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Climate Change
Forests are the lungs of the planet. They take up vast quantities of carbon dioxide and lock it away in trees and soil. These processes have helped make this planet habitable and, more recently, mitigate the impacts of our reliance on fossil fuels.
As ecosystem scientists, we think this pledge to end deforestation holds great potential. It is not, however, a new idea. At a UN climate summit in 2014, many of the same countries agreed to halt deforestation by 2030. It was a lofty goal, and it has been unsuccessful to date. Forest loss has increased by more than 40 per cent since the agreement.
The current COP26 commitment is less ambitious — countries aim only to end “net deforestation,” meaning harvesting and land clearing can continue so long as reforestation (replanting of trees) keeps pace. This falsely assumes that new forests serve the same function as old forests. That said, a major advance of the COP26 commitment is the focus on improving sustainability in the trades that have historically led to deforestation.
According to a recent report by Nature Canada, an organization that advocates for habitat and species protection, these natural disturbances are largely ignored in Canada’s forestry carbon accounting, potentially underestimating Canada’s forest carbon emissions by an order of magnitude.
Forests slow down climate change
Forests take up carbon dioxide (photosynthesis) and release it (respiration). The balance between this uptake and release determines the strength of the forest’s “carbon sink,” or how much carbon is stored within it. While taking up carbon dioxide, forests lose water through their leaves (transpiration). Deforestation affects these processes and can produce strong feedbacks to the climate system.
Deforestation impacts the global carbon cycle — the exchange of carbon between the atmosphere and the Earth and back — by removing large quantities of carbon stored in the trees and increasing losses of stored carbon from the soil. If deforested areas do not recover, future uptake of carbon dioxide is also reduced.
The loss of large tracts of intact forest can have important effects on water at the local and regional levels. Deforestation can reduce cloud formation and rainfall, increasing the risk or duration of drought in places that are already experiencing the effects of climate warming.
Interpreting Canada’s commitment
Canada has some of the most carbon-rich forests in the world. Boreal forests hold on average more carbon than their tropical counterparts. Yet the scale of forestry and other extractive activities in Canada’s boreal forests is vast. Remote sensing indicates that forestry activities impacted 650,000 hectares (1.6 million acres) of forests annually between 1985-2010.
This means that changes in land management decisions and the associated reforestation of disturbed landscapes in Canada’s boreal region can play an important role in the country’s climate change mitigation and adaptation efforts. But three central challenges must be considered in the planning, implementation and accounting for Canada to meet or ideally exceed the ambitions of its COP26 commitment to end net deforestation.
