Climate Change Economics

This paper discusses the size of impact of carbon motivated border tax adjustments on world trade and welfare. We report numerical simulation results which suggest that impacts on welfare, trade, and emissions will likely be small. This is because proposed measures use carbon emissions in the importing country in producing goods similar to imports rather than carbon content in calculating the size of barriers. Moreover, because border adjustments involve both tariffs and export rebates, it is the differences in emissions intensity across sector rather than emissions level which matters. Where there is no difference in emissions intensities across sectors, Lerner symmetry holds for the border adjustment and no relative effects occur.

Because ocean acidification has only recently been recognized as a problem caused by CO₂ emissions, impact studies are still rare and estimates of the economic impact are absent. This paper estimates the economic impact of ocean acidification on coral reefs which are generally considered to be economically as well as ecologically important ecosystems. First, we conduct an impact assessment in which atmospheric concentration of CO₂ is linked to ocean acidity causing coral reef area loss. Next, a meta-analytic value transfer is applied to determine the economic value of coral reefs around the world. Finally, these two analyses are combined to estimate the economic impact of ocean acidification on coral reefs for the four IPCC marker scenarios. We find that the annual economic impact rapidly escalates over time, because the scenarios have rapid economic growth in the relevant countries and coral reefs are a luxury good. Nonetheless, the annual value in 2100 in still only a fraction of total income, one order of magnitude smaller than the previously estimated impact of climate change. Although the estimated impact is uncertain, the estimated confidence interval spans one order of magnitude only. Future research should seek to extend the estimates presented here to other impacts of ocean acidification and investigate the implications of our findings for climate policy.

Using a multi-region and multi-sector computable general equilibrium model, this paper evaluates the border adjustment policies of carbon regulations in Japan. We consider five types of border adjustments and examine their effects on the welfare, carbon leakage, and competitiveness of the Japanese energy-intensive trade-exposed (EITE) sectors.

Our analysis shows that no single border adjustment policy is superior to the other policies in terms of simultaneously solving three primary issues: Welfare degradation, carbon leakage, and a loss of competitiveness in the EITE sectors. In addition, we show that export border adjustments are effective at restoring the competitiveness of Japanese exporters and reducing leakage. Our analysis also reveals that border adjustment in Japan significantly affects carbon leakage to China and the competitiveness of the iron and steel sectors. Finally, we show that border adjustments with and without consideration of indirect emissions have similar impacts, which indicates that the information regarding direct emissions is sufficient for implementing border adjustment in Japan.

We investigate the importance of explicitly accounting for uncertainty in the determination of optimal global climate policy. We demonstrate that the marginal risk premium determines the importance of adapting the optimal policy to uncertainty. Common integrated assessment models (IAM) of climate change suggest uncertainty has little effect because the marginal risk premium in these models is small. A rigorous investigation of the marginal risk premium and the marginal functional relationships within IAMs allows understanding the non-significance of (thin-tailed) uncertainty as a result of compensating factors in the climate cause-effect chain.