The ozone layer is a thin layer of gas in the stratosphere that protects life on Earth from harmful ultraviolet (UV) radiation from the sun.
UV radiation can cause skin cancer, eye damage, and immune system disorders, as well as harm plants and animals.
The ozone layer has been damaged by human-made chemicals called freons, which break down ozone molecules when they reach the stratosphere.
The most famous example of ozone depletion is the hole over Antarctica, which forms every winter due to the cold temperatures and the presence of ice clouds that accelerate the freon reactions.
However, recent studies have shown that another threat to the ozone layer is emerging: smoke from wildfires.
Wildfires are becoming more frequent and intense due to climate change and land use changes, such as deforestation and agriculture.
When wildfires burn, they release large amounts of particles and gases into the atmosphere, some of which can reach the stratosphere and affect the ozone layer.
How wildfire smoke damages the ozone layer
DEVI RAHMAN/AFP via Getty Images
One of the main components of wildfire smoke is black carbon, which is a type of soot that absorbs sunlight and heats the air.
Black carbon can act as a lifting agent, carrying other smoke particles and gases to higher altitudes where they can enter the stratosphere.
Once in the stratosphere, these particles and gases can interact with ozone and freons in various ways.
Some of the particles and gases from wildfire smoke can act as surfaces for freon activation, similar to ice crystals in polar regions.
This means that they can speed up the breakdown of ozone by freons, creating more ozone-depleting substances.
For example, a study found that smoke from Australian wildfires in 2020 increased the amount of chlorine radicals in the stratosphere by 40%, which are highly reactive to ozone.
Other particles and gases from wildfire smoke can directly react with ozone and destroy it. For instance, nitrogen oxides (NOx) and hydrogen cyanide (HCN) are common products of biomass burning that can reduce ozone levels in the stratosphere.
A study estimated that smoke from Canadian wildfires in 2017 depleted about 0.4% of the global stratospheric ozone column.
What are the implications of wildfire-induced ozone depletion
The effects of wildfire-induced ozone depletion are not yet fully understood, but they could have significant consequences for human health and the environment.
Ozone depletion allows more UV radiation to reach the Earth's surface, which can increase the risk of skin cancer, cataracts, and infectious diseases.
UV radiation can also damage crops, forests, and marine ecosystems, reducing biodiversity and food security.
Moreover, wildfire-induced ozone depletion could slow down or reverse the recovery of the ozone layer that has been achieved by international agreements to phase out freons.
The Montreal Protocol, signed in 1987, has been successful in reducing the production and consumption of freons, leading to a gradual healing of the ozone layer.
However, if wildfires become more frequent and severe due to climate change, they could offset or outweigh the benefits of the Montreal Protocol.
Therefore, it is important to monitor and mitigate the impacts of wildfires on the ozone layer, as well as on other aspects of the climate system.
This requires coordinated efforts from scientists, policymakers, and stakeholders to understand the complex interactions between fire, aerosols, chemistry, and radiation in the atmosphere.
It also requires actions to reduce greenhouse gas emissions and improve land management practices to prevent and control wildfires.
By doing so, we can protect not only the ozone layer but also our health and our planet.
