Ice Out: How New Hampshire Winters are Slipping Away
Despite some truly cold days, recent years have left many signs of warming winters in New Hampshire: shorter periods of continuous snow cover, more warm days mid-winter, wetter/heavier snowfalls, less opportunity for snowmobiling or cross country skiing, spottier seasons for ice-boating and dog-sledding, and foreshortened seasons for the Alton Bay Ice Runway.
New Hampshire’s winter culture is slipping away, with big implications for our tourist industry. As one UNH earth scientist put it, “For us in New England, winter is the fastest-changing season…We are losing the cold.”
Overall, climate data from New Hampshire show we have lost 21 days of snow cover and 18 nights when the temperature drops below freezing with an average temperature rise of 3 degrees in the past 100 years.(1)
One of the ways our warmer winters have been quantified is by the date of
“ice out” on our lakes, the date each spring when a lake becomes free of ice. Records go back 100-150 years, including since 1887 for Lake Winnipesaukee and 1869 for Lake Sunapee. Not surprisingly, these records have revealed consistent trends towards earlier ice melt.
One study of 29 New England lakes, including Winnipesaukee and Sunapee, studied between 64 and 163 years of records and showed “very consistent” data of progressively earlier ice-out dates, 9 days in mountainous and 16 days in lakes-region New Hampshire and Maine.(2) (This was published 20 years ago, and as shown below, trends have intensified more since then.)
Another study of Mirror Lake in Woodstock NH has shown 21 fewer days of ice over the past 50 years.(1)
Loss of lake ice is not only a marker of changing winters, it is an important determinant of summertime water quality. As one climate scientist explains, open water, unlike ice or snow cover, absorbs rather than reflects the sun’s heat, leading to an accelerated heating cycle for the lake. “The northern lake ecology is tied to this balance of having a cold, reflective surface for part of the year, and a heat-absorbing one for the rest. When ice-outs come early, the water temperatures rise; this, in turn, creates better habitats for algae and…cyanobacteria”, which destroy the pristine lakes we expect from a New Hampshire summer. “Ice, for a lake, is very, very important for setting the summer conditions.”(1)
This year, again fitting the warming trend, ice-out on Lake Winnipesaukee was declared on April 8, 2022.
New Hampshire will continue to change over the next few decades, but it’s up to us how much. For climate change not to accelerate that change into a New Hampshire beyond recognition, we must collectively make changes in our behavior and in our energy use. We must conserve, become more efficient, avoid greenhouse gas producing industries and food sources, and drastically reduce carbon-dioxide producing energy production, focussing on solar, wind, hydro and perhaps more nuclear production of electricity, and conversion of our cars, trucks, buses, trains and heating sources to electric and geothermal.
For the many ways you can make a difference in your everyday life, please see the “Checklist of Personal Actions to Reduce Climate Change” in our “Brochures and Pamphlets” section under the “Family Resources” tab of our website, nhclimatehealth.org.
— Paul Friedrichs MD
Exeter NH
References:
International Journal of Climatology 22: 1819-1827 (2002)
