November 16, 2020
by: Shane Coffield, PhD Candidate in Earth System Science at UC Irvine
It feels difficult to believe that the Australian bushfires happened just earlier this year. Since then, a pandemic, social unrest, and a pivotal U.S. election have dominated the news cycle. Through all of this, however, the climate crisis hasn’t taken a break. The wildfires in the Western US are a stark reminder of that truth. They are breaking records that were set only a year or two ago by fires which broke records shortly before that. As of this writing, more than 40 people have died and over 4 million acres have burned this summer. Why do these wildfires keep getting worse?
Wildfires can be a critical part of various ecosystem processes. Many plant species are evolutionarily adapted to occasional, low-intensity fires – for example, some California shrubs release their seeds in response to heat or smoke from fires. The problem is that the modern wildfires are more extreme and destructive than the ecosystems are adapted to. In Southern California shrublands, they’re also happening way more frequently. And, across California, it is common for fire-prone ecosystems to surround high population areas. That puts people (usually already vulnerable populations) and property in harm’s way, impacting the health of millions and causing billions of dollars in damages.
Wildfires are a complex problem, requiring complex solutions. Politicians who blame the problem entirely on poor land management or on climate change aren’t doing justice to the full issue. Let’s talk about three different components to the catastrophe that is the Western US wildfires, and potential policy paths forward:
- Land management
In August 2018 and again in June 2020, near the beginning of an already severe season, President Trump told California that we need to rake our forests. While a lack of raking probably isn’t the problem, he was correct that part of the issue has to do with the understory. In the Western US, a history of fire suppression (resulting from federal policy since the second half of the 20th century) has led to an overgrown undergrowth. We call these “ladder fuels” – small and medium sized trees that can spread fire from the forest floor into the tree canopy. These ladder fuels didn’t used to be super abundant. Historically, fires could come through the forest floor and scorch the bark on trees but not burn down the entire landscape. Fire suppression means fewer fires to clear out the undergrowth, and therefore, when they do occur, more fuel and more destructive burning. (Note that this is NOT the problem in shrublands like Southern California). There’s also an indirect effect of having too many small and medium-sized trees: they make the forest more susceptible to drought. Think of it as having too many straws in the cup. They use up the groundwater and lead to more tree death during drought, increasing the fuel for fires.
Native American tribes managed the landscape across the Western United States for thousands of years using prescribed (“good”) fires. They would perform low-intensity controlled burns in the early spring when the forests weren’t super dry to form the landscape, as well as for cultural purposes. The arrival of Western colonizers and subsequent displacement of Native Americans from their homelands drastically changed the fire regime, with Westerners and the U.S. government focusing on fire supression. In recent years, the Forest Service has begun partnering with tribes in California to better integrate traditional burning techniques and modern land management. Increasing funding and resources for the US Forest Service to bring this “good fire” back into the ecosystems at the right time of year, as well as mechanically thinning forests, could go a long way to reduce the intense fires that we’re seeing. The Emergency Wildfire and Public Safety Act currently in Congress would also be a helpful step toward mitigating the harmful effects of decades of fire suppression.
- Climate change
Despite recent comments from some lawmakers, the science on climate change is clear: the planet is warming rapidly, and humans are the cause. (For a breakdown of this issue and common myths, I highly recommend skepticalscience.com). Climate change is warming and drying much of the Western US, making wildfire seasons worse. Scientists are confident about this relationship between climate and fires based on the underlying physics and by observing when and where fires happen. Warmer temperatures cause water to evaporate faster (this is why houseplants wilt in the heat). The warm air sucks water out of the vegetation, making it more dry and flammable. And that relationship is exponential; for every degree warmer, the water withdrawal increases more and more. This signature of climate change is abundantly clear when we see more and bigger fires during periods of hotter weather. The fires in 2020 happened during a record-breaking heatwave. The hottest temperature ever reliably recorded on the planet happened this summer in Death Valley, CA. Under these heat wave conditions, everyday human activity – like yard work or construction – can lead to a spark that gets out of control before it can be stamped out. The heat waves also add stress to our power grid, which can cause sparks. Once a fire is started, these hot and dry (and often windy) conditions mean that the embers become much more dangerous, and fire spreads faster though any landscape, even if the land has been managed well. Climate change is also linked to increased frequency of lightning, as the surface warms faster than higher up in the atmosphere, creating more instability. We are very confident that climate change increases the intensity and frequency of heat waves, as well as the average temperature year round. The most important thing we can do is support policies that allow our economy to decarbonize – transitioning to the now-cheaper wind and solar energy sources – and mitigate the worst effects which are still yet to come.
Human communities ignite most of the fires in the Western US, and have generally proven ill-prepared to deal with the consequences. As suburbs expand and humans continue to move into the “wildland-urban interface”, there is more land that needs to be defended, more people at risk, and more potential to ignite these flammable fuels. At the same time, people often build particularly flammable houses, with sidings and roofs made from wood. Those houses facilitate the fire’s spread through the neighborhood. We should encourage improved building codes, expanding “defensible spaces” around houses by clearing flammable materials like brush and shrubs, and helping insurance to account for fire risk, thus incentivizing safer practices. We can also contact our legislators and encourage them to cosign legislation that helps protect at-risk communities, such as the Wildfire Defense Act, which will make our most vulnerable communities more prepared against the increasing threat of wildfires.
There is much work to be done on all three fronts, and we can all help. We can all do our part to stay informed, recognize the complexity, think critically, have conversations about these important issues, and be involved in the political process.