Global warming hastens spring's arrival
Effect of seasonal timing changes on plants and animals worries biologists
The Associated Press, March. 19, 2008
And sneezes are coming earlier in
Pollen is bursting. Critters are stirring. Buds are swelling. Biologists are worrying.
"The alarm clock that all the plants and animals are listening to is running too fast,"
Blame global warming.
The fingerprints of man-made climate change are evident in seasonal timing changes for thousands of species on Earth, according to dozens of studies and last year's authoritative report by the Nobel Prize-winning international climate scientists. More than 30 scientists told The Associated Press how global warming is affecting plants and animals at springtime across the country, in nearly every state.
What's happening is so noticeable that scientists can track it from space. Satellites measuring when land turns green found that spring "green-up" is arriving eight hours earlier every year on average since 1982 north of the
Biological timing is called phenology. Biological spring, which this year begins at 1:48 a.m. ET Thursday, is based on the tilt of the Earth as it circles the sun. The federal government and some university scientists are so alarmed by the changes that last fall they created a National Phenology Network at the U.S. Geological Survey to monitor these changes.
The idea, said biologist and network director Jake Weltzin, is "to better understand the changes, and more important what do they mean? How does it affect humankind?"
There are winners, losers and lots of unknowns when global warming messes with natural timing. People may appreciate the smaller heating bills from shorter winters, the longer growing season and maybe even better tasting wines from some early grape harvests.
But biologists also foresee big problems.
The changes could push some species to extinction. That's because certain plants and animals are dependent on each other for food and shelter. If the plants bloom or bear fruit before animals return or surface from hibernation, the critters could starve. Also, plants that bud too early can still be whacked by a late freeze.
The young of tree swallows -- which in upstate
The checkerspot butterfly disappeared from Stanford's Jasper Ridge preserve because shifts in rainfall patterns changed the timing of plants on which it develops. When the plant dries out too early, the caterpillars die, said Notre Dame biology professor Jessica Hellmann.
"It's an early warning sign in that it's an additional onslaught that a lot of our threatened species can't handle," Hellmann said.
It's not easy on some people either. A controlled federal field study shows that warmer temperatures and increased carbon dioxide cause earlier, longer and stronger allergy seasons.
"For wind-pollinated plants, it's probably the strongest signal we have yet of climate change," said
While some plants and animals use the amount of sunlight to figure out when it is spring, others base it on heat building in their tissues, much like a roasting turkey with a pop-up thermometer. Around the world, those internal thermometers are going to "pop" earlier than they once did.
This past winter's weather could send a mixed message. Globally, it was the coolest December through February since 2001 and a year of heavy snowfall. Despite that, it was still warmer than average for the 20th century.
Phenology data go back to the 14th century for harvest of wine grapes in
Unlike sea ice in the
* You can see the trees and bushes blooming earlier. A photo of
* 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,
* 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
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
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
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.
"It's all a part of life," Weltzin said. "Timing is everything."
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