Confronting Climate Change in the Great Lakes Region

Information on the following pages is documented in the report Confronting Climate Change in the Great Lakes Region: Impacts on Our Communities and Ecosystems, prepared by the Union of Concerned Scientists, updated in 2005.

Growing evidence suggests that the climate of the Great Lakes region is already changing:

• Winters are getting shorter.
• Annual average temperatures are growing warmer.
• Extreme heat events are occurring more frequently (Chagnon et al. 2003).
• The duration of lake ice cover is decreasing as air and water temperatures rise.
• Heavy precipitation events, both rain and snow, are becoming more common (Chagnon et al. 2003).

What is the likely climate future for the Great Lakes region?

In general, the climate of the Great Lakes region will grow warmer and probably drier during the twenty-first century. In 2003, the climate models used at that time predicted that by the end of the century, temperature in the region will warm by 5 to 12 degrees F (3 to 11 degrees C). Newly emerging analysis may imply a wider temperature range.

• Nighttime temperatures are likely to warm more than daytime temperatures.
• Extreme heat events will be more common.
• Seasonal distribution of precipitation is likely to change, increasing in winter and decreasing in summer. Annual average precipitation levels are unlikely to change
• Overall, the region may grow drier because any increases in rain or snow are unlikely to compensate for the drying effects of increased evaporation and transpiration in a warmer climate.
• Drying will affect surface and groundwater levels. Soil moisture is projected to decrease by 30 percent in summer. 
• The frequency of 24-hour and multi-day downpours may continue to increase.

What might these changes mean for Great Lakes ecosystems and the goods and services they provide?
 
Lakes:

• Lake levels were highly variable in the 1900s and quite low in recent years. Future declines in both inland lakes and the Great Lakes are expected as winter ice coverage decreases (Lofgren 2006a; Lofgren 2006b).
• Declines in the duration of winter ice are expected to continue.
• Loss of winter ice may be a mixed blessing for fish, reducing winterkill in shallow lakes but also reducing the stream miles suitable for trout and jeopardizing reproduction of whitefish in the Great Lakes, where ice cover protects the eggs from winter storm disturbance.
• The distribution of many fish and other organisms in the lakes and streams will change. Coldwater species such as lake trout, brook trout, and whitefish and cool-water species such as northern pike and walleye are likely to decline in the southern parts of the region, while warm-water species such as smallmouth bass and bluegill are likely to expand northward.
• Invasions by native species currently found just to the south of the region and invasions of warm-water nonnative species such as common carp will be more likely, increasing the stress on native plant and animal populations in the region.
• In all the lakes, the duration of summer stratification will increase, adding to the risk of oxygen depletion and formation of deep-water “dead zones” for fish and other organisms.
• Lower water levels coupled with warmer water temperatures may accelerate the accumulation of mercury and other contaminants in the aquatic food chain and ultimately in fish.
• Many fish species should grow faster in warmer waters, but to do so they must increase their feeding rates. It remains uncertain whether prey species and the food web resources on which they depend will increase to meet these new demands.

Streams and Wetlands:

• Earlier ice breakup and earlier peaks in spring runoff will change the timing of stream flows, and increases in heavy rainstorms may cause more frequent flooding.
• Changes in the timing and severity of flood pulses are likely to reduce safe breeding sites, especially for amphibians, migratory shorebirds, and waterfowl, and may cause many northern migratory species such as Canada geese to winter further north.
• Reduced summer water levels are likely to diminish the recharge of groundwater supplies, cause small streams to dry up, and reduce the area of wetlands, resulting in poorer water quality and less habitat for wildlife.
• Drought and lower water levels may ultimately increase ultraviolet radiation damage to frogs and other aquatic organisms, especially in clear, shallow water bodies.
• River flooding may become more common and extreme because of the interaction of more frequent rainstorms with urbanization and other land management practices that increase pavement and other impervious surfaces and degrade the natural flood-absorbing capacities of wetlands and floodplains. The result could be increased erosion, additional water pollution from nutrients, pesticides, and other contaminants, and potential delays in recovery from acid rain.
• Land use change and habitat fragmentation combined with climate change-induced shrinking of streams and wetlands will also decrease the number and type of refugia available to aquatic organisms, especially those with limited dispersal capabilities such as amphibians and mollusks, as streams and wetlands shrink.

The report also discusses the following:

• Forests
• Agriculture
• Economic, Social, and Health Impacts

How can residents of the Great Lakes region address the challenge of a changing climate?

Citizens and policymakers can take actions now to reduce the vulnerability of ecosystems and safeguard the economy of the region in the face of a changing climate. These actions represent three complementary approaches:

• Reducing the region’s contribution to the global problem of heat-trapping greenhouse gas emissions: Although some warming is inevitable as a result of historical emissions of CO2, many of the most damaging impacts can be avoided if the pace and eventual severity of climate change are moderated.

Strategies for reducing emissions include:

• Increase energy efficiency and conservation in industries and homes
• Boost use of renewable energy sources such as wind power
• Improve vehicle fuel efficiency
• Reduce the number of miles driven
• Avoid waste
• Recycle

Minimizing human pressures on the global and local environment to reduce the vulnerability of ecosystems and vital ecological services to climate change:
 
Prudent actions include:

• Reduce air pollution
• Protect water quality supplies and aquatic habitats
• Reduce urban sprawl and attendant habitat destruction and fragmentation
• Restore critical habitats
• Prevent the spread of invasive nonnative species

Anticipating and planning for the impacts of change to reduce future damage: This may include a wide range of adaptations, from shifts in fisheries management and farming activities to changes in building codes and public health management plans to prepare for extreme weather events.

Many of the actions that can be taken now to prevent the most damaging impacts of climate change can also provide immediate collateral benefits such as cost savings, cleaner air and water, improved habitat and recreational opportunities, and enhanced quality of life in communities throughout the region.

See full report:

• Union of Concerned Scientists
  

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