Complex Black Carbon Structures Intensify Climate Heating

•Improved global modeling shows 31.6% increase of direct radiative effect for black carbon in heavily polluted regions

•Particle-resolved black carbon mixing is crucial for accurate climate impact assessment

A groundbreaking international study has revealed that black carbon (soot) particles have a significantly stronger warming effect on Earth's climate than current models predict, with major implications for global climate projections.

The research, published in One Earth on May 16th, 2025, shows that black carbon particles with complex mixing structures enhance the heating effect compared to simplified models currently used in climate predictions.

Enhanced Warming in Polluted Regions

The study analyzed real black carbon particles from urban Beijing, suburban areas, and mountain sites using advanced microscopic techniques. Using Electron-Microscope-to-BC-Simulation (EMBS) tool, the team coupled the complex mixing structures of black carbon into the optical calculation and then radiative effect assessment. They found that black carbon particles with complex mixing structures are far more effective at trapping heat than the simple spherical or volume mixing models used in current climate simulations.

Figure 1 TEM images, scenario schemes, Direct radiative effect (DRE), ΔDRE, and ΔDRE/BCmass of BC particle at ambient sampling sites under different scenarios

Professor Weijun Li from Zhejiang University, corresponding author of the study, said: "Black carbon significantly affects climate by absorbing sunlight, but current climate models underestimate its direct radiative effect due to oversimplified particle mixing structures. We now evaluated: how the real morphology and mixing structures of black carbon in real air influence climate effect."

Global Climate Implications

Using machine learning alongside the Community Earth System Model, researchers found that the direct radiative effect in regions with heavy black carbon pollution is 31.6% greater when complex multi-mixing structures are considered.

Figure 2 Global distribution of the BC DRE from the original CESM and estimated using the multi-mixing structure BC model

While the global average effect increases by only 3.9%, regions with high black carbon concentrations—including eastern China, northern India, and Central Africa—show 31.6% increases in warming potential.

"This emphasizes the importance of reducing black carbon emissions for climate and clean air benefits," Professor Li explained. "Our methods better capture the radiative effects of black carbon particles in highly polluted regions and prevent underestimation of their contribution to atmospheric heating."

Advanced Research Methods

The international collaboration used transmission electron microscopy, three-dimensional optical modeling (EMBS), and machine learning to scale from individual particle analysis to global climate impacts. The team presents a multiscale approach connecting nanoscale black carbon particle properties to global climate impacts, potentially reshaping our understanding of black carbon's role in climate change. The research included scientists from China, the UK, and the United States.

The findings suggest current climate models may significantly underestimate black carbon's warming contribution, particularly in rapidly developing regions.

Paper link: https://doi.org/10.1016/j.oneear.2025.101311