24th Pacific Science Congress (PSC-24)

Methane (CH₄), Black carbon (BC), and carbon monoxide (CO), and are co-emitted from combustion and industrial processes. Due to their strong absorption of solar and infrared radiation as well as moderate atmospheric lifetime, they lead to substantial heterogenous climate forcing. Present inventories and models do a poor job at representing their emissions and radiative impacts, especially so over rapidly developing and industrialized regions. This makes quantifying attribution and validating mitigation efforts technically challenging.

This work develops a new approach based on a hierarchy of light physical models, multiple satellites, flux tower, and surface observations, and physically constrained AI to quantify emissions and radiative forcing of CH₄, BC, and CO. Integrated products reveal systematic underestimates of BC and CO emissions in industrial areas in Central and Western China, areas undergoing rapid development in South Asia, and due to forest fires in Southeast Asia. CH₄ emissions are found to match on large-scale average, but have vastly different spatial and temporal emissions than existing inventories, yielding substantial impacts on source attribution, offering support to help existing national methane pledges maximize their effectiveness.

Probabilistic forward-backward attribution and mass-conserving inversions distinguish industrial and mining signals, correct over-assignment of emissions in agricultural regions, and quantify how to convert missing CO into explicit CO-to-CO₂ increments. BC is found to exert in general a stronger local positive forcing than models currently capture, at specific places and times even surpassing that of CH₄ and CO₂ combined. CH₄ forcing gradients are spatially displaced by sampling limitations and source allocation biases.

The framework provides day-by-day, kilometer-scale estimates of emissions and forcing, reduces inventory biases, and identifies key uncertainties to target with observations and targeted control policies, which would yield maximum returns toward achieving mitigation throughout Asia: absorbing aerosols, small industrial sources, underground coal fires, and complex terrain.

Remote Sensing,Emissions,Methane,Radiative Forcing,BC