Climate Change Is Ruining Maple Syrup By Making It Less Sweet And Affecting When We Tap It

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Maple syrup season occurs between February and April of each year, when sap from sugar maple trees is extracted and converted into syrup. On average, it takes 40 gallons for sap to create a single gallon of maple syrup. Although maple syrup production has increased at a rate of 10 percent per year over the past decade, climate change has already begun to affect the industry. For example, the tapping season in New England now begins and ends approximately one week earlier than it used to. And, a new study shows that, by 2100, maple syrup season may begin one month earlier than it did between the years 1950 and 2017.

Maple syrup production is contingent upon two climate-sensitive characteristics: its sugar content and sap flow. Sugar content depends on the amount of carbohydrates the tree has stored after a year of photosynthesizing and taking up nutrients from the surrounding soil through its roots. Sap flow depends on the local area’s freeze-thaw cycle. Specifically, sap begins to flow in sugar maple trees during a very specific window: when freezing temperatures (at or below 0°C / 32°F) occur at night but warm up during the day.

A team of scientists spanning universities across Canada and the United States surveyed six sugar maple groves between the state of Virginia and Québec, Canada over the course of six years to see how sugar content and sap flow related to monthly and yearly temperatures as well as the prior year’s temperatures.

Using this information and historical temperature data, the researchers were able to develop a model that predicted how warming may impact maple syrup production if we continue to produce greenhouse gas emissions at the current rate. In addition to determining that sap production will occur earlier in the year by the end of the century, the team also found that syrup production will likely decline in Virginia and Indiana, but increase considerably in sugar maple groves further north. However, sugar content will likely decrease and become more variable from year to year.

According to co-author Dr. David Lutz, a research assistant professor of environmental studies at Dartmouth, “Maple syrup producers may want to consider adapting their technologies and collection logistics in advance, so that they are prepared for how climate change is going to affect production.”

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