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Introduction
Cyndi Spindell Berck, Peter Berck, Salvatore Di Falco, and Poojan Thakrar
The purpose of this book is to explore ways that African farmers and governments can adapt to a changing climate. We take it as given that mitigation of climate change, through reduction of greenhouse gas (GHG) emissions, is essential. However, farmers in Africa already are experiencing the effects of a changed climate, and the prognosis for effective global policies to reduce GHG is uncertain. In addition, many of the policy prescriptions for agricultural adaptation to climate change, such as increased adoption of yield-enhancing technologies, would benefit African farmers even without climate change. Therefore, responses to climate change must proceed on both the mitigation and adaptation tracks.
About two out of three people in sub-Saharan Africa (SSA) make a living in agriculture, mostly as smallholder subsistence farmers who depend directly on rainfall. Hotter weather and less predictable rainfall are already having impacts on their crop yields. These climate impacts are expected to hit SSA harder than other regions of the world.
Increased food production is essential to improve food security and reduce poverty among the growing population of Africa. Increasing the productivity of land already under cultivation is crucial for two reasons. First, much of the arable land is already under cultivation in many parts of Africa. Second, clearing more land for agriculture would compound the problem of GHG emissions by removing carbon sinks.
Agricultural production takes place in a context of overall economic development. In addition to discussing strategies to increase crop yield, the studies in this book consider a number of income-producing responses to climate change, such as the crop-livestock mix and migration for off-farm work opportunities.
This book seeks to describe some of the challenges facing African farmers and to suggest practical responses. The chapters include both original research and syntheses of existing research. Many of the contributors are part of the Environment for Development Initiative research network. This is reflected in the focus on the four countries that host EfD centers: Ethiopia, Kenya, South Africa, and Tanzania. However, empirical findings for other SSA countries are included as well.
This book is divided into five parts, after this introduction. The first part considers climate science in relation to the agronomic and agroecological factors that influence farm productivity. The second part looks at on-farm practices to increase productivity of food crops, and the third part at on-farm practices other than those related to food crop yield. The fourth part considers gender, and the fifth discusses agricultural adaptation in a broader development context. The concluding chapter summarizes policy recommendations.
Part I: climate science, agronomic, and agroecological factors
Chapters 2 through 4 explore the possible effects of climate change on agriculture in light of the diverse agroecological conditions in sub-Saharan Africa. The chapters examine important indicators, such as food security, crop yield, and geographical adaptability, to shed light on the consequences of climate change. Institutions such as social capital are also considered in light of their relationship with biophysical factors.
Chapter 2 outlines the processes by which climate change is studied, as well as potential adaptations to alleviate the expected negative consequences. Peter Berck first explains five methods of obtaining data, with their associated practicality, benefits, and drawbacks. Compared to other regions around the globe, sub-Saharan Africa suffers from a lack of quality data. This leads to climate models that can be imprecise and inaccurate. Most of the models in this book will be regression models, which use the covariance of weather, yield, and other important factors to make predictions of the effects of climate change.
This level of detail is important because the optimal adaptation strategy for a given region depends on the precise changes in climate experienced in that area. For example, in response to increased temperatures, farmers might switch from temperature-sensitive maize to heat-resistant sorghum. To combat decreased expected rainfall and increased rainfall variability, farmers would benefit from wells and irrigation, but most smallholder farmers cannot finance such projects without an increase in access to credit. By studying climate change and formulating adaptation strategies that are carefully tailored to specific agroecological conditions, some of the productivity lost to climate change can be restored.
Previous climate change literature has often addressed countries as single units. In Chapter 3, âMapping Vulnerability to Climate Change of the Farming Sector in the Nile Basin of Ethiopia,â Zenebe Gebreegziabher et al. extend the analysis to local ecological and geographic variation. The chapter analyzes four different regions in Ethiopia to discover which specific regions are most vulnerable to climate change. According to the latest IPCC report, a regionâs vulnerability is a function of both its exposure and its sensitivity to climate change effects, as well as the regionâs adaptive capability. Sensitivity can be further broken down into factors such as climate extremes or population density. Meanwhile, adaptive capability can be broken down into social capital, human capital, financial capital, and physical capital.
To assess a regionâs vulnerability to climate change, Gebreegziabher et al. construct a vulnerability index. The authors use an indicator method in which the index is calculated by combining the observables using different weights, calculated using a principal component analysis. Using this method, the authors are able to quantify the exposure, sensitivity, and adaptive capability for four different regions. When all three were taken into account, the two regions with the most vulnerability were the humid lowlands and the drought-prone highlands.
In Chapter 4, âClimate Change and Food Security in Kenya,â Jane Kabubo-Mariara and Millicent Kabara analyze the linkages between climate change and food security, proxied by food crop yields, in Kenya. The authors use county-level data collected over three decades for maize, sorghum, beans, and millet. Using this, they were able to find relationships between yield and climate variables. Next, the authors simulated the expected impact of future climate change on food insecurity based on ten climate and emission scenarios.
Most of the variables exhibited nonlinear U or inverse U-shaped relationships with crop yields. For example, while adequate rainfall is obviously crucial for crop productivity, too much rain can cause flooding, waterlogging, and rotting. Summer temperatures exhibit a U-shaped relationship for three of the four crops, while winter temperatures exhibit a hill-shaped relationship. Population density also has significant, positive effects on maize and beans. Population density can be a proxy for agricultural adaptation options and can also capture availability of farm labor.
As for the simulation results, nine of the ten simulations predict declining crop yields due to climate change, with the largest prediction being a 69% decline in yields. The simulations also predict that, if there are no changes, 73% of Kenyaâs population will be maize-insecure by 2100. Because maize is the main food crop, those who are insecure in maize are likely food-insecure in general.
Part II: on-farm practices related to food crop productivity
The next five chapters examine the relationship between climate change and farmersâ decisions related to increasing the yields from food crops. These chapters examine the adaptive measures a farmer can take and the driving forces that determine whether farmers adopt such adaptive techniques. These driving forces include behavioral considerations, such as risk aversion, which in turn are influenced by the relative wealth or poverty of individual farmers. These five chapters go to the heart of the question of how African farmers can grow enough food in a changing climate.
Chapter 5, âAdaptation to Climate Change in Sub-Saharan Agriculture: Assessing the Evidence and Rethinking the Drivers,â identifies levels of climate change perception while also evaluating how climate variables can affect risk aversion. According to previous literature, the two steps to climate change adaptation are the perception of change and the adoption of adaptation strategies. Perception does not always lead to adoption. For instance, while 83% of Ethiopian farmers perceive variations in temperature, only 44% of them use adaptation strategies. The main barriers to adoption include a lack of education and the absence of credit and capital. When examining the effectiveness of adaptation strategies, Salvatore Di Falco noted that strategies adopted in combination with other strategies rather than in isolation are more effective. Adaptation is, therefore, more effective when it is composed of a portfolio of actions rather than a single action.
Additionally, Di Falco considers the behavioral factors of risk aversion. Specifically, he asks whether farmers who are exposed to more variable rainfall are more likely to display higher risk aversion. Di Falco determines whether an individual is risk-averse, using an experiment where a farmer chooses between two different scenarios with different income means and variances. The author found that higher rainfall is negatively correlated with the probability of being risk-averse, while the coefficient of variation of rainfall is positively correlated with the probability of being risk-averse.
Chapter 6, âClimate, Shocks, Weather and Maize Intensification Decisions in Rural Kenya,â aims to measure the effects of climate change and climatic shocks in Kenya on a small farmerâs decision to allocate part of the farm to hybrid maize seeds in order to intensify productivity. In this sense, the term âclimatic shocksâ refers to the number of serious droughts in the past decade. Secondly, Bozzola et al. investigate whether adoption of improved maize seeds, which is known to increase farmersâ mean income, also increases the income variability, thus exposing the farmer to more downside risk. The authors assume that farmers choose the proportion of their farm dedicated to hybrid seeds based on both the incentive of increased mean income and the disincentive of increased income variance. Thus, the proportion of the farm dedicated to hybrid seeds is a function of each individual farmerâs tolerance for risk and aversion to a negatively skewed income distribution.
The results showed that many explanatory variables had statistically significant effects on both adoption of improved seeds and farmersâ income. Factors such as the number of educated men, soil quality, and population density were shown to have positive effects on adoption. As for climatic variables, droughts had a negative and statistically significant impact on adoption, while rainfall had a significantly positive effect on adoption. However, the regression results showed no correlation between adoption of improved seeds and either variance or skewness of the distribution of crop income.
In Chapter 7, âAdaptation to Climate Change by Smallholder Farmers in Tanzania,â Coretha Komba and Edwin Muchapondwa study climate change perception and adaptation levels. The authors survey whether farmers perceive climate change, whether they adapt their agricultural activities, and what factors influence their choice of adaptation methods. Komba and Muchapondwa used a probit to model the binary choice of whether a farmer adapts and a multinomial probit to model the particular adaptation method.
When surveyed, 98.9% of farmers said they perceived changes in both the mean and variance of both temperature and rainfall from the 1990s to the 2000s. This shows that there is overwhelming evidence that farmers in Tanzania have perceived climate change.
While almost all the farmers perceived climate change, only a fraction implemented one or more adaptation methods. Komba and Muchapondwa found a variety of factors that increase a farmerâs probability of adapting to climate change, including education and proximity to markets. Those who did not adopt methods cited a lack of water, a lack of funds, poor planning, and a shortage of seeds as barriers to adaptation. The authors urge the government to address these factors to alleviate farmersâ vulnerability to climate change.
Next, Komba and Muchapondwa investigated how farmers choose their primary method of adaptation, such as changing planting dates or increased irrigation. Farmers with access to media are 7.7% more likely to change their planting date, presumably because they have access to weather forecasts and information. Meanwhile, the inability to access credit increases the probability of changing planting dates as the primary method of adaptation by 9.9%. This is because changing planting dates is less capital-intensive than methods such as increased irrigation.
The poverty trap theory suggests that low-income individuals make choices that keep them in poverty, due to factors such as risk intolerance. Chapter 8, âRisk Preferences and the Poverty Trap: A Look at Farm Technology Uptake among Smallholder Farmers in the Matzikama Municipality,â studies this theory in South Africa. Hafsah Jumare et al. study the effects on farm technology uptake of risk aversion and loss aversion (greater sensitivity to the possibility of loss than to the possibility of gain). They also considered how farmersâ decisions are affected when their decision-making processes give too much weight to low-probability events, or too little weight to high-probability events. The authors looked at the decision to use naturally occurring drought-resistant seeds and the decision to purchase improved seeds. The latter produce higher mean yields but with more variance; because they are more expensive, they carry more risk for the farmer, who would have to repay a loan even in the case of a failed harvest.
The authors measured risk tolerance and loss aversion using a set of hypothetical lottery scenarios. Subjects were presented with two scenarios with different expected payouts and variances and were instructed to choose between the two. Education and household income were among the factors correlated with lower loss aversion. This suggests that less educated and lower-income households, all else equal, are more likely to remain in a poverty trap because they are so sensitive to the risk of loss that they avoid choices that offer possible gain.
Next, Jumare et al. model the decision to use either drought-resistant crops or improved seeds. Looking at the risk preference parameters, the authors find no evidence to suggest that risk or loss aversion influences the uptake of either option. However, a farmer who gives too much weight to a low-probability event is more likely to adopt drought-resistant crop varieties. This may be because fear of a drought causes farmers to overestimate its likelihood and thus switch to more drought-resistant crops. In addition, higher education, higher income, and being male increase the likelihood of one or both of the adaptation methods. Again, these findings support the poverty trap theory.
Agricultural production can be intensified by practices and inputs that are neutral, negative, or positive in their environmental impacts. Purchased inputs such as high-yielding seeds and fertilizer have been shown to increase crop yield, especially when these methods are used as part of a package. Under some circumstances, including a combination of sustainable intensification practices in a farming system can increase productivity while reducing the impact that external inputs have on the environment. Chapter 9, âGood Things Come in Packages: Sustainable Intensification Systems in Smallholder Agriculture,â explores systems of sustainable intensification practices. This chapter summarizes some previous research on smallholder farmersâ intensification practices that have the potential to increase productivity, while considering their environmental effects.
Examples of intensification practices include improved varieties of crops, such as those with improved drought resistance or pest tolerance. For example, a study in Malawi found a positive correlation between improved maize varieties and own maize consumption, income, and asset holdings. Diversification strategies, such as intercropping and crop rotation, restore nitrogen to the soil, as well as allowing farmers to spread their risk across different crops.
Adoption of these different intensification practices in combination usually improves productivity more than an individual practice. A study in Ethiopia examined three intensification practices: modern seeds, inorganic fertilizers, and agricultural water management. The results showed that adoption of any of the three practices resulted in higher net crop income compared to non-adoption. However, the three practices were found to be complements and the highest net income was obtained when all three were jointly adopted.
A wide range of factors influence a farmerâs decision to adopt these practices. For example, each additional year of education for the spouse of a head of household increases the probability of adopting more than two intensification practices by 12%. Farmers who relied on walking to markets are 9% less likely to adopt more than two sustainable intensification practices, indicating the importance of overall development (including road development), as further discussed in Chapter 17. Farmersâ confidence in Ethiopiaâs Productive Safety Net Program, which allows farmers to work for food or cash in case their crops fail, increases the chance of adopting more than two practices by 20%. These studies highlight the need for increased education, availability of resources, and social programs to mitigate downside risk in order for smallholder farmers to efficiently manage their crops.
Part III: on-farm practices other than those related to food crop productivity
Besides adjustments made to crop production, farms have several other dimensions for adapting to climate change. The next three chapters examine livestock preferences, the role of biofuels in agriculture, and postharvest crop losses. These three chapters provide insights into often overlooked options for adapting to climate change.
Many farmers in SSA, particularly in Ethiopia, engage in mixed crop-livestock farming. Chapter 10, âClimate Change Adaptation and Livestock Activity Choice in the Nile Basin of Ethiopia,â considers the impact of climate change on whether Ethiopian farmers manage livestock and, if so, what types of animals. Tsegazeab Gebremariam and Zenebe Gebreegziabher began by modeling the decision of whether to keep livestock. ...
