How is climate change affecting
Lake Champlain?

Mounting evidence makes clear that the Lake Champlain Basin’s climate is changing, affecting fish, wildlife, and plant communities, as well as human uses of the Lake. The type and number of fish species likely will change, as aquatic invasive species may have greater opportunity to spread. Warmer water temperatures have the potential to increase the frequency of blue-green algae blooms as well.

ice fishing on Lake Champlain

Increased surface water temperatures affect native cold-water fish species. Photo: Andrew Gilbertson

Studies in the Lake Champlain Basin and neighboring regions have documented climatic trends of increasing temperature and precipitation. Climate models predict these changes are likely to continue and increase in the coming decades. Climate change has caused, and will continue to cause, changes in the Basin’s ecology and water quality. Resource managers and stakeholders recognize the need for both individuals and communities to adapt to climate change. Climate adaptation strategies can help to mitigate many of the environmental, economic, and social risks resulting from climate change.

Climate Trends

Lake Champlain Basin migrating climate

Figure 23 | Lake Champlain Basin migrating climate

Climate trends observed in the Lake Champlain Basin are similar to those observed across the northeastern US and eastern Canada. The average temperature in Vermont has increased by 2.7 oF since 1941, and the last decade has been the warmest on record. Global climate models project continued increases in air temperatures. National and regional studies project that average air temperatures in the Basin may rise 3-6 oF by the middle of the century. By the end of the century, local temperatures may have risen by 5.5 - 8 oF, resulting in a shift to climate conditions currently experienced in the mid-Atlantic states (Figure 23).

Average Lake Champlain surface water temperatures also have increased in recent decades (Figure 24). Records from the US National Weather Service indicate that Lake Champlain has frozen over much less often in the last 50 years than in the previous half century (Figure 25). When freeze-over does occur, it is later in the winter and ice melts earlier in the spring.

water surface temperature change graphic

Figure 24 | Mean August water surface temperature change since 1964

SOL Figure 24

Figure 25 | Date of freeze-over on Lake Champlain, 1910-2015

Annual precipitation in the Vermont and Québec portions of the Basin has increased by 45.8 mm per decade since 1941, and in New York, precipitation has increased by an average of 0.22% per year between 1951 and 2006. High intensity precipitation events (greater than one inch per day) are now more frequent in the Basin, and the amount of precipitation falling in the heaviest 1% of all daily rain events has increased by more than 70% between 1958 and 2010.

Although precipitation remains difficult to forecast, most studies and models suggest that a warmer climate will lead to wetter, more energetic precipitation patterns in northeastern North America. The Lake Champlain Basin can expect more rain, especially in the winter, and will experience more intense storm events.

Weather, Climate, and Climate Change

Some people wonder what scientists mean by “global warming,” when winter in the Lake Champlain Basin often still includes long periods of bitter low temperatures, blustery wind, snow, and ice. The temperature, wind, and precipitation observed during any particular storm event are the key components of weather—the atmospheric conditions at a point in time. An average of temperatures, wind, and precipitation over several decades presents a weather pattern over time, and this pattern is known as climate. The term “climate change” refers to a long-term shift in weather patterns at a regional scale. When changes in climate across the globe are considered collectively, the global trend is towards warmer conditions. Local weather conditions may not seem particularly unusual, but global atmospheric patterns drive local weather conditions. As temperatures increase, so do the energy and moisture contained in the atmosphere, which lead to more severe local weather at times.

Consequences of Climate Change
More intense storms will result in more severe flash floods in rivers and streams. Streambank erosion and municipal combined sewer overflows are common hazards during flood events, releasing sediments, nutrients, and other pollutants that are transported to the Lake.

Increased nutrient levels combined with longer periods of warmer surface water temperatures may intensify potentially toxic algae blooms. Algae blooms degrade water quality and reduce dissolved oxygen in the water, depriving fish and other aquatic life of oxygen. Toxic algae blooms also threaten human and animal health and impair recreation where they occur.

snowy silhouettes

By the end of the century, the region can expect more winter rain and less snow. Photo: Justin Bevins

Increased surface water temperatures also affect Lake Champlain’s capacity to support native cold-water fish species such as salmon and trout and cool-water fishes like walleye and northern pike. Warmer water may also alter spawning times, potentially harming the reproductive success of cool-water fishes in Lake Champlain. Simultaneously, populations of warm-water fish species like bass and invasive white perch are likely to increase.

Biological diversity also is affected by floodwaters, which increase opportunities for invasive species to spread to new areas. More winter precipitation falling as rain, rather than snow, will alter the natural fluctuations of the water levels of shallow areas and wetlands that support spring spawning of some fish and provide habitat to many amphibians.

Climate Adaptation
Policy makers and resource managers are working to adapt to climate change by increasing the resilience of natural and human systems in the wake of intense weather events. Strategies and measures that improve the ability of these systems to absorb the impacts of severe events, and quickly recover in their aftermath, are necessary to minimize the effects of climate change.

Floodplain planning and mitigation of storm water runoff, using best management practices, will help to prevent or minimize erosion and water quality degradation. Preventing new invasive species from becoming established in the Basin is a long-term strategy to reduce climate change impacts.

What YOU can do

Plant Buffers: Volunteer to help plant trees and shrubs along waterways with a local watershed group. Roots will hold the soil and help protect habitat and water quality downstream.

Plant Native: Native trees, shrubs, flowers, and ground covers flourish with less water, fertilizer, and pest control measures. Native plants also attract wildlife including birds and pollinating insects.

Get Pervious: Replace pavement with porous surfaces like gravel, bricks, or pervious paving. Porous surfaces reduce storm water runoff and allow pollutants to be absorbed and filtered.

Be a Citizen Scientist: Anyone can volunteer to help scientists with their research. There are citizen-sourced projects that observe and monitor water quality, weather, wildlife, invasive species, and much more.

Join In: Join a lake or river organization. You can help clean up your watershed and advocate for public policies that will protect it.

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