Abstract
The El Nino–Southern Oscillation (ENSO) is one of the strongest drivers of climate variability, which directly influences agricultural production. The present study aims at assessing the impact of ENSO on agriculture in southern and eastern Africa by (1) exploring the association between ENSO, vegetation condition and soil moisture, and (2) analyzing the difference in soil moisture and vegetation condition for two extreme ENSO phases (El Nino and La Nina). Our results showed that vegetation conditions are significantly correlated with ENSO and exhibit a clear dipole pattern that reverses between El Nino and La Nina. Lagged correlation analysis confirmed the ability of soil moisture and ENSO to predict vegetation conditions. In general, the temporal and spatial evolution of soil moisture and vegetation responses showed the expected dipole pattern during the El Nino and following La Nina events. Results showed that ENSO impact on crop yield varied with geographic location, crop types, and ENSO phases. For example, yields in La Nina years have been higher in southern Africa but lower in eastern Africa. Maize yield decreases associated with El Nino events were usually larger than corresponding yield increases during La Nina events over southern Africa. Our findings highlight the impact of ENSO on agricultural production, which has significant potential to enhance the agriculture and food security-related early warning system.
Highlights
Agriculture plays a valuable role in improving food security by increasing the quantity and diversity of food and by maintaining a strong economy, providing a livelihood of 38.3% of the world’s workforce
Apart from the correlation analysis, we examined the spatiotemporal evolution of the precipitation, root-zone soil moisture (RZSM), and Normalized Difference Vegetation Index (NDVI) departure during major El Niño–Southern Oscillation (ENSO) events to evaluate the impact of ENSO on different sub-regions
We quantified the impact of a different phase of ENSO on NDVI and major crop yields in Eastern and Southern Africa
Summary
Agriculture plays a valuable role in improving food security by increasing the quantity and diversity of food and by maintaining a strong economy, providing a livelihood of 38.3% of the world’s workforce. The ENSO is one of the most significant phenomena in the Earth’s climate system, which explains variations in tropical Pacific sea surface temperatures (SST) Such variations affect tropical weather patterns but can have a global effect (Hanley et al, 2003). Higher sea surface temperatures warm the atmosphere during the El Niño phase, resulting in greater convection and rainfall over Eastern Africa. A continental high-pressure system dominates Southern Africa and suppresses regional atmospheric convection and rainfall (Mulenga et al, 2003) Such changes in precipitation due to ENSO directly affect root-zone soil moisture (RZSM), which represents the available water within the plant’s root zone of one meter or less and regulates vegetation growth and density (Wang et al, 2007). Dry RZSM conditions due to lower precipitation and higher temperatures result in water stress for plants and reduce vegetation greenness and productivity, while favorable soil moisture conditions are associated with increased vegetation activity
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