Does It Matter to the Climate If Trade Cumulus Clouds Cluster? Geophysical Research Letters

Low, marine clouds cool the Earth system, reflecting sunlight back to space. Low cloud response to environmental change is a key uncertainty in future climate projections. It is especially uncertain how much warming amplification will occur due to tropical cumulus feedback. A potentially important feedback modulator is the ability for cumulus to cluster through mesoscale circulations. Janssens et al. (2025, <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2024gl112288">https://doi.org/10.1029/2024gl112288</ext-link>) demonstrate that moisture convergence in ascending circulation branches organizes clouds into fewer and brighter structures while moisture divergence dries descending branches, reducing cloud and increasing longwave cooling. These offsetting effects result in a small net radiative effect due to organization. Janssens et al. (2025, <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2024gl112288">https://doi.org/10.1029/2024gl112288</ext-link>)'s results imply that the influence of organization on cumulus feedback is insignificant. The proposed offsetting of radiative effects across mesoscale organization patterns, or “symmetry,” is worthy of continued research. Observational support and further investigations into whether cumulus organization has other climate impacts is encouraged. Grant no. NA22OAR4320151