Reply to Comment by Millet et al. on “Tracking Ethane From Space Over a Large US Oil and Gas Region” | CU Experts

Abstract; ; We thank Millet et al. for their comment in discussing the methodology and conclusions reached in Francoeur et al. (2025,; https://doi.org/10.1029/2025gl115286; ). In general, we agree with the key points of the comment, although with significant caveats. Mainly, we agree that the thermal infrared is capable of constraining ethane emissions from space. While we also agree that spectral signals do not change in a 1:1 manner with ethane emissions, our chemical transport and radiative transfer modeling suggest that the relationship is 0.72:1. Lastly, while spectral signals are affected by vertical sensitivity and regional background, these factors are not large enough to significantly alter how trends in spectral signals reflect trends in ethane emissions. We hope that the differences observed between Francoeur et al. (2025,; https://doi.org/10.1029/2025gl115286; ) and Brewer et al. (2024,; https://doi.org/10.1038/s41467‐024‐52247‐z; ) lead to further study that advances the ability to detect atmospheric composition in the thermal infrared.;

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