A word that continues to surface when carbon offsets come up is permanence.
The idea that longevity in the practices implemented in order to generate or claim carbon offsets needs to be defined.
Dr. Mario Tenuta, professor of applied soil ecology in the department of soil science at University of Manitoba, says that it’s a complex issue.
“Permanence in terms of the world of carbon and greenhouse gas emissions is accounting for a ‘stocking away’ of emissions of carbon,” says Tenuta. In terms of soil and carbon that’s sequestration, or building up of soil organic matter, and in terms of nitrous oxide or methane emissions, it’s the reduction in emissions, particularly in how a farmer manages nitrogen fertilizer.”
Soil carbon can be built up through the addition of organic matter — which, in addition to storing carbon, has an impact on crop productivity and soil quality. Examples of soil building techniques include adding pulse crops in rotation, maintaining continuous crop cover, or converting to direct seeding.
However, if practices are changed, say by starting to use tillage, that soil carbon can be lost. In a cascade of events, tillage destroys protective organic matter through breaking of soil aggregates, affecting soil structure available to microbes, which then degrade that exposed carbon, and that carbon will eventually be lost in the form of carbon dioxide.
How is it guaranteed that carbon will stay in the soil and not lost at a later date? That’s the meaning of permanence in this situation.
In Prairie soils, we’ve seen the benefit of protecting carbon in soil by leaving it undisturbed and moving away from fallow. In Ontario and Quebec it’s a different situation — moisture is different, there’s more microbial activity, and the benefits of carbon sequestration aren’t as clear in the East as it is on the Prairies, says Tenuta.
As the government works towards a national carbon strategy and a carbon offset system, there is mention of easements on land for 100 year terms. Tenuta doesn’t think that model is practical. “When you have family that is trying to run a business for the long term and an environment for food production where markets and technology are ever-changing, you need some flexibility to modernize and change,” he says. We don’t know what the food demand or technology will be like in 100 years, so locking it in for that long is unpractical, Tenuta says.
The phrase “business as usual” also comes up when talking carbon credits. Farmers that proactively adopted zero-till for so many years already are unlikely qualify for offsets, and Tenuta understands the frustration of producers. He says the issue comes down to determining when carbon emission obligations, both domestically and internationally begin, and the timeline will be unfair to early adopters and innovators.
Listen to the full conversation between Tenuta and Haney for more on how the global carbon market might work: