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Warming Maple Tapping Season

By Climate Central

Maple syrup season has begun! Sap from maple trees is collected during the tapping season — between February and April. These are the months when temperatures are above freezing during the day and below freezing at night, making the sap flow.

  • On average, it takes about 40 gallons of sap to produce one gallon of syrup.
  • 75 percent of all U.S. maple syrup comes from New York and New England, but the area where syrup is produced extends south to Tennessee and west to Minnesota.

As temperatures have climbed due to climate change, the industry has changed.

  • The tapping season in New York and New England starts about 8 days earlier and ends 11 days earlier than 50 years ago.
  • Higher temperatures mean less sugar in the sap. That translates to more sap required per gallon of syrup.
  • During hot periods outside of winter, the sugar within the sap can be reduced by 40 percent.
  • A century ago, 80 percent of global maple syrup production was based in the U.S., with 20 percent in Canada. Those figures are now reversed, as climate change likely plays a role, along with advances in sap collecting and Canadian subsidies.

Recent advances in sap collecting methods have allowed the U.S. maple syrup industry to thrive. In the future, though, climate change is projected to alter the industry.

  • With no change in greenhouse gas emissions rates, tap season may start 30 days earlier than at present by 2100.
  • The number of sap flow days may not change in the Northeast, but maples farther south will be increasingly less viable for producing syrup.
  • Shifting ecological patterns after 2100 could mean fewer maple trees in New England and New York, possibly closing the tap on the industry.

A rise in days above freezing in winter and early spring also raises the risk of damage that the forest tent caterpillar and pear thrip can cause to maple trees.

Information is gathered from congressional testimony of Dr. Timothy Perkins, Director of University of Vermont’s Proctor Maple Research Center with additional projections from Skinner et al. (2010).