Forming the largest group of freshwater lakes on Earth and making up 21 percent of the world's total freshwater supply, it's no wonder the Great Lakes record-low water levels are concerning to people around the globe.
Lakes Michigan and Huron set new record-low water levels in December of 2012, breaking the previous record set in 1964. Water levels dipped to an all-time low at 576.15 feet, according to the US Army Corps of Engineers, Detroit District. Not only did the water levels break record lows but the levels made this the longest stretch of below average levels in the lake's recorded history dating back to 1918, and thus continuing a 14 year streak of below average levels. Many factors have contributed to the significant decrease in one of the world's most important waterways but among them, one of the most notable causes is in fact, the area's weather patterns.
2012 proved to be a year of bizzare weather for the Great Lakes region. The year was warm and dry with the lakes receiving very little snow in the 2011/2012 winter and as a result, very little runoff water. However, due to the sheer size, large surface area and volume of the Great Lakes, just one year would not result in the dramatically low water levels that have been recorded.
"Water levels don't respond to just one year," said Ann Clites, a Physical Scientist at the NOAA Great Lakes Environmental Research Lab. "These low levels are not because of the precipitation for one year, the lakes are just too big and there are too many factors to say that. However, the last 15 years of low levels got the lakes ready to hit all time record lows," said Clites.
The Great Lakes are notably different than most others due to their surface size, encompassing close to 100,000 square miles. It takes years, multiple seasons, long stretches of time to influence the water levels as radically as has been recorded today.
According to the US Army Corps of Engineers, Lake Superior has seen well above average precipitation for May but it's water levels have been below average for the past 12 months. Lake Michigan and Lake Huron are not doing much better. These two lakes, despite seeing near average precipitation this year, are expected to remain 17 to 20 inches below their long term averages over the next six months. Even though rainfall amounts this year have been close to normal, the Great Lakes water levels do not appear to be improving as fast as needed.
"It's no doubt that the changes are a result of precipitation, rain and snow, said Clites. But the long term cycle seems to have entered a different regime in the early 2000's, as Lake Michigan and Lake Superior from 1998 to 2001 had an unprecedented three foot drop in water levels."
Since then, Clites explains that the upper lakes have been consistently low since 2001. If long-term lack of precipitation is only a factor into the reasoning behind the severe low water levels, then what is the culprit? One theory is evaporation.
Due to the unusually high temperatures, the temperatures of the Great Lake's surface level waters have risen. This results in higher evaporation, as AccuWeather's Elliot Abrams explains, "The warmer the water, the higher the evaporation."
Lake Superior recorded a two degree jump in water temperatures, in the end of the 90s, possibly influencing the rate of evaporation in the Great Lakes.
"A chronic increase in normal evaporation and above normal temperatures, causes a substantial drop in the levels of the lakes," said AccuWeather's Senior Meteorologist, Jim Andrews.
This drop in lake levels, has worried more than just scientists, as the Great Lakes low levels have the potential to shake economic framework. Multiple entities have invested use of the lakes and the lake water, including, commercial navigation, hydroelectric generation, coastal zoning, recreational boating and marinas, the tourism industry and the lake's ecosystems, according to the University of Michigan's School of Natural Resources & Environment. During the CILER-GLERL Great Lakes Seminar Series, hosted by the University of Michigan, Professor of Environmental Economics, Michael Moore, lectures about the potential economic impacts to come for the region.
"Does it harm experience to beach-goers?," questions Moore. Solely dependent on the lakes, the tourism industry, including restaurants and hotels could suffer, if lake levels continue to drop. Real estate value on the shores of the lakes could also take a hit. As for marinas along the lakes, they have already been affected by low levels as boats sit closer to the bottom. "Getting into a boat is now an Olympic sport," said Moore.
Shipping companies could also be at an economic loss. "The ships can not be loaded as much because if the boats sit lower in the water they can run aground," said Abrams. Rivers linked to the Great Lakes are dependent on the lakes' water sources, so they too could shallow and limit navigation for ships and boats.
These potential economic impacts has residents, business owners and vacationers anxious, as they wait to see what's next. However, the light of hope may be dim, as Clites explains, the difference in the balance between evaporation and precipitation is that evaporation has been consistently higher and seems to be climbing. In order for water levels to increase, the lakes need both a persistently higher amount of rainfall and evaporation rates need to slow down. How long this process could take, no one knows.
"There is little that can be done by people, nothing we can do will raise the levels. It takes years to get in the hole and it takes years to get out," said Andrews.