Potential Irreversible Catastrophic Shifts of the Assimilative Capacity of the Environment

Pollution accumulation may result in more or less severe losses of natural self-cleaning capacities. We study a polluting resource management problem submitted to a potential shift from a high to a low pollution self-regeneration regime be crossed some critical pollution stock threshold. We rst describe the optimal resource exploitation policy absent the threshold. When at the threshold, the society has two options: either stabilizing the pollution level to avoid the loss of natural self-cleaning capacity or deliberately cross the threshold and switch to the low regeneration regime. We show under fairly general assumptions that there exists a unique critical pollution stock level such that thresholds located below this level will induce a switch from the high to the low regeneration regime while thresholds located above it will imply maintaining the high regime forever. We characterize the optimal policies in these two scenarios and show that triggering the low regeneration regime requires an upward jump of the resource consumption rate at the optimal switching time.

Endogenous growth and recycling : a material balance approach

In this paper we analyze the importance of recycling in the strive for sustainable development. In contrast to former approaches we emphasize the role of the waste stock as a source of valuable inputs. We enhance a Romer (1990) type endogenous growth model by a material balance condition that re°ects the circulation of matter in the economy. Di®erentiated intermediate products are produced from recycled waste and virgin resources. These material intermediates are then employed in the production of ¯nal output. They either end up as waste after consumption or are bound in the capital stock { depending on the utilization of the produced output. We show that, even in the absence of environmental policy, long-run development is sustainable in this economy. The intuition is, that, as waste is a valuable resource in our model, not recycling part of it, cannot be optimal in the long-run.non-renewable resources, recycling, endogenous growth, sustainable development

Ressource épuisable contre ressource renouvelable : le cas du gravier et du vin dans le Bordelais

L’exploitation d’une gravière a pour effet d’altérer irrémédiablement les potentialités économiques de la surface. Le gravier, ressource non renouvelable, est en concurrence avec le vignoble, ressource renouvelable. On examine l’allocation intertemporelle de ces deux ressources dans le cas de marchés concurrentiels parfaits.The exploitation of a gravel pit destroys the economic potentialities of its surface. Gravel, an exhaustible resource, competes with vineyard, a non exhaustible one. The intertemporal allocation of those two resources is examined here under the assumption of perfect competition

Optimal capture and sequestration from the carbon emission flow and from the atmospheric carbon stock with heterogeneous energy consuming sectors

We characterize the optimal exploitation paths of two primary energy resources. The first one is a non-renewable polluting resource, the second one a pollution-free renewable resource. Both resources can supply the energy needs of two sectors. Sector 1 is able to reduce the potential carbon emissions generated by its non-renewable energy consumption at a reasonable cost while sector 2 cannot. Another possibility is to capture the carbon spread in the atmosphere but at a significantly higher cost. We assume that the atmospheric carbon stock cannot exceed some given ceiling and that this constraint is effective. We show that there may exist paths along which it is optimal to begin by fully capturing the sector 1's potential emission flow before the ceiling constraint begins to be effective. Also there may exist optimal paths along which both capture devices have to be activated, in which case the potential emission flow of sector 1 is firrst fully abated and next the society must resort to the atmospheric carbon reducing device.