Large forest fires create favorable conditions for further climate change, researchers say
Large wildfires have a significant impact on the weather, as revealed by a recent study conducted by UC Riverside. The study, led by James Gomez, a doctoral candidate at UCR, aimed to explore how aerosols emitted by wildfires affect the climate during their burn. Contrary to the usual focus on how climate change influences wildfires, the research investigated how large fires may, in turn, alter the climate. This is reported by SSP.
To conduct the study, Gomez examined peak fire days and emissions from the past two decades of fire seasons, specifically targeting days with lower temperatures and higher humidity to isolate the impact of the fires. The findings, published in the journal Atmospheric Chemistry and Physics, indicate that large fires do, indeed, have a significant influence on the weather. On the days when these fires burned, temperatures rose and humidity decreased, creating conditions conducive to more fires.
The study determines that wildfires generate their own fire weather, with the most intense fires occurring in Northern California, where dense vegetation serves as ideal fuel. The research reveals that temperatures rose by approximately 1 degree Celsius per day during the fires, primarily due to the absorption of sunlight by soot emissions from the wildfires. As Gomez explains, black carbon in wildfire smoke possesses high absorbency, effectively trapping heat and contributing to the temperature elevation. In addition to direct heating, black carbon also inhibits cloud formation, reducing precipitation and exacerbating drought conditions.
The study brings attention to the impact of aerosols on climate, differentiating between reflective and absorptive aerosols. Sulfate aerosols, which are produced through fossil fuel combustion, function as reflective aerosols, cooling the environment by reflecting solar energy back into space. However, recent UCR research cautions against an unintended consequence of reducing sulfate aerosol pollution, as doing so intensifies climate change and subsequently leads to more wildfires. Moreover, sulfate aerosols aid in creating brighter, more reflective clouds that contribute to planetary cooling.
On the other hand, absorptive aerosols, such as black carbon, trap heat in the atmosphere, contributing to temperature elevation. Wildfires predominantly emit black carbon, hence increasing temperatures directly and indirectly by impeding cloud formation and reducing precipitation. The research conducted by Gomez highlights that the emitted black carbon from California wildfires has a hydrophobic nature, which means it repels water and hampers cloud production, leading to fewer clouds and inadequate rainfall—an alarming predicament for drought-prone states.
Notably, the study demonstrates that days with fewer fire emissions have a less pronounced impact on the weather. When aerosol amounts are reduced and released more slowly, the heating effect is less significant. Gomez suggests that mitigating carbon dioxide emissions, alongside implementing improved land management practices, can play a crucial role in reducing the occurrence of large wildfires. By allowing more frequent small fires and implementing prescribed burn policies, the buildup of fuel can be reduced, leading to fewer catastrophic fires—a solution well within our control.
In conclusion, the study underscores the interplay between large wildfires and the climate, highlighting the influence of wildfire-emitted aerosols on temperature and precipitation patterns. Understanding these dynamics becomes imperative in developing effective measures to mitigate the impact of wildfires and enhance overall environmental management practices. Balancing reduction in carbon emissions with proactive land management strategies is key to shaping a future with reduced wildfire risks.
