New Scientist Takes Over Japan's 1,200-Year Cherry Blossom Climate Record

A Record Spanning Twelve Centuries

For more than 1,200 years, Japanese noblemen, monks, and bureaucrats have meticulously recorded when Kyoto's cherry blossoms reach peak bloom. The tradition, stretching back to 812 AD, has produced one of the longest-running climate datasets in the world. That remarkable legacy nearly ended last year when Yasuyuki Aono, a professor at Osaka Metropolitan University and the most recent custodian of the database, died of cancer in August 2025.

A New Custodian Steps Forward

Now, the record will continue. Genki Katata, a Tokyo-based environmental biophysicist affiliated with the Canon Institute for Global Studies, has agreed to take on the role. His appointment, confirmed on Friday, ends months of uncertainty over the fate of a dataset that has become one of the most striking illustrations of global warming. The search for a successor proved difficult because the role demanded botanical expertise to identify peak bloom of the specific Yamazakura species tracked in Kyoto's Arashiyama district.

Aono's Lifetime of Work

Aono spent decades compiling peak bloom dates from imperial court documents, diaries, and other historical sources. His work drew worldwide attention in 2021 when Kyoto's cherry blossoms peaked on March 26, the earliest date in more than 1,200 years, surpassing the previous record of March 27 set in 1409. Aono completed the entry for 2025 before his death but left the 2026 line blank. A public campaign by Tuna Acisu, a data scientist at Our World in Data, ultimately helped find a successor.

A Vivid Signal of Climate Change

The dataset reveals a dramatic shift. Since roughly 1800, cherry blossoms in Kyoto have bloomed progressively earlier, moving from an average flowering date of around 17 April in 1850 to roughly 5 April in recent decades. That shift coincides with an approximately 3.4 degrees Celsius rise in local temperatures. The 2026 season continued the trend, with Kyoto's first blooms officially declared on 23 March.

Ecological Consequences

Earlier flowering carries real ecological risks. It can cause mismatches between blossoms and pollinators, and leaves flowers more vulnerable to late spring frosts. Scientists warn that continued warming could eventually prevent some cherry varieties from flowering at all in their southernmost ranges, as trees may fail to receive the winter cold needed to trigger normal bud development. Katata's commitment ensures this irreplaceable archive will not end with a blank entry.