Washington, DC’s Cherry Blooms Draw Crowds—and Climate Questions

Washington DC’s signature cherry blossoms are blooming earlier this year than ever, adding to fears that climate change-induced early warmer springs threaten tree species around the world. Although a cherry blossom expert said she wouldn’t say climate change caused the early bloom, she cautioned that the phenomenon was consistent and meant it was more likely the trees would blossom earlier in future. Peak bloom has taken place earlier than the historic average of 4 April for 16 out of the past 20 years. Since the trees were planted in 1912, average temperatures around the Tidal Basin have increased by around 2.5 degrees Celsius.  
 
However, a mild winter isn’t always an indicator of earlier blooming, and a lack of winter chill could result in delay, according to the cherry blossom expert. Earlier blooms increase the chances of a late frost damaging the blossoms. Such frosts can trigger a “false spring”, resulting in the “loss of all the blossoms”, said the expert. In 2017, half the trees’ petals were lost following three consecutive nights of temperatures below -3.9C at the point of peak bloom.
 
The cherry blossom festival, which is currently running and generates over $100m in economic activity in Washington DC each year, takes place between 20 March and 16 April. Although an early bloom would be unlikely to stop visitors, a shortage of blossoms could adversely affect attendance. The cherry trees also face the issue of rising sea levels. Since it was built 80 years ago, water levels in the Tidal Basin have risen by approximately 1.2 metres, requiring the removal of a number of trees whose roots can’t tolerate the increased water.   
 
In addition to threats to trees, climate change is putting up to half of the world’s animal species at risk of extinction according to a new study by the University of Arizona. Researchers say that if greenhouse gas emissions are not curtailed, 47% of mammals and 23% of birds are likely to experience challenges relating to their habitat and survival by 2100.



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