Does Lake Michigan's record low mark beginning of new era for Great Lakes?
Post date: Sep 11, 2013 4:51:32 PM
Uncharted Waters | A Journal Sentinel Special Report
Does Lake Michigan's record low mark beginning of new era for Great Lakes?
Despite above-average precipitation, lake has seen below-average water levels for 14 years running. Less ice cover and more dark open water may explain why.
By Dan Egan of the Journal Sentinel staff
July 27, 2013 | Part 1 of 2
Patric Kuptz means it when he says he grew up on the Great Lakes.
"I've spent most of my life within 50 feet of here," the 37-year-old said on a sunny May morning, working on a boat near his third-generation family home — a brown brick duplex at the edge of Milwaukee's South Shore Yacht Club.
This is where, as a boy, he Huck-Finned away his summers — chasing perch from the docks, splashing in the frigid surf and making all manner of mischief around the yacht club, news of which often made it home before he did.
Today, Kuptz hardly recognizes the lakeshore as the one he grew up on, pointing to a beach that didn't exist when he was a kid in the mid-1980s, when the water was about five feet higher and yacht club members needed steps to ascend from the docks to their boats. When that record-high water dropped a couple of years later and those stairs were being thrown away, the young Kuptz couldn't believe it.
He knew even back then that lake levels were a fickle thing, so he hatched a plan to stash the stairs in his garage — and sell them back to their owners when the lake bounced back.
Kuptz is glad he never acted on it because the only record water level that has returned in the last quarter century is the record low set this winter. Today it is Kuptz who is convinced the lake isn't coming back, at least not in his lifetime, and now he is the one making plans accordingly.
He sold his sailboat.
"I actually bought a power boat because I'm worried about the draft," Kuptz said of the keel-grabbing water levels. "It's nuts. I'd never seen it this low."
A great unknown
Lake Michigan is no longer just a Great Lake; it is a great unknown.
More ominous than the all-time low the lake touched this winter is the fact that it came after languishing for 14 years below its long-term average — another record. And when it did initially drop below that long-term average, it plunged three feet between 1998 and 1999 — yet another record for water lost from one year to the next.
Despite man-made tinkering, water levels in the Great Lakes have remained remarkably stable for generations. Now that exquisite balance may be headed out of whack. One culprit is a natural one. WATCH MOTION GRAPHIC >>
The lake level, of course, has been in constant flux since record-keeping began a century and a half ago. Tracking it on a graph is like looking at an EKG monitor. Little blips and dips reflect seasonal oscillations that cause the lake, in a typical year, to vary about a foot between summertime high and wintertime low.
In addition to those annual ebbs and flows are larger swings that span decades tied to long-term weather patterns, with Lake Michigan's record high topping out more than 6 feet above the record low set this January.
Draw a red line through the middle of all those highs and lows and you get what was, up until 1999, Lake Michigan's long-term average surface level — 579 feet above sea level.
That year the lake mysteriously took its 3-foot dive, and it has stayed down for nearly a decade and a half — and counting.
Previous drops into low water, in the 1920s, '30s, '50s and '60s, were always followed by a quick and sustained rebound beyond the long-term average. Usually it happened within three or four years, though the slow but steady climb during the Dust Bowl droughts took the better part of the '30s.
But with this ongoing low water, which has never shown an indication that it is on a sustained track back toward average, decades of rhythmic pulses hitched to the red line appear to have stopped, or at least stalled.
Frank Quinn, a retired hydrologist with the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory, has been tracking lake levels for more than a half century, and he's heard all manner of crazy theories for the previous lows. Atom bomb testing was a popular culprit in the 1960s, and rumors swirled for years of a secret canal under Niagara Falls channeling flows to thirstier regions.
The truth was always a little drier — the lakes were simply suffering from a lack of rain and snow.
What's going on today is different.
"Based on the precipitation we've had, we would not expect to have the record low lake levels that we have," Quinn said.
Last year was indeed extremely dry. But the past 14 years, on average, have been wetter than usual for Lakes Michigan and Huron, which are actually one body of water connected at the Straits of Mackinac.
Even so, the lakes remain about a foot and a half below their average for this time of year.
So where did all the water go?
This is not a story about climate change.
It is a story about climate changed.
After weeks of patiently waiting for ice to slowly build on Lake Superior this winter, Bob Krumenaker finally decided on a chilly Sunday in March to click into his cross country skis and venture out to one of the islands he oversees as superintendent of Apostle Islands National Lakeshore in extreme northwest Wisconsin.
The ice on this St. Patrick's Day felt solid as concrete as Krumenaker and a colleague glided their way out to Basswood Island, 1 mile offshore. Farther out, the lake was dotted with ice fishing shanties and snowmobilers. It appeared one of the world's wildest lakes had again lapsed into a deep wintertime slumber under a blanket of ice.
It was a mirage.
The reality was hidden under Krumenaker's green pullover. He wore a red life preserver.
The frozen white coastline belied a dramatic warming of the lake in recent years. Away from the sheltered shore around the islands, ice gave way to the churning black waves of a body of water that never really went to sleep. It rarely does anymore, its annual hibernation having become more often than not just a catnap.
Even the predictably iced-over shoreline regions have become dicey places to roam. This was the first time Krumenaker wore a life jacket on a ski trip.
Several weeks earlier, a well-known fishing guide who was a former local police officer had plunged through the ice near Bayfield and died.
Less than a month later, two more area residents on a snowmobile crashed through the ice near Madeline Island and died.
"Three local people, who are familiar with conditions, dying...," said Krumenaker, "has definitely rattled this community."
Mark Hoffman / Journal Sentinel
Motorists travel on an ice road across a portion of Lake Superior to Madeline Island from Bayfield. Most winter traffic between Bayfield and Madeline Island is either via the ferry or, in the depths of winter, the ice road. VIEW ALL PHOTOS >>
Standing on the iced-over shoreline this winter, it was hard to see the changes. But assistant superintendent Neil Howk pulled up a satellite image showing that even in mid-March, typically the peak time for ice coverage, it was mostly Superior's calm harbors and bays in places like Duluth, Bayfield, Copper Harbor and Thunder Bay that were frozen over.
The rest of the lake was open water, black as the type on this screen.
"Maybe 10% of the lake is covered," said Howk. "Maybe."
Researchers who have been tracking ice for decades say that is now normal. Historically, on average, about a quarter to a third of Lake Superior, an area of lake roughly the size of Massachusetts, froze over each year.
Big ice years still happen — nearly the entire lake froze in 2009 — but they have become increasingly rare, particularly since the late 1990s.
Average ice cover for Superior declined by 76% between 1973 and 2011, according to a 2012 study led by Jia Wang, an ice climatologist at NOAA's Great Lakes research laboratory. A similar phenomenon has occurred across the region, with Wang calculating a 63% drop in average ice cover for all the Great Lakes over the past four decades.
Across the same time period, scientists estimate a 1.6 degree Fahrenheit upturn in the over-lake air temperature for all the Great Lakes — with most of the change also occurring since the late 1990s.
Common sense says the stubbornly frigid inland seas would be immune to such a subtle bump in air temperature.
But it appears the opposite is true.
A thermal avalanche
When Jay Austin arrived at the University of Minnesota-Duluth in 2005, he was equipped with a doctorate in oceanography from the Massachusetts Institute of Technology-Woods Hole Oceanographic Institute, but he had little experience studying fresh water.
Jay Austin, assistant professor at the University of Minnesota-Duluth, talks about how increasing temperatures have led to more evaporation and declining water levels on the Great Lakes. WATCH VIDEO >>
"I didn't know anything about lake temperatures, so I thought a good way to learn would be to grab the data, plot it up and play with it for a week and see what happens," he said.
What Austin found happening on Lake Superior was stunning — since 1980 the lake's average summer surface water temperature has been climbing at a rate of about 2 degrees per decade, roughly double the rate of the increase in air temperature over the Superior basin.
"The intuition is that a very large lake like this would be slow to respond somehow to climate change," he said. "But in fact we're finding that it's particularly sensitive."
Austin went looking for the scientific literature explaining what was going on. He found almost nothing.
He eventually determined it's not just warm summer weather driving the increase in water temperatures — it's also what's happening in winter. The air-temperature increase, however slight, has been enough to dramatically reduce Superior's average ice cover.
And without a bright white cap to bounce solar radiation back into the sky, the lake begins to soak up heat in early spring. That jump-start on the annual warming process has a profound effect on peak surface water temperatures during the summer.
The outsized role winter ice has on Superior's summertime water temperatures literally jumped out of Austin's data. The more ice coverage in winter, the cooler the lake is likely to be the following summer; the less ice, the warmer the summer water.
"It's not one of those things that you had to do a lot of statistical analysis to convince yourself of the significance," Austin said. "You made the plot, and there it was."
A similar phenomenon is under way on Lakes Michigan and Huron.
Paul Roebber, a University of Wisconsin-Milwaukee meteorologist and associate dean of its School of Freshwater Sciences, points to a weather buoy in the middle of southern Lake Michigan that shows a 3.4 degree increase in average summer surface water temperatures since 1997.
One day last summer, the thermometer at the mid-lake buoy 43 miles southeast of Milwaukee recorded a Caribbean-like 80 degrees.
It was only the beginning of July.
"There has been a change in air temperatures. It's not dramatic, but it's just enough to not produce the ice coverage we used to have," explained Roebber. "And that makes all the difference in a system like this."
Sucked into the sky
This temperature cascade has made it possible on summer nights for oceanographer Austin to take his young son swimming in Lake Superior, something most people would never do a generation ago.
Weather patterns help illustrate the precipitation and evaporation affecting the Great Lakes. In this image, taken in December 2000, winds from the northwest sweep over Lakes Superior and Michigan. As the cold dry air crosses the relatively warm lakes, moisture is picked up from the lake surface. This water eventually falls back to earth, but not always in the Great Lakes basin.
But the warm water also has significant implications for lake levels because it is driving up evaporation rates — a key factor in the equation that kept water levels shackled to their red-line average during a record-keeping period that stretches back to the mid-1800s.
Federal data show that evaporation on Michigan and Huron has been above average every year since the low-water era started in 1999.
With little to no protective ice cap, chilled air whooshing over relatively warm water leads to more cold-weather evaporation.
The result of this thermal avalanche triggered by just a tiny bump in air temperatures: the surface of the lake is literally going poof into the sky.
"You can see that if it's a really cold day," said Roebber. "You'll see these plumes of steam coming off the lake. It's very graphic and that's an example of the lake just losing water."
The biggest change in evaporation happens when cool winds blow over the summer's ever-warming waters, and during the frigid gales of October, November and December, a time of year when evaporation can sap up to 2 inches of water per weekfrom the still relatively warm lakes.
"That evaporation really kicks in in the fall, when those cool air masses start coming in over the lakes, but the water is still warm, and over the past 10 years the water has been warmer and warmer and warmer," said Drew Gronewold, a hydrologist at NOAA's Great Lakes lab.
Roebber points to data showing how much water Michigan and Huron have lost to evaporation over the last 14 years compared to their historic average. Tally all those numbers together, and it shows evaporation has sucked more than four feet from the lakes. Evaporation is calculated by a model that relies on things such as water temperature, air temperature and wind speed.
Though some of that evaporation loss on Michigan and Huron has been offset by above-normal precipitation, people need to understand something has fundamentally changed in the lakes' historic low-water, high-water cycle, Roebber said.
Quinn, the dean of Great Lakes hydrology, said part of the drop on Michigan and Huron is tied to dry weather over the Lake Superior basin, which means lower flows coming into Lake Huron via the St. Marys River. But he agrees that the big story for Lakes Michigan and Huron is increased evaporation, only a fraction of which falls back into the lakes as precipitation.
Frank Quinn, an emeritus hydrologist with the National Atmospheric and Oceanic Administration, talks about the history and causes of low water levels on the Great Lakes. WATCH VIDEO >>
"What appears to have happened is the hydrologic regime — the climate — has changed," Quinn said.
"We're getting the precipitation, but we're losing a lot more water through evaporation...and that is what is causing the drop in Lake Michigan and Huron's water levels — the continuing low levels, the part we can't explain."
Quinn isn't saying a change like this hasn't happened before humans started taking meticulous notes of bouncing water levels in the 1800s, nor is he saying that at some point it won't be reversed.
But there is no question that since the late 1990s there has been a profound switch in the way the lakes work.
"The dynamics we have between precipitation and evaporation have changed," said Gronewold. "There are years now when we have a lot more water coming off the surface of the lake than dropping into the lake."
In those years, the sky takes more from the lakes than it gives.
Lakes need 'extraordinary' precipitation
Prehistoric water level records, detected by radiocarbon-dating the ridges of ancient beaches, reveal that about 4,500 years ago Lake Michigan was roughly 13 feet higher than it is today.
Then it underwent a steep decline over a 500-year period before settling near levels closer to what we've known. Climate variability — drought, specifically — is believed to be a factor in the big 500-year drop, according to the U.S. Geological Survey. Reconstructed records going forward from there indicate that, beyond our relatively brief recorded history showing annual and multiyear fluctuations, over the past few thousand years there have been larger swings based on roughly 160-year cycles.
It might give some people comfort that the lakes have previously experienced changes even greater than what appears to be happening today.
But it's important to remember that all this is ancient history — before the existence of cities bursting with millions of people and trillions of dollars of subdivisions, skyscrapers, factories, rail yards, roadways, navigation channels and canals, sewage treatment plants, drinking water systems and nuclear reactors, all clinging to the modern shoreline, all needing the water level to stay basically where it has been for the last century and a half.
With a fresh record-low notched in the books and signs of a new era at hand in which increased evaporation will continue, the pressing questions are:
Will Michigan and Huron rebound back toward their historic average?
Have they reached a new normal, albeit one that is significantly lower than what we've become accustomed to?
Or will they continue to drop?
In April, a spokesman for the International Joint Commission stood in front of floor-to-ceiling windows in a Concordia University conference room on a bluff above Lake Michigan and assured a group of lakeshore property owners there was little to worry about.
The Joint Commission oversees boundary waters issues between the United States and Canada.
"That water that you see out there," said John Nevin, a public information officer for the Joint Commission, "is not the new normal."
Warmer temperatures might mean slightly lower-than-average water levels going forward, but "we're going to see levels generally in their historic range," he said.
Others who study Great Lakes water levels and precipitation cycles are less sanguine.
"I don't think you can say that with any certainty, and I think available evidence suggests that it's the opposite," said Roebber, the UWM meteorologist and mathematician.
"The last 15 years essentially really prove that point. You can see it: above-normal precipitation and lake levels dropping substantially — with a loss of ice."
Most scientists agree that warmer water and air temperatures will turbo-charge Lake Michigan and Huron's precipitation-evaporation cycle; more water will be going up into the sky, and more will be coming down.
The question is whether they will balance each other out, and so far they have not.
An alarming piece of research in 2002 predicted a drop of about 4.5 feet in Michigan and Huron's long-term average in the coming decades. It was tempered by a 2010 study based on hundreds of simulations using nearly two dozen computer models. Those computer simulations yielded widely varying results, but the study concluded Michigan and Huron's average level in the coming decades is most likely to remain somewhere around a foot below the historic average.
Another NOAA researcher said all these calculations underestimate how much rivers and streams will continue to feed the lakes under a warmer air temperature regime, and therefore have exaggerated the potential water loss.
"There is a fair amount of likelihood that (the lakes) are going to drop, but it's going to be a lot less than what had previously been thought, and there is the possibility that they will rise in the long-term," said Brent Lofgren, a scientist with the NOAA Great Lakes lab.
But these are all predictions based on ever-evolving computer models trying to gauge how a warmer globe will affect — in terms of feet, if not mere inches — the hydrologic cycle of our lakes.
It does not take a scientist or a supercomputer to simply look at the Lake Michigan shoreline today and realize that, despite a decade of wetter than normal weather and despite the severely cold and wet spring, our lake isn't as great as it used to be.
And even if we have more record-setting wet months coming, it still won't be.
"It's going to likely take several seasons of above-average rainfall and snowfall and above average runoff to get Lakes Michigan and Huron back to their long-term average," said Keith Kompoltowicz, chief of the U.S. Army Corps of Engineers' watershed hydrology branch for the Detroit district.
"What we've seen this spring is what you need to get the lakes headed back. You just need to see it consistently over a number of seasons."
In other words, we now need extraordinary levels of precipitation just to get back to ordinary.
This poses its own set of potential problems.
The torrential rains of April that pulled Michigan and Huron several inches up from their record low had a downside: They triggered massive sewage overflows and unleashed flooding in Chicago. Similar rains on Lake Erie in recent years have sent into the lake plumes of fertilizer-rich soils linked to poisonous algae blooms. A 2011 outbreak covered about 2,000 square miles — three times larger than anything recorded, even in the pre-Clean Water Act days of the 1960s and '70s.
It's becoming increasingly difficult to write off these deluges as a fluke.
Meteorologists refer to the most wicked rain events as "100 year storms" — tempests so severe the odds of one happening in any given year are 1%.
But since 1997, southeastern Wisconsin has experienced six such storms, including two in July 2010.
"We've either had really bad luck," said Roebber, "or something else is happening."
He thinks that something else is a new era in which big storms will become more the norm.
Roebber said that means the focus now should not be on the lakes' historic red-line average because that's not the line he is worried about. He believes that average will continue to decline, but he is more concerned about how increased evaporation and precipitation cycles may push the swings around the average higher and lower than we've ever seen.
Historically, Lakes Michigan and Huron have been tethered to a 3-foot flux above and below their long-term average.
Roebber said it is reasonable to expect that in coming decades the highs and lows will soar and plunge four feet or more from their average — meaning water levels could swing by 8 to even 10 feet over several years.
He worries the record low set in January is just the beginning.