Global Warming Causes Spring Flowers to Bloom Earlier: Study

A new research reveals that global warming has caused spring flowers to bloom at the earliest dates in at least two historical sites, reports LiveScience.

Researcher Elizabeth Ellwood of Boston University and her colleagues used 161-year-old data on the flowering times of 32 plant species, compiled by famous naturalist Henry David Thoreau. They combined that data with an 80-year-old record from another famous naturalist Aldo Leopold. Leopold created a data set of flowering times for 23 plant species.

Thoreau observed the bloom times in Walden, Massachusetts, in 1852, and Leopold recorded flowering times at a site called "The Shack" in Wisconsin, beginning in 1935.

Earlier studies have described Thoreau records, but this is the first time that researchers have combined the information from both the records. The research team compared the historical data with modern-day spring temperatures recorded in Massachusetts and Wisconsin during the years 2010 and 2012. They found that the spring flowers bloomed 10 days earlier over a span of 161 years since Thoreau visited Walden.

On an average, native plants such as serviceberry and nodding trillium are blooming 11 days earlier, said the researchers.

In particular, the spring flowers in Walden bloomed 21 days earlier during the record-breaking warm years of 2010 and 2012. The average spring temperature at Walden pond has increased about 6 degrees Fahrenheit (3.4 degrees Celsius) since Thoreau visited the site, the LiveScience report said.

Experts also found that the average spring temperature at "The Shack" has increased by 3 degrees Fahrenheit since Leopold's visit. The spring flowers bloomed nearly a month earlier in the years 2010 and 2012 than in Leopold's time.

The study shows that the flowering plants are adapting to the changing climate. In addition, the changes in the timing of flowering will likely have broader implications for the environment, including animals and insects that depend on the plants, said the researchers.

The details of the study are published in the journal PLoS ONE.