The purpose of this paper is to explore whether international income transfers can improve or worsen the global level of biodiversity and global social welfare by changing the relative contributions to biodiversity protection and to agricultural production. Because of the public good nature of biodiversity, Warr's neutrality theorem suggests that such transfers may have no effects at all (Warr, 1983). A model is developed, based on the simplifying assumption that northern countries have little biodiversity whereas southern countries are endowed with natural capital in the form of (generally unspoilt) biodiversity-rich land. Southern countries allocate optimally land and capital to two competing productive activities, agriculture and eco-tourism. When transfers are organized from the North to the South, we show that Warr's neutrality theorem collapses. Transfers can either reduce or increase the natural capital in the South, depending on some empirically verifiable hypotheses concerning the characteristics of the eco-tourism and agricultural production functions. In addition, we demonstrate that welfare improvements can be obtained even with reductions in the level of biodiversity.

Sustainable development must satisfy the needs of present generations without compromising the ability of future generations to meet theirs. Although it looks at the economic, environmental and social aspects of sustainability, this article focuses specifically on an analysis of the concept in conjunction with the use and protection of natural resources. It shows how taking account of environmental goods, including the finite nature of certain natural resources, can change the way economists deal with the issues of growth, development and equity between generations. In this context, after a brief historical perspective on the concept of development, the paper shows how the potential for substitutability between natural and manufactured capital, for example in production technologies, lead to two paradigms, that of weak sustainability and that of strong sustainability. These two approaches are presented in an effort to explain how their merits can be mutually reinforcing.

Faut-il s’inquiéter de l’érosion de la biodiversité ? Que peut-on y faire ? Un ensemble de travaux menés au sein de l’UMR LAMETA présentent la biodiversité comme une notion singulièrement complexe, dont la valeur ne se révèle correctement sur aucun marché. Les estimations partielles qu’on peut en faire par d’autres moyens montrent néanmoins son importance, mais sa protection n’est pas chose aisée. Parce que la biodiversité concerne largement des domaines privés, et aussi des Etats souverains pour lesquels la protection de la nature n’est pas (encore) une priorité, les approches règlementaires sont d’un secours limité. Il faut s’efforcer de mieux comprendre les forces sociales qui compromettent la biodiversité, et utiliser ces mêmes forces pour la préserver.

Should we worry about the erosion of biodiversity? What can be done? Several studies carried out within the joint research unit LAMETA present biodiversity as a rather complex notion, the value of which does not accurately appear on any market. However, the partial assessments that can be made through other means show its importance, but its preservation is no easy thing. Since biodiversity greatly concerns private properties and also sovereign States for which the protection of the nature is not (yet) a priority, the statutory approaches are of limited help. We must try to gain a better understanding of the social forces that compromise biodiversity and use these same forces to preserve it.