A recent study conducted by UC Riverside researchers has revealed that soot from large wildfires in California has a significant impact on the state’s weather patterns. The study aimed to understand how wildfires, in addition to being influenced by climate change, also contribute to changes in the climate. Lead author James Gomez analyzed emissions and peak fire days from the past two decades to determine the impact of large fires on the weather. Through careful analysis of fire days with lower temperatures and higher humidity, Gomez discovered that wildfires tend to create hotter and drier conditions than usual, which can potentially lead to more fires.
The research, published in the journal Atmospheric Chemistry and Physics, identified that the most intense fires occurred in Northern California, where vegetation is more dense and provides ample fuel for wildfires. On average, temperatures were found to be 1 degree Celsius warmer per day during these fires. This increase in heat and aridity is believed to create favorable conditions for more fires to occur, essentially generating their own fire weather. The study also pointed out that soot generated by fires has the ability to trap heat, exacerbating the warming effect, while also reducing humidity in the atmosphere, making it harder for clouds to form.
The study distinguished between two types of aerosols emitted by wildfires: reflective and absorptive. Reflective sulfate aerosols, which result from fossil fuel burning, have a cooling effect on the environment by reflecting sunlight back into space and promoting cloud formation. However, efforts to reduce sulfate aerosols for air quality improvements inadvertently contribute to worsening climate change and an increase in wildfires, particularly in forests in the northern hemisphere. On the other hand, absorbing aerosols like black carbon, the most common emission from wildfires, absorb light and heat in the atmosphere, leading to higher temperatures. Additionally, the hydrophobic nature of black carbon discourages cloud formation and precipitation, exacerbating drought conditions.
Contrary to some studies that suggest fires can result in brighter and more numerous clouds, the UC Riverside study found that emissions from fires in California are not increasing cloud cover. This reduction in cloud formation and subsequent decrease in precipitation can have serious implications for drought-prone regions. The researchers noted that days with lower levels of fire emissions had a less pronounced impact on the weather, emphasizing the importance of managing emissions to mitigate the heating effect. Gomez believes that by reducing CO2 emissions and implementing better forest management practices, such as prescribed burns, the number of large wildfires can be reduced.
Ultimately, the study underscores the significance of understanding the complex interactions between wildfires, climate change, and weather patterns. By addressing the impact of soot emissions from wildfires and implementing effective mitigation strategies, policymakers and land managers can work towards reducing the frequency and intensity of wildfires in fire-prone regions like California. Gomez’s research emphasizes the importance of proactive forest management practices and collaborative efforts to combat the growing threat of wildfires exacerbated by changing climate conditions.
