We develop a model that accounts for the decay of the average contribution observed in experiments on voluntary contributions to a public good. The novel idea is that people's moral motivation is "weak"". Their judgment about the right contribution depends on observed contributions by group...

Afforestation is a cost-effective way for some countries to meet part of their commitments under the Kyoto Protocol and its eventual extensions. Credits for carbon sequestration can be mediated through markets for emissions permits. Both new and old forests are subject to pestilence and fire,...

It is possible to make a current valuation of the effects of carbon dioxide which tracks a valuation done under the metric of expected present value and also tracks realized values. The implementation of a carbon credit scheme based on green accounting could go as follows: L'évaluation des...