Cherry Blossom Front Halts Moving North, Anomaly in Blooming Period Raises Concerns for 2100

Is the cherry blossom front moving south? Are there regions where it doesn’t fully bloom? Is the cherry blossom blooming delayed due to the mild winter?

The cherry blossom blooming date seems to be getting earlier every year. According to the announcement from the Japan Meteorological Association on March 18th, this year, Tokyo is expected to bloom second earliest nationwide, following Nagoya, with an estimated blooming date of March 21st. It feels like even the cherry blossom front is collapsing. If global warming continues like this, there might even come a day when cherry blossoms bloom in February.

“I don’t think they will bloom in February. Even if it’s early, it will probably be around early March. However, it is expected that there will be regions where cherry blossoms do not fully bloom,” 

This is stated by Mr. Hisanori Ito, who is studying the cherry blossom blooming until the year 2100.

“The cherry blossom buds are formed in the previous summer and then enter a sleeping phase, during which their growth stops. Subsequently, when there is a prolonged period of low temperatures during the winter, they undergo awakening.

This process is called dormancy breaking. If the necessary low temperatures for dormancy breaking are not achieved due to a mild winter, dormancy breaking may be delayed, leading to delayed blooming instead.”

It was previously thought that warmer winters would result in earlier blooming, but it seems they actually cause delays.

A typical example is the blooming situation in 2007. That year experienced a mild winter, and while cherry blossoms bloomed in Tokyo on March 20th, they didn’t bloom in Kagoshima until March 30th.

“If dormancy breaking doesn’t progress well, it tends to prolong the period from blooming to full bloom.

This is because there are individual differences in the flower buds within a single tree. Therefore, if the temperature is right on the borderline for dormancy breaking, some flower buds may undergo dormancy breaking while others may not.”

The blooming date refers to the first day when five to six or more blossoms have bloomed on a sample tree, while full bloom refers to when approximately 80% or more of the blossoms on a sample tree have bloomed. In a mild winter, due to the sporadic nature of dormancy breaking, the period from blooming to full bloom tends to be longer, and the further south the location, the later the full bloom tends to occur.

Even in 2020, which also experienced a mild winter, the blooming date in Kagoshima was April 1st. It was the first time Kagoshima bloomed later than Sendai, which bloomed on March 28th. Moreover, the full bloom in Kagoshima was on April 19th, 18 days after the blooming date, marking the latest record up to that point.

There’s also the possibility of not being able to see cherry blossoms in full bloom.

As we enter March, the northward progression of the cherry blossom front becomes news. However, if blooming becomes delayed further south, does this mean that there won’t be a “northward progression of the cherry blossom front”?

“It’s already happening. The average blooming date in Kagoshima is March 26th. In contrast, the average blooming dates in Fukuoka and Tokyo are March 22nd and 24th, respectively. In recent years, Fukuoka and Tokyo have often been the first to bloom nationwide.”

“In northern Japan, centered around the Tohoku region, cherry blossoms are expected to bloom 2 to 3 weeks earlier, while in warmer regions like southern Kyushu, they may bloom 1 to 2 weeks later. In the Kanto region and westward, the timing is expected to remain largely unchanged.

As a result, we anticipate simultaneous blooming from eastern Japan to northern Kyushu during the week from March 25th to April 1st.”

While full bloom is defined as when 80% or more of the blossoms have bloomed, if dormancy breaking and blooming occur sporadically, full bloom may not be achieved. There are already areas like Hachijojima where cherry blossoms don’t reach full bloom.

Come to think of it, plum and peach trees also belong to the same Rosaceae family as cherry blossoms. They also require dormancy breaking. With the progression of global warming, there’s a possibility that they may fail to break dormancy properly, leading to no flowering and consequently no fruiting. This could potentially affect other crops as well.

It’s an era where past experiences may no longer be as useful.

When it comes to cherry blossoms, they used to decorate entrance ceremonies in the Kanto region, but recently, they sometimes have already fallen by the time of the entrance ceremony. The northward movement of the cherry blossom front is disappearing. It seems that the spring landscape is changing.

“In the era where what used to be common sense is no longer common sense, and the era where past experiences are no longer useful. Although heavy rain frequently occurs, and there is a need to maintain embankments, we cannot determine how many meters of embankment should be built to feel secure. Relying on experience can also lead to mistakes.”

Infrastructure is a concern, but last year’s severe heat and water shortage also dealt a severe blow to rice. Fishing grounds are also changing. It’s not enough to just say it’s lonely because we can’t see the cherry blossoms in full bloom.

“The change in the way cherry blossoms bloom is a symbol of the impact of global warming. Since it is humans who have caused global warming, it is also only humans who can prevent it. Rather than just thinking, ‘It blooms earlier every year,’ I would be happy if people could think about what we should do to pass on the environment to the next generation.”

Hisanori Ito retired after serving as an assistant professor and associate professor at the Faculty of Education, Wakayama University, and as a professor at the Faculty of Science, Kyushu University. His specialty is meteorology. His publications include “The Fate of Ozone” (co-authored, Kubapro, 2004) and “Data Analysis Methods Used in Meteorology and Oceanography” (Meteorological Research Note No. 221, 2010). He served as the director of the Fukuoka City Science Museum from 2017 to 2020.