Climate Impacts

Overview

GLISA has summarized recent research and available data on the impacts of climate change in the Great Lakes region. The summaries on this page and the more detailed pages linked to below provide details of observed and projected changes based on peer-reviewed publications and the United States Global Change Research Program (USGCRP) Fourth National Climate Assessment (NCA4).

Summaries

Temperature

 

  • Since 1951, average temperatures have increased by 2.3°F (1.3°C) in the U.S. Great Lakes region.
  • By 2050, average air temperatures are projected to increase by 3 to 6°F (1.7 to 3.3°C).
  • By 2100, average air temperatures are projected to increase by 6 to 11°F (3.3 to 6.1°C).
  • Winter temperatures have been rising faster than temperatures during other seasons.

Learn more.

Precipitation

 

  • Since 1951, total annual precipitation has increased by 14% in the U.S. Great Lakes region.
  • Total annual precipitation will likely continue to increase, but future projections precipitation vary, especially by season.
  • Lake effect snowfall is expected to increase until mid-century, afterward there is a projected transition to more winter rain.
  • The frequency of lake-effect precipitation may continue to increase in some areas.
  • Warming temperatures may cause snowfall to shift to more winter rain in the future.

Learn more.

Extreme Precipitation

 

  • The frequency and intensity of severe storms has increased. This trend will likely continue as the effects of climate change become more pronounced.
  • The amount of precipitation falling in the heaviest 1% of storms increased by 42% in the Midwest and 55% in the Northeast from 1958 through 2016.
  • Heavier storms are projected to increase in frequency at a faster rate than storms that are less intense.
  • The amount of precipitation falling during intense multi-day events has increased dramatically.

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Agriculture

 

  • A longer growing season will positively impact some crop yields through mid-century.
  • By the end of the century, more frequent and intense severe weather, more flooding and drought risks, as well as more pests and pathogens will likely reduce crop yields. 
  • Water availability and quality will likely pose challenges for agriculture.
  • Earlier warm spells, coupled with variability in spring freezes, may result in more freeze damage early in the growing season. 
  • Projected changes in precipitation coupled with rising extreme temperatures before mid-century, will reduce agricultural productivity to levels of the 1980s without major technological advances.

Learn more.

Lake Levels

 

  • Lake levels are primarily driven by precipitation, runoff, and evapotranspiration.
  • Following a period of below average water levels from 1998-2013, all of the Great Lakes have experienced higher than average water levels and some record highs in recent years (2015-2020).
  • The recent rise in water levels is primarily driven by several years of above average precipitation in the lake basins in the 2010s, as well as several years of high ice cover, including 2014, 2015, 2018, and 2019.
  • Prior to these recent highs, long-term water levels in the Great Lakes fell from record highs in the 1980s to below average for over a decade in the 2000s.
  • Warmer temperatures and higher evaporation rates were partially responsible for historical declines in lake levels.
  • Periods of both high and low water levels are likely to occur in the future, with an overall increase in variability.

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Great Lakes Ice Coverage

 

  • The number of days per winter with lake ice coverage has declined since the start of record in 1973.
  • In most areas, ice cover declines were a sudden shift as opposed to a gradual decline.  For Lakes Michigan, Erie, and Ontario the shift occurred in the mid-1980s, but for Lakes Superior and Huron the shift occurred during the 1997/98 winter.
  • Ice cover has decreased the most in the north (i.e., Lake Superior, Northern Lake Michigan and Huron) and in coastal areas
  • Ice cover on the Great Lakes will likely continue to decrease in the future.
  • Reduced ice cover results in more winter lake-effect precipitation and increased winter wave activity.

Learn more.

Algal Blooms

 

  • The Great Lakes have warmed faster than nearby air temperatures, leading to longer warm seasons and prolonged stratification.
  • More total and intense precipitation is increasing runoff and combined sewer discharge, leading to greater nutrient loads in the lakes.
  • Warmer temperatures, prolonged stratification, and increased nutrient loading are leading to increased occurrence of harmful algal blooms.
  • Hypoxic “dead zones” can result when algal blooms sink, decompose, and reduce dissolved oxygen concentrations. A greater risk of algal blooms may increase the incidence of hypoxia and fish kills.

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Fish and Wildlife

 

  • Coldwater fish populations will likely decline as warmwater fish populations become more abundant.
  • Lake stratification and an increased frequency of hypoxic conditions will reduce overall biomass productivity in lakes and waterways.
  • Many animal species will need to migrate north to adapt to rising temperatures.
  • Increased evaporation rates will decrease the total wetland area in the region during periods of low water levels, creating additional stresses on species.

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Forests

 

  • Changing temperature and precipitation will force many forest ecosystems to shift northward, but many tree species will be unable to migrate fast enough to keep up with the pace of climate change.
  • Climate change will amplify existing stressors to natural and urban forests.
  • Climate change impacts on forests will impair the ability of many forested watersheds to produce reliable supplies of clean water and other forest products.
  • Climate change will alter cultural and recreational connections to forest ecosystems.

Learn more.

Snow in the Great Lakes Region

 

  • Snowfall in the Great Lakes region can be categorized as lake-effect snow and non-lake-effect snow.
  • Observations show lake-effect snowfall is increasing around the regions of Lake Michigan and Lake Superior.
  • Regional snowfall amounts vary depending on the extent of Great Lakes’ ice cover and atmospheric conditions.
  • In the future, as air temperatures rise snow will transition to freezing rain or rain.

Learn more.

Lake-Effect Snow

 

  • During late fall and winter, cold air flowing over the relatively warm waters of the Great Lakes leads to the production of lake-effect snow and thus enhanced snowfall totals immediately downwind of the lakes.
  • Lake-effect snow production typically diminishes late in the winter season when the formation of lake ice leads to a reduction in the supply of relatively warm and moist air to the atmosphere.
  • As air temperatures continue to rise and further warm the Great Lakes, areas in lake-effect zones will continue to see increasing lake-effect snowfall as a warmer atmosphere will be able to hold increasing amounts of moisture. 
  • Areas in southern lake-effect zones may see lake-effect snow replaced by lake-effect rain, as warming winter temperatures will result in an atmosphere that is less suitable for the formation of snow. 

Learn more.

Freeze-Thaw Cycles

 

  • Freeze-that cycles (FTCs) have important impacts for a variety of economic sectors across the region, including agriculture, transportation, and infrastructure.
  • FTCs have decreased over time, with the largest region-wide decreases occurring between 2000 and 2020.
  • FTCs are likely to continue decreasing in the future, though the amount varies by location.
  • The variability of freeze-that cycles shows large fluctuations station to station.

Learn more.

Freezing Rain

 

  • Freezing rain events have important and dangerous impacts on the function of nearly all sectors regionwide
  • The frequency of these events varies depending on the location
  • While some conditions have become less favorable for creating freezing rain events, others have become more favorable and increased in strength over time
  • While future precipitation trends are extremely difficult to predict, practitioners should still prepare for the effects of prolonged freezing rain events in the future

Learn more.

Arctic Oscillation and Arctic Amplification

 

  • The Arctic Oscillation is responsible for cold air outbreaks in the Great Lakes region.
  • How the Arctic Oscillation might change in a warming climate remains a subject of active research.
  • Cold air outbreaks are likely to contribute to the rapid formation of lake ice with seasonal consequences for lake levels. 
  • Plausible scenarios for the future include general winter-time warming punctuated with short, intense cold spells.

Learn more.