May 16, 2022
By Christine Wiedinmyer
For those of us on the Colorado Front Range, fires have been forefront in our minds this winter and spring – including the red flag days, to the devastating Marshall Fire that will be impacting our community for months and years to come. We have been affected in many ways by fires, and you may be thinking that it has been happening more often. You would be correct. Fires in the Western US have been increasing in number and severity. And the fire seasons have gotten longer.
The destruction of the Marshall fire drew our attention to the more immediate threats of fire – to our homes and even our lives. But fires don’t need to be nearby to have an impact. In fact, fires affect people and places that are states and even continents away. These far reaching impacts are the result of smoke.
As part of my work as a researcher at the Cooperative Institute for Research in the Environmental Sciences (CIRES) and a former scientist at the National Center for Atmospheric Research (NCAR), I have developed and applied new tools to help us better estimate and track global fire emissions and support research into how fire smoke impacts our health and climate, as well as how we can manage it. Using satellite imagery and key measurements made in fire plumes, we can collect valuable information about where fires are burning, the severity of each fire, what they are burning, and what is entering the atmosphere as a result.
What do we know about wildfire smoke?
An important fact — smoke emitted from wildfires (or any fires) is not just one thing. Fire smoke contains particles, greenhouse gases, and reactive trace gases that can have different impacts in the air (and on people). Fires release carbon that is stored in ecosystems into the atmosphere, thus impacting the carbon cycle (think carbon dioxide). And, fires emit reactive gases that may contribute to summertime ozone concentrations (think smog).
Fires also emit particles to the atmosphere, and this is really what we are seeing in smoke plumes. Particles (or particulate matter, PM) have many different impacts on people, the climate system, ecosystems, and more. We know that particles impact human health in many different ways. For example, exposure to wildfire smoke can impact respiratory and cardiovascular outcomes and cause premature mortality, as well as less intuitive health effects such as birth outcomes.
Particles also have impacts on the climate. Depending on what the particles are made of and look like, they impact the climate system in different ways. Black carbonaceous particles (think flaming fires that produce black smoke) absorb radiation and can heat up the atmosphere. Organic carbonaceous smoke particles (think smoldering fires that produce white smoke) can diffuse radiation and potentially cool the atmosphere. Particles can also act as the seed to create cloud drops, and influence cloud cover and precipitation. These effects are all important to the moderation of the climate system.
Globally, fires (including wildfires, prescribed burns, agricultural fires, and land clearing fires – and also burning for cooking and heating in many of the developing areas of the world) produce the majority of the carbonaceous particles that are directly emitted into the atmosphere. Therefore, our understanding of the climate system in part depends on getting these emission estimates correct. This can be challenging and there are many ways we can predict how much, when and where fires emit particles into the atmosphere.
We have many different ways to estimate the emissions of smoke particles and gases into the atmosphere. Satellite data provide key information that can tell us when and where fires are burning, the severity of the fire, what is burning, and what is in the atmosphere as a result. We have new tools to enable us to predict wildfire smoke – and where it will go and who might be impacted. This can enable warnings and give people heads up to do things to protect themselves.
In light of the changing climate leading to longer wildfire seasons, more smoke, and resulting in greater impacts across the west- we need to be prepared to experience more smoke. And, we need to think about ways to manage the landscape to best deal with fires. One such way is to do prescribed burns. And while prescribed fires do produce smoke and cause concern for those in close proximity, they can be done in ways that emit less than would from a wildfire – and are done at set times with the ability to produce warning and enable those nearby to prepare. These types of management solutions need to be included as we move into the future.