Fig. 3 Wind erosion dynamics in southern Africa from 1991 to 2015.
(a) Annual average wind erosion trend; (b) spatial distribution of the wind erosion trend.

3.3 Impacts of climate change on wind erosion

Soil wind erosion in southern Africa is the result of both climatic conditions and human activities. The control variable method was used to explore the impact of climate dynamics on soil wind erosion. The average climatic conditions from 1991 to 2015, instead of the actual climatic conditions, were used as the model input to obtain SL’. Therefore, there is a difference between the actual results and the soil wind erosion estimated in 3.1, which was only affected by climate dynamics. Wind speed is the main driving force behind soil wind erosion. However, temperature and precipitation also have an influence on wind erosion because they affect soil moisture and vegetation coverage. Therefore, this study used mean annual temperature, annual precipitation, and annual average maximum wind speed as the main climatic factors in a partial correlation analysis that revealed the influence of the different climatic factors on soil wind erosion.
From 1991 to 2015, the annual average temperature and precipitation in southern Africa did not significantly change, but temperature, precipitation, and soil wind erosion were significantly related across local, smaller areas. The annual average temperature in southern Africa gradually decreased from northwest to southeast (Fig. 4c), and the Kalahari Desert and its surrounding basins were the main high-temperature areas. In general, temperature had a more significant impact on soil wind erosion in areas with higher annual average temperatures. Around 18.69% of southern Africa was affected by temperature (Fig. 4e), and temperature and wind erosion were significantly negatively correlated across 12.71% of the area (p < 0.05). For example, the high temperature and precipitation in the eastern part of the study area may promote the growth of vegetation, which would reduce soil wind erosion to a certain extent. The annual precipitation in southern Africa increased from west to east, and the annual precipitation in the subtropical monsoon climate region in the southeast was generally higher than in the rest of the study area (Fig. 4d). There was a negative correlation between soil wind erosion and precipitation across 23.96% of the area (Fig. 4f), particularly near the Kalahari Basin in the central region and Eswatini in the east. Arid and semi-arid areas with annual precipitation less than 400 mm are prone to wind erosion. However, a rise in precipitation may increase the vegetation coverage to a certain extent, which would reduce soil wind erosion. There was no significant correlation between soil wind erosion, and temperature and precipitation in 81.31% and 75.37% of southern Africa, respectively. Therefore, temperature and precipitation are not direct determinants of soil wind erosion, but they probably have an indirect impact on wind erosion because they affect vegetation growth.