Societal impact
What mud tells us about climate change
November 6, 2024
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Recipient of the 2024 NSERC Donna Strickland Prize for Societal Impact, Dr. John Smol understands the benefits of communicating his research to a variety of audiences, including local communities, policymakers, and media.
Talk of the effects of climate change is everywhere. It’s in the news daily and top of the mind for anyone thinking about environmental issues and the future of our planet. But in the late 1970s, little was known about how these pressing issues developed and who was to blame – in part, because science had yet to develop tools to measure how recent climate change and other human activities were affecting Earth’s ecosystems. As a young researcher, John Smol (Biology; Environmental Studies) was part of a new generation of scientists focused on figuring out how our planet was changing. His research had him digging deep into the bottoms of lakes, which led to significant contributions to understanding how long-term environmental changes are linked to both natural and human causes.
As the recipient of the 2024 Donna Strickland Prize for Societal Impact of Natural Sciences and Engineering Research, offered by the Natural Sciences and Engineering Research Council of Canada (NSERC), Dr. Smol is recognized for helping bring scientific evidence to policy and decision making. His research on tracking long-term environmental and climatic changes has shaped conservation efforts within and beyond Canada.
Finding answers at the bottom of lakes
The foundations of Dr. Smol’s research go back to a side project he started while a PhD student at Queen’s. Looking at correlations between algal species composition and lake water pH, he quantified how certain species were more common in highly acidic waters, while others were typically found in alkaline ones. It was the early 1980s, and the world was becoming increasingly concerned about acid rain and its potential impacts. Was acidification a natural process, or was it linked to industrial activity? The clues were buried at the bottom of lakes.
Tiny algae and animals living in lake waters, once dead, tend to sink and accumulate on the bottom. Other organic matter and chemical pollutants do the same, which turns the bottom of lakes into a muddy time machine that records information in sediment layers. While the most superficial sediments store information about the present time, the deeper layers can reveal details of how conditions were in the lake and the local environment hundreds or thousands of years ago.
Dr. Smol created his first sediment extruder using a wooden frame, a hydraulic car jack, a disposable foil ash tray, and tubing borrowed from the lab’s sink drainage system.
He and his lab helped develop some of the other equipment currently used to extract and section sediment samples from lake bottoms, like the sediment corer pictured in this photo.
Before he could start unraveling the past, Dr. Smol and collaborators first had to develop tools – like a suitable sediment corer and high-resolution sediment sectioner – to extract and sample mud profiles without mixing up the different layers of sediments. Once the coring procedures were figured out, the team started analyzing the dated lake sediment records, particularly fossilized algae found in the samples.
Acid rain was a highly controversial subject in the 1980s, but their results told the story of how lake water pH changed throughout time and, most importantly, who was to blame. “We were able to show that changes in algae assemblages were unequivocally linked to acidification caused by industries,” he says. “In many respects, our convincing sediment data helped ensure a success story for the acid rain issue: strong legislation in the U.S. and elsewhere was enacted early enough to avoid even more serious environmental damage.” The same research techniques testified to how lakes recovered following cutbacks in the copper and nickel smelter industry in Ontario as well as in other regions.
A new field emerges
Results of Dr. Smol’s acid rain research helped establish paleolimnology as a field providing critical long-term data on aquatic ecosystems. The concept of studying sediment layers to inform environmental policy led to many other applications beyond acidification. In particular, Dr. Smol has dedicated decades of work to studying the effects of recent warming on high Arctic lake ecosystems – a research program that pointed to the dramatic impact of greenhouse-gas-induced climate warming in that region years before most people recognized climate change as a critical environmental issue.
By the early-1990s, Dr. Smol’s research was already flagging pre- to post-industrial changes to the algae assemblages in Arctic and sub-Arctic lakes. “We concluded that these most recent changes were climate-driven and several alternative hypotheses that we examined, including acidification, nutrient increases, and chemical contaminants, could not explain these striking shifts.” Since then, the team has found similar evidence in paleolimnological studies around the world, including, for example, research in the Andean lakes of Ecuador and Peru.
“I refer to our research as forensic paleolimnology: we work to figure out what went wrong, why, when, and who's to blame."
– Dr. John Smol
2024 NSERC Donna Strickland Prize
While climate change is now a consensus within the academic community, climate researchers still face denialism and need to advocate for evidence-based climate policies and decision making.
“When it comes to environmental work, one of the key things is proving that the problems exist,” says Dr. Smol. "For example, in working on lake acidification, we first had to show that lake water wasn’t always that acid; in studying how lake ecosystems respond to global warming, we had to show that these recent changes are not part of some long-term natural cycle but linked to greenhouse gas emissions. Paleolimnology provides the appropriate temporal scales to assess these environmental problems.”
Dr. Smol founded and now co-leads the Paleoecological Environmental Assessment and Research Lab (PEARL), which applies paleolimnological methods to address several research questions. In the past few decades, more than 100 graduate students and postdoctoral fellows, and even more undergraduate research students, have been part of PEARL and made remarkable contributions to paleolimnology. They helped answer questions such as why Ontario lakes experience algal blooms and how road salt impacts freshwater ecosystems. In some more recent papers, the team began addressing conservation biology issues, such as using sediment indicators to track bird feces inputs and thereby track changes in vulnerable seabird populations off the coast of Newfoundland, which they have linked to both natural and human impacts.
Social impact
As recognized by the recent NSERC award, research carried out at PEARL and led by Dr. Smol has implications beyond academia: providing a record of past changes in lakes is the first step in planning present and future environmental action. How many cottages or homes can we build around a lake without threatening local aquatic ecosystems? How have different industries affected lakes? What’s the reach of oil sands pollution? Should we try to populate a fishless lake with fish species? Given the lack of direct long-term monitoring data, these and other questions asked by environmental managers may only be answered by the histories told by paleolimnologists.
For Dr. Smol, the Arctic is a great example of a “natural laboratory”, as polar lakes have relatively simple food webs, with fewer species, and typically are not directly affected by local disturbances like land-use changes. [Photo credit: NSERC; Sylvie Li Shoot Studio]
In addition, an important aspect of PEARL’s current work is co-developing research with different Indigenous communities on the impact of mining and other industrial pollution on their territories. This historical information, along with Indigenous knowledge, can help plan and advocate for environmental management best practices.
A recent paleolimnological study of North America’s deepest lake, Great Slave Lake in the Northwest Territories, found pronounced changes in algae assemblages due to accelerated 21st century warming. Changes in these algae, which are at the base of the food chain, have cascading effects that may impact commercial fisheries and recreational activities important to First Nations, Métis, and other northern communities that depend on the lake.
As a veteran scientist, Dr. Smol understands the benefits of communicating his research to a variety of audiences, including local communities, government and policymakers, and media. “My work on controversial topics such as acid rain and climate change taught me how to defend work that was being challenged, and how to make people understand the importance of this type of research. If an information vacuum exists, it will be filled by vested interest groups. Environmental science is a contact sport, and we need to make sure we put our results out there.”
Throughout his career, Dr. Smol has published over 730 papers and 24 books. He has received seven honorary doctorates and more than 100 awards, including the five major prizes offered by NSERC – he was the youngest researcher to ever win the Gerhard Herzberg Canada Gold Medal in 2004. Along with the Donna Strickland Prize, the most recent awards received by Dr. Smol are the King Charles III Coronation Medal, the Foreign Fellowship of the Geographical Society of China, the Phycological Society of America Award of Excellence, the Lifetime Achievement Award from the Association for the Sciences for Limnology and Oceanography, and the American Quaternary Association Distinguished Career Award Medal, all awarded in the last few months.
