Global Warming Brings Earlier Spring Flowers

The warmest springs on record have caused flowers in two historic sites to bloom at their earliest dates in decades.

The warmest springs on record caused flowers to bloom at their earliest dates in decades at two historic sites, according to new research.

The findings, published online yesterday (Jan. 16) in the journal PLoS ONE, show just how much climate change has altered ecosystems throughout the temperate areas of the United States. The study used 161-year-old data on flowering times from Henry David Thoreau's notebooks, as well as nearly 80-year-old data from the famous naturalist Aldo Leopold.

Scientists had previously described the Thoreau records but they hadn't combined the two naturalists' findings until now.

"Record warm temperatures (in 2010 and 2012) have resulted in record early flowering times," said study researcher Elizabeth Ellwood of Boston University. (8 Ways Global Warming Is Already Changing the World)

Famous naturalists

Henry David Thoreau was one of the most iconic figures of the 19th century. The famous naturalist and poet wrote the book "Walden" about his years living at idyllic Walden Pond in Concord, Mass. Starting in 1852 and at different points throughout his life, he also created the first "spreadsheets of flowering dates" for many well-known flowers, including the wild columbine, the pink-lady slipper orchid and the marsh marigold, Ellwood said.

Similarly, the naturalist Leopold took detailed records of first flowering times at a site called "The Shack" in wilderness near the Wisconsin River, starting in 1935.

"It's the iconic equivalent to Walden Pond for Wisconsinites," Ellwood told LiveScience.

While scholars knew of these flowering observations, many were scattered in different libraries and archives, and no one had systematically analyzed their patterns, she said.

Hotter springs, earlier blooms

To do so, Ellwood and her colleagues gathered all of Thoreau's flowering records from several archives. They then compared flowering dates with spring temperatures for 32 different flowering plants.

They found that as temperatures warmed over the last 161 years, the date of first blooms of the season crept forward, too - about 10 days earlier than when Thoreau first visited the site. During the record-breaking years of 2010 and 2012, flowering happened a full 20 to 21 days earlier. The average spring temperature at Walden Pond has increased about 6 degrees Fahrenheit (3.4 degrees Celsius) since Thoreau's time.

Similarly, at The Shack, as average spring temperatures rose about 3 degrees Fahrenheit (1.7 degrees Celsius) over the last eight decades, first flowering came a week early for the 23 species they studied. During the hottest years in the United States (2010 and 2012), flowering came 24 days earlier than in Leopold's time.

Still adapting

The research may have tracked just two sites, but has broad implications, said Elizabeth Wolkovich, a climate change ecologist at the University of British Columbia who was not involved in the study.

"One is deep within the country and one is on the coast," Wolkovich said.

That means the findings probably apply to temperate climates throughout a large swath of the United States, she told LiveScience.

Though Thoreau and Leopold's works have highlighted how much climate change alters ecosystems, in some ways, the findings are good news.

At some point, the climate will get too hot for plants to survive without evolving, but the fact that the plant flowering time is still changing in step with the temperature means they haven't hit that point yet, said David Inouye, a University of Maryland biologist who was not involved in the study.

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In incredibly detailed notebooks, Thoreau documented the flowering times of species such as the wild columbine.

Sept. 17, 2012

French photographer Samuel Blanc has been leading tours to Svalbard, Norway's archipelago in the Arctic, since 2007. This year the reduced sea ice extent allowed his expedition aboard the 12-passenger Polaris to circumnavigate the northern islands in early July rather than mid-August. Climate change is having a direct impact on the unique ecosystem isolated on these islands more than 400 miles north of Europe. In the following photos, Blanc gives us a tour of life on the archipelago's largest island, Spitsbergen. You can see more of his work at

Little Auks

In west Spitsbergen, Little Auks, such as those pictured here, and other birds aren't safe on the cliffs. Hungry polar bears have learned to climb the steep gradients in search of food.

Polar Bears and Bleeding Glaciers

The dissolved iron seen in this glacier may help fight climate change. As the iron washes into the northern seas, it can help fertilize phytoplankton blooms that draw carbon dioxide out of the atmosphere.


As global warming melts permafrost in the arctic, more carbon is released into the atmosphere. Meanwhile areas of tundra are also seeing a rise in fires.

Svalbard Reindeer


The vast stretch of open water due to thinning of the Arctic sea ice is forcing walruses to often crowd together on beaches.

Bearded Seal

This bearded seal has found a safe spot away from polar bears and sharks. Many seals however also snooze in the water, where they are at risk of becoming of meal for the Greenland shark, the world's slowest shark.

Arctic Fox

Only three percent of the total population of arctic fox are called "Blue fox" and unlike the rest of the population, these blue critters don't turn white in the winter.

Arctic Foxes

These foxes are showing their summer colors.

Ivory Gull

Sabine Gull

Svalbard Poppy

Spitsbergen, Svalbard