Overview: Vermont Climate Assessment 2021
By Michael Caduto
The reconstructed Bartonsville Covered Bridge opened for traffic on January 26, 2013. The new bridge replaced the original 1870 structure that was washed away during Tropical Storm Irene on August 28, 2011. The loss of the historic structure, and the $2.6 million cost to replace it with this 168-foot long replica, are examples of the heavy costs being incurred by Vermonters due to the meteorological impacts of global warming. PHOTO: VT Agency of Natural Resources (Marie L. Caduto).
In November 2021 the University of Vermont’s Gund Institute for the Environment published Vermont Climate Assessment: Climate Change is Here–the first comprehensive climate change study for Vermont since 2014. One of the most dramatic findings of this recent study is that, from 1900 to 2021, Vermont’s average annual temperature rose by almost 2°F. This dramatic temperature rise is driving a range of significant changes in weather patterns and extreme meteorological events that are impacting everything from public health, energy use and tourism, to water quality, agriculture and ground water supplies.
These findings mirror global studies which show that the Northeast is experiencing some of the most pronounced weather changes of any region on Earth due to global warming. If you think that Vermont winters are milder now than they were just decades ago, you’re spot on; during the past 60 some years winter temperatures in Vermont have increased 2 ½ times faster than the overall average temperature rise.
This historic increase in temperature is acting like a meteorological engine whose heat energy is driving us toward a climate that frequently generates extreme weather phenomena, both wet and dry. On average, the state now receives 7.5 inches more rain each year than it was receiving in 1900. Vermont’s storms and weather patterns now range from cataclysmic rain events that sometimes seem to be of biblical proportions—such as 2011’s Tropical Storm Irene which dropped 11 inches of rain in some areas—to periodic shifts in the water cycle that result in prolonged dry spells like that of 2020-2021.
While driving around the state, Vermonters still regularly pass Irene-impacted sites that cause a catch in the throat, like the gravel bar along the White River where a house once stood near the Route 107 iron bridge in Bethel, or the beloved old maple tree that used to grow by the Ottauquechee River behind the Woodstock History Center, but was toppled by the floodwaters. One of the iconic video records of the impact of Tropical Storm Irene—taken on August 28, 2011 by Susan Hammond—shows the surging floodwaters of the Williams River lifting up and carrying away the Lower Bartonsville Covered Bridge from where it had rested since 1870. (Viewer discretion is advised for language, as well as imagery potentially disturbing to those who value Vermont’s history.) https://www.youtube.com/watch?v=nj5ZyIafegw
In what other ways is climate change impacting our lives? Among the most significant aspects of the warmer weather is that, during the past 6 decades, Vermont’s freeze-free period has increased by three weeks. The evidence of this change is all around us: from the arrival and survival of invasive species that would not have been able to overwinter Vermont’s older, colder climate regime (such as deer ticks), to the northward shifts in the geographical ranges of many bird and insect species. The ranges of some 70 species of Vermont birds, including the common loon and hermit thrush (our official state bird), are expected to shift far enough northward in the next 25 years that they will no longer be found in Vermont. Meanwhile, in recent decades, some birds that were once found south of Vermont’s southern border have gradually become established in the state, including the Carolina wren and red-bellied woodpecker. Meanwhile, white-tailed deer numbers will continue to rise, and the moose population to decline.
Sugar maples, balsam fir and other northern forest tree species are increasingly stressed by longer, warmer growing seasons and abbreviated, milder winters—conditions which favor trees that are adapted to more southern climes, such as hickory and red oak. With the ground freezing later each autumn, and thawing earlier in springtime, foresters have fewer weeks of hard-frozen soil upon which to conduct their harvests. With warmer winters and less snowfall, ski resorts that have extensive snow-making capability often manage to blanket the slopes with sufficient artificial snow, while smaller downhill ski areas and cross-country ski centers frequently operate at the mercy of natural weather conditions.
Climate change is also impacting both the quantity of water in our ecosystems, as well as the quality of water found in our streams, lakes and rivers. Periodic extreme rainfalls and rapidly rising water levels increase erosion as soil washes away, especially where there is exposed agricultural soil. Silted waters cover the gills of fish and smother their spawning grounds, depriving fish and their eggs of life-giving oxygen. And the added nutrient burden can cause algal blooms that are sometimes toxic, such as the blue-green algae infestations that have plagued some parts of Lake Champlain and other still waters in recent years.
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This is the first of several articles analyzing the findings of the 2021 Vermont Climate Assessment. Part 2 will explore the major generators of carbon emissions and causes of climate change in Vermont. The complete findings of the 2021 Vermont Climate Assessment can be accessed here: https://site.uvm.edu/vtclimateassessment/#
