Ambiguity reduction by objective model selection, with an application to the costs of the EU 2030 climate targets

I estimate the cost of meeting the EU 2030 targets for greenhouse gas emission reduction, using statistical emulators of ten alternative models. Assuming a first-best policy implementation, I find that total and marginal costs are modest. The statistical emulators allow me to compute the risk premiums, which are small, because the EU is rich and the policy impact is small. The ensemble of ten models allows me to compute the ambiguity premium, which is small for the same reason. I construct a counterfactual estimate of recent emissions without the climate policy and use that to test the predictive skill of the ten models. The models that show the lowest cost of emission reduction also have the lowest skill for Europe in recent times

THE DOUBLE TRADE-OFF BETWEEN ADAPTATION AND MITIGATION FOR SEA LEVEL RISE: AN APPLICATION OF FUND

The effects of adaptation and mitigation on the impacts of sea level rise are studied. Without either, the impacts of sea level rise would be substantial, almost wiping out entire nations before 2100; the global effect is much smaller. Adaptation would reduce impacts by a factor 10 to 100. As adaptation depends on socio-economic status, the rank order of most vulnerable countries is not the same as the rank order of most exposed countries. Adaptation would come at a minor cost compared to the damage avoided. Because the momentum of sea level rise is so large, mitigation can reduce impacts only to a limited extent. Stabilising carbon dioxide concentrations at 550 ppm would cut impacts up to 2100 by about 10%. However, if the costs of emission reduction are also factored in, then avoided impacts are less by up to 25% (average 10%). This is partly due to the reduced availability of resources for adaptation, and partly due to the increased sensitivity to wetland loss by adaptation.Sea level rise, mitigation, adaptation

OF THE H-INDEX AND ITS ALTERNATIVES: AN APPLICATION TO THE 100 MOST PROLIFIC ECONOMISTS

The h-index is a recent but already quite popular way of measuring research quality and quantity. However, it discounts highly-cited papers. The g-index corrects for this, but it is sensitivity to the number of never-cited papers. Besides, h- or g-index-based rankings have a large number of ties. Therefore, this paper introduces two new indices, and tests their performance for the 100 most prolific economists. A researcher has a t-number (f-number) of t (f) if t (f) is the largest number for which it holds that she has t (f) publications for which the geometric (harmonic) average number of citations is at least t (f). The new indices overcome the shortcomings of the old indices.rankings

EXCHANGE RATES AND CLIMATE CHANGE: AN APPLICATION OF FUND

As economic and emissions scenarios assume convergence of per capita incomes, they are sensitivity to the exchange rate used for international comparison. Particularly, developing countries grow slower with a purchasing power exchange rate than with a market exchange rate. Different exchange rates may lead to scenarios with very different per capita income. However, these scenarios also assume convergence of energy intensities, which at least partly offsets the income effect, so that scenarios with different exchange rates would differ less in greenhouse gas emissions. Differences become smaller still if atmospheric concentrations and global warming is considered. However, differences become larger again if one considers the costs of meeting a certain stabilisation target, as the gap between baseline and target is more sensitive to the exchange rate used than the baseline itself. Differences also grow larger if one looks at climate change impacts, which are determined not just by climate change but also by development. The sensitivity to the exchange rate is purely due to imperfect data, imperfect statistical analysis of data, a crude spatial resolution, and imperfect models.Climate change, emissions scenarios, purchasing power parity, market exchange rate

ADAPTATION AND MITIGATION: TRADE-OFFS IN SUBSTANCE AND METHODS

climate change, adaptation, mitigation

Is the Uncertainty about Climate Change Too Large for Expected Cost-Benefit Analysis?

Cost-benefit analysis is only applicable if the variances of both costs and benefits are finite. In the case of climate change, the variances of the net present marginal costs and benefits of greenhouse gas emission reduction need to be finite. Finiteness is hard, if not impossible to prove. The opposite is easier to establish as one needs to shows that there is one, not impossible representation of the climate change with infinite variance. The paper shows that all relevant current variables of the FUND model have finite variances. However, there is a small chance that climate change reverses economic growth in some regions. In that case, the discount rate becomes negative and the net present marginal benefits of greenhouse gas emission reduction becomes very large. So large, that its variance is unbounded.Climate change, cost-benefit analysis, uncertainty

The Impact of a Carbon Tax on International Tourism

A simulation model of international tourist flows is used to estimate the impact of a carbon tax on aviation fuel. The effect of the tax on travel behaviour is small: a global $1000/tC would change travel behaviour to reduce carbon dioxide emissions from international aviation by 0.8$1000/tC tax would less than double air fares, and have a smaller impact on the total cost of the holiday. In addition, the price elasticity is low. A carbon tax on aviation fuel would particularly affect long-haul flights, because of high emissions, and short-haul flights, because of the emission during take-off and landing. Medium distance flights would be affected least. This implies that tourist destinations that rely heavily on short-haul flights (that is, islands near continents, such as Ireland) or on intercontinental flights (e.g., Africa) will see a decline in international tourism numbers, while other destinations may see international arrivals rise. If the tax is only applied to the European Union, EU tourists would stay closer to home so that EU tourism would grow at the expense of other destinations. Sensitivity analyses reveal that the qualitative insights are robust. A carbon tax on aviation fuel would have little effect on international tourism, and little effect on emissions.International Tourism, Tax, Carbon Dioxide, Aviation

MULTI-GAS EMISSION REDUCTION FOR CLIMATE CHANGE POLICY: AN APPLICATION OF FUND

The costs of greenhouse gas emission reduction are investigated with abatement of carbon dioxide, methane, and nitrous oxide using the FUND model. The central policy scenario keeps anthropogenic radiative forcing below 4.5 Wm-2. If CO2 emission reduction were the only possibility to meet this target, the net present value of consumption losses would be $45 trillion; with abatement of the other gases added, costs fall to$33 trillion. The bulk of these costs savings can be ascribed to nitrous oxide. Because nitrous oxide is so much more important than methane, the choice of equivalence metric between the greenhouse gases does not matter much. Sensitivity analyses show that the shape of the cost curves for CH4 and N2O emission reduction matters, and that the inclusion of SO2 and sulphate aerosols make policy targets substantially harder to achieve. The costs of emission reduction vary greatly with the choice of stabilisation target. A target of 4.5 Wm-2 is not justified by our current knowledge of the damage costs of climate change.Climate change, emission reduction, carbon dioxide, methane, nitrous oxide

A RATIONAL, SUCCESSIVE G-INDEX APPLIED TO ECONOMICS DEPARTMENTS IN IRELAND

A rational, successive g-index is proposed, and applied to economics departments in Ireland. The successive g-index has greater discriminatory power than the successive h-index, and the rational index performs better still. The rational, successive g-index is also more robust to difference in department size.rankings, individuals, departments

THE IMPACT OF A CARBON TAX ON INTERNATIONAL TOURISM

A simulation model of international tourist flows is used to estimate the impact of a carbon tax on aviation fuel. The effect of the tax on travel behaviour is small: A global $1000/tC would change travel behaviour to reduce carbon dioxide emissions from international aviation by 0.8$1000/tC tax would less than double air fares, and have a smaller impact on the total cost of the holiday. In addition, the price elasticity is low. A carbon tax on aviation fuel would particularly affect long-haul flights, because of high emissions, and short-haul flights, because of the emission during take-off and landing. Medium distance flights would be affected least. This implies that tourist destinations that rely heavily on short-haul flights (that is, islands near continents, such as Ireland) or on intercontinental flights (e.g., Africa) will see a decline in international tourism numbers, while other destinations may see international arrivals rise. If the tax is only applied to the European Union, EU tourists would stay closer to home so that EU tourism would grow at the expense of other destinations. Sensitivity analyses reveal that the qualitative insights are robust. A carbon tax on aviation fuel would have little effect on international tourism, and little effect on emissions.International tourism, tax, carbon dioxide, aviation