A Theoretical Foundation for Count Data Models

The paper develops a theoretical foundation for using count data models in travel cost analysis. Two micro models are developed: a restricted choice model and a repeated discrete choice model. We show that both models lead to identical welfare measures.

Crop selection : adapting to climage change in Africa

This paper examines whether the choice of crops is affected by climate in Africa. Using a multinomial logit model, the paper regresses crop choice on climate, soils, and other factors. The model is estimated using a sample of more than 7,000 farmers across 11 countries in Africa. The study finds that crop choice is very climate sensitive. For example, farmers select sorghum and maize-millet in the cooler regions of Africa; maize-beans, maize-groundnut, and maize in moderately warm regions'and cowpea, cowpea-sorghum, and millet-groundnut in hot regions. Further, farmers choose sorghum, and millet-groundnut when conditions are dry; cowpea, cowpea-sorghum, maize-millet, and maize when medium wet; and maize-beans and maize-groundnut when wet. As temperatures warm, farmers will shift toward more heat tolerant crops. Depending on whether precipitation increases or decreases, farmers will also shift toward drought tolerant or water loving crops, respectively. There are several policy relevant conclusions to draw from this study. First, farmers will adapt to climate change by switching crops. Second, global warming impact studies cannot assume crop choice is exogenous. Third, this study only examines choices across current crops. Future farmers may well have more choices. There is an important role for agronomic research in developing new varieties more suited for higher temperatures. Future farmers may have even better adaptation alternatives with an expanded set of crop choices specifically targeted at higher temperatures.Crops&Crop Management Systems,Climate Change,Agriculture&Farming Systems,Renewable Energy,Global Environment Facility

A Ricardian analysis of the impact of climate change on Latin American farms

This study estimates the vulnerability of Latin American agriculture to climate change using a Ricardian analysis of both land values and net revenues. Examining a sample of over 2,500 farms in seven countries, the results indicate both land value and net revenue are sensitive to climate. Both small farms and large farms have a hill-shaped relationship with temperature. Estimating separate regressions for dryland and irrigated farms reveals that dryland farms are more sensitive to temperature but irrigated farms are more sensitive to precipitation. Examining the effects from future climate change scenarios reveals thatsevere scenarios could reduce farm earnings by as much as 62 percent by 2100, whereas more moderate scenarios could reduce earnings by about 15 percent. Small and large farms are equally sensitive to global warming. Land value and net revenue analyses produce quite similar results.Climate Change,Rural Development Knowledge&Information Systems,Agriculture&Farming Systems,Crops&Crop Management Systems,Common Property Resource Development

A ricardian analysis of the impact of climate change on African cropland

This study examines the impact of climate change on cropland in Africa. It is based on a survey of more than 9,000 farmers in 11 countries: Burkina Faso, Cameroon, Egypt, Ethiopia, Ghana, Kenya, Niger, Senegal, South Africa, Zambia, and Zimbabwe. The study uses a Ricardian cross-sectional approach in which net revenue is regressed on climate, water flow, soil, and economic variables. The results show that net revenues fall as precipitation falls or as temperatures warm across all the surveyed farms. In addition to examining all farms together, the study examined dryland and irrigated farms separately. Dryland farms areespecially climate sensitive. Irrigated farms have a positive immediate response to warming because they are located in relatively cool parts of Africa. The study also examined some simple climate scenarios to see how Africa would respond to climate change. These uniform scenarios assume that only one aspect of climate changes and the change is uniform across all of Africa. In addition, the study examined three climate change scenarios from Atmospheric Oceanic General Circulation Models. These scenarios predicted changes in climate in each country over time. Not all countries are equally vulnerable to climate change. First, the climate scenarios predict different temperature and precipitation changes in each country. Second, it is also important whether a country is already hot and dry. Third, the extent to which farms are irrigated is also important.Climate Change,Environmental Economics&Policies,Global Environment Facility,Common Property Resource Development,Crops&Crop Management Systems

An analysisof crop choice : adapting to climate change in Latin American farms

The authors explore how Latin American farmers adapt to climate by changing crops. They develop a multinomial choice model of farmer's choice of crops. Estimating the model across over 2,000 farmers in seven countries, they find that both temperature and precipitation affects the crops that Latin American farmers choose. Farmers choose fruits and vegetables in warmer locations and wheat and potatoes in cooler locations. Farms in wetter locations are more likely to grow rice, fruits, and squash, and in dryer locations maize and potatoes. Global warming will cause Latin American farmers to switch away from wheat and potatoes toward fruits and vegetables. Predictions of the impact of climate change must reflect not only changes in yields or net revenues per crop but also crop switching.Crops&Crop Management Systems,Climate Change,Rural Poverty Reduction,Agriculture&Farming Systems,Global Environment Facility

An analysis of livestock choice : adapting to climate change in Latin American farms

The authors explore how Latin American livestock farmers adapt to climate by switching species. They develop a multinomial choice model of farmer's choice of livestock species. Estimating the models across over 1,200 livestock farmers in seven countries, they find that both temperature and precipitation affect the species Latin American farmers choose. The authors then use this model to predict how future climate scenarios would affect species choice. Global warming will cause farmers to switch to beef cattle at the expense of dairy cattle.Livestock&Animal Husbandry,Climate Change,Wildlife Resources,Peri-Urban Communities,Rural Urban Linkages

Changing farm types and irrigation as an adaptation to climate change in Latin American agriculture

This paper estimates a model of a farm that treats the choice of crops, livestock, and irrigation as endogenous. The model is composed of a multinomial choice of farm type, a binomial choice of irrigation, and a set of conditional land value functions. The model is estimated across over 2,000 farmers in seven Latin America countries. The results quantify how farmers adapt their choice of farm type and irrigation to their local climate. The results should help governments develop effective adaptation policies in response to climate change and improve the forecasting of climate effects. The paper compares the predicted effects of climate change using both endogenous and exogenous models of farm choice.Climate Change,Crops&Crop Management Systems,Livestock&Animal Husbandry,Agriculture&Farming Systems,Rural Development Knowledge&Information Systems

How will climate change shift agro-ecological zones and impact African agriculture ?

The study develops a new method to measure the impacts of climate change on agriculture called the Agro-Ecological Zone (AEZ) Model. A multinomial logit is estimated to predict the probability of each AEZ in each district. The average percentage of cropland and average crop net revenue are calculated for each AEZ. Then an estimate of the amount of cropland in Africa and where it is located is provided. Using current conditions, the model calculates baseline values of cropland and crop net revenue, and estimates the future impact of climate change using two scenarios-harsh and mild. Total cropland does not change much across the two climate scenarios. However, the predicted change in African crop revenue ranges from a loss of 14 percent in the mild climate scenario to 30 percent in the harsher climate scenario. The analysis reveals that the greatest harm from climate change is that it will shift farms from high to low productive AEZs. The approach not only identifies the aggregate impacts, but also indicates where the impacts occur across Africa. The central region of Africa is hurt the most, especially in the harsher climate scenario. The Agro-Ecological Zone Model is a promising new method for valuing the long-term impacts of climate change on agriculture.Climate Change,Common Property Resource Development,Forestry,Crops&Crop Management Systems,Global Environment Facility

A structural ricardian analysis of climate change impacts and adaptations in African agriculture

This paper develops a Structural Ricardian model to measure climate change impacts that explicitly models the choice of farm type in African agriculture. This two stage model first estimates the type of farm chosen and then the conditional incomes of each farm type after removing selection biases. The results indicate that increases in temperature encourage farmers to adopt mixed farming and avoid specialized farms such as crop-only or livestock-only farms. Increases in precipitation encourage farmers to shift from irrigated to rainfed crops. As temperatures increase, farm incomes from crop-only farms or livestock-only farms fall whereas incomes from mixed farms increase. With precipitation increases, farm incomes from irrigated farms fall whereas incomes from rainfed farms increase. Naturally, the Structural Ricardian model predicts much smaller impacts than a model that holds farm type fixed. With a hot dry climate scenario, the Structural Ricardian model predicts that farm income will fall 50 percent but the fixed farm type model predicts farm incomes will fall 75 percent.Crops&Crop Management Systems,Agriculture&Farming Systems,Livestock&Animal Husbandry,Climate Change,Rural Development Knowledge&Information Systems

The impact of climate change on livestock management in Africa : a structural Ricardian analysis

This paper develops the structural Ricardian method, a new approach to modeling agricultural performance using cross-sectional evidence, and uses the method to study animal husbandry in Africa. The model is intended to estimate the structure beneath Ricardian results in order to understand how farmers change their behavior in response to climate. A survey of over 5,000 livestock farmers in 10 countries reveals that the selection of species, the net income per animal, and the number of animals are all highly dependent on climate. As climate warms, net income across all animals will fall, especially across beef cattle. The fall in net income causes African farmers to reduce the number of animals on their farms. The fall in relative revenues also causes them to shift away from beef cattle and toward sheep and goats. All farmers will lose income but the most vulnerable farms are large African farms that currently specialize in beef cattle. Small livestock and large livestock farms respond to climates differently. Small farms are diversified, relying on dairy cattle, goats, sheep, and chickens. Large farms specialize in dairy and beef cattle. Estimating a separate multinomial logit selection model for small and large farms reveals that the two types of farm choose species differently and specifically have different climate response functions. The regressions of the number of animals also reveal that large farms are more responsive to climate. The results indicate that warming will be harmful to commercial livestock owners, especially cattle owners. Owners of commercial livestock farms have few alternatives either in crops or other animal species. In contrast, small livestock farms are better able to adapt to warming or precipitation increases by switching to heat tolerant animals or crops. Livestock operations will be a safety valve for small farmers if warming or drought causes their crops to fail.Livestock&Animal Husbandry,Wildlife Resources,Rural Urban Linkages,Peri-Urban Communities,Dairies&Dairying