Evidence of climate change impacts on crop comparative advantage and land use

Relative agricultural productivity shocks emerging from climate change will alter regional cropland use. Land allocations are sensitive to crop profits that in turn depend on yield effects induced by changes in climate and technology. We develop and apply an integrated framework to assess the impact of climate change on agricultural productivity and land use for the U.S. Northern Great Plains. Crop-specific yield–weather models reveal crop comparative advantage due to differential yield impacts of weather across the region's major crops, that is, alfalfa, wheat, soybeans, and maize. We define crop profits as a function of the weather-driven yields, which are then used to model land use allocation decisions. This ultimately allows us to simulate the impact of climate change under the RCP4.5 emissions scenario on land allocated to the region's major crops as well as to grass/pasture. Upon removing the trends effects in yields, climate change is projected to lower yields by 33–64% over 2031–2055 relative to 1981–2005, with soybean being the least and alfalfa the most affected crops. Yield projections applied to the land use model at present-day input costs and output prices reveals that Dakotas’ grass acreage will increase by up to 23%, displacing croplands. Wheat acreage is expected to increase by up to 54% in select southeastern counties of North Dakota and South Dakota, where maize/soy acreage had increased by up to 58% during 1995–2016.     

The research cost of adapting agriculture to climate change: A global analysis to 2050

Investments in agricultural research and development (R&D) made over the next few decades will likely prove critical in offsetting adverse climate change impacts on the global food system. In this study, we offer cost estimates of public R&D-led adaptation to climate change grounded in an explicit framework relating the flow of annual R&D expenditures to building knowledge capital and thereby raising productivity in agriculture. Our research uses a comprehensive collection of historical public agricultural R&D expenditure and a literature review of elasticity estimates linking knowledge stocks to agricultural productivity growth for key world regions. Given climate-driven crop yield projections generated from extreme combinations of crop and global circulation models, we find that offsetting crop yield losses projected by climate and crop models over 2006–2050 would require increased R&D adaptation investments of between $187 billion and $1,384 billion (in 2005 $PPP) if we invest between 2020 and 2040. This is 16–118% higher than global R&D investment if present spending trends continue. Although these costs are significant, worldwide R&D-led climate adaptation could offer favorable economic returns. Moreover, R&D-led adaptation could deliver gains in food security and environmental sustainability by mitigating food price increases and slowing cropland expansion.     

Warming temperatures will likely induce higher premium rates and government outlays for the U.S. crop insurance program

Likely climate change impacts include damages to agricultural production resulting from increased exposure to extreme heat. Considerable uncertainty remains regarding impacts on crop insurance programs. We utilize a panel of U.S. corn yield data to predict the effect of warming temperatures on the mean and variance of yields, as well as crop insurance premium rates and producer subsidies. While we focus on corn, we demonstrate that the subsidy impacts are likely to carry over to other major program crops. We find that warming decreases mean yields and increases yield risk on average, which results in higher premium rates. Under a 1°C warming scenario, we find that premium rates at the 90% coverage level will increase by 39% on average; however, there is considerable statistical uncertainty around this average as the 95% confidence interval spans from 22% to 61%. We also find evidence of extensive cross‐sectional differences as the county‐level rate impacts range from a 10% reduction to a 63% increase. Results indicate that exposure to extreme heat and changes in the coefficient of variation are large drivers of the impacts. Under the 1°C warming scenario, we find that annual subsidy payments for the crop insurance program could increase by as much as $1.5 billion, representing a 22% increase relative to current levels. This estimate increases to 3.7 billion (57%) under a 2°C warming scenario. Our results correspond to a very specific counterfactual: the marginal effect of warming temperatures under current technology, production, and crop insurance enrollments. These impacts are shown to be smaller than the forecasted impacts under a commonly used end‐of‐century general circulation model for even the most optimistic CO₂ emissions projection.     

Effect of changes in population density and crop productivity on farm households in Malawi

This study examines the ex‐ante farm‐household effects of changes in family size, yield potential, and yield gaps using a farm‐household simulation model that reflects the economic and biophysical conditions of central Malawi. Disparities between growth in human population and crop yields present challenges for farm‐household crop production and income in sub‐Saharan Africa. We focus on the effect of growth in yield potential and a more efficient use of livestock manure as approaches to improving crop production and incomes in the face of looming population pressures. Our results suggest that, even without considering climate change, expected changes in population density and crop prices in 2050 mean that per person crop production and income may fall by 21% compared to 2013 values if yield potential and yield gaps remain constant. However, per person crop production and income could increase in 2050 by 8% compared to 2013 values if (1) growth rates of yield potential rise for maize by 1.13% each year and for legumes rise by at least 0.4% each year, and (2) farmers use livestock manure more efficiently. Our foresight approach to considering crop production at the farm‐household scale supplements macro‐scale analyses of the production dimension of food security.     

Inter‐ and intra‐seasonal crop acreage response to international food prices and implications of volatility

Understanding how producers make decisions to allot acreage among crops and how decisions about land use are affected by changes in prices and their volatility is fundamental for predicting the supply of staple crops and, hence, assessing the global food supply situation. This study makes estimations of monthly (i.e., seasonal) versus annual global acreage response models for the world's principal staple food crops: wheat, corn, soybeans, and rice. Primary emphasis is given to the magnitude and speed of the allocation process. Estimation of intra‐annual acreage elasticity is crucial for expected food supply and for input demand, especially in the light of the recent short‐term volatility in food prices. The econometric results indicate that global crop acreage responds to crop prices and price risks, input costs as well as a time trend. Depending on respective crop, short‐run elasticities are about 0.05 to 0.40; price volatility tends to reduce acreage for some of the crops; comparison of the annual and the monthly acreage response elasticities suggests that acreage adjusts seasonally around the globe to new information and expectations. Given the seasonality of agriculture, time is of an essence for acreage response. The analysis indicates that acreage allocation is more sensitive to prices in the northern hemisphere spring than in winter and the response varies across months.     

Modeling climate change and agriculture: an introduction to the special issue

This issue of Agricultural Economics is a special issue containing articles on model performance in assessing the effects of climate change, bioenergy policy, and socioeconomics on agriculture. The contributions present results from a global economic model intercomparison activity undertaken as part of the AgMIP Project ( www.agmip.org ). The origins of the comparison activities can be traced to a project that was organized by the OECD in late 2010 to compare results from three models. The current phase of the research includes 10 models and was designed in part to support of the IPCC fifth assessment report (AR5). The special issue includes seven peer‐reviewed articles that present thematic results from a range of modeling strategies, with partial and general equilibrium modeling as a high level distinction but a myriad of differences within these two model types. A central common element is harmonization on biophysical effects using crop models and socioeconomic effects using drivers from the Shared Socioeconomic Pathways developed as part of the AR5 process. The special issue provides broad insights into how the modeling communities approached the interactions of climate, socioeconomics, bioenergy policy on agricultural outcomes, including land use, prices, consumption, and production.     

Climate change impacts on rain-fed and irrigated rice yield in Malawi

There is extensive scientific evidence on climate impacts and adaptation in rice (Oryza sativa L.), but the majority relates to production in South Asia and China. Only a handful of studies have been conducted in Sub-Saharan Africa and none in Malawi. In this paper, the climate impacts on rain-fed and irrigated rice yield have been assessed by combining the downscaled outputs from an ensemble of general circulation models (GCM) (HADCM3, INCM3 and IPCM4) with data from the LARS-WG weather generator to drive the CERES-Rice crop model. This was calibrated and validated using 10 years (2001–2010) field data from three rice schemes to simulate the baseline (1961–1990) yield (t?ha^?1) and then model future yield changes for selected (B1 and A2) emissions’ scenarios for the 2050s. Although relatively small increases in average yield were projected (+8% and +5% for rain-fed and irrigated rice, respectively), there was large uncertainty (?10% to +20% yield change) when considering different GCMs and emission scenario. Farmer responses to cope with the projected impacts include both autonomous and planned adaptation strategies, such as modifying planting dates to maximize crop growth calendars and available soil moisture, increased use of on-farm water conservation measures and land levelling to improve water efficiency in rice schemes dependent on surface irrigation.     

Distributional heterogeneity in climate change impacts and adaptation: Evidence from Indian agriculture

This study estimates the distributional heterogeneity in the effects of climate change on yields of three major cereal crops: rice, maize, and wheat in India using district-level information for the period 1966–2015. We distinguish between the effects of changes in growing season weather from those due to changes in long-term climate trends and the heterogeneity in these effects across the distribution of crop yields by estimating naïve and climate penalty inclusive models using fixed-effect quantile panel models. We observe an absence of adaptation against rising temperatures for rice and wheat. However, we find a statistically significant presence of adaptation for wheat and maize for changes in precipitation, though the magnitude is small. Moreover, we find that the effects are asymmetric, and are larger at the lower tail of productivity distribution and smaller at the upper tail of the distribution. A 1°C increase in temperature lowers rice and wheat productivity by 23% and 9%, respectively at the first quantile, but the damage is only 6% and 5% at the ninth quantile. Heterogeneity in impacts and adaptation estimates over the yield distribution curve and across crops suggests the importance of customizing strategies for adaptation to changing weather and climate conditions across regions, crops, and current productivity levels.     

Assessing effects of federal crop insurance supply on acreage and yield of specialty crops

Crop insurance may affect harvested acreage and yield by influencing producers’ behavior such as land allocation and input use. Although specialty crops are a major source of farm income, especially on the U.S. west coast, they have not received as much attention as field crops in previous empirical studies. This paper assesses the effect of moral hazard and adverse selection associated with the federal crop insurance program (FCIP) on the acreage and yield of major specialty crops in California. An econometric method that expands the switching regression model is developed to assess the effect. Results suggest that federal crop insurance can change specialty crop growers’ production responses to climate and soil conditions. The moral hazard effect tends to increase the acreage and yield of the specialty crops, whereas the adverse selection effect tends to have the opposite effect. The overall effect of the FCIP on acreage and yield of specialty crops is found to be moderate.     

水足迹视角下京津冀县域粮食作物水土资源匹配格局

目的 农业水土资源是粮食生产的决定因素，探明京津冀粮食生产中水土资源匹配格局特征对区域经济发展有深远的影响。方法 文章从水足迹的视角出发，分析了1980—2018年京津冀县域5种主要粮食作物（小麦、玉米、稻谷、大豆、薯类）的产量、播种面积、水足迹、耕地面积的时空变化，运用水土匹配系数法及ArcGIS深入研究了1983年、1998年、2003年和2016年水土资源匹配格局，并进一步剖析区域农业水土匹配对农业生产的影响。结果 （1）当前京津冀水土匹配系数区间为［0.02，1.25］，超出区间范围［0.281， 0.431］；粮食生产格局与水土匹配系数空间格局均为“冀中南高、北部低”。（2）研究时段内，京津冀粮食总产量提高1.14倍，播种总面积降低19.28%，粮食单产量显著提高；灌溉提高粮食单产量，水土匹配系数与粮食单产量呈正相关。（3）1980—2019年京津冀5种作物蓝水足迹均值（136.64亿m³）是绿水足迹均值（99.60亿m³）的1.37倍，各作物水足迹变化不同，间接反映地区农业种植结构的改变。（4）京津冀水足迹总量提高2.45倍，耕地总量下降20.59%，水土匹配系数变大，农业水土匹配程度差，间接指示研究区域地下水开发程度高。结论 京津冀县域水土资源匹配存在较大提升空间，应从当地水土资源存在的问题出发，适当调整作物种植结构，关注区域地下水超采等限制农业发展的因素，促进京津冀地区农业水土资源可持续发展。     

Evaluating the impact of rising fertilizer prices on crop yields

Because of tensions on fossil energy and phosphorus markets, the rise in fertilizer prices observed during the last decades may continue in the future, putting into question production pathways relying heavily on crop intensification. To evaluate how, in this context, economic choices may alter crop yields, we first construct different fertilizer price scenarios to 2050 based on an econometric relation with oil and gas prices. Other possible scenarios, such as the continuation of historical trends, are also considered. The resulting changes in fertilizer price range between +0.8% and +3.6% per year over the 2005–2050 period. These scenarios are tested in a global land‐use model incorporating an endogenous representation of the land–fertilizer substitution. We find that the supply‐side response to rising fertilizer prices could lower crop yields in 2050 from ?6% to ?13%, with a corresponding increase in global cropland area ranging between 100 and 240 Mha if the demand for food and nonfood products has to be met. The sensitivity of these results is tested with regard to assumptions on food consumption, change in potential yield and nutrient use efficiency.     

Farm households’ risk perception,attitude and adaptation strategies in dealing with climate change: Promise and perils from rural Pakistan

Pakistan is highly vulnerable to extreme climatic events, such as floods and droughts. This study determines the farmers’ risk perception, risk attitude, adaptation measures and various aspects of vulnerability to climate change (e.g. floods, droughts, heavy rainfalls, pests and disease) at farm level in rural Pakistan. The risk perception and attitude of farm households are crucial factors that influence farm productivity, investment and management decisions at this level. A well-designed questionnaire was used to interview 720 farm households from six districts of the Khyber Pakhtunkhwa province. A binary logit model was used to determine the main factors that affect the choice of adaptation strategies of the farm household. The findings revealed that crop diversification, changing crop varieties, altering the crop calendar, varying the fertilizer used, mulching and farm insurance were the main adaptation strategies followed by farm households. The results of the binary logit model revealed that age, education, farm size, household size, credit accessibility, annual income and the perception on the increase in temperature and decrease in rainfall had significant influence on the selection of the adaption strategies. The findings of this study can provide guidance, policy recommendations and reference for future researchers.     

Risk aversion and land allocation between annual and perennial crops in semisubsistence farming: a stochastic optimization approach

This article analyzes the effect of production uncertainty on farmland allocation decisions between perennial and annual crops, focusing on a representative farmer's attitude toward risk. A dynamic stochastic optimization model that considers net planting—the difference between new plantings and removals of perennial crops that achieve full production cycle—is used. The effect of uncertainty on the representative farmer's decisions to increase or decrease perennial crops’ acreage, on the optimal path, is examined. Our results reveal that the response of optimal path of net planting to uncertainty related to perennial crop production is highly affected by the farmer's attitude toward risk. A risk‐averse or a low‐risk loving farmer tends to reduce land allocation to perennial crops under uncertainty, while a high‐risk loving farmer will do exactly the opposite. Also, due to disutility of farming, the farmer tends to reduce land allocation to perennial crops when prices are high enough for him to attain a desired income level expectation. One implication of this research is the need for mechanization—in sub‐Saharan countries in particular—that increases per‐acreage yield and output in semisubsistence agriculture.     

Farmers’ risk preferences and their climate change adaptation strategies in the Yongqiao District,China

Farmers’ risk preferences play an important role in agricultural production decisions. This study characterizes risk preferences among farmers in Yongqiao and determines how these risk preferences are related to their choices regarding climate change adaptation strategies. We find that most farmers in the study area were aware of climate change. They were taking measures to protect their livelihoods against perceived changes to the local climate. The risk experiment result shows that the representative subject was risk averse, and women were more risk averse than men. The relationships between farmers’ risk preferences and different climate change adaptation choices were different. Farmers’ risk aversion was negatively and significantly related with adaptation strategies on planting new crop varieties and adopting new technology, but it had a significantly positive effect on purchasing weather index crop insurance. The results also indicate that the level of education, farming experience, farm size, household income and perception of climate change impacts influence farmers’ adaptation decisions.     

Factors influencing the profitability of fertilizer use on maize in Zambia

Fertilizer use remains very low in most of Africa despite widespread agreement that much higher use rates are required for sustained agricultural productivity growth. This study uses longitudinal farm survey data to estimate maize yield response functions in a relatively high-potential zone of Zambia to determine the profitability of fertilizer use under a range of small-farm conditions found within this zone. The theoretical framework used in this study incorporates agronomic principles of the crop growth process. We generalize the asymmetric production models and define a concept of yield scaling factors. The model distinguishes different roles of inputs and non-input factors in crop production. We estimate the effects of conventional production inputs as well as of household characteristics and government programs on maize yield. The results indicate that recommended fertilizer application rates in the two specific years were often unprofitable, given observed price conditions and the yield response to fertilizer. However, there was substantial variability in yield response to fertilizer based upon the rate of application, the timeliness of fertilizer availability, the use of animal draught power during land preparation, and whether the household incurred the death of an adult member in the past three years. These modifying factors, as well as variations in input and output prices due to proximity to roads and markets, substantially affected the profitability of fertilizer use on maize.     

The potential impact of climate change on Taiwan's agriculture

This paper intends to estimate the potential impact of climate change on Taiwan's agricultural sector. Yield response regression models are used to investigate the climate change's impact on 60 crops. A price‐endogenous mathematical programming model is then used to simulate the welfare impacts of yield changes under various climate change scenarios. Results suggest that both warming and climate variations have a significant but non‐monotonic impact on crop yields. Society as a whole would not suffer from warming, but a precipitation increase may be devastating to farmers.     

Impacts of considering climate variability on investment decisions in Ethiopia

Extreme interannual variability of precipitation within Ethiopia is not uncommon, inducing droughts or floods and often creating serious repercussions on agricultural and nonagricultural commodities. A dynamic climate module is integrated into an economy‐wide model containing a detailed zonal level agricultural structure. This coupled climate‐economic model is used to evaluate the effects of climate variability on prospective irrigation and infrastructure investment strategies, and the ensuing country‐wide economy. The linkages between the dynamic climate module and the economic model are created by the introduction of a climate‐yield factor (CYF), defined at the crop level and varied across Ethiopian zones. Nine sets of variable climate (VC) data are processed by the coupled model, generating stochastic wet and dry shocks, producing an ensemble of potential economic prediction indicators. Analysis of gross domestic product and poverty rate reveal a significant overestimation of the country's future welfare under all investment strategies when climate variability is ignored. The coupled model ensemble is further utilized for risk assessment to guide Ethiopian policy and planning.     

Impediments to inland resettlement under conditions of accelerated sea level rise

Global mean sea level rise (GMSLR) stemming from the multiple effects of human-induced climate change has potentially dramatic effects for inland land use planning and habitability. Recent research suggests that GMSLR may endanger the low-elevation coastal zone sooner than expected, reshaping coastal geography, reducing habitable landmass, and seeding significant coastal out-migrations. Our research reviews the barriers to entry in the noncoastal hinterland. Using three organizing clusters (depletion zones, win-lose zones, and no-trespass zones), we identify principal inland impediments to relocation and provide preliminary estimates of their toll on inland resettlement space. We make the case for proactive adaptation strategies extending landward from on global coastlines and illustrate this position with land use planning responses in Florida and China.     

Short‐run and long‐run dynamics of farm land allocation: panel data evidence from Denmark1

This study develops and estimates a dynamic multi‐output model of farmers’ land allocation decisions that allows for the gradual adjustment of allocations that can result from crop rotation practices and quasi‐fixed capital constraints. Estimation is based on micro‐panel data from Danish farmers that include acreage, output, and variable input utilization at the crop level. Results indicate that there are substantial differences between the short‐run and long‐run land allocation behaviour of Danish farmers and that there are substantial differences in the time lags associated with different crops. To our knowledge, this is the first dynamic micro‐model of land allocation estimated on data from the temperate climate zone. Since similar farming conditions are found in northern Europe and parts of the United States and Canada, this result may be of wider interest.