Posted on Sat, Mar. 22, 2008

WASHINGTON | The 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 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 report by 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.

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 New York are laying eggs nine days earlier than in the 1960s — often starve in those last-gasp cold snaps because insects stop flying in the cold, ornithologists said. University of Maryland biology professor David Inouye noticed an unusually early February robin in his neighborhood this year and noted, “Sometimes the early bird is the one that’s killed by the winter storm.”

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 University of 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 University of Massachusetts professor of aerobiology Christine Rogers. “It’s a huge health impact. Seventeen percent of the American population is allergic to pollen.”