City lights that blaze all night are profoundly disrupting urban plants’ phenology – shifting when their buds open in the spring and when their leaves change colors and drop in the fall. New research I coauthored shows how nighttime lights are lengthening the growing season in cities, which can affect everything from allergies to local economies.
In our study, my colleagues and I analyzed trees and shrubs at about 3,000 sites in U.S. cities to see how they responded under different lighting conditions over a five-year period. Plants use the natural day-night cycle as a signal of seasonal change along with temperature.
We found that artificial light alone advanced the date that leaf buds broke in the spring by an average of about nine days compared to sites without nighttime lights. The timing of the fall color change in leaves was more complex, but the leaf change was still delayed on average by nearly six days across the lower 48 states. In general, we found that the more intense the light was, the greater the difference.
We also projected the future influence of nighttime lights for five U.S. cities – Minneapolis, Chicago, Washington, Atlanta and Houston – based on different scenarios for future global warming and up to a 1% annual increase in nighttime light intensity. We found that increasing nighttime light would likely continue to shift the start of the season earlier, though its influence on the fall color change timing was more complex.
This kind of shift in plants’ biological clocks has important implications for the economic, climate, health and ecological services that urban plants provide.
On the positive side, longer growing seasons could allow urban farms to be active over longer periods of time. Plants could also provide shade to cool neighborhoods earlier in spring and later in fall as global temperatures rise.
But changes to the growing season could also increase plants’ vulnerability to spring frost damage. And it can create a mismatch with the timing of other organisms, such as pollinators, that some urban plants rely on.
A longer active season for urban plants also suggests an earlier and longer pollen season, which can exacerbate asthma and other breathing problems. A study in Maryland found a 17% increase in hospitalizations for asthma in years when plants bloomed very early.
How the fall color timing will change going forward as night lighting increases and temperatures rise is less clear. Temperature and artificial light together influence the fall color in a complex way, and our projections suggested that the delay of coloring date due to climate warming might stop midcentury and possibly reverse because of artificial light. This will require more research.
How urban artificial light will change in the future also remains to be seen.
One study found that urban light at night had increased by about 1.8% per year worldwide from 2012-2016. However, many cities and states are trying to reduce light pollution, including requiring shields to control where the light goes and shifting to LED street lights, which use less energy and have less of an effect on plants than traditional streetlights with longer wavelengths.
Urban plants’ phenology may also be influenced by other factors, such as carbon dioxide and soil moisture. Additionally, the faster increase of temperature at night compared to the daytime could lead to different day-night temperature patterns, which might affect plant phenology in complex ways.
Understanding these interactions between plants and artificial light and temperature will help scientists predict changes in plant processes under a changing climate. Cities are already serving as natural laboratories.
LANDMARK CITY COUNCIL VOTE PROTECTS ABORTION RIGHTS: New York City Council on Thursday voted on an abortion and reproductive health care rights legislative package, named the “NYC Abortion Rights Act.”
MAYOR ADAMS OUTLINES NEW VISION FOR FERRY SYSTEM: Following a scathing state comptroller’s audit on the previous mayor’s handling of the costs of operating the city’s ferry system, Mayor Eric Adams yesterday unveiled “NYC Ferry Forward.”
TEXT NOTIFICATION LAUNCHES ON MONKEYPOX: A new SMS-text notification effort, launched yesterday, will deliver the latest monkeypox information directly to New Yorkers.
If you would like to sponsor a notice, a photo, or an article about your favorite organization, or even wish a loved one Happy Birthday, send your content to Jennifer Hopewell, [email protected]
If Buddy Scotto had his way, there would be gondolas plying the waters of the Gowanus Canal...
Could humans live through another ice age? Probably. But like the frog in the frying pan, they may have more trouble with the man-made, incremental warming of oceans and the LOSS of ice in glaciers.
Ask anything about Brooklyn. Historical queries, urban legends, clarification on rumors — let us do the research for you! Submit your question here.
Have an opinion? Submit it as a letter to the editor using this form!
New York City’s most populous borough, Brooklyn, is home to nearly 2.6 million residents. If Brooklyn were an independent city it would be the fourth largest city in the United States. While Brooklyn has become the epitome of ‘cool and hip’ in recent years, for those that were born here, raised families here and improved communities over the years, Brooklyn has never been ‘uncool’.
The Brooklyn Daily Eagle and brooklyneagle.com cover Brooklyn 24/7 online and five days a week in print with the motto, “All Brooklyn All the Time.” With a history dating back to 1841, the Eagle is New York City’s only daily devoted exclusively to Brooklyn.
https://brooklyneagle.com/articles/2022/07/13/light-pollution-is-disrupting-the-seasonal-rhythms-of-plants-and-trees-lengthening-pollen-season-in-us-cities/
The Brooklyn Daily Eagle and brooklyneagle.com cover Brooklyn 24/7 online and five days a week in print with the motto, “All Brooklyn All the Time.” With a history dating back to 1841, the Eagle is New York City’s only daily devoted exclusively to Brooklyn.
DAILY TOP BROOKLYN NEWS News for those who live, work and play in Brooklyn and beyond Leave this field empty if you're human: