4 présentations

• 
  14h00 - 14h30

  Information structures and environmental agreements

  • Samar Garrab, prés., Royal Military College of Canada

  We consider international agreements for the protection of the environment where the signatories agree to cooperate in order to determine the level of their joint emissions. In a stylized model, we evaluate the impact of two information structures on the stability of an International Environmental Agreement (IEA) over time. We, first, analyze the impact of signatories’ leadership on the steady-state pollution stock and the corresponding size of the internally and externally stable coalition. We, then, consider the impact of taking into consideration the pollution stock dynamics and the evolution of the coalition size by all players in the decision making process as well as in the corresponding steady-state values.

• 
  14h30 - 15h00

  Self enforcing environmental agreements, taxes and delayed information in a continuous time Fish Wars model

  • Rajani Singh, prés., University of Warsaw
  • Agnieszka Wiszniewska-Matyszkiel, Institute of Applied Mathematics and Mechanics, Warsaw University

  In this paper, we analyse a continuous time version of Fish Wars with the infinite time horizon and state-dependent constraints on controls. We calculate the social optimum and a Nash equilibrium which always leads to the depletion of the resource even if the social optimum results in the sustainability. We propose two ways of solving the problems of enforcing optimality: either by a tax-subsidy system or by an environmental agreement even if we assume that it takes time to detect any defection of a player. We also propose a general algorithm of finding financial incentives enforcing the optimal profile in a large class of differential games.

• 
  15h00 - 15h30

  Ecosystem dynamics and fishing management scenarios for the coastal fishery in French Guiana

  • Coralie Kersulec, prés., GREThA

  We apply an ecosystem-based fishery management approach on the small-scale fishery of French Guiana. To achieve this, we rely on a multi-species, multi-fleet model inspired by Ecosim. The model is calibrated using data (provided by IFREMER) of fishing landings and efforts from 2006 to 2017 for 13 species and 4 fleets. The calibration exhibits the importance of illegal fishing (Suriman, Brazil) in the ecosystem dynamic. From the calibrated model, we contrast different fishing management scenarios at the horizon 2050 including a status quo scenario and closure scenario.

• 
  15h30 - 16h00

  Recycling under environmental, climate and resource constraints

  • Etienne Lorang, prés., CEC / INRA
  • Gilles Lafforgue, Toulouse Business School

  We study the recycling opportunity of an industrial sector constrained by climate, resource and waste capacities. A final good is produced from virgin and recycled materials, and its consumption releases waste and GHG emissions. We identify the optimal trajectories of resources use, mainly depending on the emission rates of each resource and by the relative scarcity of their stocks. Recycling is sometimes an opportunity to reduce the impact of consumption on primary resources and waste but can still affect the environment. Last, we show that the emissions ceiling and recovery rates are complementary to improve the environmental efficiency.