Decorating the gentle hills of the Arnold Arboretum, the soft, white petals of magnolia trees are already riding the wind, spiraling to their ambrosial demise well before they usually ever bloom.
Across the region, as the weather warmed in recent weeks, trees, plants, and flowers have begun sprouting buds and their full post-winter regalia significantly earlier than ever before, scientists say.
“This is insane,’’ said John O’Keefe, retired coordinator of the Fisher Museum at the Harvard Forest in Petersham.
In addition to the unfurled glory of the magnolias, trees such as red maples, aspens, and black cherries are blossoming as much as a month before the earliest recorded bloom, which was in 2010, he said.
“Everything now is progressing faster,’’ O’Keefe said. “It’s been a crazy spring.’’
The cause is clear: the winter that wasn’t.
The lack of snow, few deep freezes, and mild temperatures that surged last week into the 80s - more than 30 degrees above normal - have wrought an array of ecological anomalies: birds flocking north faster than before, unusually high pollen counts for March, and some crops developing at a reckless pace.
The chief concern about the seemingly unprecedented timing is that a sudden plunge in temperatures into the 20s, as has been forecast for this week, could have serious consequences for trees, animals, and crops.
At the Arnold Arboretum in Jamaica Plain on Monday, Michael Dosmann pointed at one magnolia tree with large purple flowers that were on the verge of opening. “I’m worried about this one,’’ he said. “If the forecast is right, this is going to look like mulch.’’ Neither he nor colleagues could recall an earlier arrival of such verdant foliage throughout the region. “If it’s not the earliest in the 140 years we’ve kept records, it’s among the earliest,’’ he said.
A cold snap could kill tree buds and flowers already in bloom, and some scientists raised concerns about bees dying in droves, potentially reducing pollination on a large scale, as well as the stresses on trees having to produce a new set of leaf buds for those killed off by frost.
Joan Walsh, director of bird monitoring at Mass Audubon, worries about the dangers for all the hummingbirds, swallows, killdeers, and other birds that have flocked to the north in larger numbers than she has ever heard of for this time of year.
“It could be a real problem,’’ she said. “There are always some birds that get it wrong and come too early, but what’s profoundly different this year is that the bulk of birds are arriving early. It’s not just a few oddballs.’’
For Richard Pelletier, owner of the Nashoba Valley Winery in Bolton, the concern is his orchards, much of which he said are blooming about three weeks ahead of schedule, earlier than ever before. As he gazed out an office window at the thousands of trees on his property, he said he worried about losing peaches and apples, the buds of which had begun to blossom.
“There’s no doubt we’re putting ourselves more at risk,’’ he said, estimating he could lose as much as 20 percent of his apples and peaches because of the sudden return of the cold. “Mother Nature is a funny lady. We take everything day by day.’’
While scientists say it’s hard to point at any specific weather event as evidence of climate change, they say that volatile weather patterns and higher temperatures are predicted by the models of global warming.
Richard Primack, a professor of biology at Boston University who specializes on the effects of climate change on plants and animals, called the lack of cold weather and the early blooming this year “unprecedented.’’
“That the ground in the Boston area didn’t even freeze over this year is really unbelievable - just extraordinary,’’ he said.
He added that we should become accustomed to such unexpected weather - and the consequences. “This may be an extreme year now,’’ he said, “but it’s predicted that this will be a fairly typical year in the coming decades.’’
O’Keefe said the changes in the climate are nothing less than frightening. He worries about the stresses on trees and the impact on our ability to grow food.
“Just in the past year we have experienced a range of extreme weather events that are well outside of what we have previously experienced,’’ he said. “That’s scary.’’