Impacts of Predicted Changes in Tropospheric Stability on Tropical High Cloud Feedbacks 379 views

The largest source of uncertainty in global climate models’ (GCMs) response to greenhouse gas forcing is the cloud feedback, which refers to changes in top-of-atmosphere radiative flux due to the response of clouds to warming. Better constraining this feedback could significantly narrow the range of predicted warming across GCMs. The goal of this study is to determine whether the inter-model spread of changes in tropical high cloud characteristics is directly related to inter-model variability of changes in tropospheric stability. We analyze data from 22 fully-coupled climate models to compute changes in tropical static stability profiles between a control and perturbed experiment and explore relationships to high cloud feedback values published in Dawson and Schiro (2025). We find that models with more positive high cloud feedbacks tend to exhibit weaker increases in upper-tropospheric static stability across the tropics, with significant anticorrelations between stability responses and high cloud altitude and optical depth feedbacks. To test potential mechanisms underlying the high cloud altitude feedback relationship, we correlate stability responses with changes to high cloud top temperature but find no significant relationship. Additionally, we highlight anticorrelations between stability changes and the high cloud optical depth and amount feedbacks along the equator. This more pronounced increase in high cloud amount and thickening in more stable models suggest links between cloud feedbacks, stability, and circulation changes that can be explored further in future work. In sum, this study highlights that inter-model spread in tropical upper-tropospheric stability is important for driving changes in high clouds’ response to warming in the tropics across fully-coupled GCMs, and thus provides a potential avenue for mechanistically constraining high cloud changes across models.

BS (Bachelor of Science)

English

All rights reserved (no additional license for public reuse)

2025-05-02