the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Jun 2026
The radiative effect and climate responses of present-day wildfire emissions
Abstract. Aerosols exert spatially inhomogeneous radiative effects (REs) that can drastically perturb global and regional climate. While studies have investigated the impacts of regional anthropogenic aerosol emissions on climate, there is no past work systematically exploring the impacts of regional wildfire emissions. This study investigates the interconnection between wildfires and the atmosphere, focusing on the global RE and climate responses from wildfire emissions. We examine the effects of carbonaceous aerosols and O3 precursors via atmosphere-only and ocean-atmosphere coupled simulations using EC-Earth3, driven by the CMIP6 wildfire emissions. Additional atmosphere-only perturbation simulations with wildfire emissions removed from selected regions, i.e., Boreal North America, South America, Africa, Boreal & Central Asia, and Equatorial Asia, were also performed to determine their local and remote effects. We identify which regions experience stronger RE and separate direct influences of emissions on radiation from secondary mechanisms. Our simulations indicate that the global RE of short-lived wildfire emissions is negative (cooling), dominated by aerosol-cloud interactions, with aerosol-radiation interactions and side effects via O3, water vapor and surface albedo being particularly important in specific regions. The slow, ocean-mediated response dominates the total climate response to wildfire emissions, showing substantial global cooling, and pronounced regional effects on precipitation especially in the tropics. Wildfire emissions affect regions both locally and remotely to the emissions, as they alter circulation, land-atmosphere coupling, convection, and energy transport across the globe, producing a highly interconnected climate response. Overall, this study demonstrates that short-lived wildfire emissions can be a substantial modifier of the global climate system.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-3239', Anonymous Referee #1, 03 Sep 2026
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RC2: 'Comment on egusphere-2026-3239', Anonymous Referee #2, 15 Sep 2026
This study uses the EC-Earth3 model to study the radiative impact and climate response associated with wildfire emissions. The authors first estimate the contribution of the aerosol direct effect, aerosol-cloud interactions, and other terms (e.g., albedo, O3, …) to the overall radiative effect of biomass burning. They next analyze the fast (atmosphere-only configuration) and slow (coupled model) responses to both region-specific and global fire emissions. The paper is well written and addresses a very important topic.
I have a few significant comments that mostly pertain to the model description and evaluation. Once these comments are addressed, I will be happy to support publication.
Major comments
1 The radiative perturbation from wildfires does not capture the impact on CH4. The authors should estimate how wildfires impact CH4 lifetime and assess the associated radiative effect (see Thornhill, 2021, for instance).
2 While such information can be found in Noije et al. (2022), the present manuscript needs to provide the reader with a brief description of the treatment of wildfire emissions (e.g., injection height, emission diameter for aerosols, hydrophilic/hydrophobic assumptions for BC and OA, mixing, SOA treatment, …) as well as the photochemical mechanism used here. It seems that important changes were made in the latest version of EC-Earth3-AerChem regarding the treatment of POA and BC emissions from wildfires (see Section 2.4 of Noije et al.), which seem especially relevant to this study but are not discussed.
3 Related to comment 2, the authors refer to Gliss et al. (2021) for an assessment of EC-Earth3 performance. This study provides a comprehensive multi-model assessment of aerosol optical properties. However, it’s not focused on biomass burning, and this study should include some evaluation of the simulated aerosol properties in fire-prone regions. Examples of recent evaluations include Petrenko et al. (ACP, 2025) and Brown et al. (Nature Communications, 2021). The authors should also discuss the model performance for O3 and include additional evaluations focused on wildfires if such work has not been done for EC-Earth before (e.g., Guo et al., JGR, 2026).
4 In addition to Table 2, it would be interesting for the authors to discuss the decomposition of the precipitation response into its different components (Inst, RA, SH; Myhre et al., 2018, GRL).
5 The configuration of EC-Earth3 (like most models) used here is missing some important processes associated with fires. For instance, fires are not interactive and thus do not respond to the changes they induce. This could be important given the significant impacts on precipitation and temperature described here. Downstream effects are also not represented, including the deposition of absorbing aerosols on snow or changes in dust emissions following fire scars. Some of these effects are mentioned in the introduction, but the authors should also discuss their implications for the results presented here in the conclusion. Are there plans to include some of these feedbacks in future versions of EC-Earth-AerChem (e.g., some versions of EC-Earth already have a dynamic fire model)?
Minor comments
1 Introduction: The authors refer to the ARI and ACI in the introduction, but these terms are not defined until Section 2.2. I would suggest adding the reference to Ghan in the introduction to clarify at the very least.
2 Section 2.4: Please provide the contribution of wildfire emissions to the global source of each compound. Also, provide the list of NMVOC species represented in the model and the associated emission breakdown. I suggest using Tg(C)/yr for reporting NMVOC emissions. The authors should discuss the impact of wildfires on SOA in their simulations.
3 The speciation of NOx from wildfires in EC-Earth should be discussed. Many studies have highlighted the role of PAN in extending the lifetime of NOy and delaying O3 production. Is this represented in the current model? If not, the authors should discuss possible implications on their results.Citation: https://doi.org/10.5194/egusphere-2026-3239-RC2
Data sets
Data for "The radiative effect and climate responses of present-day wildfire emissions" by Mourgela et al. (Part 1) R.-N. Mourgela https://doi.org/10.5281/zenodo.19681847
Data for "The radiative effect and climate responses of present-day wildfire emissions" by Mourgela et al. (Part 2) R.-N. Mourgela https://doi.org/10.5281/zenodo.20043242
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- 1
Review of the manuscript entitled “The radiative effect and climate responses of present-day wildfire emissions”by Rafaila-Nikola Mourgela, Iulian-Alin Rosu, and Apostolos Voulgarakis
General comments：
This study investigates the global and regional radiative effects and climate responses of present-day wildfire emissions using the EC-Earth3 Earth system model, with both atmosphere-only and fully coupled ocean–atmosphere simulations. The authors employ a well-established framework to decompose the radiative effect (RE) into aerosol–radiation interactions (ARI), aerosol–cloud interactions (ACI), and a residual term, and further separate the climate response into fast and slow components. The topic is timely and relevant, given the growing importance of wildfires in the context of climate change. However, the manuscript has several significant shortcomings. These include the neglect of the snow darkening effect of light-absorbing aerosols (dust, black carbon (BC), and organic carbon (OC) aerosols) and direct dynamical diagnostics related to Walker circulation. Addressing this issue will substantially strengthen the paper.
The neglect of the snow darkening effect of light-absorbing aerosols (SDE) likely biases the surface albedo response, which may even reverse the sign of the radiative and temperature responses at mid- to high latitudes. The manuscript did not consider the snow darkening effect of dust, black carbon (BC), and organic carbon (OC) aerosols in their model configuration. This process is known to directly reduce surface albedo, particularly over snow- and ice-covered regions in the mid- to high latitudes of the Northern Hemisphere (Flanner et al., 2007; Xie et al., 2018; Shi et al., 2019). However, in Figure 3c, the model simulates an increase in surface albedo over most boreal regions in response to wildfire emissions. This is opposite to the expected direct effect of BC/OC deposition, which would darken the snow surface and reduce albedo.
Furthermore, the omission of SDE may have direct implications for the sign and magnitude of the radiative and temperature responses presented in this study. In their simulations, the negative RE (cooling) over the NH high latitudes (Figure 4a) leads to surface cooling, which would enhance snow cover and further increase surface albedo (Figure 3c), thereby creating positive snow-albedo feedback that amplifies the cooling. However, if SDE were included, the deposition of BC and OC would directly reduce snow albedo, increasing the absorption of shortwave radiation at the surface. This would increase the surface radiative forcing and surface temperature, which would in turn reduce snow cover and further lower albedo, creating warming-positive feedback that is qualitatively opposite to the authors’ current conclusion. Given that SDE is particularly significant in mid- to high-latitude regions, this omission could fundamentally alter the sign of the high-latitude climate response to wildfire emissions. The authors should thoroughly discuss this discrepancy and compare their results with previous studies that have explicitly included SDE.
Additionally, the manuscript links the total precipitation change and the SST change patterns to a weakened Walker circulation, as an El Niño-like atmospheric conditions. These interpretations are not supported by direct dynamical diagnostics related to Walker circulation (e.g., overturning streamfunction, zonal wind shear, vertical velocity, or heat flux convergence). The authors should add this analysis about the weakened Walker circulation to enhance the persuasiveness of the manuscript.
References
Flanner, M. G., Zender, C. S., Randerson, J. T., and Rasch, P. J. 2007: Present day climate forcing and response from black carbon in snow, J. Geophys. Res., 112, D11202, https://doi.org/10.1029/2006JD008003.
Xie, X.N., X.D. Liu, H.Z. Che, X.X. Xie, X.Z. Li, Z.G. Shi, H.L. Wang, T.L. Zhao, Y.G. Liu, 2018: Radiative feedbacks of dust-in-snow over eastern Asia in CAM4-BAM, Atmospheric Chemistry and Physics, 18, 12683–12698, https://doi.org/10.5194/acp-18-12683-2018.
Shi, Z., Xie, X., Li, X., Yang, L., Xie, X., Lei, J., Sha, Y., and Liu, X., 2019: Snow-darkening versus direct radiative effects of mineral dust aerosol on the Indian summer monsoon onset: role of temperature change over dust sources, Atmospheric Chemistry and Physics, 19, 1605–1622, https://doi.org/10.5194/acp-19-1605-2019.