Climate Change in the Great Lakes Region

Executive Summary Fact Sheet »

GLISA has summarized the best research available on the impacts of climate change in the Great Lakes region into an easy-to-read, two page document.

Temperature

Temperature »

  • Since 1900. average temperatures have increased by 2.0°F (1.1°C) in the U.S. Great Lakes region.
  • By 2050, average air temperatures are projected to increase by 1.8 to 5.4°F (1 to 3°C). 
  • By 2100, average air temperatures are projected to increase by 3.6 to 11.2 °F (2 to 6.2°C). 
  • Winter temperatures have been rising faster than temperatures during other seasons.
Precipitation

Precipitation »

  • Since 1900, total annual precipitation has increased by 11% in the U.S. Great Lakes region.
  • Total annual precipitation will likely continue to increase, but projections of future precipitation vary.
  • Summer precipitation may decline or increase less than precipitation in other seasons.
  • Warmer temperatures will lead to less precipitation falling as snow, and more falling as rain. 
  • Lake-effect precipitation may continue to increase in some areas.
Extreme Weather Events

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 37% in the Midwest and 71% in the Northeast from 1958 to 2012.
  • 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.
Snow and Ice Cover

Great Lakes Ice Coverage »

  • From 1973 to 2010, annual average ice coverage on the Great Lakes declined by 71%.
  • From 1975 through 2004, the number of days with land snow cover decreased by 15 days, and the average snow depth decreased by 2 inches (5.1 cm).
  • Snow and ice levels on the Great Lakes and on land will likely continue to decrease.
  • Reduced lake freezing will result in more exposed water that could increase lake-effect precipitation.
Lake Temperature and Stratification

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 conspiring to increase the 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.
Fish and Wildlife

Fish and Wildlife »

  • Coldwater fish populations will likely decline in population 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, creating additional stresses on species.
Forests

Forests »

  • Changing temperature and precipitation will force many forest ecosystems 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. 
Lake Levels

Lake Levels »

  • Long-term water levels in the Great Lakes have fallen since reaching record highs in the 1980s.
  • Warmer temperatures and higher evaporation rates may be partially responsible for declining lake levels.
  • Land use and lake regulations also affect lake levels, though no major management changes have occurred since 2000.
  • While most models project continued, long-term declines in lake levels, the range of projections is large, and periods of high lake levels remain plausible.
Water Availability

Groundwater Availability »

  • Despite increasing precipitation, land surfaces in the Great Lakes region are expected to become drier overall due to increasing temperatures and evaporation rates.
  • More frequent summer droughts could affect soil moisture, surface waters, and groundwater supply.
  • The seasonal distribution of water availability will likely change. Warmer temperatures may lead to more winter rain and earlier peak streamflows.
Agriculture

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.

 

Photo credits: Tourism, Lake Levels: Michigan Sea Grant. Water availability: Rob Lopez, flickr. Stormwater: Detroit River Keepers. Satellite images: NASA-MODIS. Extreme Weather: All others: Daniel Brown, B.J. Baule, GLISA