Vermont's maple syrup industry has entered a renaissance in the 21st century following decades of decline, becoming one of the Green Mountain State's preeminent industries.
In 2018, the value of Vermont's maple syrup production exceeded $54.3 million, and accounted for over 38% of all the maple syrup produced nationwide, making it the largest producer in the U.S.
The revival comes as Americans are turning their backs on refined sugars for natural products like maple syrup, agaves, and honey. However, that newfound success could come under threat from climate change.
Vermont's average temperature rise since 1895 has been around 2.6° F, well above the national average of 1.9° F.
The consequences of that kind of change could add another layer of uncertainty to a business that's already unpredictable.
"The season is getting harder to predict," says Joshua Rapp, a regional scientist at Mass Audubon. "When to tap, when the best flows are going to be, and that matters for when you're planning your year."
The sugar maple tree's range extends across the northeastern and Midwestern United States, but researchers predict rising temperatures could move the optimal range for syrup production even further north into Canada by 2100.
That northward shift would give a further advantage to Quebec, which already produces over 70% of the world's maple syrup and sets the world price.
Planning is essential in maple syrup production. During the season, some days might produce no sap, while other "ideal sap flow days" could account for half a season's yield. The sap is boiled into syrup at processing centers where it takes about 40 gallons of collected sap to make just 1 gallon of syrup.
Canada might dominate the market, but Vermont holds its own. The state only uses about 4% to 12% of the sugar maple trees suitable for syrup production, but 6 million of the U.S.'s 13.3 million taps are in Vermont. In 2019, Vermont's sugar makers produced over 2.07 million gallons of syrup.
The production calendar has never been precise, but sugar makers historically tapped their trees in mid-March, the first day in a season that usually ran 6 to 8 weeks. The season has shrunk by a week since 1870, with the smaller window lowering the probability that ideal sap flow days will occur.
"You could be doing everything right, have the latest technology, but if you don't tap at the appropriate time, you're going to miss the ideal weather," says Mark Isselhardt, maple specialist at the University of Vermont Extension.
Sap flow is dependent on a cycle of freezing overnight temperatures and above freezing daytime temperatures that build enough pressure in a tree to release the clear liquid.
Inconsistent weather cycles have interrupted that cycle, something that Burr Morse, a 7th generation sugar maker at Morse Farm in Montpelier, says has made an impact.
"I think in the last 20 years we've had more bad seasons than we did before that. Just because of the weather… the nights didn't quite get freezing enough."
Those temperature spikes can have devastating effects. In 2012, a dramatic spike in warm weather decimated production region wide, with some days in March climbing above 70°F.
"Throughout the whole region, from Minnesota to Nova Scotia, all syrup made after that [temperature spike] was off taste and not suitable for table grade," says David Marvin, owner of Butternut Mountain Farm in Morrisville, which has been in operation since 1972. "It took us 6 years to sell that product... It was very, very problematic because those industrial syrups are not as valuable as syrup made for the table."
Jacob Powsner who runs syrup production at Baird Farm says the property produced half as much product as usual in 2012. "Sugar makers are fine with volatile weather to a certain point." he says. "We like wacky weather that goes from 25 to 50 degrees, as long as it stays in that range."
Snowpack is responsible for keeping temperatures within that ideal range. Vermont's forests rely on a thick blanket of snowpack between winter and spring to keep trees and soils healthy. From 1963 to 2010, Vermont saw at least 75 days with 1 inch of snow on the ground, but in 2011, there were only 13.
Unlike other big agricultural industries, sugaring is local and family owned, with parents passing down farms to their children and grandchildren.
Vermont's sugar makers are attuned to the changing landscape of their industry. Sugar makers take deliberate steps to protect their forests, not just for the syrup or timber, but because healthy maples contribute to capturing and sequestering carbon dioxide in the atmosphere.
Technological advancements in sap collection have increased yields and extended harvesting seasons beyond the boundaries of the past. Traditional collection using buckets has been replaced by hundreds of miles of vacuum pump-operated tubing.
"It's reduced the labor that is required to make sap," says Marvin, who operates over 27,000 taps at Butternut Mountain Farm. "One person can cover a lot more taps in a day because we don't have to gather."
"We just have to make sure the system is in good condition."
Sugar makers carefully track which trees they tap, monitor soil quality and tap sanitation, curb invasive pests, and manage competition from other tree species.
Rising temperatures could eventually overwhelm any mitigation strategies if they become too severe, but sugar makers have been able to adapt to a changing landscape as best they can.
"Good management is key. There are a lot of sugar makers that are doing good management on their land," says Keith Thompson of the Vermont Department of Forests, Parks and Recreation. "It's not just about keeping the individual trees healthy, it's about keeping the entire forest healthy."