Think of Japan in the spring, and the image that comes to mind is likely the country’s famous cherry blossoms, also known as “sakura.”

The flowers, which experience a peak bloom that only lasts a few days, have been revered in Japan for more than a thousand years. Crowds celebrate with viewing parties, flocking to the most popular locations to take photos and have picnics underneath the branches.

But this year, the cherry blossom season has come and gone in the blink of an eye, in one of the earliest blooms on record — and scientists warn it’s a sign of the larger climate crisis threatening ecosystems everywhere. Yasuyuki Aono, a researcher at Osaka Prefecture University, has gathered records from Kyoto back to 812 A.D. from historical documents and diaries. In the central city of Kyoto, cherry blossoms peaked March 26, the earliest in more than 1,200 years, Aono said.

In the capital Tokyo, cherry blossoms reached full bloom March 22, the second-earliest date on record.

“Sakura blooms are very temperature sensitive,” said Aono. “Flowering and full bloom could be earlier or later depending on the temperature alone,” he said. “The temperature was low in the 1820s, but it has risen by about 3.5 degrees Celsius to this day.” This year’s seasons in particular influenced the blossom dates, he added. The winter was very cold, but the spring came fast and unusually warm, so “the buds are completely awake after enough rest.”

There are two sources of increased heat, which is the main factor making the flowers bloom earlier: urbanization and climate change. With increased urbanization, cities tend to get warmer than the surrounding rural area, in what is called the heat island effect. But a bigger reason is climate change, which has caused rising temperatures across the region and the world.

And these earlier dates aren’t just a matter of tourists scrambling to catch peak bloom before the petals all fall — it could have a lasting impact on entire ecosystems, and threaten the survival of many species.

Different plants and insects may respond to the rise in heat at different paces, throwing their life cycles out of sync. Whereas they once timed their growth simultaneously each spring, now flowers may bloom before insects are ready, and vice versa — meaning the insects may not find enough food to eat from the plants, and the plants don’t have enough pollinators to reproduce.

Words to Learn 相关词汇

【蜂拥到】 fēngyōng dào flock to visit or come to someone or something in large numbers

【不同步】bù tóngbù out of sync in an unsynchronized or uncoordinated manner

想起春天的日本，映入脑海的应该是日本著名的樱花。

盛花期只有几天的樱花一千多年来在日本备受推崇。人们举办赏花会来庆祝，蜂拥到热门景点拍照，在樱花树下野餐。

但是今年，樱花季眨眼之间来了又去，花期前所未有地早。科学家警告说，这预示着更大规模威胁各地生态系统的气候危机即将到来。

大阪府立大学的研究员青野靖之收集了京都从公元812年至今的历史文献和日志。青野指出，京都市中心的樱花在3月26日达到全盛，这是1200多年来最早的一次。

在日本首都东京，樱花在3月22日达到了全盛，这是有记录以来第二早的盛花期。

青野说：“樱花对气温十分敏感。光是气温变化就可以提早或推迟花期。19世纪20年代气温较低，但自那以后气温已经上升了约3.5摄氏度。”

他补充道，今年的春季对花期影响尤其大。冬天非常寒冷，但是春天很快就来了，而且异常温暖，因此“花骨朵在足够的休息后完全觉醒了”。

导致樱花早开的主要因素是来自城市化和气候变化两大源头的高温。随着城市化水平提高，城市的温度通常比周边乡村地区更高，这就是所谓的热岛效应。但是更大的原因是导致该地区和全球气温升高的气候变化。

樱花提早盛开不止让游客难以在花谢之前一睹盛景，而且还会对整个生态系统产生持久的影响，威胁许多物种的生存。

不同的植物和昆虫可能以不同的节奏来应对温度的升高，导致它们的生命周期不再同步。过去它们每年春季的成长是同步的，而现在也许昆虫还未准备好，花就开了，或者反过来。这意味着昆虫可能无法从植物获取足够的食物，而植物则没有足够的传粉昆虫来繁殖后代。

(chinadaily.com.cn)