Will global warming doom maple syrup?

This article was produced by Daily Climate, one of The Daily Green's most trusted sources of news about global warming. It is republished with permission.

SABBATH DAY POINT, N.Y. - All farming depends on the weather, but few foods are more dependent on a specific climate than maple syrup. After all, for the sugar maple's sap to run at all requires cooperative weather - freezing nights followed by warmer days.

But with the buildup of invisible greenhouse gases in the atmosphere, those temperature swings don't happen as reliably. At risk is an American tradition that stretches back even before Europeans discovered the "New World."

"Weather controls it all," says Marty Fitzgerald, a fifth-generation sugarmaker in upstate New York. And, in recent years, the weather has been weird.

* * *

Extracting sap from maple trees - the business of maple sugaring - employs everything from little tin funnels and hanging pails to plastic spigots and light blue tubing that turn the forest into a spider's web of tripwires, often at chest height. Sugar makers collect the sap any number of ways: hustling a pail down the mountainside to the sugar shack, using gravity to deposit it in the holding tank, even vacuum pumping the sap downhill.

At the Carney sugarbush - the term of art for a stand of maple trees-in upstate New York, Rick Bartlett splits the difference. While 700 hundred trees bear 1,000 or so metal taps and buckets, centralized collecting bins-plastic garbage cans-connected by tubing dot the mountainside and feed into a 300 gallon collector near the sugar shack where the sap is boiled into syrup by Fitzgerald.

It takes a mature tree - 40 to 50 years old - to produce maple syrup safely. By that age, the sugar maple has reached a diameter of roughly 10 inches and, according to the standard Ontario tapping rule, can handle one tap. For every five inches in diameter the tree grows after that, the rule says, it can handle one more tap.

Even with tubing, only a high price or a deep love can justify all the labor involved. Given that an average maple will produce sap with a sugar content of just two percent-sap right out of the bucket often tastes more metallic than sweet-Bartlett must collect more than 40 gallons of sap to create just one gallon of syrup.

And whether there's any sap to collect depends on the weather.

* * *

Sugar maples require a cold recharge, weeks of temperatures below freezing, to convert the starch the tree has stored during the summer months to the sucrose that will power its budding in the spring. It is the sucrose that gives the tree's sap its sweetness, and no other tree, not even other maples, produces it in such abundance. But bitterly cold weather, without protective snowfall, can also freeze and kill the maple's relatively shallow roots.

For the tree's sap to run at all requires cooperative weather, says Timothy Perkins, who directs the Proctor Maple Research Center at the University of Vermont, an large sugarhouse on a hill east of Burlington surrounded by more than 35 acres of sugar maples.

Perkins explains that the so-called sapwood just beneath the maple's bark is filled with gas, not water like most other trees. In cold weather, the gas allows the maple to freeze from the inside out, turning the sap in its limbs to ice. This ice, because it creates an area of lower pressure than the gas that usually fills the sapwood, actually pulls more sap towards the frozen section. This process sucks the sap up the tree from the roots to reach branches that can tower more than 150 feet above the ground.

Then, when the tree begins to warm during the day, the sap ice thaws and pushes liquid away in every direction. Drill a hole an inch and a half into the maple's rough, channeled bark, and the liquid will follow the path of least resistance, dripping out at a steady rate.

Of course, that rate depends on the tree. "The more limbs on a tree, the more it will run generally," Bartlett says. "Out in the deep woods, sometimes you don't get as much." Once the temperature swings end, usually in early April, so does the sap run. And Perkins has found that since the 1970s, the sap run has been three days shorter than in the past-starting a week earlier but ending about 10 days earlier.

The first runs of sap produce the best syrup and quality slowly degrades over the course of the season, which historically has lasted about a month. Color determines the value of the syrup, from Vermont Grade A, a light amber syrup with a delicate maple flavor that can fetch more than $60 per gallon, to Vermont Grade B, a darker syrup tasting more of caramel and commanding a lower price. Below that are the commercial grades that end up in everything from baked beans to tobacco products.

Maple syrup's increasing popularity-an all natural "organic" sweetener-combined with back-to-back poor seasons in Quebec has driven the price up in recent years. Last year, the Quebec season lasted just under a week due to a quick transition from a cold March to a very warm April. And while Vermont and New York farmers had a relatively good year-combining to make 800,000 gallons or so-that's not even 10 percent of the amount Quebeckers make even in a bad year.

* * *

The evaporator at Carney's sugarbush is a wrought iron classic with three pans and a 15-foot chimney, all of which Frank Carney, the late proprietor and namesake of the outfit, bought used in the 1950s. The contraption dominates the splayed, chinked wooden walls, cobwebbed windows and rusting roof of the sugarhouse, nestled among some sugar maples a hundred yards or so up the mountain.

During a typical run, Fitzgerald keeps the fire going, pitching four-foot logs into the custom-built furnace, while watching the sap as it boils. A woodland alchemist, he observes as the sap thickens and flows from one pan to the next, occasionally pausing to scoop away some foam or dipping a piece of pork fat in a pan that is threatening to boil over. Fragrant clouds of steam bathe him before escaping out of every available opening in the sugarhouse walls, even roiling out from beneath the roof.

When the amber liquid reaches the final chamber, Fitzgerald employs the sixth sense common to all sugarmakers to judge when the sap has become syrup. He confirms that sixth sense with a special "sirop" thermometer, which notes that syrup should boil at 7˚ F higher than water, then a hydrometer, which checks the viscosity.

Cranking open the spigot, Fitzgerald then pours off the syrup into a bucket and pours it through a felt strainer atop a metal filter box to catch the "sugar sand"-bitter niter. A metallic gurgle sounds from within and a final spigot releases sweet, brown syrup that is poured into plastic quart and gallon jugs by Marianne Bartlett, Rick's wife.

All this work results in 50 to 200 gallons of syrup a year, depending on the weather. Last year, they made 110 gallons but the year before that only 80. When asked whether this will be a good year, Fitzgerald says "That's one of those unknown unknowns. It all depends on the weather."

* * *

The weather in upstate New York and New England has been weird in the last decade by all accounts. Droughts; little snow one season, blizzards the next; and ice storms that damage the limbs of many maple trees have become almost common: 1998, 2003, 2008. Since 1907, Lake George has failed to freeze over completely only four times, all since 1991.

It's not just small farmers that notice the changes in the weather. Sam Cutting, Sr., a 40-year veteran of the maple trade, has also noticed that the seasons and storms are becoming more extreme and unpredictable. Cutting owns Vermont's Dakin Farm, established in 1792 and now grown into an operation that can sell more than 50,000 gallons of syrup a year.

"This is a weather-related industry," Cutting says. "There are always problems in the maple industry: gypsy moths, floods, droughts."

But it is these weather-related problems that seem to be growing with every year, along with the steady creep into February and even January of the tapping season's start. Bartlett began tapping in February this year and the season appears to be a bit short, ending for the Carney sugarbush on March 29 or so. "It pretty much stopped running," he says, though it was a relatively good season overall. "This year we made 122 gallons."

According to research from Barry Rock, professor of natural resources at the University of New Hampshire, the New England region, including upstate New York, has already warmed an average of 0.7˚ F over the last century, with the bulk of that warming in the winter - an average gain of 1.8˚ F.

That warming has already had an impact: This year some sugarmakers in New Hampshire were unable to make any Grade A syrup.

Such warming gives rise to fluke weather but also a host of other problems. For example, without prolonged cold, insect pests, such as pear thrips, can survive the winter to infest a tree year after year. And man's impact is not limited to warming the winters.

Chemical pollutants form acid clouds that bathe trees in searing vapor or leach critical nutrients out of the soil. Non-native pests, such as the Asian longhorned beetle, destroy trees quickly. And even native wildlife can rapidly become a significant threat. Deer populations have exploded in some areas and, without predators to control them, graze away the tender maple shoots and saplings.

"You have to look at the entire picture," says Perkins. "Acid rain is always here now as a low-level stress. Then, when there's some sort of climactic disturbance or pest outbreak, the trees go into a spiral of decline."

* * *

It is the 3˚ to 10˚ F warming predicted over the next century by the United Nations Intergovernmental Panel on Climate Change that may doom the sugar maple in the northeastern U.S. Even the U.S. Environmental Protection Agency concedes that the sugar maple will not survive the century in New England. Its Climate Action Report from 2002 notes, "In addition, climate change is likely to cause long-term shifts in forest species, such as sugar maples moving north out of the country."

In other words, it is not a question of if the sugar maple will disappear, it is a question of when. Such shifts of species have taken place gradually in the past, over hundreds of years, allowing adaptation, but not in this case. Already, according to research from ecologist Brian Beckage of UVM, tree species have shifted more than 90 meters up the slopes of the Green Mountains since 1964 in search of cooler climes.

The cost will be tremendous if these predictions hold true. Maple syrup production in the Northeast, a $65 million a year industry, will cease to exist and with it a critical financial lifeline for small family farmers in the region. Already, according to preliminary data from one of Rock's graduate students, the sap from northeastern maples is getting less sweet.

The mix of woods in commercial forests will change, potentially threatening 300,000 forestry and forest-product jobs, such as those at paper and saw mills across the region.

And, according to the New England Regional Assessment performed by Rock and his team, the loss of sugar maples would dampen the bright colors of New England's fall foliage - a major tourist attraction and multi-billion dollar earner for residents. Already, preliminary data seems to indicate that fall foliage is not as brilliant as in the past. "I'm a Vermonter and when I think of New England I think of certain things: maple syrup, colorful fall foliage," Rock says. "But with 6˚ to 10˚ warming we won't have maples."

State governments have begun to act, launching the Regional Greenhouse Gas Initiative, an effort by the 10 Northeast states to limit carbon dioxide emissions from power plants. The Obama administration has called for similar legislation nationally.

But some amount of climate change is already in the works and can't be stopped. That's bad news for sugar maples and sugarmakers. The giants of the past are already dead or dying.

"There used to be trees 200 to 300 years old, you could hang five buckets on 'em," Frank Carney said in 2003 before he passed away. "We don't have any more growing like that."

David Biello has been covering the environment, energy and science for 10 years at publications ranging from Scientific American to Elle. His brother is an organic farmer south of Plattsburgh, N.Y., who sugared for the first time this year.

Reprinted with permission of Hearst Communications, Inc

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