Is maple syrup threatened by climate change?

Is the production of maple syrup, an emblematic symbol of Quebec identity, threatened by climate change? If so, what will be the impacts on maple syrup production? We are often asked this question.

Following my heart, with the firm intention of setting the record straight and learning more, I consulted several scientific works on the subject. I then had the chance to discuss it with Frederic Tomesco in this excellent article published by The Montreal Gazette.

First, it is important to understand that the maple grove is a natural ecosystem that has been present naturally for over 6,000 years in North America. You don't plant a maple tree like you plant a vine. The role of the maple producer is to maintain the forest and maintain a balance that respects all the species associated with it. The maple tree will have reached approximately 40 years of age before it can be tapped to ensure its conservation. The sap collected by maple producers represents approximately 6% of the energy used by the maple tree to grow. (Ouimet et al. 2021, La drf: plus de 50 ans à votre service, Gouvernement du Québec).

One of the most obvious impacts of climate change on maple groves is the increase in average temperatures. Milder winters and warmer summers disrupt the natural cycle of sugar maple trees (Acer saccharum), compromising their ability to produce quality sap. Studies such as those conducted by the University of New Hampshire indicate that sugar maple trees are sensitive to warmer winter temperatures, which can lead to reduced syrup production.

It should be noted that in maple syrup production, the seasons vary considerably from one year to the next, strongly influenced by the weather, as in viticulture. In recent years, improvements in equipment, advances in knowledge and technology have greatly improved the yield of maple groves. Due to all these variables, it becomes complex to assess the short-term impact of climate change on a farm.

Many maple syrup producers are noting the progress of the first maple syrup production. A team from Enquêtes Exclusives, the iconic show broadcast on M6 in France, was at La Ferme du Loup in February 2024. It was raining in the middle of winter, an unusual situation for us. However, scientists agree that climatic influences on maple syrup production are rarely as simple and clear as this single example.

Rising temperatures and changing seasons

However, temperatures in Quebec are expected to continue rising at least until the end of the century, with increased warming during nights and winters. An increase in winter rain showers is expected, causing freezing rain that is harmful to trees.

The decrease in snow cover will damage the roots of trees left unprotected during the coldest days. Summer droughts will reduce the trees' energy reserves and the sugar content of maple sap.

While the individual effects of each change seem relatively predictable, they will vary across regions and specific farm locations. One might expect that more southern regions would have earlier, less productive harvest seasons, and more northern regions would have a longer harvest season.

Impacts on the quality and quantity of maple sap

More worrying than the direct impacts on maple production are the complex interactions of climate change with the health of trees and maple groves.

Sugar maples are also vulnerable to diseases and pests that thrive in changing climates. For example, milder winters can encourage the spread of fungal diseases, affecting tree health; the arrival of new insects attracted by a warmer climate could also pose risks, such as the invasion of the Asian long-horned beetle, which could lead to the death of millions of maple trees. Droughts, reducing energy reserves, can cause maple trees to die. Insect outbreaks, such as the gypsy moth, add to the stress, consuming reserves.

However, for a maple tree, growing a new leaf takes energy. Some years, environmental conditions will be conducive to accumulating more reserves, but most of the time these reserves will be used more to cover the energy needs related to stress. From now on, maple stands may require periods without tapping to recover. Maple trees, reacting slowly to their environment, can suffer significant declines without apparent signs for several years.

Outlook for the future of maple syrup

Faced with these challenges, maple syrup producers must adapt to new climate realities to ensure the sustainability of their industry. This may include adopting new forest management practices or using innovative technologies to maximize syrup production. We can see abundant signs of global change. Further south, ash trees are slowly dying due to clay, another invasive exotic insect. At La Ferme du loup and our neighbors, large beech trees are suffering from beech bark disease. Scientists agree that it is important to conserve these companion species to keep this ecosystem alive, but the canary is in the mine.

After reading about the issue, I conclude that the current risk for Quebec maple producers is not the decline in maple syrup production, but rather the threat of losing diversity and seeing maple groves decline. If we do not act today, the consequences could be disastrous for maple syrup producers, namely the total loss of assets and investments in this industry. Nature is strong; maple groves will possibly regain their natural balance in 100, 200, or even 300 years. But is this really the legacy we want to leave to our children and grandchildren?

Sources:

Climate Change and the Sustainability of Sugar Maple Forests: An Integrated Model Approach

Climate Change Impacts on Maple Syrup Production in the Northeastern US: An Analysis at High Spatial Resolution

Projected Influences of Changes in Weather Severity on Sugar Maple, Acer Saccharum, Sap Production

Canada's Changing Climate Report

National Geographic : “How Climate Change disrupts fall foliage”