How Climate Change Impacts Forests

Climate change is altering the natural disturbance regimes to which Connecticut forests are adapted.

Learn about current and expected changes in the following areas:

Precipitation
Temperature
Drought
Snowpack
Wind Events
Ice Storms
Invasive Species
Changes in Species Composition
Herbivory
Changes in Local and Regional Economies

 

Precipitation:

Climate model projections of changes in spring precipitation (%) by the middle of the 21st century relative to the late 20th century under a high emissions scenario. Hatching represents areas where the majority of climate models indicate a statistically significant change. So, the entirety of Connecticut is expected to undergo a significant increase in spring precipitation by mid-century. Source: NOAA State Summaries 2019

Annual average precipitation is projected to increase, with increase most likely occurring the spring and winter, during the dormant season. Connecticut will experience an increase in both total precipitation and in the number of extreme precipitation events. Heavy rainfall events increase the risk of soil erosion, nutrient deposition, and the spreading of contaminants and pathogens.

Extreme precipitation events and wind- and pressure-driven storm surges can result in flooding, especially in coastal communities when these events occur in conjunction with high tides (Frumhoff et al., 2007, Runkle et al. 2017). Flood disturbance influences forest health, species diversity, and regeneration. These events may occur more frequently and may be larger in duration and extent, leading to a greater overall effect on the forested ecosystem.

Sea level rise has caused an increase in tidal floods associated with precipitation that exceeds local thresholds of water levels. As sea level has risen along Connecticut's coast, the number of tidal flood days has also increased. Here, you can see that the most recent decade had the greatest number (18) of floods of any 10-year period. Data from New London is being used as a metric for all of Connecticut's coastal and flood plain areas. Source: NOAA State Summaries, 2019

Temperature:

Temperatures in Connecticut have increased over 3°F since the beginning of the 20th century. Forest productivity is changing as a result of our warming climate. With warmer temperatures lasting longer, our plants have a longer growing season and more time to photosynthesize. This can lead to enhanced forest growth and carbon sequestration. However, plant respiration also increases with increasing temperatures (Sendall et al. 2015). It is therefore possible that increases in growth and productivity are offset by increases in respiration.

Rising temperatures affect leaf phenology (bud break, leaf maturation, and leaf senescence), which increases vulnerability to late spring frosts and soil freezing, stressing trees and reducing their productivity. Warmer temperatures paired with drier conditions during the growing season can also cause tree stress and decrease overall forest productivity (i.e., tree growth).

Observed and projected temperature changes (compared to the 1901-1960 average) in Connecticut's air temperature. Projected changes for 2006–2100 are from global climate models for two possible futures: one in which greenhouse gas emissions continue to increase (higher emissions) and another in which greenhouse gas emissions increase at a slower rate (lower emissions). Temperatures in Connecticut are depicted by the orange line. Shading indicates the range of annual temperatures from the set of models. Unprecedented warming is projected to continue through the 21st century. Less warming is expected under a lower emissions future and more warming under a higher emissions future. Source: NOAA State Summaries, 2019

Drought:

Although annual precipitation is increasing, the number of consecutive days without precipitation will also increase. Droughts are among the greatest stressors on forest ecosystems, and often lead to secondary effects like insect and disease outbreaks, and increased fire risk. Droughts are playing a greater role shaping Connecticut’s landscape.

Connecticut’s longest drought on record lasted 46 weeks beginning in June 2016 and ending in May 2017. Visit the U.S. Drought Monitor to track droughts in Connecticut.

Snowpack:

Light snow cover in a Connecticut forest. Photo Credit: Nathan Piche, CT DEEP Forestry 

Rising global air temperatures have seasonal effects. Air temperatures are increasing most in the winter, which contributes to a decrease in snowfall and snow pack.

Wind Events:

Overstory pine damage from hurricane Sandy (2012). Photo credit: Jerry Milne, CT DEEP Forestry 

Ice Storms:

Ice storms are a common disturbance in Connecticut forests, and are becoming more common in our warming climate.

Invasive Species:

Invasive plants are already a major issue threatening Connecticut forest health, and it is likely that they will disproportionately benefit under changing climatic conditions.

Changes in Species Composition:

Herbivory:

Changes in Local and Regional Economies:

 

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Content last updated in July 2021.