by Peter Bursztyn
Wetlands are odd places. Most people associate them with biting insects which ensure they keep visits to
wetland brief. That’s a pity because wetlands harbor an impressive variety of plant life. Many animal species
make wetlands their homes for at least part of the year.
In mediaeval times wetlands were felt to be a source of disease. Malaria was so named because of the
miasma (bad air = ‘mala aria’) associated with wetlands. One thousand workers died during construction of the Rideau Canal (Ottawa to Kingston). Astonishingly, half were malaria victims – malaria is not just a tropical disease!
Malaria was eradicated from Europe and North America, largely by draining mosquito-infested wetlands. The State of New Jersey is styled the “Garden State”, but in 1901, it was unofficially the “Mosquito State”! In 1912, after a decade of intense lobbying by the state entomologist, a bill mandating mosquito control was signed into law. New Jersey’s marshes were drained, mosquito numbers plummeted, and malaria was almost eradicated by 1934.
For the most part, marshes were drained for agriculture. The soil in former wetlands is rich and may be
tens of metres thick. England’s fenland, a lowland arc around The Wash, was drained between 1630 and 1650 by Dutch engineers. As the waterlogged peat dried, it shrank, dropping its surface below that of nearby rivers. Dykes were built (100km of sea defenses, 160km of river embankments) and pumps installed, powered by Dutch-style windmills. Wind power gave way to steam, then diesel and finally electricity.
Florida’s Everglades, and the Louisiana’s bayous are well known. Both suffered severe degradation due to ill-advised engineering works. These have been partly reversed to correct the damage. Closer to home, the Holland Marsh was drained to create some of Ontario’s most productive farmland. That too caused problems, partly by doubling Lake Simcoe’s phosphorous inputs which promoted weed growth and algal blooms. Other wetlands were drained for suburban housing. As extreme weather has become normal, some of these areas are now flooding; building permits should never have been granted!
Barrie has a small wetland (Bear Creek Eco Park), the eastern edge of which is crossed by Ferndale Drive, south of Tiffin Street. Just 3-4 kilometres west of Barrie’s western edge lies the Minesing Swamp. This “wetland of international significance” extends over 6000 hectares.
There are many types of wetland. Some are tropical, others arctic. Some cling to hillsides. Some are grassy or harbor shrubby vegetation; others are forested. Some – improbably – are even found in deserts! At their base one generally finds peat – slowly decomposing vegetation.
Humans have used peat for thousands of years. Dried peat was a heating or cooking fuel where firewood was scarce. Peat was pounded into gaps in house walls for draft-proofing. Today, we mine peat for gardening. Garden centre plants are potted into peat. Surprisingly, this is a huge market and with machinery mining the peat, the potential for environmental damage is great.
The question we should consider is, what service(s) do wetlands provide? Wetlands harbour a great diversity of plant and animal life. For many people, this is an intangible and hard to value in dollar terms. This is a pity, but consider two readily measured services.
During dry spells, wetlands gradually release water, helping maintain river flows. When rain does fall, wetlands absorb the water like a moist sponge. In doing so, they slow runoff, spreading it over a longer period, often preventing flooding. Even when flooding does occur, its peak height is reduced.
When wetlands are drained for agriculture or settlement, embankments must be erected to keep streams from overflowing the repurposed land. Long stretches of the Mississippi are contained by levees; heavy rainfall cannot be absorbed by land full of impermeable surfaces like roads, parking areas and rooftops.
Another underappreciated service provided by wetlands is carbon sequestration. Worldwide, peatlands are thought to store more carbon than all other types of vegetation combined, despite representing just 3-4% of the earth’s surface.1 The Congo just auctioned 5% of its wetland, the world’s 4th largest, for petroleum exploration 2 . Exploration and exploitation will require draining an area of peat containing about three years-worth of the world’s fossil-fuel derived carbon emissions. But, what right do we have to ask one of the world’s poorest countries not to exploit their resources?
In our far north, as climate change melts Canadian permafrost, our once frozen wetlands begin to emit methane, a greenhouse gas 20 to 25 times more potent than carbon dioxide.
Canadians must stop pretending we contribute little to the world’s carbon emissions. Our greenhouse gas emissions are substantial and we need to pull our weight in the battle to control climate change!
(1) “Swamplands” by Edward Struzik, Island Press, Washington DC, 2021, p3 & p5.
(2) “An oil auction in Congo bodes ill for the climate”, The Economist, London, UK, July 27 th , 2022.
“Emissions from drained peatlands are estimated at 1.9 gigatonnes of CO 2e annually. This is equivalent to 5% of global anthropogenic greenhouse gas emissions, a disproportionate amount considering damaged peatlands cover just 0.3% of landmass.
Fires in Indonesian peat swamp forests in 2015, for example, emitted nearly 16 million tonnes of CO 2 a day; which is more than the entire economy of the United States. Worldwide, the remaining area of near natural peatland (over 3 million km 2 ) sequesters 0.37 gigatonnes of CO 2 a year. Peat soils contain more than 600 gigatonnes of carbon which represents up to 44% of all soil carbon, and exceeds the carbon stored in all other vegetation types including the world’s forests.”
“Issues Brief: Peatlands and Climate Change”