The flowers, which experience a “maximum flowering” that lasts only a few days, have been revered in Japan for more than a thousand years. Crowds are celebrated with shows, flocking to the most popular places to take photos and have picnics under the branches.
But this year, the cherry blossom season has been happening in the blink of an eye, in one of the first flowers recorded, and scientists warn that it is a symptom of the biggest climate crisis threatening ecosystems around the world. everywhere.
And in the capital of Tokyo, cherry blossoms came to bloom on March 22, the second oldest date recorded.
“As global temperatures heat up, the last spring frosts occur earlier and flowering occurs earlier,” said Dr. Lewis Ziska of Columbia University Health Sciences.
Maximum flowering dates vary each year, depending on numerous factors, including inclement weather and precipitation, but have shown an overall trend of increasingly early displacement. In Kyoto, the peak date fluctuated around mid-April for centuries, according to Aono data, but began to begin in early April during the 19th century. The date has only fallen at the end of March a handful of times in recorded history.
“Sakura flowers are very sensitive to temperature,” Aono said. “Flowering and full flowering could be earlier or later, depending only on the temperature,” he said. “The temperature was low in the 1820s, but it has risen about 3.5 degrees Celsius (6.3 degrees Fahrenheit) to the present day.”
He added that this year’s seasons especially influenced flowering dates. Winter was very cold, but spring came quickly and unusually hot, so “the buds are fully awake after getting enough rest.”
Its first flowering, however, is just the tip of the iceberg of a global phenomenon that could destabilize countries’ natural systems and economies, said Amos Tai, an assistant professor of earth sciences at Hong Kong University. Kong.
There are two sources of increased heat, which is the main factor that makes flowers bloom earlier: urbanization and climate change. With increasing urbanization, cities tend to be warmer than the surrounding countryside, in what is called the heat island effect. But a more important reason is climate change, which has led to rising temperatures in the region and the world.
And these earlier dates are not just a matter of tourists facing maximum flowering before all the petals fall, as it could have a lasting impact on entire ecosystems and threaten the survival of many species.
For every action there is a reaction
Plants and insects are highly dependent on each other and both use environmental cues to “regulate the time of the different stages of their life cycle,” Tai said. For example, plants detect the temperature around them and, if it is hot enough for a constant period, they begin to bloom and the leaves begin to emerge. Similarly, insects and other animals depend on temperature during their life cycles, which means that higher heat can cause faster growth.
“The relationship between plants, insects and other organisms has developed over many years, from thousands to millions of years,” Tai said. “But in the recent century, climate change is destroying everything and disrupting all these relationships.”
Different plants and insects can respond to the increase in heat at different rates, leaving their life cycles out of sync. While they once timed their growth simultaneously each spring, now the flowers can bloom before the insects are ready, and vice versa, that is, “insects may not find enough food to eat from plants and plants do not have enough pollinators (to reproduce), ”he said.
“Ecosystems are not used to this kind of big fluctuations, it causes them a lot of stress,” Tai said. “Productivity can be reduced and ecosystems can even collapse in the future.”
It is not limited to cherry blossoms
And the effects of climate change are not limited to cherry blossoms. “Cherry blossoms attract attention, people love to go and see them, but many other plants also experience changes in their life cycle and can have an even stronger influence. On the stability of their ecosystems.” , said Tai.
In some regions, farmers may be forced to change the types of crops they grow. Some climates will become too hot for what they are growing now, while other climates will see more flooding, more snow and more humidity in the air, which will also limit what can be grown.
“(Farmers) have a lot more difficulty predicting when they will have a good year, when they will have a bad one,” Tai added. “Agriculture is now more like a gamble, because climate change is randomizing things that happen in our ecological systems.”