ARI SHAPIRO, HOST:
Canopies of pink and white flowers are blanketing Washington, D.C., right now after the city's cherry trees hit full bloom last week. D.C.'s first cherry trees were a gift from Japan. And in the city of Kyoto, the cherry trees bloomed even earlier. In fact, Kyoto's peak bloom was the earliest on record for 1,200 years, following a pattern of earlier and earlier bloom since the 1800s.
AILSA CHANG, HOST:
When a cherry tree blossoms can reflect climate change. A pattern of early blooms can indicate warming springtime temperatures, but it's complicated.
NAOKO ABE: The impact from climate change is indisputable, I think. However, the decisive factor for the cherry blossoms is the range of temperature.
CHANG: Naoko Abe is a journalist and author of "The Sakura Obsession." She says cherry trees need a full month of cold temperatures in order to properly blossom when it gets warmer.
ABE: If they don't get the chilly weather for a month, then they blossom later because they can't wake up properly (laughter).
SHAPIRO: So while early blooms caused by warm springs are troubling, delayed blooms may also be the result of warming winters. And the south of Japan has already seen delayed blooms in recent years.
ABE: In southern Japan, the winter isn't cold enough for long enough, and so the blossoms are coming out later as much as by a week.
SHAPIRO: As winter temperatures continue to rise, Abe says the delays may grow to the point where trees don't blossom at all.
CHANG: The trees in D.C.'s Tidal Basin are Yoshino cherries. That variety also makes up about 70% of all the cherry trees in Japan. Yoshinos are easy to propagate. They begin blossoming after only five years. And they gained popularity in Japan in the 19th century, while other cherry species were forgotten and went extinct.
ABE: This variety was planted en masse, like a thousand trees or 2,000 trees at a time all over Japan. And eventually, they took over the old varieties.
SHAPIRO: But Yoshinos are very susceptible to temperature change and to disease, and having one dominant variety magnifies those impacts.
ABE: We have to prevent that. We - and we can prevent that. We have to start thinking differently and start thinking that Yoshino cherries are not the only cherries.
SHAPIRO: Abe says that if we don't start to diversify our cherry tree varieties, in a century, we might not have cherry blossoms at any time of year.
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