Climate

These averages, however, can be misleading since the climate is changing. The Hubbard Brook Ecosystem Study 30 miles west of Eaton in Woodstock, New Hampshire is the longest running and most comprehensive ecosystem study site in the world. Meticulous climate and streamflow records have been maintained there for more than 60 years. Their data show that northern New Hampshire is seeing more dramatic changes than the rest of New England.

Here are some key findings, many of which we are experiencing in Eaton. Air temperatures have increased and winters are warming more than other seasons. Heavy precipitation events are on the rise, and there is a 70% increase in “extremely heavy storms”. Most of these occur during summer months. This greater precipitation has increased streamflow dramatically.

Winters are dryer with an average decrease of snowpack of 12”. There are 24 fewer days with snow on the ground. We have earlier and drier spring seasons, and spring run-off is earlier by a week. Duration of lake ice cover has decreased, “Ice in” is an avg. of 7 days later – and “ice out” an avg. of 14 days earlier. The number of ice-cover days at Mirror Lake near Hubbard Brook has declined by 25 days since 1956.

Average annual temperatures are predicted to rise 4 to 9°F. This may combine with changes in extreme precipitation events to double the frequency of 1-6 month droughts. Increased temperatures will shorten the winter season and reduce snowpack, having a severe impact on the skiing industry. This will also impact trees and other forest plants by damaging roots, killing vegetation, and degrading habitats. Hotter summers are likely to increase the temperatures in some coldwater streams too high for native species such as brook trout to thrive. Flooding alters flows of streams and rivers and increases the amount of pollutants and sediments that wash into them, altering habitat, affecting reproduction, and causing direct mortality.

For wildlife, the erosion and increased sedimentation from extreme storms washes away or covers spawning habitat and sweeps animals downstream or kills them. Mussels are particularly sensitive to sedimentation, and can be buried under the load, which also clogs their filter feeding mechanisms, killing them. Stormwater also floods nest sites along the banks of rivers and ponds or in the saltmarshes downstream, affecting loons, wood turtles and others. Extreme storms can also disrupt bird migrations and make breeding and nesting sites inhospitable, forcing birds into marginal habitats.

Climate change will facilitate the introduction and spread of invasive species, including new diseases and pathogens. For instance, the hemlock woody adelgid, whose range is limited by temperature, has been steadily pushing north and reached Moultonborough by 2015. Loss of hemlock would have dramatic effects on forest composition, wildlife habitat, and ecosystem processes in terrestrial and aquatic ecosystems. West Nile Virus will likely become more of a threat if milder winters and wetter summers facilitate mosquito survival and breeding.