1,200‑year cherry record continues
Prof. Yasuyuki Aono’s long-running cherry-blossom timing record—spanning about 1,200 years—will be maintained after his death to preserve the dataset for future study. The archive of bloom dates has been used as a long-term baseline for floral timing and climate observations (theguardian.com).
Japan’s 1,200-year record of Kyoto cherry blossom dates will continue after the death of the scientist who rebuilt and maintained it. (theguardian.com) Professor Yasuyuki Aono of Osaka Metropolitan University died on August 5, 2025, and another researcher in Japan agreed this week to keep the series going. The record tracks the full flowering of mountain cherry trees in Kyoto. (theguardian.com) Aono spent years pulling bloom dates from diaries, chronicles and festival records, with the earliest entry dating to 812. Our World in Data said he and colleagues collated the Kyoto series from historical documents stretching back to the ninth century. (theguardian.com) (ourworldindata.org) Cherry blossom timing is a seasonal clock: warmer springs push flowers open earlier, colder springs hold them back. That makes a long bloom record a long climate record. (ourworldindata.org) The Kyoto series has become one of the best-known biological records of warming because it runs across about 12 centuries in one place. In 2025, peak bloom in Kyoto was on April 4, according to Our World in Data’s summary of the dataset. (ourworldindata.org) A 2022 paper by Nikolaos Christidis, Aono and Peter Stott found Kyoto’s full flowering season had shifted by more than a week because of human influence and urban warming. The paper said the March 26, 2021 full bloom was the earliest date recorded in more than 1,200 years. (omu.repo.nii.ac.jp) That study used a phenological model, which is a way of estimating plant timing from daily temperatures, and 14 climate models with and without human-caused warming. The authors found that urban warming accounted for about half of the observed shift. (omu.repo.nii.ac.jp) The Kyoto record is also unusually specific. Aono focused on Yamazakura, or Japanese mountain cherry, rather than the Somei-yoshino trees used in many modern blossom forecasts. (theguardian.com) Keeping the series alive means future researchers can compare new bloom dates with the same historical baseline Aono spent his career assembling. The spring clock he preserved will keep ticking in Kyoto. (theguardian.com)
