Great Lakes Flooding: The Warning Signs That Homes Must Be Moved
Every fall, I take my environmental studies class camping at Sleeping Bear Dunes National Lakeshore on Lake Michigan. Some years the beach extends more than three meters to the water. This year, in many spots, there was no beach at all.
The story is the same throughout the Great Lakes. During my summer research trip to Lake Ontario and the St. Lawrence River, I lost track of the number of submerged docks and buildings; swimming near the shore of Lake Huron was a bad idea because of the high risk of electrocution from inundated boathouses that still had the juice flowing.
Water levels in the Great Lakes have always fluctuated. But climate change is throwing past patterns out of whack. Almost every Great Lake reached record levels in 2019. And the latest studies predict that levels might reach even higher in 2020.
But instead of engineered solutions, we should be concentrating on getting out of the way.
Lake Michigan's high water levels consumed beaches at Sleeping Bear Dunes National Lakeshore in 2019. Daniel Macfarlane / Author provided
My research looks at the ways that Canada and the U.S., along with the bilateral International Joint Commission, have tried to understand and control water in the Great-Lakes St. Lawrence River Basin for well more than a century.
Both countries have made large diversions in and out of the Great Lakes, such as the Chicago Sanitary and Ship Canal, as well as numerous smaller diversions and canals.
In the 1950s, dams along the St. Lawrence transformed this gigantic river into a hydropower pool and navigation channel and, controversially, to help regulate water levels in Lake Ontario. Control works in the St. Marys River partially regulate Lake Superior. Niagara Falls is treated like a tap to generate both hydropower and beauty. Then there is the 100-plus years of perpetually dredging channels and harbours for navigation.
Cumulatively, these anthropogenic interventions have likely changed water levels on the lakes by less than one meter.
Meanwhile, communities have steadily encroached on the water. We turned seasonal sandbars into subdivisions. Metropolises like Toronto and Chicago extended their footprints hundreds of meters into the lake.
And it's not only large dams, diversions and cities that have impacts. Thousands of small individual actions add up, such as the breakwalls, retaining walls and the rip-rap (graded stone or crushed rock) property owners erect to protect boathouses, cottages and other structures.
Collectively, we might be the proverbial fool who built our house on sand — often literally.
These engineered interventions have myriad ecological impacts and unintended consequences, such as invasive species and impaired water quality. They've also instilled a societal hubris that we can — and should — control water on a large scale in the Great Lakes-St. Lawrence system.
High water levels inundate a waterfront home on the St. Lawrence River in May 2017.
However, natural forces — rain, snow, ice cover, temperature, evaporation — are the biggest determinant of water levels in the Great Lakes.
As long as humans have kept records, Great Lakes water levels have oscillated. Depending on which of the Great Lakes one considers, the maximum range of water level fluctuations has been about one to two meters in the past 150 years. For example, very high water occurred in the early 1950s, early 1970s, mid-1980s and mid-1990s.
Now, pushed by a changing climate, the swings in levels that used to take several decades are occurring in half a decade. Instead of a gradual rise and fall, the lakes are going from extreme to extreme.
For example, Lakes Michigan and Huron hit record lows in 2013, and docks on Georgian Bay didn't reach the water. To compensate, the U.S. Army Corps of Engineers proposed putting riffles, basically water speed bumps, on the bottom of Lake Huron's outflow at the St. Clair River.
Now Lake Huron is close to record high levels and docks are under water. If those St. Clair riffles had been installed, the water levels on Lakes Huron and Michigan would be even higher today. This is the type of short-sighted thinking we need to avoid.
Water needs breathing space. We need to move out of the way, rather than try to move water out of our way.
Humans have removed, impaired or destroyed many of the lakes' natural buffers, which accommodate fluctuating water. We've eradicated shoreline wetlands and beaches and covered them with concrete.
If a property along the Great Lakes is getting wet now, it will almost certainly be wetter in the future. While there is some scientific uncertainty about exactly what climate change will do to water levels, the extreme highs and lows will get worse. Volatility is the new normal.
Like climate change, when it comes to addressing Great Lakes levels, the biggest hurdles aren't scientific — they are political, economic and social.
Any new infrastructure along Great Lakes shorelines must be flexible, adaptable and resilient.
But we must also realize that the answer isn't more infrastructure. Infrastructure is too often the cause of our environmental issues.
We need to remove structures entirely and avoid building anything near the water's edge. This will have the added benefit of making more of the Great Lakes accessible to everyone. Since governments zoned vulnerable areas for construction, government funding should be provided.
We should use the opportunity to restore natural shorelines and wetlands. These provide many benefits for both water quality and water quantity. In terms of the latter, they can serve as water retention areas, while wetland plants provide erosion control.
This is all going to be very hard for many people to hear — there will be major resistance. But not moving is going to cost more in the long run. We think we can control water levels, but we need to think differently.
Reposting with permission from our media associate The Conversation.
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By Melissa Gaskill
Two decades ago scientists and volunteers along the Virginia coast started tossing seagrass seeds into barren seaside lagoons. Disease and an intense hurricane had wiped out the plants in the 1930s, and no nearby meadows could serve as a naturally dispersing source of seeds to bring them back.
Restored seagrass beds in Virginia now provide habitat for hundreds of thousands of scallops. Bob Orth, Virginia Institute of Marine Science / CC BY 2.0<p>The paper is part of a growing trend of evidence suggesting seagrass meadows can be easier to restore than other coastal habitats.</p><p>Successful seagrass-restoration methods include <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304377099000078?via%3Dihub" target="_blank">transplanting shoots</a>, <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1061-2971.2004.00314.x" target="_blank" rel="noopener noreferrer">mechanized planting</a> and, more recently, <a href="https://www.nature.com/articles/s41467-020-17438-4" target="_blank" rel="noopener noreferrer">biodegradable mats</a>. Removing threats, proximity to donor seagrass beds, planting techniques, project size and site selection all play roles in a restoration effort's success.</p><p>Human assistance isn't always necessary, though. In areas where some beds remain, seagrass can even recover on its own when stressors are reduced or removed. For example, seagrass began to recover when Tampa Bay improved its water quality by reducing nitrogen loads from runoff by roughly 90%.</p><p>But more and more, seagrass meadows struggle to hang on.</p><p>The marine flowering plants have declined globally since the 1930s and currently disappear at a rate equivalent to a football field every 30 minutes, according to the <a href="https://www.unep.org/resources/report/out-blue-value-seagrasses-environment-and-people" target="_blank" rel="noopener noreferrer">United Nations Environment Programme</a>. And research published in 2018 found the rate of decline is <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB005941" target="_blank" rel="noopener noreferrer">accelerating</a> in many regions.</p><p>The causes of decline vary and overlap, depending on the region. They include thermal stress from climate change; human activities such as dredging, anchoring and coastal infrastructure; and intentional removal in tourist areas. In addition, increased runoff from land carries sediment that clouds the water, blocking sunlight the plants need for photosynthesis. Runoff can also carry contaminants and nutrients from fertilizer that disrupt habitats and cause algal blooms.</p><p>All that damage comes with a cost.</p>
The Value of Seagrass<p>As with ecosystems like rainforests and <a href="https://therevelator.org/mangroves-climate-change/" target="_blank">mangroves</a>, loss of seagrass increases carbon dioxide emissions. And that spells trouble not just for certain habitats but for the whole planet.</p><p>Although seagrass covers at most 0.2% of the seabed, it <a href="https://www.unenvironment.org/news-and-stories/story/seagrass-secret-weapon-fight-against-global-heating" target="_blank">accounts for 10%</a> of the ocean's capacity to store carbon and soils, and these meadows store carbon dioxide an estimated 30 times faster than most terrestrial forests. Slow decomposition rates in seagrass sediments contribute to their <a href="https://www.researchgate.net/publication/238506081_Assessing_the_capacity_of_seagrass_meadows_for_carbon_burial_Current_limitations_and_future_strategies" target="_blank" rel="noopener noreferrer">high carbon burial rates</a>. In Australia, according to <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15204" target="_blank" rel="noopener noreferrer">research</a> by scientists at Edith Cowan University, loss of seagrass meadows since the 1950s has increased carbon dioxide emissions by an amount equivalent to 5 million cars a year. The United Nations Environment Programme reports that a 29% decline in seagrass in Chesapeake Bay between 1991 and 2006 resulted in an estimated loss of up to 1.8 million tons of carbon.</p>
Eelgrass in the river delta at Prince William Sound, Alaska. Alaska ShoreZone Program NOAA / NMFS / AKFSC; Courtesy of Mandy Lindeberg / NOAA / NMFS / AKFSC<p>Seagrasses also protect costal habitats. A healthy meadow slows wave energy, reduces erosion and lowers the risk of flooding. In Morro Bay, California, a 90% decline in the seagrass species known as eelgrass caused extensive erosion, according to a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771420303528?via%3Dihub" target="_blank" rel="noopener noreferrer">paper</a> from researchers at California Polytechnic State University.</p><p>"Right away, we noticed big patterns in sediment loss or erosion," said lead author Ryan Walter. "Many studies have shown this on individual eelgrass beds, but very few studies looked at it on a systemwide scale."</p><p>In the tropics, seagrass's natural protection can reduce the need for expensive and often-environmentally unfriendly <a href="https://www.nioz.nl/en/news/zeegras-spaart-stranden-en-geld" target="_blank" rel="noopener noreferrer">beach nourishments</a> regularly conducted in tourism areas.</p><p>Seagrass ecosystems improve water quality and clarity, filtering particles out of the water column and preventing resuspension of sediment. This role could be even more important in the future. By producing oxygen through photosynthesis, meadows could help offset decreased oxygen levels caused by warmer water temperatures (oxygen is less soluble in warm than in cold water).</p><p>The meadows also provide vital habitat for a wide variety of marine life, including fish, sea turtles, birds, marine mammals such as manatees, invertebrates and algae. They provide nursery habitat for <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/32636/seagrass.pdf?sequence=1&isAllowed=y" target="_blank" rel="noopener noreferrer">roughly 20%</a> of the world's largest fisheries — an <a href="https://www.floridamuseum.ufl.edu/science/seagrass-meadows-harbor-wildlife-for-centuries/" target="_blank" rel="noopener noreferrer">estimated 70%</a> of fish habitats in Florida alone.</p><p>Conversely, their disappearance can contribute to die-offs of marine life. The loss of more than 20 square miles of seagrass in Florida's Biscayne Bay may have helped set the stage for a widespread <a href="https://www.wlrn.org/2020-08-14/the-seagrass-died-that-may-have-triggered-a-widespread-fish-kill-in-biscayne-bay" target="_blank">fish kill</a> in summer 2020. Lack of grasses to produce oxygen left the basin more vulnerable when temperatures rose and oxygen levels dropped as a result, says Florida International University professor Piero Gardinali.</p>
Damaged Systems, a Changing Climate<p>Governments and conservationists around the world have already put a lot of effort into coastal restoration efforts. And that's helped some seagrass populations.</p><p>Where stressors remain, though, restoration grows more complicated. <a href="https://www.rug.nl/research/portal/en/publications/the-future-of-seagrass-ecosystem-services-in-a-changing-world(3a8c56db-7bed-4c9e-ac7f-c72453e2a102).html" target="_blank">Research</a> published this September found that only 37% of seagrass restorations have survived. Newly restored meadows remain vulnerable to the original stressors that depleted them, as well as to storms — and <a href="https://www.ecowatch.com/tag/climate-crisis">climate change</a>.</p>
Seagrass in Dry Tortugas National Park, Florida. Alicia Wellman / Florida Fish and Wildlife / CC BY-NC-ND 2.0<p>In Chesapeake Bay a cold-water species of seagrass is currently hitting its heat limit, especially in summer, according to Alexander Challen Hyman of University of Florida's School of Natural Resources and Environment. As waters continue to warm due to climate change, the species likely will disappear there.</p><p>Climate-driven sea-level rise complicates the problem as well. Seagrasses thrive at specific depths — too shallow and they dry out or are eaten, too deep and there isn't enough light for photosynthesis.</p>
But There’s Good News, Too<p>Luckily, left to its own devices, a seagrass meadow can flourish for hundreds of years, according to a <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.1861" target="_blank" rel="noopener noreferrer">paper</a> published last year by Hyman and other researchers from the University of Florida. The researchers arrived at their conclusion by looking at shells of living mollusks and fossil shells to estimate the ages of meadows in Florida's Big Bend region on the Gulf Coast.</p><p>That area has extensive, relatively pristine seagrass meadows. "Our motivation was to understand the past history of these systems, and shells store a lot of history," said co-author Michal Kowalewski.</p><p>A high degree of similarity between living and dead shells indicates a stable area, while a mismatch suggests an area shifted from seagrass to barren sand. The researchers found that long-term accumulations of shells resembled living ones, suggesting that the seagrass habitats have been stable over time.</p><p>That stability allows biodiversity to thrive, creating conditions where specialist species can survive and flourish, according to Hyman.</p><p>Discovering the long-term stability of seagrass meadows has implications for choosing restoration sites, Kowalewski notes.</p><p>"There must be reasons they thrive in one place, while a mile away they don't and fossil data says they probably never did," he said. "If we remove a seagrass patch, we cannot hope to plant it somewhere else. It's not just the seagrass that is special. The location at which it's found is special, too."</p><p>A better approach is conserving these habitats in the first place, but we're not doing enough of that right now. The UN reports that marine protected areas safeguard just 26% of recorded seagrass meadows, compared with 40% of coral reefs and 43% of mangroves.</p>
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