How will climate change impact fog and low clouds in the Namib desert?

In this contribution, a statistical model built on observations (ERA5, SEVIRI) is used with climate model data from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to estimate the cloud-system responses to climate change in the Namib desert.

Fog, which is the most relevant non-rainfall water source for plants and animals in the coastal parts of the Namib Desert, may become increasingly important for local ecosystems as regional climate simulations predict a warmer and drier climate for southern Africa in the future. However, projecting changes in fog using global circulation models (GCMs) or even regional climate models (RCMs) is challenging because these numerical models often cannot resolve, or have yet to incorporate, many processes that drive fog development.

A statistical model is developed to predict fog and low cloud (FLC) occurrence in the Namib region by combining reanalysis products with satellite data. Assuming that the relationships learned by the statistical model in the current climate remain valid in the future, this model can utilize climate model outputs from CMIP6 as predictors to estimate changes in FLCs in the region.

It is found that under low-emission scenarios like SSP1-2.6, FLC cover remains mostly constant. In contrast, higher-emission scenarios such as SSP3-7.0 project a decrease in FLC cover by up to 10%, with this decline accelerating around 2050.