Two Hundred Years of Forest Fires in Ontario, Canada

Two Hundred Years of Forest Fires inOntario, Canada

28 February 2007

published by

Canada — The authors begin by noting that recently, according to the IPCC,”global climate has been warming as a result of increases of radiativelyactive gases (carbon dioxide, methane, etc.) in the atmosphere primarily causedby human activities,” and that “human-induced climate change couldlead to an increase in forest fire activity in Ontario, owing to the increasedfrequency and severity of drought years, increased climatic variability andincidence of extreme climatic events, and increased spring and fall temperatures,”noting further that “climate change therefore could cause longer fireseasons (Wotton and Flannigan, 1993), with greater fire activity and greaterincidence of extreme fire activity years (Colombo et al., 1998; Parker et al.,2000).”

What was done
In a study designed to see if any of these negative prognostications have cometo pass, Girardin et al. reconstructed a history of area burned within theprovince of Ontario for the period AD 1781-1982 from 25 tree-ring widthchronologies obtained from various sites throughout the province, spurred on,perhaps, by the increase in area burned within Ontario that is known to haveoccurred from 1970 through 1981 (Podur et al., 2002).

What was learned
The three Canadian researchers report that “while in recent decades areaburned has increased, it remained below the level recorded prior to 1850 andparticularly below levels recorded in the 1910s and 1920s,” noting furtherthat “the most recent increase in area burned in the province of Ontariowas preceded by the period of lowest fire activity ever estimated for the past200 years (1940s-1960s).”

What it means
Although the researchers say that, according to theory, “one should expectgreater area burned in a changing climate,” especially one that is drivenby anthropogenic-induced increases in atmospheric CO2 concentrations, theirfindings supply no support for this contention. In fact, they argue stronglyagainst it.

Girardin, M.P., Tardif, J. and Flannigan, M.D. 2006. Temporal variability inarea burned for the province of Ontario, Canada, during the past 200 yearsinferred from tree rings. Journal of Geophysical Research 111:10.1029/2005JD006815.

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