Global Warming Rushes Timing of Spring

Unlike sea ice in the Arctic, the way climate change is tinkering with the natural timing of day-to-day life is concrete and local. People can experience it with all five senses:

You can see the trees and bushes blooming earlier. A photo of Lowell Cemetery, in Lowell, Mass., taken May 30, 1868, shows bare limbs. But the same scene photographed May 30, 2005, by Boston University biology professor Richard Primack shows them in full spring greenery.

You can smell the lilacs and honeysuckle. In the West they are coming out two to four days earlier each decade over more than half a century, according to a 2001 study.

You can hear it in the birds. Scientists in Gothic, Colo., have watched the first robin of spring arrive earlier each year in that mountain ghost town, marching forward from April 9 in 1981 to March 14 last year. This year, heavy snows may keep the birds away until April.

You can feel it in your nose from increased allergies. Spring airborne pollen is being released about 20 hours earlier every year, according to a Swiss study that looked at common allergies since 1979.

You can even taste it in the honey. Bees, which sample many plants, are producing their peak amount of honey weeks earlier. The nectar is coming from different plants now, which means noticeably different honey at least in Highland, Md., where Wayne Esaias has been monitoring honey production since 1992. Instead of the rich, red, earthy tulip poplar honey that used to be prevalent, bees are producing lighter, fruitier black locust honey. Esaias, a NASA oceanographer as well as beekeeper, says global warming is a factor.

In Washington, seven of the last 20 Cherry Blossom Festivals have started after peak bloom. This year will be close, the National Park Service predicts. Last year, Knoxville's dogwood blooms came and went before the city's dogwood festival started. Boston's Arnold Arboretum permanently rescheduled Lilac Sunday to a May date eight days earlier than it once was.

Even western wildfires have a timing connection to global warming and are coming earlier. An early spring generally means the plants that fuel fires are drier, producing nastier fire seasons, said University of Arizona geology professor Steve Yool. It's such a good correlation that Weltzin, the phenology network director, is talking about using real-time lilac data to predict upcoming fire seasons. Lilacs, which are found in most parts of the country, offer some of the broadest climate overview data going back to the 1950s.

This year, though, it's the early red maple that's creating buzz, as well as sniffles. A New Jersey conservationist posted an urgent message on a biology listserv on Feb. 1 about the early blooming. A 2001 study found that since 1970, that tree is blossoming on average at least 19 days earlier in Washington, D.C.

Such changes have "implications for the animals that are dependent on this plant," Weltzin said, as he stood beneath a blooming red maple in late February. By the time the animals arrive, "the flowers may already be done for the year." The animals may have to find a new food source.