling off.
According to a research paper published in the scientific journal Biological Conservation, the long-term records of the timing of cherry blossoms in Kyoto also help researchers reconstruct historical climate patterns and examine the association between local temperature increases and global warming.
The average temperature for March in Kyoto has climbed to 10.6 degrees Celsius (51.1 F) in 2020 from 8.6 C (47.5 F) in 1953, according to data from the Japan Meteorological Agency. So far this year’s average March temperature in Japan has been 12.4 C (54.3 F).
But Aono cautioned that there could be other explanations for this year’s record bloom beyond global warming.
“In addition to greenhouse gases, there are many other factors that affect the climate, such as solar cycles and oceanic influences, which are particularly strong in Asia, so we cannot be too sure,” Aono told NBC News.
“We need to carefully assess whether or not it will be repeated in the future.”