Relationship Between West African Monsoon Precipitation Characteristics and Maize Yields Across Sub-Saharan West Africa


Book Description

Sub-Saharan Africa faces significant challenges to its food security in the coming decades as climate change and rapid population growth strains its agricultural systems. In a region where crops are near exclusively rainfed, precipitation from the West African Monsoon (WAM) plays a significant role in the region’s food production. This study aims to add to the limited literature on the relationship between country-level maize yields and the WAM, particularly through the use of high resolution precipitation estimates to characterize the spatiotemporal variability of the monsoon. Multi-year annual precipitation characteristics of the monsoon such as total precipitation, number of non-precipitating days, and timing were derived and aggregated across the maize growing regions of West African countries. Aggregated precipitation metrics were linearly regressed against country-level maize yields that have undergone timeseries analysis to remove trends occurring independently of the WAM. The metrics most correlated with maize yields while maintaining statistically significant slopes were the minimum of total precipitation, standard deviation of the number of non-precipitating days, and the minimum monsoon end date. The strong positive correlations of the minimum of total precipitation and minimum monsoon end date metrics suggest that the worst performing areas in terms of total precipitation and monsoon end date drive down annual country-level maize yields. The positive correlation found using the standard deviation of the number of non-precipitating days is uninterpretable as an instance of Simpson’s paradox, as the opposite relationship is discovered in analyses using individual countries. These results show the efficacy of analyzing maize yields against satellite mapped precipitation characteristics of the WAM.




Relationships Between Rainfall Characteristics and Environmental Predictors in the West African Region


Book Description

Mesoscale Convective Systems (MCS) are a substantial source of the water requiredfor agriculture and human consumption in West Africa. Understanding the lifecyclebehaviour of West African mesoscale storms poses unique challenges as thesesystems traverse strong thermodynamic gradients in their westward porpagationfrom land to ocean. MCS in this region are known to be associated with AfricanEasterly Waves (AEWs). The topography of eastern Africa, namely the EthiopianHighlands and Darfur Mountains have been shown to play an intricate role inthe genesis of these waves through MCS initiation in that region. We investigatethe topographic influence on the formation of these systems using the WeatherResearch and Forecasting model by recreating the atmospheric state over an eightday period for three cases with varying topography: realistic, half-height, and notopography. As a case study, we use a MCS observed on August 30-31 duringthe NASA African Monsoon Multidisciplinary Analysis field experiment of 2006.This sensitivity study reveals that the topography influences the development andstructure of the reference MCS event. The model persisted in simulating the MCSin conjunction with an AEW in each run, which highlights the robustness of thewell-known connection between the two systems in West Africa. The developmentof the simulated MCSs differ in each run due to their interaction with the AEWand the onshore flow that are in turn impacted by the topography.We examine further the topographic influences on the evolution and energeticsof AEW and the formation of convective systems within these AEW. The WeatherResearch and Forecasting (WRF) model is employed to simulate the evolution over a36-day period for three cases with varying topography: realistic, half-height, and notopography. An energetics analysis for AEW reveals that baroclinic processes thatdevelop low-level waves north of the jet strengthens due to a stronger monsoonalflow in the flattened topography environment. A noticeably weaker contributionfrom barotropic and baroclinic instabilities at the jet level in West Africa in theflattened topography simulation explains the weakening of those waves at thatlevel. The results show that topography in Africa plays more of a role in the wavedevelopment as they propagate westward rather than in their initiation over East Africa.Satellite rainfall estimates reveal a consistent rainfall maximum offshore WestAfrica during the monsoon rainy season. A 16-year rainfall climatology is conductedto examine the cause of such copious amounts of rainfall. Composites of dailyrainfall and mid-level meridional winds centered on the days with maximum rainfallin August show that the day with heaviest rainfall follows the strongest mid-level northerlies. Reflectivity and rain type composites show that stratiform raindominates the region. The composites suggest that the dominant contributionto the offshore rainfall maximum derives from the trailing stratiform portion ofmesoscale convective systems in the northerly phase of African Easterly Wavespropagating off the continent. Sensitivity simulations done with the WRF modelrecreates the rainfall maximum and indicates the weakening of the maximum astopography on the African continent is flattened.




Climate Change, Water and Food Security


Book Description

The rural poor, who are the most vulnerable, are likely to be disproportionately affected.




Understanding Rainfall Variability Over West Africa and Climate Sensitivity in the Tropics


Book Description

West African rainfall plays an important role in tropical climate and hydrological cycle. This study aims to advance our understanding of the West African rainfall across different timescales, from the diurnal cycle to interannual variations. Then, the study is extended to understand the climate sensitivity in the tropics with an increase of greenhouse gases. First, on a short timescale, the diurnal cycle of warm season rainfall over West Africa is investigated. In both the climatology and the 2006 case study, most of West Africa shows a single diurnal peak of rainfall in either the afternoon or at night. Afternoon rainfall peaks are associated with an unstable lower troposphere. Nocturnal rainfall peaks are associated with rainfall systems propagating westward. They occur most frequently about 3°-10° of longitude downstream of regions with afternoon rainfall peaks. Rainfall systems in the convection-permitting simulation show similar westward propagation with afternoon peaks associated with elevated topography and nocturnal peaks downstream of the topographic afternoon rainfall regions. However, the model fails to reproduce the observed afternoon rainfall peaks in several regions far away from the downstream of elevated topography. Second, on a longer timescale, the climatology and interannual variations of the West African monsoon demise are investigated using the Tropical Rainfall Measuring Mission and the Global Precipitation Climatology Project precipitation datasets along with the ERA-Interim reanalysis. During monsoon demise, the rainfall maximum progresses southward smoothly from the Sahel to the Gulf of Guinea. The climatological monsoon demise date is October 20th. The demise date varies between October 5th and 30th. An early (late) demise is associated with an anomalously strong (weak) North Atlantic subtropical high. The monsoon season total rainfall is found to be significantly correlated with the demise date. Finally, idealized regional model simulations are used to understand the climate sensitivity over the broad tropical region. The model is configured with idealized continents and oceans. With a doubling of CO2, the land and the ocean warm at different rates. The changes of the continental heat lows, subtropical highs and land-based rainfall in the tropics are explored and linked to the surface warming.




Turn Down the Heat


Book Description

This report focuses on the risks of climate change to development in Sub-Saharan Africa, South East Asia and South Asia. Building on the 2012 report, Turn Down the Heat: Why a 4°C Warmer World Must be Avoided, this new scientific analysis examines the likely impacts of present day, 2°C and 4°C warming on agricultural production, water resources, and coastal vulnerability. It finds many significant climate and development impacts are already being felt in some regions, and that as warming increases from present day (0.8°C) to 2°C and 4°C, multiple threats of increasing extreme heat waves, sea-level rise, more severe storms, droughts and floods are expected to have further severe negative implications for the poorest and most vulnerable. The report finds that agricultural yields will be affected across the three regions, with repercussions for food security, economic growth, and poverty reduction. In addition, urban areas have been identified as new clusters of vulnerability with urban dwellers, particularly the urban poor, facing significant vulnerability to climate change. In Sub-Saharan Africa, under 3°C global warming, savannas are projected to decrease from their current levels to approximately one-seventh of total land area and threaten pastoral livelihoods. Under 4°C warming, total hyper-arid and arid areas are projected to expand by 10 percent. In South East Asia, under 2°C warming, heat extremes that are virtually absent today would cover nearly 60-70 percent of total land area in northern-hemisphere summer, adversely impacting ecosystems. Under 4°C warming, rural populations would face mounting pressures from sea-level rise, increased tropical cyclone intensity, storm surges, saltwater intrusions, and loss of marine ecosystem services. In South Asia, the potential sudden onset of disturbances to the monsoon system and rising peak temperatures would put water and food resources at severe risk. Well before 2°C warming occurs, substantial reductions in the frequency of low snow years is projected to cause substantial reductions in dry season flow, threatening agriculture. Many of the worst climate impacts could still be avoided by holding warming below 2°C, but the window for action is closing rapidly. Urgent action is also needed to build resilience to a rapidly warming world that will pose significant risks to agriculture, water resources, coastal infrastructure, and human health.




Genomics and Breeding for Climate-Resilient Crops


Book Description

Climate change is expected to have a drastic impact on agronomic conditions including temperature, precipitation, soil nutrients, and the incidence of disease pests, to name a few. To face this looming threat, significant progress in developing new breeding strategies has been made over the last few decades. The first volume of Genomics and Breeding for Climate-Resilient Crops presents the basic concepts and strategies for developing climate-resilient crop varieties. Topics covered include: conservation, evaluation and utilization of biodiversity; identification of traits, genes and crops of the future; genomic and molecular tools; genetic engineering; participatory and evolutionary breeding; bioinformatics tools to support breeding; funding and networking support; and intellectual property, regulatory issues, social and political dimensions. ​




Statistical Methods in the Atmospheric Sciences


Book Description

Statistical Methods in the Atmospheric Sciences, Third Edition, explains the latest statistical methods used to describe, analyze, test, and forecast atmospheric data. This revised and expanded text is intended to help students understand and communicate what their data sets have to say, or to make sense of the scientific literature in meteorology, climatology, and related disciplines. In this new edition, what was a single chapter on multivariate statistics has been expanded to a full six chapters on this important topic. Other chapters have also been revised and cover exploratory data analysis, probability distributions, hypothesis testing, statistical weather forecasting, forecast verification, and time series analysis. There is now an expanded treatment of resampling tests and key analysis techniques, an updated discussion on ensemble forecasting, and a detailed chapter on forecast verification. In addition, the book includes new sections on maximum likelihood and on statistical simulation and contains current references to original research. Students will benefit from pedagogical features including worked examples, end-of-chapter exercises with separate solutions, and numerous illustrations and equations. This book will be of interest to researchers and students in the atmospheric sciences, including meteorology, climatology, and other geophysical disciplines. - Accessible presentation and explanation of techniques for atmospheric data summarization, analysis, testing and forecasting - Many worked examples - End-of-chapter exercises, with answers provided




African Handbook of Climate Change Adaptation


Book Description

This open access book discusses current thinking and presents the main issues and challenges associated with climate change in Africa. It introduces evidences from studies and projects which show how climate change adaptation is being - and may continue to be successfully implemented in African countries. Thanks to its scope and wide range of themes surrounding climate change, the ambition is that this book will be a lead publication on the topic, which may be regularly updated and hence capture further works. Climate change is a major global challenge. However, some geographical regions are more severly affected than others. One of these regions is the African continent. Due to a combination of unfavourable socio-economic and meteorological conditions, African countries are particularly vulnerable to climate change and its impacts. The recently released IPCC special report "Global Warming of 1.5o C" outlines the fact that keeping global warming by the level of 1.5o C is possible, but also suggested that an increase by 2o C could lead to crises with crops (agriculture fed by rain could drop by 50% in some African countries by 2020) and livestock production, could damage water supplies and pose an additonal threat to coastal areas. The 5th Assessment Report produced by IPCC predicts that wheat may disappear from Africa by 2080, and that maize— a staple—will fall significantly in southern Africa. Also, arid and semi-arid lands are likely to increase by up to 8%, with severe ramifications for livelihoods, poverty eradication and meeting the SDGs. Pursuing appropriate adaptation strategies is thus vital, in order to address the current and future challenges posed by a changing climate. It is against this background that the "African Handbook of Climate Change Adaptation" is being published. It contains papers prepared by scholars, representatives from social movements, practitioners and members of governmental agencies, undertaking research and/or executing climate change projects in Africa, and working with communities across the African continent. Encompassing over 100 contribtions from across Africa, it is the most comprehensive publication on climate change adaptation in Africa ever produced.




Adaptation to Climate Change and Variability in Rural West Africa


Book Description

This book presents conceptual and empirical discussions of adaptation to climate change/variability in West Africa. Highlighting different countries’ experiences in adaptation by different socio-economic groups and efforts at building their adaptive capacity, it offers readers a holistic understanding of adaptation on the basis of contextual and generic sources of adaptive capacity. Focusing on adaptation to climate change/variability is critical because the developmental challenges West Africa faces are increasingly intertwined with its climate history. Today, climate change is a major developmental issue for agrarian rural communities with high percentages of the population earning a living directly or indirectly from the natural environment. This makes them highly vulnerable to climate-driven ecological change, in addition to threats in the broader political economic context. It is imperative that rural people adapt to climate change, but their ability to successfully do so may be limited by competing risks and vulnerabilities. As such, elucidating those vulnerabilities and sources of strength with regard to the adaptive capacities needed to support successful adaptation and avoid maladaptation is critical for future policy formulation. Though the empirical discussion is geographically based on West Africa, its applicability in terms of the processes, structures, needs, strategies, and recommendations for policy transcends the region and provides useful lessons for understanding adaptation broadly in the developing world.




Shock Waves


Book Description

Ending poverty and stabilizing climate change will be two unprecedented global achievements and two major steps toward sustainable development. But the two objectives cannot be considered in isolation: they need to be jointly tackled through an integrated strategy. This report brings together those two objectives and explores how they can more easily be achieved if considered together. It examines the potential impact of climate change and climate policies on poverty reduction. It also provides guidance on how to create a “win-win†? situation so that climate change policies contribute to poverty reduction and poverty-reduction policies contribute to climate change mitigation and resilience building. The key finding of the report is that climate change represents a significant obstacle to the sustained eradication of poverty, but future impacts on poverty are determined by policy choices: rapid, inclusive, and climate-informed development can prevent most short-term impacts whereas immediate pro-poor, emissions-reduction policies can drastically limit long-term ones.