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A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa

Since 2015, Sub-Saharan Africa (SSA) has experienced an unprecedented rise in acute food insecurity (AFI), and current projections for the year 2020 indicate that more than 100 million Africans are estimated to receive emergency food assistance. Climate-driven drought is one of the main contributing...

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Autores principales: Shukla, Shraddhanand, Husak, Greg, Turner, William, Davenport, Frank, Funk, Chris, Harrison, Laura, Krell, Natasha
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7816988/
https://www.ncbi.nlm.nih.gov/pubmed/33471787
http://dx.doi.org/10.1371/journal.pone.0242883
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author Shukla, Shraddhanand
Husak, Greg
Turner, William
Davenport, Frank
Funk, Chris
Harrison, Laura
Krell, Natasha
author_facet Shukla, Shraddhanand
Husak, Greg
Turner, William
Davenport, Frank
Funk, Chris
Harrison, Laura
Krell, Natasha
author_sort Shukla, Shraddhanand
collection PubMed
description Since 2015, Sub-Saharan Africa (SSA) has experienced an unprecedented rise in acute food insecurity (AFI), and current projections for the year 2020 indicate that more than 100 million Africans are estimated to receive emergency food assistance. Climate-driven drought is one of the main contributing factors to AFI, and timely and appropriate actions can be taken to mitigate impacts of AFI on lives and livelihoods through early warning systems. To support this goal, we use observations of peak Normalized Difference Vegetation Index (NDVI) as an indicator of seasonal drought conditions following a rainy season to show that delays in the onset of the rainy season (onset date) can be an effective early indicator of seasonal drought conditions. The core of this study is an evaluation of the relationship of the onset dates and peak NDVI, stratified by AFI risks, calculated using AFI reports by the United States Agency of International Development (USAID)-funded Famine Early Warning Systems Network (FEWS NET). Several parts of SSA, mostly located in East Africa (EA), reported the “Crisis” phase of AFI—requiring emergency food assistance—at least one-third of the time between April 2011 to present. The results show that the onset date can effectively explain much of the interannual variability in peak NDVI in the regions with the highest AFI risk level, particularly in EA where the median of correlation (across all the Administrative Unit 2) varies between -0.42 to -0.68. In general, an onset date delay of at least 1 dekad (10 days) increases the likelihood of seasonal drought conditions. In the regions with highest risks of AFI, an onset delay of just 1 dekad doubles the chance of the standardized anomaly of peak NDVI being below -1, making a -1 anomaly the most probable outcome. In those regions, a 2-dekads delay in the onset date is associated with a very high probability (50%) of seasonal drought conditions (-1 standardized anomaly of NDVI). Finally, a multivariate regression analysis between standardized anomaly and onset date anomaly further substantiates the negative impacts of delay in onset date on NDVI anomaly. This relationship is statistically significant over the SSA as a whole, particularly in the EA region. These results imply that the onset date can be used as an additional critical tool to provide alerts of seasonal drought development in the most food-insecure regions of SSA. Early warning systems using onset date as a tool can help trigger effective mid-season responses to save human lives, livestock, and livelihoods, and, therefore, mitigate the adverse impacts of drought hazards.
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spelling pubmed-78169882021-01-28 A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa Shukla, Shraddhanand Husak, Greg Turner, William Davenport, Frank Funk, Chris Harrison, Laura Krell, Natasha PLoS One Research Article Since 2015, Sub-Saharan Africa (SSA) has experienced an unprecedented rise in acute food insecurity (AFI), and current projections for the year 2020 indicate that more than 100 million Africans are estimated to receive emergency food assistance. Climate-driven drought is one of the main contributing factors to AFI, and timely and appropriate actions can be taken to mitigate impacts of AFI on lives and livelihoods through early warning systems. To support this goal, we use observations of peak Normalized Difference Vegetation Index (NDVI) as an indicator of seasonal drought conditions following a rainy season to show that delays in the onset of the rainy season (onset date) can be an effective early indicator of seasonal drought conditions. The core of this study is an evaluation of the relationship of the onset dates and peak NDVI, stratified by AFI risks, calculated using AFI reports by the United States Agency of International Development (USAID)-funded Famine Early Warning Systems Network (FEWS NET). Several parts of SSA, mostly located in East Africa (EA), reported the “Crisis” phase of AFI—requiring emergency food assistance—at least one-third of the time between April 2011 to present. The results show that the onset date can effectively explain much of the interannual variability in peak NDVI in the regions with the highest AFI risk level, particularly in EA where the median of correlation (across all the Administrative Unit 2) varies between -0.42 to -0.68. In general, an onset date delay of at least 1 dekad (10 days) increases the likelihood of seasonal drought conditions. In the regions with highest risks of AFI, an onset delay of just 1 dekad doubles the chance of the standardized anomaly of peak NDVI being below -1, making a -1 anomaly the most probable outcome. In those regions, a 2-dekads delay in the onset date is associated with a very high probability (50%) of seasonal drought conditions (-1 standardized anomaly of NDVI). Finally, a multivariate regression analysis between standardized anomaly and onset date anomaly further substantiates the negative impacts of delay in onset date on NDVI anomaly. This relationship is statistically significant over the SSA as a whole, particularly in the EA region. These results imply that the onset date can be used as an additional critical tool to provide alerts of seasonal drought development in the most food-insecure regions of SSA. Early warning systems using onset date as a tool can help trigger effective mid-season responses to save human lives, livestock, and livelihoods, and, therefore, mitigate the adverse impacts of drought hazards. Public Library of Science 2021-01-20 /pmc/articles/PMC7816988/ /pubmed/33471787 http://dx.doi.org/10.1371/journal.pone.0242883 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 (https://creativecommons.org/publicdomain/zero/1.0/) public domain dedication.
spellingShingle Research Article
Shukla, Shraddhanand
Husak, Greg
Turner, William
Davenport, Frank
Funk, Chris
Harrison, Laura
Krell, Natasha
A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa
title A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa
title_full A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa
title_fullStr A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa
title_full_unstemmed A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa
title_short A slow rainy season onset is a reliable harbinger of drought in most food insecure regions in Sub-Saharan Africa
title_sort slow rainy season onset is a reliable harbinger of drought in most food insecure regions in sub-saharan africa
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7816988/
https://www.ncbi.nlm.nih.gov/pubmed/33471787
http://dx.doi.org/10.1371/journal.pone.0242883
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