5 Facts About the 2021 Cherry Blossom Blooms

Cherry trees early bloom signal to scientists further temperature changes with harsher climate to follow, slowly affecting ecosystems around the world.

April 09, 2021

By: Makenzie LaPorte

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Cherry blossoms in Kyoto haven't bloomed this early in 1200 years

Japan’s beautiful and infamous tourist attraction- the white and pink cherry blossoms, “sakura,” bloomed much earlier than scientists, and much of the world expected. The March 26, 2021 peak bloom date surpassed the previous record-holder of March 27, 1409, which was nearly a century before Christopher Columbus sailed to America. Scientists have recorded and studied this “long-term pattern toward earlier spring flowering,” and correlate it to climate change.

One month of a temperature below 41 degrees is required for a successful bloom

Cherry blossoms are very sensitive to temperature and rely on it to properly grow, peak and repeat. Naoko Abe, author of The Sakura Obsession, explains that if the cherry trees do not get an adequate amount of chilly weather prior to blooming, they will result in a delayed blossom because “they can’t wake up properly.” She also adds that the impact derived from climate change is indisputable, “however, the decisive factors for the cherry blossoms is the winter temperature.”

Washington D.C.’s first cherry trees were a gift to the United States from Japan in 1912

This species of tree given to the U.S. from Japan are “Yoshino cherry trees,” which are essentially a hybrid from 70% of all cherry trees in Japan. They’re known for their rapid and prosperous growth merely after 5 years, however, they’re “very susceptible” to changes in temperature and surrounding environments. According to the National Park Service, “the peak bloom date of the Washington cherry blossoms has advanced forward by nearly a week from April 5 to March 31. This evidence is how scientists are reconstructing past climate to better hypothesize the future of all ecosystems.

Urbanization and human interference known as the heat island effect could be to blame for the early bloom

With an increase in urbanization and human interference, there’s a correlation between cities getting warmer than the rural areas surrounding them, commonly known as the “heat island effect.” It’s theorized that earlier spring blooming and temperature changes are larger indications for many ecosystems throughout the world and the detrimental impacts climate change is placing on them.

Environmental cues are key

Plants will sense surrounding temperatures in order to time their budding and growth periods. If warmer weather is persistent, the plants are cued to begin flowering and their leaves begin to appear, and similarly with insects. However, not all plants and organisms have the same life cycles, i.e., they may respond to the increase in temperature at opposing paces, further throwing them off their usual cycles. Amos Tai, associate professor of Earth System Science at the Chinese University of Hong Kong adds, whereas plants and other organisms once timed their growth simultaneously each spring, now flowers may bloom before insectes 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).”