B.C. forests no longer carbon sinks
Scientists looks to better management of landscapes to dampen wildfire effects
VANCOUVER If the catastrophic fire seasons of 2017 and 2018 are the new normal, it won’t matter what B.C. electrifies in its battle for carbon neutrality.
In each of those years, wildfires in this province unleashed almost 200 million tonnes of Co2-equivalent greenhouse gases, or three times the amount of carbon dioxide from all human activities, according to Werner Kurz, a senior scientist at the Pacific Forestry Centre in Victoria.
To reverse that trend, our forests will need a serious design overhaul.
A team of scientists from the United States and Canada is undertaking a four-year partnership to find ways to achieve emission reductions from wildfires through landscape management, fuel load reduction and the creation of a bio-economy that makes use of forest waste, the Pacific Institute for Climate Solutions announced this week.
Kurz explains the situation: The average annual direct emissions from wildfires in B.C. during the 1990s was 6 Mt CO2E — that’s six million tonnes of greenhouse gases stated as CO2 equivalents. In the 2000s, forest fires released 16 Mt CO2E annually. In each of 2017 and 2018, that figure was closer to 197 Mt CO2E, or 33 times more than the average year in the ’90s.
“Houston, we have a problem,” said Kurz, who was a lead author of several Intergovernmental Panel on Climate Change reports on land use and forestry.
Human-caused CO2 emissions in B.C. are currently about 64.5 Mt CO2E annually, with a target of 38 Mt CO2E by 2030, according to the provincial government, which has launched a massive program of electrification called Cleanbc to help get us there.
But rather than helping us achieve any sort of carbon neutrality, our forests are now working against us, through a combination of pine beetle-killed forests and super-intense fire seasons.
“In the ’90s our forests were a net carbon sink,” he said. “In the next decade, the 2000s, they were smaller sinks and in some cases sources. In the 2010s, forests have been a source of carbon nearly every year.”
Long-term trends toward higher temperatures, lower precipitation and the frequency of ignition events such as lightning strikes have us moving briskly in the wrong direction.
“We could wait and see if things get worse and maybe 2017 and 2018 will repeat themselves, or we could explore ways to do things differently to reduce the risk of wildfires, the area burned, and the severity of wildfires in terms of their emissions,” he said. “That’s what this collaboration is about.”
The wildfire and carbon project is a $1-million partnership between Canadian researchers and the USDA forest service to “de-escalate the devastating forest wildfires that are increasingly occurring due to climate change.”
Certain forest-management practices, from fire suppression to hurry-up reforestation, have contributed to the dire situation we find ourselves in today, said UBC forestry professor Lori Daniels, Kurz’s co-principal investigator.
“We are paying a huge cost in carbon today because we were so good at putting out fires in the past,” she said. Combined with a policy-driven aversion to prescribed burning, B.C. is grappling with forests that are loaded with fuel — fallen needles and dead branches — that lead to intense, destructive fires.
Dense forests may not even be particularly efficient at storing carbon. “What happens if we thin out the forest and reduce the stress on those trees competing for a limiting resource like soil moisture?” asked Daniels. “Will the trees left behind grow faster and sequester more carbon? There is lots of evidence that under some circumstances, that is the case.”
Reducing fuel loads and thinning the forest is a time-consuming and expensive task, though communities like Kelowna are doing just that. But taking fuel out of the forest will require a biomass economy, some way to make useful products or energy rather than simply burning it in piles.
“If it is going to be burned, we should do that at high efficiency and displace fossil fuel with a form of sustainable energy,” she said. “Lots of small communities are still reliant on fossil fuels, so these are linkages that we can make.”
When it comes to regenerating forests, our approach needs to be more nuanced than clear-cutting and replanting trees that are prized by logging companies. Agricultural style monocultures may not be the way to healthy forests.
B.C. has been focused on growing back the same species of trees that were harvested as quickly as possible, she said.
Often that means that non-market broadleaf trees like alder or aspen are weeded out with herbicides to allow the conifers to thrive. That may be a mistake.
“We thought that we were accelerating through the natural stages of regeneration,” she said. “In truth, we are seeing research that shows those broadleaf trees play a really important role.”
Broadleaf species contribute to nutrient cycling by growing and shedding leaves.
They provide protection from growing-season frosts and shade in times of drought, both of which can improve the survival rate of conifer seedlings.
Exacerbated by climate change, B.C. wildfires in the last two years have released 33 times the amount CO2 than the average year in the 1990s.