A new study of the planet-warming emissions released during Canada’s record 2023 wildfires suggests the majority came not from trees, but from soil and peat.
The study says it estimates for the first time that about three-quarters of those emissions came from burning below ground.
The study led by McMaster University researchers comes as Ontario battles a historic 2026 fire season with some blazes edging into the carbon-rich Hudson Bay Lowlands, the world’s second-largest peat complex.
The findings suggest increasingly intense wildfires are exposing Canada’s vast stores of soil and peat carbon, raising the risk of a climate feedback loop in which fires release more planet-warming emissions that help drive further warming.
The study estimates the 2023 fires released roughly as much CO2 as Canada’s total reported annual greenhouse gas emissions.
Author Alemu Gonsamo says since so much of what’s burning lies underground, better managed forests won’t solve the core problem: only steep cuts to global emissions can.
“There is no alternative than reducing the greenhouse gas emissions,” said Gonsamo, an associate professor at McMaster who studies how forest ecosystems respond to climate change.
The study was published Monday by the academic journal Geophysical Research Letters.
This report by The Canadian Press was first published July 27, 2026.
By Jordan Omstead | Copyright 2026, The Canadian Press. All rights reserved.