Posts Tagged ‘Great Lakes’

Great Lakes Are on Thin Ice

Friday, March 23rd, 2012

The Great Lakes winter ice cover has dropped dramatically over the past 40 years, according to a new report. On average, peak ice has fallen by 71 percent; Lake Michigan’s ice cover has shrunk even more than that.

Researchers at the National Oceanic and Atmospheric Administration (NOAA) compared satellite photos dating to 1973.  Jia Wang, a NOAA ice climatologist, said the changes are stark.  In a year like 1979, ice covered about 94 percent of the lakes in the coldest months of that winter.  “This winter the maximum ice cover is about five percent,” Wang said.  “It’s the lowest ever since the satellite era.”  The drop in ice cover is largely a result of rising temperatures due to climate change.  There are also other factors at play this year in particular, such as El Nino weather patterns.  According to Wang, such a loss of winter ice can cause several problems for the Great Lakes ecosystem.  For example, it can accelerate wintertime evaporation from the lakes, which could reduce water levels.  The trend could also stimulate more and earlier algae blooms, which damage water quality and habitat.  Additionally, it leaves the shoreline more exposed to waves, exacerbating erosion.

The changes in the Great Lakes could make them a dead zone. According to the University of Michigan’s Don Scavia, “By end of the century, Illinois will feel like Texas.  And Michigan will feel like Arkansas.”  Scavia, who leads the university’s Environmental Sustainability Institute, laid out a disconcerting list of changes already taking place in the Great Lakes region as the result of climate change.  According to Scavia the changes include the last frost in spring occurs earlier and earlier, while the first frost in fall is later and later.  This is extending the growing season, as well as changing what plants and crops can grow in the region.  Storms are more intense, and major weather events happen more frequently.

The most alarming potential scenario is the possibility that the Great Lakes to become a dead zone, a body of water that lacks oxygen and no fish or plants can survive.  This happened to Lake Erie in the 1960s, resulting from algal blooms caused by industrial pollution, human waste and farm run-off.  Lake Erie’s devastation led to the passage of the federal Clean Water Act in 1972.  Oxygen levels in the lake improved in the 1980s, but worsened again in the 1990s.  Recent studies have shown that algae in Lake Erie is returning.

Although lakefront residents may enjoy the more temperate beachfront this year, ice is crucial in maintaining coastal wetlands and water depth.  The wetlands act as an incubator for wildlife in the Great Lakes basin.  Wetlands — the marshy shorelines that harbor numerous plants and animals — require the constant variation of the seasons and Great Lakes water levels.  The lack of substantial ice coverage results in greater evaporation, which leaves water levels across the Great Lakes lower over the long term.

“Having low water levels next year doesn’t make me nervous.  Having low levels over the last 10 years makes me worry,” said Donald Uzarski, director of Central Michigan University’s Institute for Great Lakes Research.  “We’ll see what happens with respect to the water levels.  When the water level’s lower, the coastal wetlands stretch out towards the water’s edge,” out into exposed shoreline areas that are usually under water.

Rather surprisingly, extreme summer and winter temperatures are actually considered good for wetlands. These conditions can feed the growth of wetlands, which are “very dynamic and very responsive to water levels,” according to Kurt Kowalski of the United States Geological Survey.  Climatologists studying lake ice have noticed a steadier pattern of temperatures within the last 10 years.  “The frequency of mild winters has been on the increase.  We’re certainly in a trend for milder winters now,” said Ray Assel, a retired climatologist, recently of the Great Lakes Environmental Research Laboratory.

According to the Canadian Ice Service, ice cover on the Great Lakes for the week of March 5, 2011 was approximately 36 percent and close to the historical average of 38 percent.  By contrast, ice cover for the week of March 5, 2012 has been exceptionally low and is only about 12 percent.

Writing on the earthsky.org website, Deanna Conners says that “In fact, ice cover has been so low this year on Lake Erie that officials began removing the ice boom that prevents large chunks of ice from flowing out into the Niagara River on February 28, 2012.  This is the earliest date for removal since the boom was first installed in the mid 1960s.  The ice boom acts to prevent ice damage to hydropower intake equipment.  Early boom removal is our harbinger of an early spring in western New York.  Dare I say that I think the groundhog was wrong this year?”

Another sign of the times comes from the Daily Great Lakes Seaway Shipping News, which notes that “Shipments of iron ore on the Great Lakes totaled 3,587,016 net tons in January, an increase of 24 percent over a year ago, and 57 percent ahead of the month’s five-year average”.  In typical winters when the Great Lakes have a more widespread ice cover, the billion dollar shipping activity comes to a virtual halt.  Click on this link to view a map of the extent of Great Lakes ice during the cold and snowy winter of 1979, the last time the Great Lakes were more than 95 percent frozen over.

Temperatures Rising in America’s Freshwater Lakes

Wednesday, August 10th, 2011

The waters of the Great Lakes are warmer than usual this year, prompting scientists to worry that this may not be a good thing.  All five Great Lakes have been at or near record-high temperatures compared with the 30 years when such measurements have been taken.  The bad news is that there’s still a month remaining before the lakes typically reach their warmest temperatures.  Jay Austin, a physics professor at the Large Lakes Observatory in Duluth, MN, says the water is warmer because last winter there was little or no ice cover to reflect sunlight.   Scientists are unsure if it’s a blip or the new normal.  A warmer Lake Superior might be a plus for the tourism industry, but it might be bad for fishing, wildlife habitat and water levels.

“Swimmers are enjoying it,” said Al Oleksuik, who lives near the Welland River in Chippewa.  “I notice a difference here.  (The water is 24 C). It usually doesn’t hit that until mid-August. I have a feeling we’re headed towards (26 C), which is extremely warm.”  Austin said the lake is 5 to 7 C warmer than it usually is in mid-July, while the Great Lakes in general are running 2 to 7 C warmer.  “It’s going to set records, or come close, depending on where you are,” he said.

Writing in Chimes, a publication of Grand Rapids-based Calvin College, Geneva Langeland says that “Lake Michigan is warming up?  Swimmers who brave the lake’s often frigid waters might beg to differ.  But Lake Michigan’s waves aren’t alone in their slight temperature uptick; NASA satellite data suggest that lake temperatures worldwide have risen in the last 25 years, most likely as a result of global climate change.  Phillip Schneider and Simon Hook, researchers at NASA’s Jet Propulsion Laboratory in California, departed from the typical strategy of measuring global warming trends by gauging air temperatures near Earth’s surface.  Instead, the study, published in the 2010 issue of Geophysical Research Letters, used infrared satellite imagery to track changing surface temperatures in 167 large lakes splashed across the globe — including our very own Great Lakes.  The satellite data suggest that, over the past 25 years, water temperatures in large lakes have risen between .81 and 1.8 degrees Fahrenheit per decade.  These shifting temperatures varied widely among continents and hemispheres.”

According to Langeland, “Schneider and Hook noted the greatest change in northern Europe; in general, the loftier latitudes of the Northern Hemisphere consistently reported the largest temperature upticks.  The Great Lakes land squarely in that northern region.  Huron, Superior, Michigan, Erie and Ontario together comprise the world’s largest freshwater lake system.  It should come as no surprise that the ‘Big Five’ were valuable players in this study.  In fact, the Great Lakes host nine temperature-gauging buoys that were vital in verifying NASA’s satellite temperature readings.  As Schneider said, ‘The results have implications for lake ecosystems, which can be adversely affected by even small water temperature changes.’  A degree or two might be imperceptible to us, but this tiny change can have surprising repercussions.  Every organism thrives within a particular temperature range.  Altering a habitat’s air and water temperatures even slightly will kill off some creatures while allowing others to unexpectedly thrive.”

Lakes in the American West are experiencing similarly increasing temperatures.  Warming that meets statistical significance was found in Lake Tahoe along the California-Nevada border; Pyramid Lake in Nevada; and the Great Salt Lake in Utah, which were warming at a rate of more than one degree Fahrenheit per decade.  “One of the things we want to do in the future is compare these results with what the climate models predict in the region,” Hook said.  “Measuring a model’s performance in replicating changes of the recent past gives scientists a way to test the accuracy of the models being used to project future conditions.”

“Our analysis provides a new, independent data source for assessing the impact of climate change over land around the world,” Schneider said. “The results have implications for lake ecosystems, which can be adversely affected by even small water temperature changes.”