What Does Climate Change Mean for Maple Syrup?

Maple syrup is the MVP of sweeteners in my kitchen. I can always count on a lazily dispensed drizzle to improve upon simple parts — a bowl of oatmeal, a plate of pancakes, a piece of salmon — with its signature woodsy-sweetness. But the routineness of its use belies the susceptibility of syrup harvests to changes in the weather. And that’s before you factor in climate change. 

To produce sap, maple trees rely on a precise choreography of temperatures — below freezing overnight and above freezing during the day. Anticipating when the longest series of such “freeze-thaw cycles” will occur within a concentrated timeframe has traditionally been key to a good season; if taps are idle for too long between sub-freezing nights, they can gum up and choke off future flow. The sweet spot to tap in New England and Quebec has historically been in late winter, says Joshua Rapp, a senior forest ecologist at Mass Audubon. A degree of guesswork, nonetheless, has always been involved — especially further south, where the best weather for tapping comes earlier and less predictably. Periodic weather extremes have also factored in to make harvests variable as a matter of course — an effect that consumers are spared from, because Canada, the world’s top producer, has a syrup stockpile it dips into during lean years. 

But now, because of climate change, the weather is getting weirder and syrup yields are fluctuating more. “It’s becoming more common to have bad years,” Rapp tells me. Despite this increased noise from season to season, the industry has so far adapted and absorbed the new challenges, shielding eaters from climate change’s sticky impacts. But the longer-term future is less certain.

Steven Roberge, a professor of natural resources at the University of New Hampshire, has watched climate change create “more fuzz, more extremes” that are impacting the industry in his state. The historically gentle transition from winter to spring has become abrupt. Snow cover has also decreased — by three weeks over the past century across the northeast. Less snowy winters, Roberge tells me, have left forest floors bare for longer and tree roots more susceptible to rapid warm-ups near the end of the season, which can hurt sap quality, and to deep freezes that drive frost deeper underground, which can tank yields on warm days that would otherwise be promising.

In many parts of the sugar maple’s range, producers are tapping earlier. Kyle Dewees, owner of Whiskey Hollow Maple in north-central Pennsylvania, says he has to be ready to tap between early January and mid-February, despite the fact that area producers used to begin collecting sap on March 1. Having to start the season sooner is a challenge for producers like him who bottle their own syrup, he says, since preparations to collect sap from his 5,500 trees in Bradford County must now overlap with the work of supplying wholesale accounts and attending industry events in late December and early January. “It’s making us busier,” Dewees tells me. 

The best time to tap is also becoming harder to pin down, which concerns Rapp. He’s seen recent years in Massachusetts with thaws in January and February that were fakeouts of sorts, seeming to signal the start of the juiciest sap flow, when in fact that period occurred later, in March. In cases like that, tapping too early could have lowered yields — at least for producers relying on traditional harvesting methods. 

Most commercial producers, however, have moved away from collecting sap with buckets and gravity, and toward a vacuum system that creates more forgiveness in the timing of harvesting. A vacuum tube is affixed to each tap, drawing sap out of the tree and preventing air exposure, which keeps taps from clogging up if there are longer warm spells between good flow days. The system has helped syrup yields stay where they should be, on average, says Roberge, “even though the conditions over the years have degraded” because of climate change.

While producers are adapting today, the longer-term effects on the industry are less clear, as warming is expected to redraw the map of where sugar maples grow. Rapp projects that by the end of the century, commercial sap production will dry up below southern Pennsylvania, while new growing regions will open up in Canada. That could further increase Canadian production; though a representative for the Quebec Maple Syrup Producers Association last year told the Economist that it’s too early to draw conclusions about what climate change will mean. Warming, after all, helps pests thrive and makes damaging ice storms more common. In 2023, ice storms helped cut Canadian output by 40% over the previous year, which along with rising demand caused that globally important stockpile to dwindle to a 16-year-low, before yields rebounded sharply in 2024 and helped replenish the supply.

In New Hampshire, Roberge is confident that the American syrup industry will weather warming, thanks to producers’ nimbleness and technological advances — including an innovation in sap processing that has made it possible to produce indistinguishable syrup from the red maple, a hardier cousin of the sugar maple that grows farther south. Already accounting for around a quarter of the commercial maple syrup supply, it might become a more important component in the future, Roberge speculates. 

As for syrup from sugar maples, climate change might eventually drive up its price. Rapp’s research has found that warming will make sap less sugary, which means producers will need more of it — and more energy — to concentrate it into syrup with the right sweetness. That might make syrup costlier over time. “You’d expect prices to go up if you have to work harder to get it,” he says. 

So far, the maple industry has taken climate change in stride. But as with other crops like chocolate and olive oil, warming may eventually show up in syrup’s price tag — all the more reason to pour it on generously now.