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This story is an excerpt from Daniel Macfarlane’s book The Lives of Lake Ontario: An Environmental History.
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Since the deep past, the climate of the Lake Ontario region has noticeably shifted at least several times. Such shifts presented both challenges and opportunities for different human societies. The various Indigenous groups that occupied the Lake Ontario basin, and their resource and food acquisition strategies, needed to be attuned to climatic realities. For those groups, and the Euro-Americans who later arrived, an especially frigid winter or a particularly dry summer could determine if a community starved. Yet, as I noted earlier in this book, seasonal unpredictability was likely the biggest obstacle introduced by the climatic downturn of the Little Ice Age, at least in the Lake Ontario region.
By limiting when and where certain human activities were possible, climate and environmental factors helped direct the course of empires in North America, both Indigenous and Euro-American. During conflicts that involved Lake Ontario, such as the Seven Years’ War, the American Revolution or the War of 1812, big weather events or the timing of the spring ice break-up could decide the outcome of a military campaign or handicap a lake fleet. The harsher conditions of the Little Ice Age encouraged the fur trade, but for a time dissuaded Europeans from migrating to northern North America on a larger scale; milder weather in the 19th century went hand in glove with the expansion of permanent colonization efforts. Those living in these settlements still remained vulnerable to the weather and needed to adapt their subsistence strategies to the climate they encountered in the Lake Ontario watershed. Such adaptations had social, political, and economic ramifications: a society based on trading furs, which requires constant mobility, organizes itself quite differently than one reliant on agriculture and grain, which requires a sedentary population.
Thus, the geopolitical organization that prevailed at various times around Lake Ontario — Indigenous nations, the French and British empires, the Canadian and American nation-states — hinged to at least some extent on the shifting climate of the region. The warming that took place in the 19th century led to conditions that were generally stable and favoured societal and agricultural flourishing. Prolonged economic and population growth characterizes Lake Ontario’s modern era. Technological innovations and rising living standards meant that human societies were more sheltered, literally and metaphorically, from harsh weather; but technology and progress also fostered societal hubris about our ability to control nature. The shifting range of lake levels experienced in the second half of the 20th century, and the severity of pollution and invasive species, reflected, even if indirectly, the impact of pumping more and more greenhouse gases into the atmosphere.
In July 2020, Lake Ontario’s average surface water temperature was the warmest ever recorded. Since 1995, Lake Ontario has warmed on average over two degrees Celsius, which is more than any other Great Lake. Two degrees Celsius may not sound like much, but these averages can be misleading. The difference in the human body between a normal temperature and a fever is a little more than half a degree Celsius, after all. In terms of the lake, a one degree Celsius increase in water temperature decreased the survival rate of lake trout hatchlings by 150 per cent. Global warming threatens to undo past solutions, exacerbate current challenges, and create new problems. But when, how, and how much remain uncertain. Make no mistake: we are already in a climate crisis. But it is on track to get much worse. The two countries that share Lake Ontario are two of the biggest climate villains in terms of emissions per capita. And neither is remotely on pace to sufficiently reduce its carbon emissions within the short time frames this climate emergency requires.
Warmer air holds more moisture, which has repercussions for Lake Ontario’s water regime. In addition to altered precipitation and ice patterns, climate change alters the heat exchange between the atmosphere and the lake. The region will probably experience wetter springs and winters, though with more rain and less snow in the latter, and drier summers. As early as 2001, scientists contended that Lake Ontario’s annual rise and fall were taking place one month earlier. Greater precipitation and inflow will likely occur in some years, leading to higher water levels; in other years, lack of precipitation or ice cover (which results in more winter evaporation) might prevail, which would lower lake levels. We have recently seen both highs and lows in the alarming span of just two years. What all this means for lake levels is hard to predict. Almost all the Great Lakes, including Lake Ontario, have seen record high levels and summer temperatures in the last few years. Some recent projections do predict that levels across the Great Lakes are more likely to experience small drops. But such prognostications are difficult, since climate change is throwing off the standard predictors and inputs, and models are just informed guesses. Uncertainty remains the name of the game.
In most cases, shoreline resiliency measures and related infrastructural changes (e.g., storm walls, riprap, raising homes) will not suffice. No future construction should be allowed too close to the lake, at least not without a great deal of study. Properties affected by high water levels should be bought out, or buildings moved back — with generous terms offered, since it was governments that authorized or grandfathered in homes and buildings in the affected areas.
Considering the countless toxics, chemicals, nutrients and other things we have poured into Lake Ontario, we are lucky that it is resilient and has a high assimilative capacity. But we are pushing the lake to its limits, plus human actions combined with climate breakdown are also potentially lowering those limits. In other words, we may be undercutting the very resilience and adaptability that has allowed Lake Ontario to cope with our many abuses. Human-caused ecological stressors can be worse than the sum of their parts when combined with climate change. Lake Ontario’s water temperature will likely keep getting warmer into the foreseeable future. Warmer water can affect oxygen concentrations, nutrient cycling, eutrophication and aquatic species distribution. Winter is one of the best deterrents against invasives, but accidentally introduced species will be more likely to survive in warmer waters. A hotter lake can exacerbate existing problems, pushing some issues from minor nuisances to major challenges or undoing past improvements and remediations. A hotter lake could cause tipping points associated with the thermocline, the band of water between the warmer upper epilimnion and the colder lower hypolimnion, which is crucial to stratification, seasonal overturn and the mixing of dissolved oxygen and warmer/colder water. If this broke down, there would be unknown repercussions for the distribution and availability of nutrients, as well as the distribution and location of pollutants. Such changes could alter the entire food web, with the ripple effects for species composition, energy flows and biodiversity in the lake extremely hard to predict.
Cherry Beach, in Toronto, is a popular swimming spot in the summer, when Lake Ontario’s water quality allows. Photo: Christopher Katsarov Luna/The Narwhal
Heavy ice cover has been decreasing since the mid-19th century. For the last few decades, studies have shown that ice formation has declined as a result of climate change. Lake Ontario’s deepest parts rarely ice over, so any substantial reduction will be nearer to the shore. By the middle of our current century, heavy ice seasons may be gone entirely, with very light ice seasons becoming the norm. Less ice cover would have knock-on effects for the lake, potentially affecting fish populations and drinking water quality, though researchers are still unsure about the implications. In fact, scientists still know relatively little about the winter ecology of the Great Lakes compared to other seasons, when it is easier to conduct research. Reduced ice cover could also increase lake effect snow, resulting in larger snow and precipitation events. Ice storms could become more prevalent. A higher frequency and greater intensity of storms in other seasons seems likely too.
Physical changes to Lake Ontario will have economic and cultural repercussions. Given that the southern periphery of the lake is a preeminent North American snow belt, and big snowfalls are woven into the cultural fabric of the region, how might altered winter patterns change society in Upstate New York? As a result of hotter growing seasons, agriculture and crop yields in the basin over the next few decades will suffer in some ways, but maybe benefit in others. A changed climate regime could have appreciable repercussions for Lake Ontario’s fruit and wine belts, though in what ways remains a matter of conjecture. Cottaging, recreation and tourism will be impacted. Boating is obviously a prime activity in the Great Lakes, and the boating season might shift or look different. At parks such as Chimney Bluffs and Sandbanks, will the picturesque sand landforms change? Beaches disappear when there are high water levels. Lack of sufficient ice cover, especially near the shore, will eliminate winter activities like ice fishing and iceboating. At the Bay of Quinte, for example, ice was sometimes thirty inches thick in the 1950s; in the 21st century, it is less than half of that. Embodied understandings of when it is safe to cross ice will be impaired or nullified, with potentially tragic consequences. In addition to direct economic impacts, degraded environments have negative psychological and spiritual effects; conversely, studies abound demonstrating the mental health and happiness benefits of interacting with water.
Toronto’s average summer air temperature swelled over the last half-century. This rise was doubtless more pronounced at Toronto because of deforestation, urban development and the urban heat island effect. As the number of hot days climbs, residents will want to go into the lake to cool off, especially those without air conditioning or other options. At the same time, beaches will be less safe because of hotter weather. Warmer lake temperatures lead to a greater frequency of E. coli, cyanobacteria and algal blooms, including the toxic kind, which will thwart beaches, swimming and boating opportunities. Public water supplies for the millions of people who rely on Lake Ontario for drinking water will be threatened. This was foreshadowed in 2014 when Toledo had to shut down its public water supply, drawn from Lake Erie, for three days because of toxic algal blooms. The greater frequency of extreme weather events will result in more flooding that stresses infrastructure: sudden precipitation swells urban runoff and causes combined sewer system overflows. Continued population growth will likely decrease land cover and amplify the spread of impermeable surfaces — buildings, parking lots, roads, etc. — in the Lake Ontario watershed. It is all too easy to forget that the health of Lake Ontario is tightly linked to what we do with the land, tributaries and groundwater throughout the basin.
Higher water levels have been eroding shorelines along with houses and infrastructure, threatening septic systems, nuclear power stations and fuel refineries. We too often respond with engineered solutions, rather than respecting the lake and being patient, moving back or out of the way. Those trying to protect their property resort to installing riprap, retaining walls and other water protections below the lake’s high water mark — in some cases, this constitutes the appropriation and privatization of public bottom lands. Armouring shorelines generally does not work in the long run anyway, but just pushes the erosive force of the water to the next unprotected section. Those property owners, in turn, are tempted to take similar measures, which merely passes the problem along.
Some littoral infrastructure like marinas and docks, which obviously require water of sufficient depth, are threatened by fluctuating water levels, both low and high. Less ice cover would help extend the commercial shipping season, but might result in more winter evaporation and thus lower water levels for deep-draft vessels. There are definitely limits to how much we can, and should, try to alter Lake Ontario and St. Lawrence levels to benefit shipping.
We should be doing everything we can to limit further anthropogenic climate change. But it is too late to stave off all climate change impacts: even if we magically cut off all greenhouse emissions tomorrow, we have already started feedback loops that will continue to warm the Earth for some time. Nevertheless, there is still a small window to prevent the worst impacts. As the environmental history of Lake Ontario suggests, we are capable of adapting in multiple ways. But will those adaptations be appropriate? Will they be just and equally shared? After all, the historical adaptations to changing environments in the Lake Ontario context created winners and losers, a tendency the deeply unequal and stratified contemporary American and Canadian societies would likely accentuate.
Catch more news at Great Lakes Now:
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Featured image: Just as humans have forever changed the waterfront of Lake Ontario, like Toronto’s Tommy Thompson Park, anthropogenic climate change is shifting the water quality and the waterbody’s ability to bounce back. Photo: Christopher Katsarov Luna/The Narwhal
