Climate change and world agriculture

Climate change and world agriculture

Book reviews and sustainable; and conserving soil, water, energy and biological resources. This book provides a timely perspective on how the princip...

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Book reviews

and sustainable; and conserving soil, water, energy and biological resources. This book provides a timely perspective on how the principles of ecology and economics can be integrated to make agriculture environmentally sound, sustainable and productive. The author delineates some of the changes that are needed if future food production is to be sufficient to feed the rapidly expanding world population. In a fairly concise way Harris clarifies many of the complex issues facing economists and ecologists as they seek to augment agricultural production within the constraints imposed by the resources of the ecosystem. Ample figures and tables enhance the text. This book is recommended to economists, ecologists, agriculturalists, political leaders and all who are sound

concerned about the future, especially about how agriculture will be able to provide the food that is essential to human survival. David Pimentel Cornell University Ithaca, NY, USA ‘R. Lal and B.A. Stewart, Soil Degradation, Springer-Verlag, New York, NY, 1990. ‘D. Pimentel, World Soil Erosion and Conservation, Cambridge University Press, Cambridge, UK, in press. %.R. Gliessman, Agroecology, SpringerVerlag, New York, NY, 1990. 4Facts and Figures: International Agriculturat Research, Rockefeller Foundation and IFPRI, New York, NY, and Washington, DC, 1990, Table 1. 5M.B. Green, H.M. Le Baron and W.K. Moberg, Managing Resistance to Agrochemicals: From Fundamental Research to Practical Strategies, American Chemical Society, Washington, DC, 1990.

Up-to-date summary of the research CLIMATE CHANGE AND WORLD AGRICULTURE by Martin Earthscan,

Party

London,

7990

Martin Parry is widely recognized as one of the world’s leading authorities on the possible impacts of climate change on agriculture. This book demonstrates why. It is a well-written, characteristically careful sifting of the evidence on what we know and do not know about these impacts, combined with balanced judgements of their significance for agriculture, globally and in major regions. Parry was the lead author of the agricultural impacts report of the Intergovernmental Panel on Climate Change, and this book is an expanded version of that report. The book opens with an account of the present vulnerability to climate of many farmers in dry, rainfed agricultural regions. It continues in Chapter 2 with a discussion of how rising atmospheric concentrations of carbon dioxide (CO,) and other ‘greenhouse’ gases are expected to increase global average

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temperature and precipitation. Chapter 2,also includes some speculation, based on results from general circulation models (GCMs), of how temperature, precipitation and soil moisture may change in major regions (eg Central North America, Southeast Asia). Parry is careful to point out, however, that even for these large regions the results are quite uncertain because the GCMs are unable to predict regional climate changes with any precision. The uncertainty is greater for precipitation than for temperature, a matter of particular concern because around the world where agriculture is now marginal the reason typically is the scarcity of and uncertainty about precipitation. Chapter 3 contains an insightful discussion of techniques for studying and estimating agricultural impacts of climate change, with emphasis on the linkages between first-order impacts on crop productivity, second-order responses at the farm enterprise level, and third-order impacts at regional and national levels. Chapter 4 begins the discussion of first-order impacts by focusing on how CO7 enrichment of the atmosphere might enhance crop

productivity by stimulating photosynthesis and water use efficiency. The chapter continues with an account of the various ways higher temperature and changed precipitation may directly affect crop productivity negatively in some areas and positively in others - and indirectly through effects on soil fertility, erosion and various pests and diseases. Chapter 5 deals with possible changes in agricultural potential among major regions of the world under climate change. Parry points out that all the studies of these changes have been done in the more developed countries. The studies generally concur in showing a northerly shift of major grain-growing regions in the northern hemisphere, eg one study showed the American Cornbelt shifting in a north-by-northeast direction about 17.5 km for every 1°C increase in global temperature. Other studies found a similar or even greater shift in Europe, with the entire Northern European plain becoming a potential maize-growing region. The regional changes in agricultural potential imply regional changes in agricultural production and land use, and these are the focus of Chapter 7. The general conclusion is that midlatitudes production would probably be decreased more than northern latitudes production would be increased. The implications of this for global food security are discussed in Chapter 6. Using a variety of crop impact and economic models, most of them developed in the USA, Parry concludes that the roughly 20% yield declines in mid-latitudes grain-exporting regions predicted by the models would not cause a major interruption in world food supplies. However, the consequent price increases (7% with a 10% yield decline) could strongly disadvantage the less-developed importing countries. In Chapter 8 Parry discusses two kinds of agricultural adaptation to climate: changes in land use and changes in management, eg more (or less) irrigation, changes in fertilizer use. in pest management practices, in crop and animal husbandry, and so on. Parry does not directly estimate the effects of these various adaptations in

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Book reviews

offsetting climate change impacts. However, the adaptation possibilities presumably helped to shape his conclusion in Chapter 9 that although the projected climate change would have little effect on the level of global food production, the effect on production costs is ‘unclear’. But, Parry adds, the costs could be very high. To which this reviewer responds, yes, but they also could be very low. My response to Parry’s statement about possible cost effects is based in part on my judgement that the evidence he presents for climate change impacts on global agriculture as easily supports a conclusion that the costs could be low as one that they could be high. In addition, however, it is my belief that Parry gives insufficient weight to the role of adaptations in compensating for the adverse consequences of climate change. Parry is careful to note in a number of places that all the climate impact studies he reviews assume current technologies. And the only adaptations he considers are those that farmers could choose from among the current suite of technologies. But as the climate changes over the next several decades, scientists in agricultural research institutions can be expected to develop new technologies better adapted to the

emerging climate regime. Research at Resources for the Future on the effects of climate change on agriculture in the midwestern USA indicated that the process of adaptive technological response could virtually eliminate the negative impact of the kind of climate change Parry considers. ’ None of this detracts in any serious way from Martin Parry’s accomplishment with this book. It is essential reading for anyone who wants to be up to date on research on effects of climate change on world agriculture. Pierre Crosson Resources for the Future Washington, DC, USA ‘P.R. Crosson and L.A. Katz, with J. Wingard, Agricultural Production and Resource Use in the MINK Region Without and With Climate Change, Processes for identifying regional influences of and responses to increasing atmospheric CO2 and climate change (the MINK project), Report IIA, Resources for the Future, Washington, DC, 1991; W.E. Easterling III, M.S. McKenney, N.J. Rosenberg and K.L. Lemon, A Farm-Level Simulation of the Effects of Climate Change on Crop Productivity in the MINK Region, Processes for identifying regional influences of and responses to increasing atmospheric CO2 and climate change (the MINK project), Report IIB, Resources for the Future, Washington, DC, 1991.

Showing the promise of general equilibrium analysis MACROECONOMIC CONSEQUENCES OF FARM SUPPORT POLICIES edited by Andrew 6. Stoeckel, David Vincent and Sandy Cuthbertson Duke University Press, Durham, NC, and London, UK, 1989 Over the last 10 years there has been a substantial increase in quantitative analysis of agricultural protection. Major studies by the World Bank and the OECD have helped to highlight the heavy costs of current agricultural policies and their frequently disruptive effects on international markets.’ The monitoring of agricultural policies and

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their costs has become a major component of the OECD’s work on agriculture.’ This volume attempts to contribute further to public awareness of the costs of agricultural policies in order to stimulate pressure for reform. A number of national or regional computable general equilibrium (CGE) models are used to evaluate the macroeconomic impacts of agricultural protection. The primary focus is on the policies of industrial countries (the European Community, Japan and the USA), although there is a chapter on Korea. There is also a chapter which examines the impact of industrialcountry policies on various groupings of developing countries. The volume

contains a summary written by the editors which highlights the principal conclusions of the country and regional studies. The major lesson to be drawn from the volume is that agricultural protection is an implicit tax on nonagricultural sectors, and generally reduces national income. This point has been made by parallel analysis at the OECD.’ Protection is an expensive way of retaining jobs in agriculture. For the economy as a whole, rather than protecting jobs or wages, protectionist agricultural policies generate less employment or lower real wages. It is argued that if these negative effects were more widely appreciated a sizeable coalition of non-agricultural interests could be mobilized to press for the reform of agricultural policy. The view is expressed that the costs of protection provide strong justification for unilateral reform of policy, and consequently it is not necessary for countries to wait for multilateral agreement on reform through the GATT process. In fact, many of the models used in the book do not take into account the likely effects of multilateral reform on domestic markets. Some of the country chapters acknowledge that the negative impact on agriculture of reform could be reduced if countries were to act in concert, because world prices would rise to partially offset the decline in domestic subsidies. This argument was made in the OECD’s Ministerial Trade Mandate study and is supported by a number of related studies.4 A chapter by Loo and Tower pursues the point made in the World Bank’s 1986 World Development Report, and more recently by a joint OECDlWorld Bank study,5 that the reform of agricultural policies in industrial countries could lead to significant income gains for developing countries. This is despite possible higher costs for imported food. The popular argument of the 1960s that ‘trade is better than aid’ is supported by this analysis. The general equilibrium approach used is well suited to this argument and makes a significant contribution in this regard. As demonstrated by numerous partial equilibrium models, the agricultu-

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