Suchergebnisse

One of the proposed alternatives to Kyoto's cap-and-trade approach is a regime based on an internationally harmonized carbon tax. In this paper, we consider and compare the enforcement problems associated with a tax regime and a cap-and-trade regime, respectively. The paper tries to convey two main points. First, both types of regime require an effective enforcement mechanism. However, such a mechanism is unlikely to be adopted as part of a regime with full participation, because the political process leading up to its adoption tends to water down the enforcement mechanism to a point where it no longer has much bite. And even if this is somehow avoided, countries expecting compliance to be difficult or costly will almost certainly decline to sign - not to mention ratify - the resulting agreement. Second, the implications of non-compliance in a tax regime differ in important ways from the corresponding implications in a cap-and-trade regime. In a cap-and-trade regime emissions trading can make inaction legitimate for buyers of emission permits. In particular, overselling of permits by one (or a few) permit exporting countries might completely undermine the regime's environmental effect. In a tax regime, by contrast, one country's non-compliance can not make inaction by other countries legitimate. It follows that an agreement based on a harmonized carbon tax will always have some effect, provided that at least one country complies.

AbstractLinkage of national cap-and-trade systems is typically advocated by economists on a general analogy with the beneficial linkage of free-trade areas and on the specific grounds that linkage will ensure cost effectiveness among the linked jurisdictions. The paper analyses the less obvious effects of linkage with the bottom–up approach of the Paris Agreement where each country sets its nationally determined contribution for its own carbon dioxide ($$\hbox {CO}_{2}$$CO2) emissions. An appropriate and widely accepted specification for the damages of $$\hbox {CO}_{2}$$CO2 emissions within a relatively short (say 5–10 year) period is that marginal damages for each jurisdiction are constant (although they can differ among jurisdictions). With this defensible assumption, the analysis is significantly clarified and yields simple closed-form expressions for all $$\hbox {CO}_{2}$$CO2 permit prices. Some implications for linked and unlinked voluntary $$\hbox {CO}_{2}$$CO2 cap-and-trade systems are derived and discussed. A numerical example illustrates the results.

Recent contributions show that climate agreements with broad participation can be implemented as weakly renegotiation-proof equilibria in simple models of greenhouse gas abatement where each country has a binary choice between cooperating (i.e., abate emissions) or defecting (no abatement). Here we show that this result carries over to a model where countries have a continuum of emission choices. Indeed, a Pareto-efficient climate agreement can always be implemented as a weakly renegotiation-proof equilibrium, for a sufficiently high discount factor. This means that one need not trade-off a 'narrow but deep' treaty with a 'broad but shallow' treaty.