Impacts of Climate Change

The True Impact of the Napa Wildfires


The Napa wildfires

The aftermath of October’s Napa wildfires was as tragic as it was dramatic. The impact included loss of homes and property, and most importantly the loss of life. Obviously, the residents of Napa will be most affected by the fires, but the impact for all Bay Area residents in the long term might not be so obvious.

The future impact of wildfires

The impact of these fires to our air will be seen long into the future. The primary impact is the health ramifications to those who regularly breathe in air polluted by wildfires, which are occurring more frequently.

Smoke produced by wildfires is composed primarily of carbon dioxide, water vapor, carbon monoxide, particulate matter, hydrocarbons and other organic chemicals, nitrogen oxides, trace minerals and several thousand other compounds. The actual composition of smoke depends on the fuel type, the temperature of the fire, and the wind conditions. Different types of wood and vegetation are composed of varying amounts of cellulose, lignin, tannins and other polyphenolics, oils, fats, resins, waxes and starches, which produce different compounds when burned.

Particulate matter is the pollutant of concern from wildfire smoke for the relatively short-term exposures (hours to weeks) typically experienced by the public. Particulate matter is a generic term for particles suspended in the air, typically as a mixture of both solid particles and liquid droplets. The solid material tends to be very small in size.

Particulate matter in wood smoke has a size range near the wavelength of visible light (0.4 – 0.7 micrometers). For purposes of comparison, a human hair is about 60 micrometers in diameter.

Particulate matter in wood smoke efficiently scatters light and reduces visibility. Moreover, such small particles can be inhaled into the deepest recesses of the lung and are thought to represent a greater health concern than larger contaminants.

As climate-change fuels increasingly frequent wildfires that hit closer and closer to densely populated urban centers, the haze they produce is becoming a public health crisis.

Scientists expect more acres of American forests to go up in smoke each year from fires. Because of climate change, the future will bring increased levels of smoke pollution at higher intensities.

Part of the reason for the Napa wildfires was that the heavy rain in the drought-busting winter of 2017 caused vegetation to grow. After the recent dry spell, that increased vegetation became dry and flammable. A spark, combined with the strong Diablo winds, touched off the wildfires that spread at speeds never seen in the past. The volatility in the weather patterns, which climate change will make more of a common occurrence, will cause similar events in the future.

The key is resilience

People in potential affected areas need be more resistant to the future threat of wildfires. Our leaders should take the lead in protecting the people they serve. Some ways of increasing resiliency include better management of our forests and better funding for the U.S. Forest Service, which oversees national forest land. The agency does not have the money to conduct preventative maintenance tasks, such a clearing out underbrush and removing dead trees.

Author’s Note: this post was drafted before the December 2017 breakout of wildfires in southern California.