Washington Cherry Blossom Festival

 By Richard B. Primack

 

“To him who contemplates a trait of natural beauty no harm or disappointment can come.” Henry David Thoreau in Excursions.

 

The cherry blossom festival in Washington, DC is a celebration of the beauty of nature. But planning for the festival is challenging because the timing of the peak display of cherry flowers on the National Mall depends on the weather. This year was the second earliest flowering date for the cherry trees in the last 100 years. 

 

Photo 1: Cherry trees flowering in Washington, DC. (photo source: Washington Post)

It is impossible to predict in advance when the cherry trees will bloom each spring, because warm weather speeds up flowering and cool weather delays flowering. But over the last 50 years, the cherry trees in Washington have bloomed about 2 weeks earlier than in the past due to a warming climate. And the prediction is that this earlier flowering trend will continue over the coming half century as the climate continues to warm. 

Figure 1: Cherry trees have been flowering ever earlier over the past 50 years. (figure source: Washington Post)

 

This shift has happened because cherry trees respond primarily to spring temperatures, and springs have been getting warmer due to ever increasing levels of atmospheric carbon dioxide and other greenhouse gases. Aside from temperature, other factors, such as precipitation, humidity and sunlight, have relatively little effect on the flowering times. 

In addition to earlier flowering times, it is also possible that these rising temperatures could harm trees directly through heat and drought, or indirectly through increases in insect pests and disease. The results might be a diminished floral display in future years. 

For more details, see full article: LINK