Fog and low clouds in the Namib Desert may be more resilient than previously thought

Abstract. Fog and low clouds (FLCs) are essential moisture sources for Namib desert ecosystems. However, their response to climate change remains uncertain because fog processes are not resolved in climate models. Here, we apply a cloud-controlling factor framework in which FLC anomalies are expressed as a linear function of large-scale meteorological drivers, including estimated inversion strength (EIS), relative humidity at 700 hPa (R700), sea surface temperature (SST), and the eastward and northward components of 10 m wind (U10, V10). Sensitivities of FLCs to these drivers are quantified using a statistical model. By applying these sensitivities to projections of the corresponding predictors from CMIP6, we produce the first observationally constrained projections of Namib FLC occurrence. Projected trends remain uncertain and scenario-dependent; however, a robust physical signal emerges. Changes in FLCs are governed by competing influences: SST increase over the southeast Atlantic region reduces FLCs, while increased lower-tropospheric stability as well as circulation changes enhance them. Overall, these results suggest that Namib FLCs may be more resilient to climate change than previously assumed, raising the question of whether similar compensating mechanisms operate in other eastern-ocean boundary-layer upwelling systems, such as those of the Atacama Desert and California.