Climate Change and Agriculture

Global Studies

Döll, Petra. 2002. "Impact of Climate Change and Variability on Irrigation Requirements: A Global Perspective," Climatic Change, Vol. 54, No. 3, August, pp. 269-293.
ABSTRACT: Anthropogenic climate change does not only affect water resources but also water demand. Future water and food security will depend, among other factors, on the impact of climate change on water demand for irrigation. Using a recently developed global irrigation model, with a spatial resolution of 0.5° by 0.5°, we present the first global analysis of the impact of climate change and climate variability on irrigation water requirements. We compute how long-term average irrigation requirements might change under the climatic conditions of the 2020s and the 2070s, as provided by two climate models, and relate these changes to the variations in irrigation requirements caused by long-term and interannual climate variability in the 20th century. Two-thirds of the global area equipped for irrigation in 1995 will possibly suffer from increased water requirements, and on up to half of the total area (depending on the measure of variability), the negative impact of climate change is more significant than that of climate variability.

Chen, Chi-Chung and Bruce A. McCarl. 2001. "An Investigation of the Relationship between Pesticide Usage and Climate Change," Climatic Change, Vol. 50, No. 4, September, pp. 475-487.
ABSTRACT: One concern of agriculturalists when regarding climate change involves the effects on pest populations. Climate change may allow pest migration or population expansions which may adversely affect agricultural productivity, profitability and possibly even viability. We examine the effect of current climate variations on the average and variability of U.S. per acre pesticide costs across the U.S. as a proxy for investigating the consequence for pest populations. Empirically, we find that increases in rainfall increases average per acre pesticide usage costs for corn, cotton, potatoes, soybeans, and wheat while hotter weather increases pesticide costs for corn, cotton, potatoes, and soybeans but decreases the cost for wheat. We also investigated the influence of climate on the variability of pesticide costs. There we find that hotter temperatures increase pesticide cost variance for corn, potatoes, and wheat while decreasing it for soybeans. Rainfall increases cause an increase in cost variability for cotton while decreasing it for corn, potatoes, soybeans, and wheat.

Rosenzweig, C., and D. Hillel. 2000. "Soils and global climate change: Challenges and opportunities," Soil Science, Vol. 165, pp. 47-56.
ABSTRACT: In the interplay of the soil and the atmosphere, the soil can be both a contributor to and a recipient of the impacts of climate change. In the past, land management has generally resulted in considerable depletion of soil organic matter and the relase into the atmosphere of such radiatively active gases as carbon dioxide, methame, and nitrous oxide. Global climate change, to the extent that it occurs, will strongly impact all soil processes. At this time, the task of soil management should be to restore soil organic carbon in order to enhance soil structure and fertility and to help counter the atmospheric greenhouse effect. Widely varying estimates of the soil's organic carbon content and of the potential for soil carbon sequestration point to the need to conduct a comprehensive inventory of this important property.

Tubiello, F.N., M. Donatelli, C. Rosenzweig, and C.O. Stockle. 2000. "Effects of climate change and elevated CO2 on cropping systems: Model predictions at two Italian locations," European Journal of Agronomy, Vol. 12, pp. 179-189.
ABSTRACT:The potential effects of future climate change were investigated, corresponding to a doubling of atmospheric CO2 from 350 to 700 ppm, on agricultural production of four different cropping systems at two Italian locations, Modena and Foggia. Climate change scenarios, derived from two general circulation models (GCMs), were used as weather input to a soil-plant growth simulator, CropSyst. The model was recently modified to include the effects of elevated CO2 on crop photosynthesis and transpiration. Six different crops in total were simulated at the two Italian sites. At Modena, a 3-year maize-maize-wheat rotation and a 2-year soybean-barley-summer sorghum rotation were studied. At Foggia, a 2-year sunflower-wheat-fallow rotation, and a 2-year wheat-fallow-spring sorghum rotation were simulated. Results suggested that the combined effects of elevated atmospheric CO2 and climate change at both sites would depress crop yields if current management practices were not modified. Specifically, warmer air temperatures accelerated plant phenology, reducing dry matter accumulation and crop yields by 10-40%. By investigating adaptation strategies, it was found that a combination of early planting for spring-summer crops and the use of slower-maturing winter cereal cultivars succeeds in maintaining crop yields at current levels at both sites. For irrigated maize and soybean production at Modena, 60-90% more irrigation water was required under climate change to keep grain yields at current levels. This implies that adaptation to climate change may be limited for irrigated crops, depending on site-specific water availability.

Kates, Robert W. 2000. "Cautionary Tales: Adaptation and the Global Poor," Climatic Change, Vol. 45, No. 1, April, pp. 5-17.
ABSTRACT: Many who study global change, particularly from industrialized countries, are optimistic about the capacity of agriculture to successfully adapt to climate change. This optimism is based on historic trends in yield increases, on the spread of cropping systems far beyond their traditional agroecological boundaries, and the inherent flexibility of systems of international trade. Analysis of the success (or in rare cases, failure) of adaptation is by analogy-either to analogous socioeconomic or technological change or to short term environmental change. Such studies have been limited to industrialized countries.
This paper uses five analogs from developing countries to examine potential adaptation to global climate change by poor people. Two are studies of comparative developing country responses to drought, flood, and tropical cyclone and to the Sahelian droughts of the 1970s and 80s that illustrate adaptations to climate and weather events:. Two address food production and rapid population growth in South Asia and Africa. Three types of adaptive social costs are considered: the direct costs of adaptation, the costs of adapting to the adaptations, and the costs of failing to adapt. A final analog reviews 30 village-level studies for the role that these social costs of adaptation play in perpetuating poverty and environmental degradation.

Döös, Bo R., and Roderick Shaw. 1999. "Can we predict the future food production? A sensitivity analysis," Global Environmental Change, Vol. 9, No. 4, December, pp. 261-283.
ABSTRACT: An attempt is made to assess the sensitivity of food production to various aspects of global change and environmental degradation during the next few decades. As a tool for this study a spreadsheet accounting system for food demand and supply is used. Taking into account the uncertainties of the various influencing factors, such as new technologies, improved management, increased fertilizer use, climatic change, expansion of irrigation, soil degradation and loss of agricultural land, the study indicates that one cannot say with any certainty whether or not food supply will meet expected demand in 2025, especially in Less Developed Countries. Bringing into use 10% of available potential cropland will make little difference.

Rötter, R., and S.C. van de Geijn. 1999. "Climate Change Effects on Plant Growth, Crop Yield and Livestock," Climatic Change, Vol. 43, No. 4, December, pp. 651-681.
ABSTRACT: A review is given of the state of knowledge in the field of assessing climate change impacts on agricultural crops and livestock. Starting from the basic processes controlling plant growth and development, the possible impacts and interactions of climatic and other biophysical variables in different agro-environments are highlighted. Qualitative and quantitative estimations of shifts in biomass production and water relations, inter-plant competition and crop species adaptability are discussed. Special attention is given to the problems encountered when scaling up physiological responses at the leaf- and plant level to yield estimates at regional to global levels by using crop simulation models in combination with geo-referenced, agro-ecological databases. Some non-linear crop responses to environmental changes and their relations to adaptability and vulnerability of agro-ecosystems are discussed.

Rounsevell, M.D.A., S.P. Evans, and P. Bullock. 1999. "Climate Change and Agricultural Soils: Impacts and Adaptation," Climatic Change, Vol. 43, No. 4, December, pp. 683-709.
ABSTRACT: This article reviews the current state of knowledge on the response of soils to climate change, and the implications such changes have for agriculture. The article is based on the material reported in the IPCC second assessment report (Watson et al., 1996) and updated with more recent information, where appropriate. The review highlights the importance of understanding the dynamics of soil processes when addressing climate change impacts on agriculture. Rapid soil responses to climate change (e.g. soil water, organic carbon and erodibility) have been widely investigated and reported in the literature. However, it is important that longer-term processes (e.g. pedogenesis) are not ignored by the research community because these have potentially important implications for long-term agricultural land use and are often irreversible. The use of good land management practices, as currently understood, provides the best strategy for adaptation to the impact of climate change on soils. However, it appears likely that farmers will need to carefully reconsider their management options, and land use change is likely to result from different crop selections that are more appropriate to the changing conditions. Perhaps the greatest impact of climate change on soils will arise from climate-induced changes in land use and management.

Patterson, D.T., J.K. Westbrook, R.J.V. Joyce, P.D. Lingren, and J. Rogasik. 1999. "Weeds, Insects, and Diseases," Climatic Change, Vol. 43, No. 4, December, pp. 711-727.
ABSTRACT: The geographic distribution, vigor, virulence, and agricultural impact of weeds, insects, and plant pathogens will be affected by climatic changes accompanying the global "greenhouse effect." Weed/crop competitive interactions, particularly among species differing in photosynthetic pathway (C3 v C4), may be altered, with the C3 species favored by increasing CO2. Physiological and biochemical changes induced in host crop plants by rising CO2 may affect feeding patterns of pest insects. Compilation of climatic thresholds for phenological development of pest insects reveals the potential for shifts in pest behavior induced by global warming and other climatic change. Generation times may be reduced, enabling more rapid population increases to occur. Poleward migration may be accelerated during the crop season. The epidemiology of plant diseases also will be altered. Prediction of disease outbreaks will be more difficult in periods of rapidly changing climate and unstable weather. Environmental instability and increased incidence of extreme weather may reduce the effectiveness of pesticides on targeted pests or result in more injury to non-target organisms. Biological control may be affected either negatively or positively. Overall, the challenge to agriculture from pests probably will increase.

Reilly, J. M. and D. Schimmelpfennig. 1999. "Agricultural Impact Assessment, Vulnerability, and the Scope for Adaptation," Climatic Change, Vol. 43, No. 4, December, pp. 745-788.
ABSTRACT: Climate change assessments which have considered climate impacts of a 2xCO2 climate, using models of the global agricultural system, have found small impacts on overall production, but larger regional changes. Production shifts among regions can be considered one mechanism for adaptation. Adaptation at the farm level, through changes in crops, cultivars, and production practices, is another adaptation mechanism. Existing studies differ in how important these mechanisms will be. Studies that have considered yield effects at specific sites have found very wide ranges of impacts. A useful way to evaluate the impacts of climate change, given the uncertainty about future impacts, is to consider vulnerability. Studies have defined vulnerability in terms of yield, farm profitability, regional economy, and hunger. Vulnerability and climate impacts, particularly in terms of higher order effects on profitability and sustainability, will depend on how society and the economy develop. Lower income populations and marginal agricultural regions, particularly arid or flood prone areas, are most vulnerable to climate change.

Parry, M., C. Rosenzweig, A. Iglesias, G. Fischer, and M. Livermore. 1999. "Climate change and world food security: A new assessment," Global Environmental Change, Vol. 9, Suppl. 1, October, pp. S51-S67.
ABSTRACT:Building on previous work quantitative estimates of climate change impacts on global food production have been made for the UK Hadley Centre's HadCM2 greenhouse gas only ensemble experiment and the more recent HadCM3 experiment (Hulme et al., 1999). The consequences for world food prices and the number of people at risk of hunger as defined by the Food and Agriculture Organisation (FAO, 1988) have also been assessed. Climate change is expected to increase yields at high and mid-latitudes, and lead to decreases at lower latitudes. This pattern becomes more pronounced as time progresses. The food system may be expected to accommodate such regional variations at the global level, with production, prices and the risk of hunger being relatively unaffected by the additional stress of climate change. By the 2080s the additional number of people at risk of hunger due to climate change is about 80 million people (±10 million depending on which of the four HadCM2 ensemble members is selected). However, some regions (particularly the arid and sub-humid tropics) will be adversely affected. A particular example is Africa, which is expected to experience marked reductions in yield, decreases in production, and increases in the risk of hunger as a result of climate change. The continent can expect to have between 55 and 65 million extra people at risk of hunger by the 2080s under the HadCM2 climate scenario. Under the HadCM3 climate scenario the effect is even more severe, producing an estimated additional 70+ million people at risk of hunger in Africa.

Karing, Peeter, Ain Kallis, and Heino Tooming. 1999. "Adaptation principles of agriculture to climate change," Climate Research, Vol. 12, No. 2-3, pp. 175-183.
ABSTRACT: An analysis of climate change impacts on the level of agricultural production is presented based on long-term experimental data on yields of crops grown in different soils and climatic zones. Mathematical models combining available data on the biology of agricultural crops and their response to climatic conditions have been used. The principle of maximum plant productivity is the basis of this modelling effort. The potential and meteorologically possible yields under existing environmental conditions were calculated using the potato dynamic model POMOD. The analyses were completed under different climate change scenarios. According to the climate change scenarios HADCM2 and ECHAM3TR, mean potato yields will increase by about 6 to 8%. The yield increase is larger (10 to 16%) on coastal islands and in North Estonia. A new approach and classification of micro-climate geo-complexes was developed. Agricultural production was found to be highly sensitive to micro-climatic variations. The proposed approach permits more objective use of meteorological data in changing climatic conditions. Shifts in agroclimate were established using this modelling approach. The sums of degree-days, particularly above 0 and 5°C, have significantly risen during the period 1807-1995. The development of potato varieties adapted to a changing climate is possible. A strategy for adaptation of agriculture to climate change is presented.

Dhakhwa, Gyanendra B. and C. Lee Campbell. 1998. "Potential Effects of Differential Day-Night Warming in Global Climate Change on Crop Production," Climatic Change, Vol. 40, No. 3-4, December, pp. 647-667.
ABSTRACT: Recent studies on the nature of global warming indicate the likelihood of an asymmetric change in temperature, where night-time minimum temperature increases more rapidly than the day-time maximum temperature. We used a physically based scenario of asymmetric warming combined with climate change scenarios from General Circulation Models (GCMs) outputs and the EPIC (Erosion Productivity Impact Calculator) plant process model to examine the effects of asymmetric temperature change on crop productivity. Our results indicated that the potential effects of global change on crop productivity may be less severe with asymmetric day-night warming than with equal day-night warming.

Mearns, L.O., C. Rosenzweig, and R. Goldberg. 1996. "The effect of changes in daily and interannual climatic variability on CERES-Wheat: A sensitivity study," Climatic Change, Vol. 32, pp. 257-292.
ABSTRACT: We investigate the effect of changes in daily and interannual variability of temperature and precipitation on yields simulated by the CERES-Wheat model at two locations in the central Great Plains. Changes in variability were effected by adjusting parameters in the Richardson daily weather generator. Two types of changes in precipitation were created: one with both intensity and frequency changes; and another with change only in persistence. In both types mean total monthly precipitation is held constant. Changes in daily (and interannual) variability of temperature result in substantial changes in the mean and variability of simulated wheat yields. With a doubling of temperature variability, large reductions in mean yield and increases in variability of yield result primarily from crop failures due to winter kill at both locations. Reduced temperature variability has little effect. Changes in daily precipitation variability also resulted in substantial changes in mean and variability of yield. Interesting interactions of the precipitation variability changes with the contrasting base climates are found at the two locations. At one site where soil moisture is not limiting, mean yield decreased and variability of yield increased with increasing precipitation variability, whereas mean yields increased at the other location, where soil moisture is limiting. Yield changes were similar for the two different types of precipitation variability change investigated. Compared to an earlier study for the same locations wherein variability changes were effected by altering observed time series, and the focus was on interannual variability, the present results for yield changes are much more substantial. This study demonstrates the importance of taking into account change in daily (and interannual) variability of climate when analyzing the effect of climate change on crop yields.

Rosenzweig, C., and M. L. Parry. 1994. "Potential impact of climate change on world food supply," Nature, Vol. 367, pp. 133- 138.
ABSTRACT: A global assessment of the potential impact of climate change on world food supply suggests that doubling of the atmospheric carbon dioxide concentration will lead to only a small decrease in global crop production. But developing countries are likely to bear the brunt of the problem, and simulations of the effect of adaptive measures by farmers imply that these will do little to reduce the dispatiry between developed and developing countries.

Chen, Robert S., and Robert W. Kates. 1994. "Climate change and world food security," Global Environmental Change, Vol. 4, No. 1, March, pp. 3-6.
ABSTRACT: What is known about the implications of climate change for world food security? This special issue draws on material presented at a recent international workshop at the University of Oxford. It focuses especially on the distributional impacts of a changing climate and the different levels and sources of vulnerability to environmental change. It reviews recent results from two international agricultural models and examines the potential impacts on agriculture of measures to prevent climate change. A companion special issue of the journal Food Policy addresses the regional and global context of future food security in relationship to a changing environment.

Fischer, G., K. Frohberg, M. L. Parry and C. Rosenzweig. 1994. "Climate change and world food supply, demand and trade: Who benefits, who loses?," Global Environmental Change, Vol. 4, No. 1, March, pp. 7-23.
ABSTRACT: This paper summarizes the findings of a major interdisciplinary research effort by scientists in 25 countries. The study examined the potential biophysical responses of major food crops to changing atmospheric composition and climate, and projected potential socioeconomic consequences. In a first step crop models were used to estimate how changing climatic conditions might alter yields of major crops at a number of sites representing both major production areas and vulnerable regions at low, mid and high latitudes. Then a dynamic recursive national-level model of the world food system was used to assess socio-economic impacts for the period 1990 up to year 2060.

Reilly, John, Neil Hohmann and Sally Kane. 1994. "Climate change and agricultural trade: Who benefits, who loses?," Global Environmental Change, Vol. 4, No. 1, March, pp. 24-36.
ABSTRACT: Estimates of the potential effect of three different climate scenarios for world agriculture are made. The scenarios show that the impacts differ significantly among the scenarios and among countries. The direct impact of climate change on yield, the global effect on commodity prices, and the export/import status of a country are shown to determine the economic winners and losers. The trade effects and the high degree of uncertainty should be critical considerations in adaptation policies.

Bohle, Hans G., Thomas E. Downing and Michael J. Watts. 1994. "Climate change and social vulnerability: Toward a sociology and geography of food insecurity," Global Environmental Change, Vol. 4, No. 1, March, pp. 37-48.
ABSTRACT: Coping with climatic variations or future climate change must be rooted in a full understanding of the complex structures and causes of present vulnerability, and how it may evolve over the coming decades. A theory of the social vulnerability of food insecurity draws upon explanations in human ecology, expanded entitlements and political economy to map the risk of exposure to harmful perturbations, ability to cope with crises, and potential for recovery. Vulnerable socio-economic groups in Zimbabwe and the potential effects of climate change illustrate some of the applications of the theory.

Ruttan, Vernon W., David E. Bell, and William C. Clark. 1994. "Climate change and food security: Agriculture, health and environmental research," Global Environmental Change, Vol. 4, No. 1, March, pp. 63-77.
ABSTRACT: The battle to achieve sustainable growth in agricultural production must be fought out along a broad multidisciplinary front. Poverty undermines health and degrades the environment. Environmental problems link the agricultural and health research agendas. Environmental changes underway at the global level will require changes in food production and health practices. Effective bridges must be built between the `island empires' of the agricultural, environmental, and health sciences. More effective linkages must be built between the suppliers of knowledge and technology and the users.

Parry, Martin L., and Cynthia Rosenzweig. 1993. "Food supply and risk of hunger," The Lancet, Vol. 342 No. 8883, November 27, pp. 1345-1347.
ABSTRACT: We provide here an evaluation of the potential effect of climate change, induced by greenhouse gases, on food production and the number of people at risk of hunger due to such changes. This is a modelling exercise, starting with existing models of climate change itself, then how crop yields might respond under those different scenarios and then assimilating the economic consequences of those yields in the world food trade model. This global study is being coordinated by the US Environmental Protection Agency and scientists in twenty-five countries took part.

Allen, R.G., and C. Rosenzweig. 1991. "CO2-induced climatic changes and irrigation-water requirements," Journal of Water Resources Planning and Management, Vol. 117, No. 2, March/April, pp. 157-178.
ABSTRACT: Effects of CO2-induced climatic changes on irrigation-water requirements (IR) in the Great Plains region were evaluated using results of global atmospheric-circulation models with a water balance-IR model. Increases were predicted for evapotranspiration Et due to predicted increases in air temperature, solar radiation, and wind speed under doubled concentrations of atmospheric carbon dioxide (2×CO2). Predicted increases in humidity under the 2×CO2 scenarios and shifting of crop life cycles to months with lower levels of solar radiation partially counteracted predicted increases in Et. Increases in irrigation requirements were caused primarily by increases in evaporative demands and changes in precipitation patterns. Increases in net seasonal IR for alfalfa were larger due to predicted increases in length of frost-free growing seasons and higher evaporative demands as compared to winter wheat and corn. Decreases or only modest increases in seasonal irrigation requirements were projected under 2×CO2 scenarios for corn and winter wheat due to reductions in length of crop life cycles and projected increases in bulk stomatal resistances.