Opinion | Climate change drives shifts between high, low Great Lakes water levels

(Waves on Lake Superior crash against the Duluth, Minn. waterfront Sept. 10, 2014. Randen Pederson, CC BY)

The North American Great Lakes contain about one-fifth of the world’s surface fresh water. In May, new high water level records were set on Lakes Erie and Superior, and there has been widespread flooding across Lake Ontario for the second time in three years. These events coincide with persistent precipitation and severe flooding across much of central North America.

As recently as 2013, water levels on most of the Great Lakes were very low. At that time some experts proposed that climate change, along with other human actions such as channel dredging and water diversions, would cause water levels to continue to decline. This scenario spurred serious concern. Over 30 million people live within the Great Lakes basin, and many depend directly on the lakes for drinking water, industrial use, commercial shipping and recreation.

Related: Surging Great Lakes water levels shrink beaches, flood docks in Michigan
August 2019: Rising waters of Lake Michigan assault Grand Traverse coast. In photos.


But since 2014 the issue has been too much water, not too little. High water poses just as many challenges for the region, including shoreline erosion, property damage, displacement of families and delays in planting spring crops. New York Gov. Andrew Cuomo recently declared a state of emergency in response to the flooding around Lake Ontario while calling for better planning decisions in light of climate change.

As researchers specializing in hydrology and climate science, we believe rapid transitions between extreme high and low water levels in the Great Lakes represent the “new normal.” Our view is based on interactions between global climate variability and the components of the regional hydrological cycle. Increasing precipitation, the threat of recurring periods of high evaporation, and a combination of both routine and unusual climate events – such as extreme cold air outbursts – are putting the region in uncharted territory.

Recent monthly water levels on Lake Superior and Lake Erie (black dots). Blue bars are the record high for each calendar month, and black bars are the record lows. Water levels for May 2019 are presented as a red bar for clarity. Image developed using the online Great Lakes Dashboard (https://www.glerl.noaa.gov/data/dashboard/GLD.html) maintained by the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory (GLERL) and the University of Michigan Cooperative Institute for Great Lakes Research (CIGLR), CC BY-ND

Calculating the lakes’ water budget

Current water levels on the Great Lakes are setting records. Lake Superior, the largest freshwater lake on Earth by surface area, surpassed its record of 602.82 feet for the month of May, and is poised to set a new record for the month of June. Lake Erie, the world’s ninth largest lake by surface area, surpassed not only its record water level for the month of May, but also its all-time monthly water level record of 574.28 feet, which has stood since June 1986.

These extremes result from changes in the Great Lakes’ water budget – the movement of water into and out of the lakes. Water levels across the lakes fluctuate over time, influenced mainly by three factors: rain and snowfall over the lakes, evaporation over the lakes, and runoff that enters each lake from the surrounding land through tributaries and rivers. Runoff is directly affected by precipitation over land, snow cover and soil moisture.

Runoff from melting snow that accumulates around the Great Lakes each winter, shown here on March 25, 2019, is one element of the lakes’ water budget. NASA Earth Observatory

Interactions between these factors drive changes in the amount of water stored in each of the Great Lakes. For example, in the late 1990s surface water temperatures on Lakes Superior and Michigan-Huron rose by roughly 2 degrees C. Water evaporates more rapidly when it is warmer, and during this period evaporation rates were nearly 30% above annual average levels. Water levels on Lake Michigan-Huron dropped to the lowest levels ever recorded.

Then in 2014 the Midwest experienced an extraordinary cold air outbreak, widely dubbed the “polar vortex.” The lakes froze and evaporation rates dropped. As a result, water levels surged.

At roughly the same time, precipitation was increasing. The 2017 Lake Ontario flood followed a spring of extreme overland precipitation in the Lake Ontario and Saint Lawrence River basins. The 2019 flood follows the wettest U.S. winter in history.

What do these trends mean for water levels? In addition to the current onset of record highs, water levels in Lake Erie have been rising earlier in spring and declining earlier in fall. More winter precipitation is falling, often as snow. The snow is melting earlier in response to rising temperatures and shorter winters. The resulting runoff is then amplified in years like 2019 with large springtime rains. The net effect of this combination of hydrological events is that Lake Erie’s current water levels are much higher than usual for this time of year.

The role of climate change

Great Lakes water levels have varied in the past, so how do we know whether climate change is a factor in the changes taking place now?

Precipitation increases in winter and spring are consistent with the fact that a warming atmosphere can transport more water vapor. Converting water from vapor to liquid and ice releases energy. As a result, increased atmospheric moisture contributes to more precipitation during extreme events. That is, when weather patterns are wet, they are very wet.

Flooding in New York state along the Lake Ontario shoreline, May 28, 2019.

Changes in seasonal cycles of snowmelt and runoff align with the fact that spring is coming earlier in a changing climate. Climate models project that this trend will continue. Similarly, rising lake temperatures contribute to increased evaporation. When weather patterns are dry, this produces lower lake levels.

Wet and dry periods are influenced by storm tracks, which are related to global-scale processes such as El Niño. Similarly, cold air outbreaks are related to the Arctic Oscillation and associated shifts in the polar jet stream. These global patterns often have indirect effects on Great Lakes weather. It is uncertain how these relationships will change as the planet warms.

Tools for better forecasts

Rapid changes in weather and water supply conditions across the Great Lakes and upper Midwest are already challenging water management policy, engineering infrastructure and human behavior. We are undoubtedly observing the effects of a warming climate in the Great Lakes, but many questions remain to be answered.

Soils in most of the Great Lakes states are extremely wet. For example, in 99th percentile zones, soil moisture is higher than 98% of the entire historical record. NOAA (https://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Soilmst/Soilmst.shtml#)

The Great Lakes are, collectively, a critical water resource. Government agencies and weather forecasters need new tools to assess how future climate conditions may affect the Great Lakes water budget and water levels, along with better shorter-term forecasts that capture changing conditions.

Innovative techniques, such as incorporating information from snow and soil moisture maps into seasonal water supply forecasts, can help capture a full picture of what is happening to the water budget. The bigger point is that past conditions around the Great Lakes are not a reliable basis for decision-making that will carry into the future.The Conversation

Drew Gronewold, Associate Professor of Environment and Sustainability, University of Michigan and Richard B. Rood, Professor of Climate and Space Sciences and Engineering, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Kevin Grand
Wed, 06/05/2019 - 6:41am

These "experts" are really trying to cover their bases now.

First, "global warming" (I guess that "climate change" has officially lost its effectiveness and now a new label is needed to garner attention), was causing the lake levels to drop.

Now, they're claiming that "global warming" is causing lake levels to rise.

You cannot argue it BOTH ways and expect to retain any credibility.

Rob Dale
Wed, 06/05/2019 - 8:48am

Actually the phrase was changed from "global warming" because it was confusing the public. Some took it to mean that cold weather would never be around, or that every spot on the surface of the Earth would get warmer with time. That's not the case.

What is the case is that the overall temperature of the Earth's atmosphere and oceanic system is on the rise, thanks in large part to human influence.

Ruth A Skelly
Sat, 06/15/2019 - 6:27am

HAHAHAHA. 'Climate Change' is WEATHER. 'human influence' happens when humans toss their trash into lakes, rivers, streams, campsites,etc. , ships/boats dump their refuse.... ya know THOSE kinds of behaviors.

Wed, 06/05/2019 - 8:10am

This constant refrain that EVERYTHING is blamed on climate change is tedious and not helpful to the cause its trying to solve. If we have a drought - It's climate change! Too much rain the very next year it's cliamte change! Simple fact is people have short memories and always think that the year they're in is the most/worst ___________ of any year. The late 80s had extreme high water and this has been a periodic occurrence as long as man was there to record it as well as prehistory times. Even the rate is change argument is dubious since weather science has such a short time frame. While climate change is a plausible explanation to changes we see, this pointing at every weather pattern is comparable to climate change deniers pointing at polar vortexes as their proof that no such phenomena exists. Stop it!!!

Wed, 06/05/2019 - 8:11am

Climate Change is Natural.

Wed, 06/05/2019 - 9:06am

The climate changes. As do weather trends. And as the weather and climate change, so does the water level in the Great Lakes. Having spent my summers beside Lake Erie for over 50 years, I remember seeing water level changes of this magnitude and speed several times before. The degree to which the lakes freeze over and the amount of winter snow has always been a factor in the water levels the following spring. Our family cottage loses approximately 2 feet of beach to increased water level for every 10% of ice cover over 70% in January. The current high water levels are very logical and should have been expected, given last winter's temperatures and the very rainy and cool spring. Any lakefront property owner or developer who didn't allow for temporarily higher-than-record water levels in their most recent construction deserves whatever damage they get.

In the 1970s and 80s it was very common for the ice bridge between the UP and Isle Royale to form, allowing wolves to leave and arrive. During the 1990's through the 2010s, no ice bridge for 3 decades forced the wolf pack into decline, a decline from which introducing new wolves last year may or may not rescue both wolves and the island's foliage from the unchecked growth of the moose herd. If climate change in Michigan turns out to be a return to the early 20th century pattern of colder winters and warmer summers than recently, wolves, and possibly moose, will once again be able to come and go from Isle Royale without human intervention.

Sue Miller
Wed, 06/05/2019 - 9:06am

It’s a fact that the weather conditions are changing dramatically around the Great Lakes. We are fortunate to have climatologists studying these changes and working on improved predictive models. These models then form the basis for decision making. Thank you to the all these scientists working to help us understand and prepare for these changes.

Wed, 06/05/2019 - 9:37am

Are you suggesting that climate change is a recent phenominum, or that maybe the water levels in the lakes are recent. Would be surprised if the authors of the article would confirm your suggestions. I would be willing to say that both the water levels [especially when frozen] has been much high in the Great Lakes.

The other side of you concern would be Lake levels at 'record' low levels, I expect that the vast majority of people [authors include] would prefer to have the high levels than the lowest levels.
Now if you had identified a cause for the extremes in the Lake levels that would be more interesting to hear, and if those causes were controllable or at least something we could influence that would be significant and very helpful.
To be clear I am one of those who believes the climate, the weather over the Great Lakes and beyond are dynamic and have been in a state of flux since the beginning of 'time' [earth], so I lean to man needs to be adaptable rather then believe he is so significant he can control the climate or even the weather.

Gary Lea
Wed, 06/05/2019 - 9:58am

Look; the "some experts" referenced by this article's author had actually written, "Competing effects of shifting precipitation and warmer temperatures suggest little change in Great Lake levels over much of the century until the end of the century, when net decreases are expected under higher emissions." This opinion piece misleads by stating, "...water levels to continue to decline." Well yeah, 'continue,' if, by use of that word you intended to compare now with the end of this century!

Wed, 06/05/2019 - 11:19am

The climate has been changing since the earth was formed. It has been warming ever since the last ice age. Low water levels were recorded way back in the 1930's for the great lakes and when they went low again (but not as low as the historical records) the media and others tried to blame man - dredging etcetera - completely ignoring the fact that water levels were lower back in the 1930's. Now they are back up. This is called Nature's variability. We have no control over the climate - may be hard for many to believe that human beings are insignificant when it comes to things like climate but we are - insignificant.

The idiocy that I've seen over the years is amazing. We all know there was an ice age and we all know that North America had a subtropical climate prior to the ice age - we aren't back to that yet - so it was normal for the climate to be a lot warmer than it currently is.

Wed, 06/05/2019 - 11:48am

Thank you for this very informative article. Anyone who has read the literature and articles such as this recognize the truth of climate change. Attending seminars on this topic is also useful.

This problem won't be solved with the attitudes of commenters here. These are the same folks who love to comment on things about which they have strong opinions, but lack the knowledge and expertise to be trusted about anything they post. They LOVE to get their adrenaline flowing and see how "clever" they can be. They have no concern for future generations.

Please keep educating us. It truly will be future generations who will have to solve this. I wonder how they will feel about the mess that was left them?

Wed, 06/05/2019 - 4:15pm

What problem? The climate changing is not something anyone can stop. As you can see from the NOAA archives of lake levels, yearly climate changes have a huge impact on them.

Wed, 06/05/2019 - 4:43pm

Thank you for validating my comment.

Fri, 06/07/2019 - 10:17am

You never look to have you views validate, you never have considered [never asked pointed questions] of what those who differ from your point of view have said. You never try to understand their differing perspective, you never consider that they may have information, an understanding, an experience that is different from what you believe and that you may learn from them.

Thu, 06/06/2019 - 11:40am

Bernadette your tendency is accept an argument based on the political side it falls on rather than whether it makes any sense. For instance if some left wing "expert" states that earth quakes are increasing because of atmospheric CO2 and therefore we need the Green New Deal, you're fine with labeling critics of that position as Climate change deniers. That's quite ... something.

Wed, 06/05/2019 - 4:27pm

The levels are only a record for the 160 years the levels have been measured. According to your theory presented, the lake levels in 1816 should have been much higher as that was the "year without a summer". The lakes would have been frozen over nearly 100% and the summer temperatures were very cool by comparison as it snowed in New England in July of that year. Also as shown in the NOAA data, the 1930's during the dust bowl, the lakes were very low. As we know now, this was due to the upper level low which forms over the Gulf of Mexico every year was some 300 miles further west than normal, causing the moisture to fall in the Rocky Mountains instead of the Plains. Yes, the actions of the climate have a great impact upon the lakes, every year. Although the last two years, the average surface temperatures have dropped in contrast.

Wed, 06/05/2019 - 5:21pm

To the climate deniers that post the same idiot arguments every time AGW is mentioned: Please die off as soon as possible so that my generation can attempt to fix the environmental catastrophe you've left us

Fri, 06/07/2019 - 1:50pm

Bones this isn't really about the legitimacy of climate change, which I think is a real thing. It's about the fact that literally everything, without any proof is now blamed on climate change, which is unscientific nonsense and not helpful in achieving a solution. I thought you were an old guy?

Dave Fiebig
Thu, 06/06/2019 - 12:03am

It is just the weather. It used to be "a big snow storm is coming", now we hear "A HUGE POLAR VORTEX IS COMING" or "A HUGE CYCLONE BOMB IS COMING". Even the weather report is becoming "fake news". Come on, it is just the weather. The great lakes will rise and the great lakes will fall, and there is not a damn thing you can do about it.

Sun, 06/09/2019 - 2:38pm

Why are republicans science deniers? Are thermometers, thermostats, measuring cups, protractors, rulers, etc. all just fake news? How did we ever discover vaccines or invent things like the internet? How did we send people and spacecraft into space? When did science become so subjective and political? Why do we have scientists, doctors, engineers? Are they all just liars trying to impose socialism on everyone? Why are we supposed to put more trust in God and religious leaders who want us to "believe" things, rather than scientists who want proof? You people need to grow the F up! Our children are depending on adults to protect them, not you medieval lunatics with your voodoo dolls who want to destroy the earth and humankind for a quick buck. Just stop the nonsense!

Mon, 06/10/2019 - 5:25pm

Science became 'subjective and political' when the research became dominated by politicians directing government grant money. What the politicians will pay for is what the grant request will mirror.
Reality of media reporting is that what passes for science is at best statistical anomalies. Simply because something is present when events happen does mean they cause the event. Without a well define mechanism of one impacting the other and the reproducibility of that mechanism you don't have science you have speculation. The media seldom have the knowledge or experience to evaluate what is science so they report what is likely to evoke the emotions of readers.

Don't under estimate the magic of science, gravity is one of the best examples of magic.

Chris Geerer
Sat, 08/17/2019 - 10:19am

Why is this article captioned “opinion”? I see nothing that’s “opinion” here. I see scientific claims backed by evidence. Where they are unsure, they are clear about the need for more data. This is not opinion and labeling it as such merely confirms the Trumpists who argue that climate change is a hoax.

Mary Pat
Tue, 08/27/2019 - 8:38am

Excellent article. Thank you. I currently have property on the shore of Lake Huron and my neighbours along the coast who have been there since they were children over 50 years ago have NEVER seen water levels or erosion like they have in 2018 or 2019.