NASA

How is climate change affecting the Great Lakes?

CLEVELAND, Ohio -- Across the globe, climate change is increasing temperatures, spurring on extreme weather, harming ecosystems and raising sea levels. But what does it mean for the Great Lakes?

For the 30 million Americans and Canadians who live in the Great Lakes basin, climate change, primarily attributed to human activities increasing greenhouse gas emissions, is a real threat to the home of 84 percent of North America's surface fresh water.

Rising temperatures could lower water levels in the lakes, intensify harmful algal blooms and threaten fish and wildlife.

Here’s what the research says about how the globe's shifting climate affects these vast bodies of water in terms of temperature, precipitation, extreme weather, water quality and harmful algal blooms, fish and wildlife, ice coverage, water levels, shipping, tourism and recreation.

-- Kelly Reardon, cleveland.com meteorologist

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Average lake surface water temperatures each month, comparing the 1995-2004 period with 2006-2015 period.

U.S. EPA

Temperatures

The average air temperature in the Great Lakes region has risen by 2 degrees since 1900, says a NOAA team called Great Lakes Integrated Sciences and Assessments (GLISA). But the Great Lakes' waters have warmed faster than the nearby air temperature in recent years -- Lake Superior has been warming twice as fast as the surrounding air since 1980.

Since 1995, the average surface water temperatures have increased slightly for each of the Great Lakes, according to the EPA, primarily due to warming during the spring and summer months, earlier thawing of winter ice and overall declining winter ice cover.

The onset of the first ice cover on inland lakes is 6-11 days later than the middle 19th century and the breakup of ice in the spring is 2-13 days earlier. This seemingly shorter winter, and open lake waters earlier in the spring, is causing the lakes to warm for longer periods of time, amplifying the effects of warmer summer air temperatures, according to GLISA research.

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Future predictions of precipitation changes with a higher greenhouse gas emissions scenario.

NOAA

Precipitation

Predicting future changes in precipitation, and evaporation, over the Great Lakes can be a bit tricky since they vary so much across the region. Columbia University says the western region of the Great Lakes generally tends to be drier, while the southeast receives more precipitation, like lake-effect snow and rain. Climate change is expected to accentuate this trend, drying the western regions further and increasing precipitation in the southeast. However, with air temperatures modeled to rise with climate change, less precipitation will fall as snow and more as rain, on average.

Changes in precipitation across the eight Great Lakes states are much more clear. Overall, total precipitation has increased by 11 percent since 1900, according to GLISA. In the future, precipitation across those states is anticipated to increase, though models vary widely on exactly how much due to differences in future projections of greenhouse gas emissions.

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How the intensity of 1 percent of the strongest storms has changed from the 1951-1980 period to the 1981-2010 period.

Great Lakes Integrated Sciences and Assessments

Extreme weather

Another result of climate change: more severe and extreme weather events. The frequency and intensity of storms in the Great Lakes region have already increased, and will continue to do so as the effects of climate change become more pronounced, reports NOAA. Heavier storms are projected to increase in frequency faster than less intense storms, and the Great Lakes region is predicted to experience larger increases in total precipitation than most other parts of North America. However, the exact increase in future total and extreme precipitation varies by different model projections. Regardless of the exact numbers, more severe storms lead to negative economic impacts that result from costs of damage, preparation, clean up, and disruption in business. With higher intensity storms comes an increased risk for erosion as well.

Looking at the past, GLISA research suggests the amount of precipitation falling in the heaviest 1 percent of storms increased by 37 percent over the Midwest and 71 percent in the northeast during events from 1958 to 2012.

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Lake Erie algal bloom of 2011.

NASA

Water quality and harmful algal blooms

More rain in the future over the Great Lakes basin means more runoff with sewer discharge into the lakes, reports GLISA, increasing the occurrence of harmful algal blooms.

Rising carbon dioxide concentrations and warming lake temperatures increase the risk for harmful algal blooms as well, especially for Lake Erie. Future changes in land use could have a far greater impact on water quality than climate change, but it's the coupling of both land use changes and climate change that could exacerbate poor water quality, according to a GLISA report.

Algal blooms can kill fish, as when they sink they decompose and reduce dissolved oxygen concentrations, inducing hypoxia. Basically, this means when marine life and organisms are trapped in waters that are oxygen-depleted, they die, and massive fish kills can result, says the GLISA team.

The resulting poor water quality can prove dangerous for humans too, with toxic water and beach closures.

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Rapidly-growing colonies of the double-crested cormorant have become a destructive force around the Great Lakes killing vegetation in their nesting areas as they gobble up forage and game fish.

D'Arcy Egan, The Plain Dealer

Fish and wildlife

With increasing lake temperatures, cold-water fish populations in the Great Lakes are predicted to decline while warm-water fish populations surge. Increasing evaporation rates, due to warming air temperatures, will decrease the wetland area, putting stress on regional species, says GLISA. Many species will eventually need to migrate north to adapt to rising temperatures.

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Ice and snow cover the Great Lakes March 9, 2003.

NASA

Ice coverage

Lake Superior could have little to no open-lake ice cover during a typical winter within the next 30 years, according to GLISA studies. Already, from 1973 to 2010, the annual ice coverage on the Great Lakes has declined by a whopping 71 percent. Breaking down ice coverage loss in the same period for each lake:

Lake Ontario lost 88 percent

Lake Superior, 79 percent

Lake Michigan, 77 percent

Lake Huron, 62 percent

Lake Erie, 50 percent,

While not a Great Lake, Lake St. Clair lost 37 percent

In the future with climate change, snow and ice levels on the Great Lakes, and on land in the region, will likely continue to decline. Ice cover on the Great Lakes has huge impacts on regional precipitation, as reduced lake freezing results in more exposed water which supplies moisture to the atmosphere above, increasing lake-effect precipitation -- both rain and snow. The GLISA team, including scientists from NOAA, the University of Michigan and Michigan State University, says although long-term trends show a decline in Great Lakes ice coverage, high-ice winters, like in 2013-2014 and 2014-2015 can still occur.

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This figure displays how water levels in each of the Great Lakes have changed since 1860. For each year, the shaded band shows the range of monthly average water levels, and the line in the middle shows the annual average. The graph uses the 1981 to 2010 average as a baseline for depicting change. Choosing a different baseline period would not change the shape of the data over time. Lakes Michigan and Huron are shown together because they are connected at the Straits of Mackinac and have the same water level. Data from NOAA.

U.S. EPA

Water levels

Overall, water levels in the Great Lakes are falling since reaching record highs in the 1980s, due to warmer air temperatures allowing for higher evaporation rates, regardless of the recent, short-term record highs due to increased rainfall and snow melt from the winter.

The future is a little hazy, as many models disagree on the fate of water levels, says GLISA. Most studies suggest that long-term water levels will, on average, drop. Some recent reports suggest they could increase, illustrating the large range in projections.

Columbia University agrees most climate models suggest declining lake levels over the next 100 years, pointing out one study that hypothesizes a drop as large as 8.2 feet, overall. Another model they discussed forecasts a wetter future with a very small increase in lake levels, but the university seems to believe actual levels in the future will end up somewhere in the middle, with water levels falling between 0.23 and 2.5 meters (0.75 to 8.2 feet) over the next century.

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The Richard Reiss heads toward the mouth of the Cuyahoga River as it makes its way out of Cleveland.

David Anderson, cleveland.com

Shipping, tourism and recreation

Under the assumption of falling future Great Lakes water levels, the shipping, tourism and recreation industries could be greatly affected.

One peer-reviewed article published in "Climatic Change" in 2011 by Wilfrid Laurier University professor Frank Millerd concluded possible future lower lake levels could restrict vessel cargos, increasing the number of trips and the cost of moving cargo. The data shows impacts vary from a 5 percent increase in vessel operating costs from a climate change scenario "representing a possible climate in 2030" to more than 22 percent for doubling of atmospheric carbon dioxide. However, there are some potential benefits to climate change for the shipping industry: warming lake temperatures, for instance, extend the navigation season due to declining ice cover.

While winter recreation and tourism in the Great Lakes region could suffer due to reduced snow cover and shorter winters, says GLISA, summer tourism may grow. Yet, the anticipated increase in lake contamination and decreasing lake levels could lead to less desirable shorelines when beaches are in high demand in the summer.

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View of shoreline from the Edgewater Beach House Tuesday, May 30.

Marvin Fong, The Plain Dealer

What's being done to fix this?

The $300 million annual Great Lakes Restoration Initiative, run by the U.S. EPA, is aimed to clean up toxins, combat invasive species, promote nearshore health, restore wetlands and other habitats with other efforts to preserve the Great Lakes. The initiative was originally launched in 2010 to accelerate efforts to protect and restore the Great Lakes.

The EPA hopes to increase property values and property taxes by cleaning up "areas of concern:" 43 highly contaminated sites targeted for clean up by the United States and Canada, preventing the introduction of silver and bighead carp, species that threaten the region's economy and ecology; and working with the agricultural community to reduce nutrient runoff to sensitive waterways, according to the website.

Related coverage: U.S. EPA praises Great Lakes Restoration Initiative, 3 months after trying to eliminate program

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Visitors to South Bass Island's State Park can rent kayaks and jet skis to play on Lake Erie June 14, 2014 during a visit to Put-In-Bay island.

John Kuntz, The Plain Dealer

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