Earth, Air, Fire and Water
U of G ecologist studies Earth's past in peatlands to help predict trends, including climate change impacts
BY ANDREW VOWLES
|Prof. Merritt Turetsky is part of a long-term research project on climate change in the boreal region. Photo by Martin Schwalbe|
There's a time bomb ticking under our feet, one that Prof. Merritt Turetsky, Integrative Biology, hopes to help defuse.
About one-third of the world's carbon has been locked into northern soils, including the vast peatlands that sprawl over much of northern Canada's boreal region, says Turetsky. Release all that pent-up carbon dioxide and methane into the atmosphere — perhaps by warming those soils through climate change beyond an unknown threshold — and who knows what ecological consequences you'd unleash.
Learning more about that “carbon bomb” and how to prevent it from exploding is the primary focus of this ecosystem ecologist. Her research uses the classical “elements” of earth, air, fire and water to tackle the modern-day challenge of global warming, including defusing some myths about that “time bomb” itself.
A new arrival at Guelph last year, Turetsky is continuing her work with a larger, decades-old research project in Alaska and Canada's North. A clue to that interest hangs in her office in the science complex. From behind her desk, she glances repeatedly at a wall enlivened by three colourful ecosystem illustrations of Arctic tundra, boreal forest and freshwater marshes.
She's already spent plenty of time in Alaska and in the northern reaches of the Prairie provinces. Much of that landmass is home to boreal forests, including peatlands. That peat consists of partly decayed vegetation whose decomposition has been inhibited by wet conditions and by the underlying permafrost.
Drill down and lift out a core of peat several metres thick and you're looking at a climatic record in its layers of material, including alternating warm and cool periods.
“If you look down at your feet in one of these ecosystems, it's incredible to think that you're standing on 14,000 years of data,” says Turetsky. Referring to the chemistry of the upper layers in a soil profile, she says she can also detect the fingerprint of human activities from mining to urbanization. “I can tell you when unleaded gasoline came in.”
Reading the past in peat is one thing. More challenging is predicting what's to come.
She says change is occurring in the North, including slumping of permafrost in Canada and Siberia. Apart from ecological concerns, it's the frozen soil that supports infrastructure, including roads, pipelines and buildings. “They're all built on permafrost. Once that goes, everything goes down.”
Melting will speed up decomposition of material and release of those trapped greenhouse gases. But there are other complications, including fire and water.
Peat formation and maintenance rely partly on the depth of the underlying water table. Apart from increasing decomposition, will warming temperatures dry the soil and increase the risk of fires?
Turetsky has studied peatland fires, both naturally occurring and on field test sites and in managed burns. She's still “fire-chasing,” trying to learn more about whether warmer, drier conditions will release more carbon.
Besides the climate change implications, her work may help resource managers better tackle peatland fires. Peat fires often smoulder underground, making them a stubborn foe for firefighting teams.
“We knew nothing about boreal peatland fires except that when peat starts to burn, it's nearly impossible to put out,” says Turetsky.
Other factors complicate the picture. Change the amount of forest cover in the North and you alter the area's albedo, or how much of the sun's energy is absorbed or reflected by vegetation.
Plants play another role in a good news/bad news scenario. Turetsky has found that thawing permafrost causes more peat decomposition and release of methane (a more powerful greenhouse gas than carbon dioxide) than occurs in still-frozen areas. But that additional meltwater boosts production of plants, particularly Sphagnum mosses, which lock more of that carbon into their tissues and prevent it from accumulating in the atmosphere.
Turetsky works with a long-term ecological research (LTER) project at Bonanza Creek, based near Fairbanks in the Alaska Interior. The Bonanza Creek Experimental Forest was established in 1963; the research project in the 5,000-hectare site has been running for two decades, supported by the U.S. National Science Foundation and the U.S. Department of Agriculture Forest Service.
Scientists use the site to study the long-term consequences of climate change in the boreal region. Working with graduate students and post-docs — all affiliated with the LTER — Turetsky began the first ecosystem-scale manipulation of water tables and soil temperatures in Alaskan peatlands to study how vegetation and decomposition rates respond to climate change. She will continue her affiliation with that project here at Guelph.
Growing up in Connecticut and New Jersey, she found herself drawn to the outdoors. In high school, she became a local environmental advocate. She was still considering environmental law or business when she encountered research as an undergraduate at Pennsylvania's Villanova University.
“I fell in love with the ability to pose novel questions about topics that I and hopefully the public deem important.”
After completing her PhD in Alberta and a post-doc with the U.S. Geological Survey, Turetsky joined the faculty of Michigan State University. Her research there on how wildfires pump mercury into the atmosphere garnered coverage by Time magazine, Science News and the Christian Science Monitor.
She arrived in Guelph last spring with her husband, Prof. Andrew McAdam, Integrative Biology. They met at the University of Alberta and were on faculty together at Michigan State.