Lake Ontario is one of the Great Lakes that may be severely negatively affected by climate change. DINA DONG/THE VARSITY

As summer approaches, students are exchanging their scantrons for swimsuits and pencils for popsicles. For many, summer plans will involve the Great Lakes.

The Great Lakes are an epicentre of recreational, economic, and ecological activity. 9.8 million Canadians, about a third of our country’s population, rely on them. Carved thousands of years ago by retreating glaciers, the Great Lakes are a unique ecosystem housing a fifth of the world’s freshwater.

However, concealed by the rolling waves and the glassy surface of the lakes is evidence of environmental damage caused by humans over the last few centuries.

We have not always been kind to the Great Lakes. Heavy human use of the lakes has resulted in habitat loss and fragmentation, the introduction of invasive species, and environmental pollution. The invasion of zebra mussels and clouds of green algae blooming from phosphorus runoff are just two consequences of human activity to make headlines.

More than 3,500 species of plants and animals call the Great Lakes home, and for some, this is the only place where they can exist. Faced with the growing consequences of climate change, the Great Lakes system is coming under even more stress and is possibly reaching a tipping point.

The Environmental Law and Policy Center report

In March, the Environmental Law and Policy Center (ELPC), an American non-profit advocacy group, released a report detailing the effects of climate change on the Great Lakes.

Although it is widely understood that the consequences of climate change – like rising temperatures and more extreme weather events – will affect everyone, this report also detailed specific consequences for those who live in the Great Lakes region.

Increasingly severe weather patterns will bring hotter, drier summers to the area, causing heat waves. They will also bring wetter springs and winters, which will trigger flooding and increased water flow.

From the early 1900s to 2015, the Great Lakes region experienced a 10 per cent increase in precipitation, compared to the rest of the United States, which had only experienced an increase of four per cent.

“We’re seeing more and more of these… powerful wind storms, rain storms, [and] thunderstorms in the summer, and more milder winters for sure,” said Dr. Harvey Shear, a professor of geography at UTM, who teaches courses on the Great Lakes.

However, the ELPC anticipates that by 2100, the Great Lakes region will have less moisture in the summer, leading to fewer periods of intense precipitation at the start of the season.

Intensifying heat will bring about more days with temperatures above 33 degrees Celsius. By 2100, the ELPC report predicts that the Great Lakes region will experience an additional 30 to 60 days of such temperatures per year.

These intensified patterns of precipitation and hotter temperatures will translate into devastating consequences for the environment and our society. Shortened growing periods, increased disease, and the rising prevalence of waterborne pathogens will directly affect humans.

Nothing new

While it may seem like a shock to find that the Great Lakes region will experience such severe changes in the near future, researchers are not surprised by some of these consequences.

“We have modified the Great Lakes over the last 400 years to the point where they’re almost unrecognizable from what we would have seen if we [went] back in time,” explained Shear.

A case in point is the St. Lawrence River, which has been carved out to accommodate human activities since 1680. Construction began for the St. Lawrence Seaway in 1954 to directly connect the Great Lakes to the Atlantic Ocean. The $470.3 million seaway enabled cities like Toronto and Chicago to expand their commercial shipping industries, bringing in more than $6 billion USD per year to the Great Lakes region.

However, the seaway’s completion resulted in the decimation of the system by invasive species like sea lampreys. Sea lampreys are circular-mouthed fish with hooked teeth that attach themselves to native fish, feeding on their bodily fluids and abandoning them to succumb to their wounds. During their parasitic stage, lampreys kill approximately 40 pounds of fish over 12 to 18 months.

Spiny water fleas, zebra mussels, and other invasive species have also found their way to the Great Lakes system through shipping freighters. When taking on water in their ballast tanks, which are designed to stabilize vessels that are unloading or taking on cargo, these ships will also take on waterborne invasive species. Zebra and quagga mussels, in particular, are known for clogging water intake pipes and being costly to remove.

As temperatures continue to rise, native inhabitants of the lakes will endure added stress from an ecosystem where they are already competing with their non-native neighbours, likely forcing these species to shift to more northern regions.

These concerns are not new — the original 1971 edition of Dr. Seuss’ children’s book, The Lorax, referenced the dire state of Lake Erie. In the 1930s, runoff from fertilizer and waste from humans and animals introduced phosphorus into the lake. Annual phosphorus input soared from about 3,000 tons in 1800 to 24,000 tons in 1960, after the introduction of the mineral in cleaning agents after World War II. The high phosphorus levels caused an overgrowth of algae, clouding the water and killing off other species in a phenomenon known as eutrophication.

State and provincial governments around Lake Erie took action to limit the addition of phosphorus to soap, and began working with local farmers to reduce the amount of phosphorus input by more than half. However, new sources of phosphorus appeared in the 1990s, returning phosphorus levels in Lake Erie to previous conditions.

These algal blooms are more than an eyesore. A species of cyanobacteria called Microcystis causes such harmful algae blooms by producing a toxin called microcystin. The toxin can cause diarrhea, vomiting, and in high enough quantities, liver failure in humans.

Microcystis gripped Toledo, Ohio in 2014, when Lake Erie was subjected to two harmful algae blooms that year due to a one-two punch of increased precipitation and warmer temperatures. The toxin overwhelmed the city’s water filtration system, leaving half a million residents without clean water for three days.

Not all strains of Microcystis produce this toxin, but researchers have found that warmer growing conditions have increased the prevalence of the toxic strain, suggesting that this phenomenon could become more prevalent in the future.

Although some of these consequences listed in the ELPC report are not a result of climate change alone, climate change could worsen their effects in the coming years.

The looming storm

The consequences of climate change are not so far off. Shear noted that significant shifts can happen quickly within a year or two, intensifying extreme weather events.

“With climate change you’re dealing with very long-term changes over decades which makes it easy to attribute extreme weather events to normal year to year variation,” said Shear.

A more tangible consequence of the changing climate, continued Shear, is the uptick of unpredictable weather events, such as violent wind storms. In fact, climate change may have caused the Toronto Islands and the Harbourfront to flood in spring 2017

Shear further explained that we have hardened the surfaces of urban areas with hectares of paved roads and roofs that don’t absorb water. “So when it does rain, there’s nowhere for the water to go but straight into the streams and into [the] lake.”

“[The] Lake Ontario water level was fairly consistent,” he continued, “and then the water level began to rise because of the rainfall and snowmelt… that [had] nowhere to go.”

Concurrent flooding in Montréal, due to extra water in the Ottawa River and St. Lawrence Seaway, denied the officials the option of draining Lake Ontario into the sea to lower the water level.

Although the islands reopened later that summer, visitor attendance was down for the rest of the season, costing the city approximately $5 million in lost ferry revenue, in addition to costs from property damage.

That 2017 flood should be a sobering sign that the Great Lakes will not stay the way they are for very long.

Economic damage

Viewing environmental damage through an economic lens helps put the consequences of changing conditions into perspective. The Great Lakes provide over 1.5 million jobs and generate $60 billion in wages annually for local workers. The regional economy of the Great Lakes system is valued at $6 trillion, which is more than the GDP of countries such as Japan, Germany, France, and the United Kingdom.

With the prospects of decreased employment, damaged infrastructure, and forgone revenue, it raises the question of whether or not we are willing to lose an ecosystem that benefits local economies so much. It’s not that the Great Lakes will cease to exist, but that the system will cease to be a sustainable habitat for not only plants and animals, but for ourselves as well.

Starting change

Seeing the consequences of our past actions shows how much of an impact our behavior can have. But how can we begin to undo the damage that we have done?

Canada and the United States have pledged to reduce the amount of phosphorus in the Great Lakes by 40 per cent by 2025. However, this goal has proven to be tougher to match now than it was in the past. Unregulated farms, dissolved phosphorus, and different phosphorus sources causing the algal blooms have made it harder for the countries to meet their targets. With the added threat of rising temperatures, the threat of algal blooms is imminent.

The Ontario Great Lakes Strategy 2016 progress report outlined the collective efforts of the government, scientists, Indigenous peoples, and private-sector organizations to work toward returning the Great Lakes to a state where they are not at risk of ecological collapse. However, governments have yet to impose hard-hitting restrictions on certain behaviours such as the use of phosphorus by the agriculture industry.

In 2018, then-Ohio governor John Kasich signed an executive order to restrict agricultural runoff, which contributes to algal blooms, by setting requirements for how nutrients in animal waste and fertilizer should be stored.

But government intervention isn’t the only source of change in our society. Organized groups of concerned citizens have a created huge impact on these pressing matters.

According to Shear, citizen activism has led to eradication of all sources of mercury in the Lake Superior Basin and to the cleanup of the Love Canal disaster in New York in the mid-twentieth century.

Love Canal was the site of a failed energy project that became a landfill, which was eventually buried and sold to the city for development. Decades later, chemicals began to seep up through the ground, exposing the region’s residents to carcinogens and teratogens, which are implicated in deforming embryos.

“It was citizen activism in Niagara Falls, Ontario that linked with citizen activists in Niagara Falls, New York that really brought [the provincial, state, and federal governments] to shut down Love Canal… to prevent the contamination of the Niagara River,” said Shear. “So citizen activism can really work.”

In building our cities, we did not plan to bring harm to our environment. Rather, we were careless and uninformed about how our actions could damage the very home we live in. As we learn about why these ecologically devastating events occur and how human activity causes them, we must take action to prevent further damage and restore what we can.

We could otherwise negligently trek forward and continue to make decisions that harm not only ourselves, but those who will come after us.

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