Cherry trees require a season of cold to blossom, which is why they succeed on the East Coast of the US. Climate change not only makes the trees bloom earlier but also might threaten their whole existence.
The last Saturday afternoon of March 2024 is busy at the Brooklyn Botanic Garden. Most trees are still bare, but the visitors are flocking to get pictures under the first flowering cherry trees. Pathways in the Japanese garden are filled with people gazing at the white and pink blossoms. The garden has many species of cherry trees, and most of them are still waiting to bloom.
Cherry trees on the east coast of the United States first originated from Japan, which gifted some trees in the early 20th century. The most notable places to visit the cherry blossoms nowadays are Washington D.C. and New York. Cherry tree season marks the spring officially started. Warm and sunny days early in the spring are wonderful for picnic plans, but they also carry the message of climate change.
Peak Bloom Day in D.C.
20 Year Rolling Average
10 Year Rolling Average
Average Peak Bloom
is now in March
April 17
April 7
March 28
March 18
March 8
1920
1940
1960
1980
2000
2020
Source: U.S. Environmental Protection Agency
Peak Bloom Day in D.C.
20 Year Rolling Average
10 Year Rolling Average
April 17
Average Peak
Bloom is
now in
March
April 7
March 28
March 18
March 8
1940
1960
1980
2000
2020
Source: U.S. Environmental Protection Agency
In recent years, flowering of the cherry trees has become a closely watched annual event not only in Japan but also in the United States.
The hype is new, but researchers have logged the peak bloom dates of cherry trees for more than a century.
They have found that the peak bloom date in Washington D.C. has moved to arrive five days closer to winter.
The same phenomenon has also been observed in Japan and New York. Trees that used to bloom in April are slowly starting to become a March phenomenon. Experts say it is one of the effects of a warming climate.
One thing to know about cherry trees is that they don't just flower when the weather is warm enough.
There are also other factors in play, like pollutants, precipitation, or winter conditions. This makes it nearly impossible to predict the exact peak bloom more than 10 days beforehand.
“The complicated part is that the territories have to experience also a certain amount of chill in the winter,” says Jonathan Auerbach, a statistician who organizes the International Cherry Blossom Prediction Competition with his researcher colleagues.
The requirement for the winter chill is also the reason why cherry trees thrive in places like New York and Washington D.C. But winters are getting warmer.
“There is an apocalyptic future in which cherry trees don't live at all if they're not getting the requisite cold,” says Auerbach.
This future is not looming just around the corner, but it could become a reality if people don't act on climate change. The goals of the prediction contest are not only to gather information but to also raise awareness and get people talking about the effects of a warming planet.
This year cherry trees in Washington D.C. experienced their second earliest peak bloom, when the official peak bloom day was set on March 17. Peak bloom is agreed to be the day when 70 percent of Yoshino cherry trees are in full bloom.
The Washington Post followed one cherry tree's process from bare to bloom. Reporters thought they had plenty of time to follow the tree, but the peak bloom date came almost two weeks earlier than what would be considered average.
Cherry trees flowering is just one of the signs that spring in general is happening earlier.
“I think we should be alarmed,” says Auerbach.
By changing the temperature humans are distorting the cues that ecosystems rely on to be stable, he adds.
“As temperatures rise, some species will thrive. And there are some other species that we love, like cherry trees, that may not thrive. As climate warms, we are endangering those species.”