Global Warming Ushers Spring Forward

March 19, 2008 -- The capital's famous cherry trees are primed to burst out in a perfect pink peak about the end of this month. Thirty years ago, the trees usually waited to bloom till around April 5.

In central California, the first of the field skipper sachem, a drab little butterfly, was fluttering about on March 12. Just 25 years ago, that creature predictably emerged there anywhere from mid-April to mid-May.

And sneezes are coming earlier in Philadelphia. On March 9, when allergist Donald Dvorin set up his monitor, maple pollen was already heavy in the air. Less than two decades ago, that pollen couldn't be measured until late April.

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," Stanford University biologist Terry Root said.

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.

What's happening is so noticeable that scientists can track it from space. Satellites measuring when land turns green found that, north of the Mason-Dixon Line, spring "green-up" is arriving on average eight hours earlier every year since 1982.

In much of Florida, southern Texas and Louisiana, the satellites show spring coming a tad later, and bizarrely, in a complicated way, global warming can explain that too, the scientists said.

Biological timing is called phenology. Biological spring, which this year begins at 1:48 a.m. EDT on 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.