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Climate change and agriculture

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Climate change could widen the inequality between the developed and developing countries

GLOBAL WARMING AND AGRICULTURE — Impact Estimates by Country: William R. Cline; Published in arrangement with Peterson Institute of International Economics, Washington by Viva Books Pvt. Ltd., 4737/23, Ansari Road, Daryaganj, New Delhi-110002. Rs. 495.

K. S. Kavi Kumar

Climate change is now high on the political and public agenda. In the developing countries, special attention is being paid to the impact this global phenomenon will have on agriculture. This is because climate change has the potential to seriously affect the food security of a vast majority of the world’s poor. On the other hand, the northern latitude countries — mostly the developed countries — could benefit from the increased growing period due to increase in temperatures. Thus, climate change could contribute to the widening of inequality between the developed and the developing countries. Global studies focussing on agriculture so far have indicated that the climate change impact could be relatively minor in the first half of the 21st century and even beneficial for a few countries.

Approaches

This book, in a detailed analysis covering more than 100 countries, seeks to provide a more accurate assessment of the agriculture-related impact of climate change. Although the economic dimensions of the impact on agriculture have been studied rather extensively the world over, the subject continues to be a hotly debated one in the area of research. There are two broad approaches — agronomic-economic approach and the Ricardian approach. In the first, the physical impacts (namely, changes in yield and/or area) are assessed through detailed crop simulation exercises and the results are introduced into an economic model exogenously as Hicks neutral technical changes. Since the scope for adaptation is rather limited in the agronomic-economic approach, the Ricardian approach was evolved in mid-1990s as an alternative. This is similar to the Hedonic pricing approach adopted for environmental valuation. While all possible adaptations are accounted for in the impact estimation based on this largely statistical approach, the constant relative prices assumption could lead to biases. Thus, each approach has its own strengths and weaknesses. In this book, impact estimates based on both the approaches, available for countries across the world, have been used for the analysis.

Written in the format of a research report, this book stands apart from the rest in the depth of analysis and the rigour of treatment. The second chapter provides a detailed review of relevant literature, although some of the more recent important studies do not figure since it was written in 2007. Carbon dioxide, the key greenhouse gas responsible for climate change, can act as aerial fertilizer and boost crop yields. However, to benefit from this carbon fertilization effects, the crops must not be limited by other crucial inputs.

Some of these important issues concerning climate change and agricultural impacts are highlighted in the third chapter. Systematic climate projections are essential pre-requisites for accurate estimation of the impact. The fourth chapter elaborates on the methodology adopted for estimating the country-level temperature and precipitation projections for the 2080s based on the grid-level estimates arrived at from six climate models. Armed with the temperature and precipitation estimates and the climate response functions synthesised from available literature, the next chapter gives country-wise estimates of agricultural impacts that account for, and don’t account for, carbon fertilization effects. While the sixth chapter briefly discusses dynamical issues, the seventh presents the conclusions.

Methodology

The strengths of the book lie in its transparent methodology and wholesome presentation of the results — in the main text and several appendices — that enable further research in this crucial area of policy. However, the analysis is somewhat weak where it brings together the impact-results from the crop-models and the Ricardian approach. While the yield changes are taken from the crop-models, the changes in net-revenue (or land values) are picked up from the Ricardian studies.

In the analysis, the changes (in percentage terms) of these two are somewhat erroneously treated on a par, casting doubts on the validity of the overall impact estimations. While the detailed country-by-country impact estimates presented in the book are very relevant for identifying the vulnerable regions, the almost complete silence on adaptation issues makes the analysis less relevant from adaptation policy perspective.


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