TITLE:
A Multi-Metric and Multi-Driver Analysis of Long-Term Aridity Change over Africa (1951-2020)
AUTHORS:
Noel Banda, Tanimu Abubakar Sadiq, Tianyu Wang, Nyasulu Matthews
KEYWORDS:
Aridification, Aridity Index, Potential Evapotranspiration, Climate Change, Africa
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.2,
February
13,
2026
ABSTRACT: Africa is highly vulnerable to growing aridification, with more than 60% of the total area classified as arid, supporting more than half a billion people (~525 million). Despite widespread drying, the climatic drivers of the long-term dryness remain uncertain. We employed a multi-metric framework to assess the climatic components of growing aridification in Africa using the Aridity Index (AI) and its climatic drivers, precipitation (P) and potential evapotranspiration (PET), during 1951-2020. Our results suggest widespread drying trends across 88.9% of Africa, with nearly half of it, about 43%, experiencing significant dryness. We reveal that increasing PET in about 85.7% of the continent emerges as a dominant driver of drying, compared to precipitation-driven drying, which covers roughly 20.3%, suggesting that atmospheric moisture demand might play a leading role. Further analysis of PET decomposition indicates that warming temperatures are the main driver of rising atmospheric moisture demand, in line with anthropogenic global climate warming. This trend is evident in accelerated dryland expansion since 1985, particularly over southern, eastern, and western Africa, where drylands are rapidly expanding. Net drying dominates most regions. East Africa, in contrast, exhibits a more complex pattern characterized by seasonal moistening, reflecting complex hydroclimatic responses. These results demonstrate that increasing PET induced by warming is the main contributor to increasing dryness in Africa, while precipitation changes play a secondary role. We propose that adaptation strategies consider both the rising atmospheric moisture demand and rainfall variability under continued global climate warming.