DURHAM, N.H. – New Hampshire’s maple syrup producers say they are feeling the impact of climate change, as winters become warmer and frigid nights so critical to their business become fewer.

Producers joined climate experts and Democratic U.S. Sen. Maggie Hassan of New Hampshire on Tuesday to talk about the state’s changing climate and how it is affecting one of the state’s most important industries.

Some producers talked of seeing a steep drop in the amounts of sap they are getting, while others are dealing with another trend attributed to warmer temperatures in which the sap goes up to the top of the trees rather than down to taps.

The U.S. Department of Agriculture says Connecticut, Maine, Massachusetts, New Hampshire, New York, Pennsylvania and Vermont produced 3.78 million gallons of syrup in 2016.