Journal Article

Impacts of California Wildfires on CO2 and Other Trace Gases

Karandana Gamalathge, Thishan Dharshana, Jiang, Xun, Wang, Xinyue, Li, Liming, Tai, Nolan, Yung, Yuk L.

2024

Overview

Wildfires have broad impacts on the atmosphere, ecology, and society. This study leverages satellite data and chemistry‐transport models to analyze the impact of wildfires on trace gases in California during the August‐October periods of 2018, 2019, and 2020. During these months, Southern California experiences minimal precipitation, leading to a high Vapor Pressure Deficit, which results in decreased photosynthetic activities. This reduction, combined with increased biomass burning, causes a rise in CO2 concentrations. Increased CO and CH4 levels are also seen in TROPOMI retrievals tied to the increase in biomass burning. The CarbonTracker model captures these elevated CO2 concentrations, though with a reduced amplitude of increased CO2. Similarly, the GEOS‐Chem model successfully simulates high CO levels but underestimates the observed enhancements. These findings will improve the understanding of fire's influence on trace gases and refine future numerical models on surface emissions and transport. Plain Language Summary The impacts of fires on trace gases (CO2, CO, and CH4) are examined from August to October in 2018, 2019, and 2020. During California's dry season, elevated concentrations of these trace gases are noted in satellite data, but the contributing mechanisms differ. CO concentrations primarily stem from biomass burning emissions, while CO2 levels are affected by increased biomass burning and reduced photosynthetic activities. In contrast, CH4 levels are impacted by both agriculture and biomass burning. These findings shed light on the complex relationship between fires and atmospheric trace gases, offering crucial insights to enhance future numerical models. A deeper understanding of the trace gas emissions from wildfires is also essential for assessing their impact on the climate system, air quality, and public health. Key Points Increased CO2, CO, and CH4 levels during August‐October (fire period) in California The underlying mechanisms for elevated concentrations of the trace gases differ for CO2, CO, and CH4 Models simulate higher levels of CO2 and CO but underestimate the observed enhancements, suggesting biases in the surface emissions and transports

• Publisher: John Wiley & Sons, Inc
• Subject: Air quality / Biomass / Biomass burning / Burning / Carbon dioxide / Carbon dioxide concentration / Carbon dioxide emissions / Climate models / Climate system / Dry season / Emissions / Fires / Gases / greenhouse gases / Impact analysis / Mathematical models / Methane / Numerical models / Outdoor air quality / Photosynthesis / Photosynthetic activity / Public health / Satellite data / Satellites / Trace gas emissions / Trace gases / Vapor pressure / Vapour pressure / Wildfires