Analysis of fog occurrence changes in the Namib Desert across time and space and impacts on natural and artificial fog collection

In the Namib Desert, along the South-Western African coast, fog represents the main water input for local flora and fauna. During the last years, changes in the timing of fog occurrence and in the quantity of water that can be harvested from it, have been observed in several areas of the world, including the Namib Desert. A deeper insight into fog presence and fog water yield changes can help to understand to what extent Namib Desert’s ecosystem is being and will be affected in future by climate change. This information can also contribute to local environmental protection and carbon dioxide sequestration strategies, as fog water can be used for reforestation and land restoration. An 8-year-long dataset of harvested fog water rates recorded daily in 13 ground stations along the Namib Desert was statistically analysed to inspect advection fog occurrence evolution. The results show a noticeable intra-annual and inter-annual variability in rates and seasonality of harvested fog water. On the other hand, observed trends in collected fog water time series are generally decreasing, but longer time series are required to confirm the trend since El Niño Southern Oscillation (ENSO) phenomenon presence in the analysed period might have had an impact. The main hypothesis is that changes in fog occurrence and its characteristics are due to climate modifications, given that no extensive human activities are present in the area. However, further analyses on fog-related climatic and meteorological factors, possibly including remote sensing or reanalysis datasets aiming to increase the available data timespan, are envisioned to understand to what extent fog collection in the Namib Desert will be affected in future by climate change.