Fire air pollution reduces global terrestrial productivity.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Ecology

Background:

• Fire emissions produce ozone (O3) and aerosols, key air pollutants affecting the terrestrial carbon cycle.
• Ozone damages vegetation photosynthesis via stomatal uptake, while aerosols can enhance it by increasing diffuse radiation.
• Understanding these dual impacts is crucial for predicting ecosystem productivity.

Purpose of the Study:

• To quantify the net impact of fire-induced ozone damage and aerosol diffuse fertilization on global gross primary productivity (GPP).
• To assess these impacts over the 2002-2011 period using advanced models and measurements.

Main Methods:

• Integration of multiple state-of-the-art ecosystem and atmospheric models.
• Utilization of diverse measurement datasets for validation and calibration.
• Analysis of the period 2002-2011 to capture decadal trends.

Main Results:

• Excluding fires, ozone reduced global GPP by 4.0 ± 1.9 Pg C yr-1, while aerosols increased it by 1.0 ± 0.2 Pg C yr-1.
• Fire pollution further decreased GPP by 0.86 ± 0.74 Pg C yr-1 (0.91 ± 0.44 Pg C yr-1 by O3, +0.05 ± 0.30 Pg C yr-1 by aerosols).
• These effects show contrasting spatial distributions.

Conclusions:

• Fire-induced air pollution, primarily ozone, significantly reduces global GPP.
• The net negative impact of fire pollution on ecosystem productivity is a growing concern in a warming climate.
• Future climate change may exacerbate these negative impacts on the land carbon cycle.