Forests and Climate Change

By Tony Rotherham

Old pasturelands that will never again provide grazing for cattle are gradually reverting to forest. But it is a slow process. The Federal Government has a “2 Billion Tree” program designed to plant millions of trees to increase the size of our forests and fight climate change.

As trees grow they absorb carbon dioxide from the atmosphere, build the carbon into the wood and emit the oxygen back into the air. This helps to reduce the volume of greenhouse gas (GHG) in the atmosphere and fight climate change. Plantations of spruce and pine grow at a rate of 10-15 cubic metres of wood per hectare each year. Each cubic metre of solid wood holds about the same amount of carbon emitted by burning 270 litres of fuel in your car.

After 30-40yrs of growth, the trees are ready for harvest and the logs are delivered to local sawmills, sawn into lumber and used to build houses. The wood and carbon is then kept in long-term storage for the life of the building.

Climate change can affect forests in at least two ways

Global warming might increase the incidence and severity of forest fires or the area damaged by insect epidemics.

In Canada, annual loss to forest fires varies dramatically depending on the weather. The year 1978 was a good one – only about 300,000 ha were lost to fire. The year 1995 was a bad one 7.4 million ha burned. Using annual losses to judge the effects of climate change can be deceptive. Long term trends are a better measure of the impacts of climate change. The average loss during the 10-year period, 2000-2009, was 1.75 million ha. Between 2010 and 2019 the average loss was 2.9 million ha, significantly higher, but one very bad year can have a big effect on the trendline.

Our forest in the Eastern Townships is a mix of 20+ species of hardwoods and conifers. The combination of hardwood lots, and rainfall that is well-distributed throughout the summer, makes our forests quite resistant to fires. But they can occur. The Acadian Forest Region in New Brunswick is similar to ours, a mix of hardwoods and conifers. The Great Miramichi Fire in 1825 burned 1.6 million ha across the northern half of the province, killing more than 300 people.