Human-induced climate crisis is causing Japan’s cherry trees to bloom earlier

(CNN) — Every spring, crowds flock to admire the Japanese cherry blossom, a dazzling pink and white flower revered in the country for more than a thousand years.

But world famous sakura plants are flowering much earlier than normal due to human-induced climate change, a new study has found.

Researchers from the Met Office in the UK and Osaka Metropolitan University in Japan say the climate crisis and urban warming have pushed the flowering time from ‘peak bloom’ forward by 11 days.

In 2021, cherry blossoms in the historic central city of Kyoto peaked on March 26 – the first full bloom date in 1,200 years. This year, the cherry blossoms take on color on April 1.
The scientists, who published their findings in the journal Environmental Research Letters on May 20, said the extremely early flowering of cherry blossoms is now more common.

The trend of earlier flowering peaks coincides with rising temperatures. Average March temperatures in downtown Kyoto have risen several degrees since pre-industrial times, influenced by both climate change and urban warming, scientists have observed.

Part of the reason is increased urbanization. Cities tend to be warmer than surrounding rural areas because buildings and roads absorb heat from the sun more than natural landscapes – a phenomenon known as the heat island effect.

But scientists say a bigger reason is the climate crisis, in which the burning of fossil fuels has caused rising temperatures in the region and around the world.

If global-warming greenhouse gas emissions continue as they are, by the end of the century, Kyoto’s cherry blossoms could start arriving even sooner – within almost a week, according to the report. ‘study.

“Our research shows that not only have human-induced climate change and urban warming already impacted cherry blossom bloom dates in Kyoto, but that extremely early bloom dates, such as in 2021, are now estimated to be 15 times more likely, and are expected to occur at least once a century,” said lead author and Met Office climatologist Dr Nikos Christidis.

“Such events are expected to occur every few years by 2100, when they would no longer be considered extreme.”

Cherry blossoms are in full bloom at Lake Biwa Canal in Kyoto City, Kyoto Prefecture on April 4.

Michihiro Kawamura/The Yomiuri Shimbun/AP

The first cherry blossoms have wider ramifications for Japan’s economy and ecology, and are a symptom of the wider climate crisis threatening ecosystems everywhere.

“The spring cherry blossom bloom is an important cultural event in Japan,” said author Yasuyuki Aono of Osaka Metropolitan University. The spring festivals that come with blooms are a big contributor to the local economy, so being able to predict the timing of blooms can be essential.

The peak flowering period lasts only a few days. During this time, hanami – Japanese for “flower viewing” – is a popular activity.

It’s common for locals and tourists to picnic under the cherry trees, and businesses sometimes offer special food or produce during the week.

Why the first cherry blossoms are important

But it’s not just a matter of tourists scrambling to catch the peak bloom before the petals have all fallen – it could have a lasting impact on entire ecosystems and threaten the survival of many species.

The impact of rising temperatures on the natural calendar has implications for agricultural and land management practices in the country, according to the study.

It also impacts plants, insects and animals, which are highly dependent on each other for their development and life cycles. A change in this cycle can trigger a chain reaction, causing damage to ecosystems.

For example, plants sense the temperature around them, and if it is warm enough for a consistent period, they begin to flower and their leaves begin to emerge. Likewise, higher heat can accelerate the growth of insects and other animals.

Different plants and insects may react to increased heat at different rates, throwing their life cycles out of sync. Whereas they once timed their growth simultaneously each spring, flowers may now bloom before the insects are ready, and vice versa, which means there may not be enough food for the insects or plants.

Changing bloom dates aren’t limited to Japan or cherry blossoms. Spring has arrived early in parts of the UK this year and climate change is causing plants in the British Isles to flower, on average, a month earlier than before, according to a recent study.

The same phenomenon is already happening for many economically valuable crops and plants, posing big challenges for food security and farmers’ livelihoods.

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