Maple syrup producers say they are tapping trees a month earlier than a generation ago.

ACWORTH, N.H. (AP) – The state’s maple syrup producers say they can see the effects of global warming in their own backyards: They are tapping their trees about a month earlier than their ancestors did.

A giant chart on the wall of the Clark Sugar House in Acworth shows the maple syrup season began changing about 20 years ago.

Since 1896, generations of Clarks attached their buckets in March, during the week of town meeting, and almost never made syrup before then. But in the mid-1980s, they began tapping mostly in February, and March became the month for boiling and bottling instead.

“Most everybody’s tapping a lot earlier than they used to,” said Arvin Clark, 72, who has been running syrup production at the farm since 1959.

The Clarks’ chart might just be a glimpse of the future.

Scientists around the world, including some at the University of New Hampshire, predict that by 2050 New England’s average temperature will rise between 6 degrees and 10 degrees. That warming will vastly alter the climate needed to support a northern hardwood forest, including sugar maples.

The change could have a big impact in Maine, where maple sugaring is so common that Gov. John Baldacci last week tapped trees on the grounds of the gubernatorial mansion.

Maine has been the country’s No. 2 syrup producer behind Vermont, with production rising from less than 12,000 gallons a year through most of the 1980s to 230,000 gallons in 2002.

A delicate balance of sun and rain, snowfall and freezing temperatures is what helps the tree turn its starch into sugar. For the sap to run, nights need to be below freezing, ideally in the mid-20s. Days need to be in the mid-40s.

For now, the warming trend has simply changed the ideal dates for tapping. But eventually, some experts say it will reduce sap production and leave the trees more vulnerable to insects and disease.

The trees could spread north as the freeze-thaw cycle becomes more unpredictable and the seasons start and end earlier. Those that remain will produce less syrup of lower quality.

That’s bad news for New Hampshire’s maple syrup manufacturers, who annually pump $4 million into the state’s economy.

“I think the sugar maple industry is on its way out,” University of New Hampshire researcher Barrett Rock said in 2002. Rock led major research on the risks associated with global climate change.

Tim Perkins, director of the Proctor Maple Research Center at the University of Vermont, is doing research on whether climate change has already affected the amount of sap producers can expect from their trees. He declined to preview his results, but agreed that climate change will hurt syrup production in New England.

“We might still have maple, but that also doesn’t mean they’re going to produce sap,” he said.

This year, production is generally good because last year’s weather conditions were just right.

But a spell of unseasonably warm weather earlier this month hurt sap production and quality, said Bill Eva, president of the Maple Producers Association and owner of Longview Maple Products in Hancock.

“All of a sudden, I dropped down to dark,” which isn’t as marketable, he said.

Eva said he’s always tapped in February, “but if I look at my dad’s records back in the 1930s and 1940s, any time he tapped trees in February he made a comment that it was too early,” he said.

AP-ES-03-21-04 1339EST