“Climate change is causing significant and far-reaching impacts on the Great Lakes and the Great Lakes region.”
So begins the executive summary of a new report from the Environmental Law & Policy Center called “An Assessment of the Impacts of Climate Change on the Great Lakes.” It’s the work of 18 leading American and Canadian scientists and experts, written to “educate policymakers and the public about significant changes affecting the Great Lakes, and the vital importance of taking actions now to protect our natural resources.”
Here are some of the findings:
• In the past century, the Great Lakes basin has warmed 1.6 degrees in annual mean temperature, compared to 1.2 degrees for the rest of the contiguous United States. By the end of this century, average temperatures could rise an additional 2.7 degrees to 7.2 degrees, depending on future greenhouse-gas emissions.
• A warmer atmosphere holds more moisture, which increases the frequency of heavy rain and snow. U.S. annual precipitation increased 4 percent between 1901 and 2015, except in the Great Lakes region, which saw a 10 percent increase.
• Climate change causes more extreme weather. Extremely warm days (higher than 90 degrees) will increase for states bordering the Great Lakes. The number of extremely cold days (lower than 32 degrees) will decrease.
• Changes in seasonal precipitation are already affecting farmers in Great Lakes states. Climate change will likely reduce crop yields by 10 to 30 percent by mid-century in southern parts of the Great Lakes watershed.
• Rain events exceeding six inches now occur regularly, exceeding the capacity of culverts and storm sewers to handle runoff, causing infrastructure and home damage.
• Climate change will likely threaten drinking-water quality and place great stress on water infrastructure.
• The Great Lakes already have higher levels of E. coli bacteria than other U.S. coastal regions. That is expected to continue due to excess nutrients – primarily nitrogen and phosphorus – from farms running into surface water.
• Climate change has already increased bacteria levels in the Great Lakes as the water warms earlier in the spring and as that warming contributes to vertical mixing that changes lake ecosystems. Sewer overflows, the dumping of ship ballast water and nutrient runoff from agriculture and industry all contribute to the growth of bacteria and several invasive species in the lakes. Heavier rainstorms and warmer weather exacerbate these challenges.
• The geographic ranges of fish, demographics within species, system productivity, species-specific productivity, spatial arrangement of species, and their physiological state and performance will all change in response.
The entire report is available at elpc.org.