In 2010 and 2012, plants in the eastern United States produced flowers earlier than at any point in recorded history, says a new study.
The study came to these conclusions from data collected by U.S. environmental writers Henry David Thoreau and Aldo Leopold. Thoreau began observing bloom times in Massachusetts in 1852, and Leopold got started in Wisconsin in 1935.
Researchers compared their historical data with modern, record setting high temperatures in Massachusetts and Wisconsin during 2010 and 2012. They discovered that the two warm spells triggered spring-flowering plans to blossom up to 4.1 days earlier for every 1 degree Celcius rise in average spring temperatures. This translates to 2.3 days for every 1 degree Fahrenheit.
This is not the first study to show that flowering times have come earlier as a result of rising temperatures, however, what researchers don't yet know is how long the plants will be able to "keep up" with global warming by budding increasingly earlier. So far plants in the eastern U.S. are coping with the changing temperatures.
Elizabeth Ellwood, a biologist at Boston University in Massachusetts, says:
"It's just remarkable that they can physiologically handle this."
Unfortunately, Ellwood thinks that "something's gotta give" and "at some point this won't be the case anymore as winter gets shorter."
Scientists are concerned about whether plants will be able to adapt fast enough as climate changes radically, and if they will reach a point where they can't adapt any longer. They also worry that plants will flower early and a late winter freeze will destroy the buds, which would weaken the plant.
Researchers have already found evidence that Arctic plants are not responding to warmer temperatures in the same way that they used to, and as northern climates warm, more southern species are moving northward where they could outcompete native species.
Ellwood also notes that early blooming "has tremendous implications" for the environment as a whole. Because plants soak up and evaporate water, and take in carbon dioxide during photosynthesis, they can influence Earth's water cycle and atmosphere. For example, more evaporation could mean more cloud cover, which could thus affect rainfall.
The study was published in the journal PLoS ONE on January 16.