Declining Discount Rates: The Long and the Short of it

The last few years have witnessed important advances in our understanding of time preference and social discounting. In particular, several rationales for the use of time-varying social discount rates have emerged. These rationales range from the ad hoc to the formal, with some founded solely in economic theory while others reflect principles of intergenerational equity. While these advances are to be applauded, the practitioner is left with a confusing array of rationales and the sense that almost any discount rate can be justified. This paper draws together these different strands and provides a critical review of past and present contributions to this literature. In addition to this we highlight some of the problems with employing DDRs in the decision-making process, the most pressing of which may be time inconsistency. We clarify their practical implications, and potential pitfalls, of the more credible rationales and argue that some approaches popular in environmental economics literature are ill-conceived. Finally, we illustrate the impact of different approaches by examining global warming and nuclear power investment. This includes an application and extension of Newell and Pizer [‘Discounting the benefits of climate change mitigation : how much do uncertain rates increase valuations?’ Journal of Environmental Economics and Management 46 (2003) 52] to UK interest rate data.     

Behavioural Economics,Hyperbolic Discounting and Environmental Policy

This paper reviews some recent research in “behavioural economics” with an application to environmental issues. Empirical results from behavioural economics provide a reminder that human behaviour is context-dependent, implying that policy may go awry if based upon models of behaviour which are inappropriate to the contexts in which decisions are made. Recognizing that agents may, in some contexts, systematically make mistakes raises challenging questions about the role of “paternalism” in government policy. The paper considers the research into hyperbolic discounting, and examines the implications for environmental policy. We develop a model of resource management under hyperbolic discounting, which shows that if a planner is unable to commit to a policy, the temptation to re-evaluate the policy in future could lead to an inadvertent collapse in the stocks of a natural resource.     

The future of Europe - and Britain's economic future in Europe: the perspective of a Europe-based multinational

The paper asks why Europe matters, what a company like Unilever wants from Europe, what developments will deliver these conditions and whether it matters if Britain is in or out of Europe. It concludes that the most important benefit from Europe has been the Single Market. Developments which promote it such as EMU should be supported but other economic issues such as competitiveness and unemployment also need to be addressed. The benefits of the Single Market can most easily be secured inside Europe.     

Equity weighting and the marginal damage costs of climate change

Climate change will give rise to different impacts in different countries, and different countries have different levels of development. Equity-weighted estimates of the (marginal) impact of greenhouse gas emissions reflect these differences. This paper analyses the impact of equity weighting on the marginal damage cost of carbon dioxide emissions, and reaches four main conclusions. First, equity-weighted estimates are substantially higher than estimates without equity-weights; equity-weights may even change the sign of the social cost estimates. Second, estimates differ by two orders of magnitude depending on the region to which the equity weights are normalised. Third, equity-weighted estimates are sensitive to the resolution of the impact estimates. Depending on the assumed intra-regional income distribution, estimates may be more than twice as high if national rather than regional impacts are aggregated. Fourth, variations in the assumed inequality aversion have different impacts in different scenarios, not only because different scenarios have different emissions and hence warming, but also because different scenarios have different income differences, different growth rates, and different vulnerabilities.     

Regulation by Prices, Quantities, or Both: A Review of Instrument Choice

Choosing appropriate policy instruments is an important partof successful regulation. Once objectives are agreed and suitabletargets adopted, policy-makers can employ command-and-controlregulation and/or economic instruments, and choose between fixinga price or a quantity. This paper examines the relative advantagesof price, quantity, and hybrid instruments according to: theirefficiency under uncertainty; the trade-off between crediblecommitment and flexibility; implementation; international considerations;and political economy. Various illustrations of the theory areprovided, with two detailed applications to climate change andtransport policy, specifically congestion and ‘safetypricing’. Footnotes ¹ E-mail address: cameron.hepburn{at}economics.ox.ac.uk     

Credible Carbon Policy

The paper sets out the credibility problem in carbon policy,provides a number of examples of non-credibility in recent energypolicy, and identifies the costs of failing to address it. Thetime inconsistency of carbon policy—arising because ofmultiple objectives, the irreversibility of energy investments,and the scope for ex-post reneging on ex-ante commitments toset policy instruments, such as carbon taxes or emission permits,at appropriate levels—is set in a conceptual framework.Analogies with monetary policy are drawn, and a solution tothe time-inconsistency problem is proposed through the establishmentof an energy/carbon agency.     

Estimates of Cash-Based Income Tax Evasion in Australia

This article provides new estimates of the size of the cash economy in Australia over the period from 1950–51 to 1989–90. This series is used to estimate income tax revenue losses for each year and to examine the factors which influence the incentive to evade income tax.     

Resilient and Inclusive Prosperity within Planetary Boundaries

The current model of economic growth generated unprecedented increases in human wealth and prosperity during the 19th and 2Oth centuries. The main mechanisms have been the rapid pace of technological and social innovation, human capital accumulation, and the conversion of resources and natural capital into more valuable forms of produced capital. However, there is evidence emerging that this model may be approaching environmental limits and planetary boundaries, and that the conversion of natural capital needs to slow down rapidly and then be reversed Some commentators have asserted that in order for this to occur, we will need to stop growing altogether and, instead, seek prosperity without growth. Others argue that environmental concerns are low-priority luxuries to be contemplated once global growth has properly returned to levels observed prior to the 2008 financial crisis. A third group argues that there is no trade-off and, instead,, promotes green growth： the （politically appealing） idea is that we can simultaneously grow and address our environmental problems. This paper provides a critical perspective on this debate and suggests that asubstantial researc＇h agenda is required to come to grips with these challenges. One place to start is with the relevant metrics： measures of per-capitawealth, and, eventually, quantitative measures of prosperity, alongside a dashboard of other sustainability indicators. A public andpoliticalfocus on wealth （a stock）, and its annual changes, could realistically complement the current focus on market-based gross output as measured by GDP （a flow）. This could have important policy implications, but deeper changes to governance and business models will be required.