M. Robert Mendelsohn, professeur à la Yale School of Forestry and Environmental Studies, États-Unis, vient d'achever un séjour de trois mois à la FAO en qualité d'expert invité. Il a participé aux activités en cours en mettant au point les méthodes améliorées évaluant l'incidence économique des changements climatiques sur les pays en développement, principal groupe désigné bénéficiaire des activités de l'Organisation. La méthode suivie par M. Mendelsohn et par d'autres s'inscrit dans la «deuxième vague» de recherches sur les effets du réchauffement de la planète entreprises dans les années 90. Ces nouvelles études analysent la façon dont les agriculteurs s'adaptent au changement climatique et notamment aux variations de température et de précipitations. Les agriculteurs ont en particulier recours à des techniques consistant par exemple à modifier les dates des semis, recourir à de nouvelles pratiques de labour et adopter d'autres variétés.
Recientemente concluyó una misión de tres meses como científico visitante en la FAO Robert Mendelson, profesor de la Escuela de Yale de Estudios Forestales y Medioambientales. Su labor sirvió para complementar las actividades en marcha identificando metodologías mejoradas para evaluar el impacto económico del cambio climático en los países en desarrollo, uno de los objetivos principales de las actividades de la Organización. El método adoptado por Mendelson y otros es una aportación a una segunda «oleada» de investigación sobre los efectos del calentamiento mundial que se está llevando a cabo en la década de los noventa. Estos nuevos estudios tratan de la adaptación del agricultor al cambio climático, especialmente de la forma en que estos se ajustan a los cambios de temperatura y de precipitaciones. Las técnicas que emplean los agricultores incluyen el cambio de la fecha de siembra, prácticas de cultivo y variedades.
During the last 12 or so years, FAO has developed a strong interest in climate change issues. Owing to the complexity and the interdisciplinary nature of the issue, climate change is dealt with in FAO by a cross-departmental group spanning the Sustainable Development, Agriculture, Forestry, Fisheries and Economic and Social Departments and the Legal Office.
Robert Mendelsohn, a professor at Yale School of Forestry and Environmental Studies, United States, recently completed a three-month assignment at FAO as a visiting scholar.
Visiting expert Robert Mendelsohn at FAO headquarters |
The approach taken by Mendelsohn and others contributes to a "second wave" of research on the effects of global warming that has been undertaken in the 1990s. These new studies look at farmer adaptation to climate change, especially how farmers adjust to changing temperature and precipitation. The techniques farmers use include changing planting dates, tilling practices and crop varieties.
The speed with which farmers adopt a new technology is another important aspect of these studies, as its use in developing countries is seen to be reducing some of the potential damage caused by global change. Agriculture could also be helped by higher CO2 levels, which have been found to increase productivity (carbon fertilization), and by reduced water consumption, another consequence of increased CO2 concentrations.
The results of recent research on climate change paint a less alarming picture than the first findings on the "greenhouse effect" in the early 1980s. "Over the last decade, climate science has changed, suggesting less dramatic scenarios of climate change. Furthermore, a less gloomy overall picture emerges from the more comprehensive research that has been done. Not only are natural scientists suggesting less severe outcomes, but economists' research findings indicate that economic systems can adapt to a much greater extent than was previously thought," says Mendelsohn.
Although it is highly uncertain just how climate will change in different areas during the next century, the temperate and polar regions are seen as benefiting from warming, while the tropics, especially arid tropical regions in Africa, are likely to be adversely affected. It is possible that the climates of some countries may be transformed.
Nevertheless, scientists are now predicting that a mild warming will have a beneficial effect on the world's aggregate food scenario; the total amount of food production is likely to be robust with respect to climate change. In developed countries, productivity will probably increase as a result of global warming, with any reductions in crop yield being more than offset by farmer adaptations and carbon fertilization.
Because they tend to be less capital- and technology-intensive and because they are very vulnerable to today's weather variability, developing countries' agricultural systems are likely to be even more vulnerable to climate change. Moreover, within countries, some regions may be adversely affected by climate change, while others may benefit.
It is FAO's mission to assist agriculture in the developing world. To date, however, only a handful of studies have been carried out on the probable effect of climate change on agriculture in the developing world. Current FAO models could easily be adapted to evaluate the climate change impact and FAO, therefore, has an important role to play in extending research into regions such as Africa, where data are meagre, to provide a comprehensive picture of what may happen.
As Mendelsohn says, "For developing countries, it is important to have models that can predict what will happen to actual yields, given climate change. By explaining what will happen, the new research can help link policy and science more firmly."