Rainfall Variability and Trends over the African Continent Using TAMSAT Data (1983–2020): Towards Climate Change Resilience and Adaptation

Niranga Alahacoon,Matamyo Simwanda,Manjula Ranagalage,Vincent R Nyirenda,Mahesh Edirisinghe,Enc Perera

doi:10.3390/rs14010096

Abstract

This study reveals rainfall variability and trends in the African continent using TAMSAT data from 1983 to 2020. In the study, a Mann–Kendall (MK) test and Sen’s slope estimator were used to analyze rainfall trends and their magnitude, respectively, under monthly, seasonal, and annual timeframes as an indication of climate change using different natural and geographical contexts (i.e., sub-regions, climate zones, major river basins, and countries). The study finds that the highest annual rainfall trends were recorded in Rwanda (11.97 mm/year), the Gulf of Guinea (river basin 8.71 mm/year), the tropical rainforest climate zone (8.21 mm/year), and the Central African region (6.84 mm/year), while Mozambique (−0.437 mm/year), the subtropical northern desert (0.80 mm/year), the west coast river basin of South Africa (−0.360 mm/year), and the Northern Africa region (1.07 mm/year) show the lowest annual rainfall trends. There is a statistically significant increase in the rainfall in the countries of Africa’s northern and central regions, while there is no statistically significant change in the countries of the southern and eastern regions. In terms of climate zones, in the tropical northern desert climates, tropical northern peninsulas, and tropical grasslands, there is a significant increase in rainfall over the entire timeframe of the month, season, and year. This implies that increased rainfall will have a positive effect on the food security of the countries in those climatic zones. Since a large percentage of Africa’s agriculture is based only on rainfall (i.e., rain-fed agriculture), increasing trends in rainfall can assist climate resilience and adaptation, while declining rainfall trends can badly affect it. This information can be crucial for decision-makers concerned with effective crop planning and water resource management. The rainfall variability and trend analysis of this study provide important information to decision-makers that need to effectively mitigate drought and flood risk.

Highlights

There has been a clear change in the global climate in recent decades that could significantly impact environmental, social, and economic sustainability [1,2,3]
Intending to provide a successful solution to the aforementioned challenges, this study focuses on the African continent-wide analysis of long-term rainfall variability and trends based on TAMSAT data, using diverse geographical contexts and timeframes
The section focuses on detailed statistical presentations of annual rainfall for different geographical units, in the form of climate zones, major river basins, regions, and countries, and analyzes spatial and temporal changes in long-term monthly, seasonal, and annual rainfall at the continental scale

Summary

Introduction

There has been a clear change in the global climate in recent decades that could significantly impact environmental, social, and economic sustainability [1,2,3]. The changes in spatial and temporal variability of rainfall have been observed in various parts of the world [4]. In 2021, for example, almost all the continents experienced severe flooding. The variability in rainfall can have a significant impact on ecosystems and their biodiversity, positively or negatively [10,11,12]. Climate variability directly impacts agriculture and poses a significant threat to food security and livelihoods, especially in poor or developing countries [13]. Africa has been identified by various studies as increasingly vulnerable to climate change and variability, with one of the significant impacts being the reduction in agricultural production due to the continent’s low adaptive capacity [20,22]. About 80% of the total human population in Africa is dependent on agriculture or agricultural products, while in most African countries, the fiscal contribution of the agricultural sector to GDP is more than 40% [23]

Methods

Results

Discussion

Conclusion