JP

Non-Nuclear, Low-Carbon, or Both? The Case of Taiwan

The Fukushima nuclear accident in Japan has renewed debates on the safety of nuclear power, possibly hurting the role of nuclear power in efforts to limit CO2 emissions. I develop a dynamic economy-wide model of Taiwan with a detailed set of technology options in the power sector to examine the implications of adopting different nuclear power policies on CO2 emissions and the economy. Absent a carbon mitigation target, limiting nuclear power has a small economic cost for Taiwan, but CO2 emissions may increase by more than 3.5% by 2035 when nuclear is replaced by fossil-based generation. With a low-carbon target of a 50% reduction from year 2000 levels by 2050, if the nuclear option and carbon sequestration are not viable, gas-fired power would provide almost 90% of electricity output due to the limited renewable resources. In particular, wind power would account for 1.6% to 4.9% of that output, depending on how it relies on other back-up capacities. With both non-nuclear and low-carbon policies, deploying carbon sequestration on fossil-based generation can significantly reduce the negative GDP impact on the economy. Lastly, lowering carbon mitigation costs further is possible with expanded nuclear capacity.

Nonlinear Effects of Coexisting Surface and Atmospheric Forcing of Anthropogenic Absorbing Aerosols: Impact on the South Asian Monsoon Onset

The direct radiative effect of absorbing aerosols consists of absorption-induced atmospheric heating together with scattering- and absorption-induced surface cooling. It is thus important to understand whether some of the reported climate impacts of anthropogenic absorbing aerosols are mainly due to the coexistence of these two opposite effects and to what extent the nonlinearity raised from such coexistence would become a critical factor. To answer these questions specifically regarding the South Asia summer monsoon with focus on aerosol-induced changes in monsoon onset, a set of century-long simulations using the Community Earth System Model, version 1.0.3 (CESM 1.0.3), of NCAR with fully coupled atmosphere and ocean components was conducted. Prescribed direct heating to the atmosphere and cooling to the surface were applied in the simulations over the Indian subcontinent, either alone or combined, during the aerosol-laden months of May and June. Over many places in the Indian subcontinent, the nonlinear effect dominates in the changes of subcloud layer moist static energy, precipitation, and monsoon onset. The surface cooling effect of aerosols appears to shift anomalous precipitative cooling away from the aerosol-forcing region and hence turn the negative feedback to aerosol-induced atmospheric heating into a positive feedback on the monsoon circulation through latent heat release over the Himalayan foothills. Moisture processes form the critical chain mediating local aerosol direct effects and onset changes in the monsoon system.

© 2013 American Meteorological Society

Nuclear exit, the US energy mix, and carbon dioxide emissions

If the United States were to adopt a policy to phase out nuclear generation, as has happened recently in other developed countries, what would the environmental and energy-mix implications be? Based on alternative scenarios of nuclear exit that consider the influence of potential policies to limit greenhouse gas emissions, a model of the US and global economy indicates that, under current policy, a US nuclear exit would increase carbon dioxide emissions, and likely raise electricity prices and reduce gross domestic product by relatively small amounts. Those economic impacts would be increased by additional measures to limit carbon dioxide emissions.

© 2013 the authors

Nutrient supply ratios and nitrogen fixation define biogeochemical provinces

Phytoplankton productivity is regulated by the ocean nitrogen inventory. Over long timescales fixed nitrogen is removed by denitrification, but this loss is balanced to some extent by biological fixation of dissolved nitrogen gas. Although the global distribution and productivity of nitrogen fixing organisms has been shown to be influenced by the availability of nitrogen, phosphorus and iron, the complex behaviour of the system as a whole is not yet fully understood. Here we present a simplified ecological theory that predicts the global distribution of nitrogen fixers, and explains observed global variability in surface nitrate, phosphate and iron. The model unites prior observations and previously conflicting theories. Using the theory to divide the ocean into four observable provinces, we make testable predictions regarding how ocean ecology and biogeochemistry are controlled by atmospheric iron deposition and oceanic nutrient supply. Our model provides a consistent quantitative framework through which we may better understand the ecological niche of nitrogen fixers, and their potential role in regulating Earth's climate.

Off-line algorithm for calculation of vertical tracer transport in the troposphere due to deep convection

A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical transport within the scheme includes entrainment and detrainment processes in convective updrafts and downdrafts. Output from the proposed parametrisation scheme is employed in the National Institute for Environmental Studies (NIES) global chemical transport model driven by JRA-25/JCDAS reanalysis. The simulated convective precipitation rate and mass fluxes are compared with observations and reanalysis data. A simulation of the short-lived tracer 222Rn is used to further evaluate the performance of the cumulus convection scheme. Simulated distributions of 222Rn are evaluated against observations at the surface and in the free troposphere, and compared with output from models that participated in the TransCom-CH4 Transport Model Intercomparison. From this comparison, we demonstrate that the proposed convective scheme in general is consistent with observed and modeled results.

2013 the authors

Out of Passivity: Potential Role of OFDI in IFDI-based Learning Trajectory

This study discusses how outward foreign direct investment (FDI) can complement the inward FDI-based technological capability-building process, through an analysis of the Shanghai Automotive Industry Corporation case. When a firm is upgrading its technological capability, outward FDI can allow learners to have access to human-embedded skills and knowledge and other intellectual assets that are hardly accessible through the inward globalization strategy. Access to a wide range of external resources is a critical ingredient for improving technological capability, and it can also promote self-learning capability by encouraging subsequent learning-by-doing practices. Accordingly, outward FDI can augment “active” nature in the “passive” learning mode created by the inward globalization strategy.

© 2012 Authors

Passenger Transport in China Under Climate Constraints: General Equilibrium Analysis, Uncertainty, and Policy

Vehicle sales and road travel volume in China have grown rapidly in recent years, and with them energy demand, greenhouse gas emissions and local air pollution. Aviation and rail travel have also grown, while ceding a large share to private vehicles. What path will household transport demand in China take in the future? How might it interact with policies which limit greenhouse gases, and what are the implications for energy use, the environment and the economy? To contribute policy insights and a foundation for future study in this area, I undertake a new calibration of the Chinese household transport sector in the MIT Emissions Prediction & Policy Analysis (EPPA) computable general equilibrium (CGE) model, implementing income elasticities of demand for vehicle travel and vehicle stock growth based on historical data. To bracket uncertainty in the literature, I impose three scenarios of future growth in demand for purchased (air, rail and marine) and vehicle modes. These are explored under a no-policy baseline, a climate-stabilization policy, and with a policy that extends the emissions-intensity goal of China’s Twelfth Five-Year Plan—both policies are modelled as caps creating prices on carbon. Examining the results, I find that trends in growth are only modesty affected by policy continuing present energy-intensity goals, with small decreases in travel activity and energy intensity of vehicles combining for a reduction in refined oil use; such a policy has modest cost and affects household transport less than other sectors. In contrast, my results show that a stringent emissions cap has large impacts on vehicle efficiency, limits vehicle ownership and general travel activity levels. Compared to the no-policy baseline, a smaller vehicle fleet (250 million total, or 200 per 1000 capita). Sixteen percent of the fleet is new energy vehicles (plug-in hybrid-electrics), while total refined oil use increases by 2050 to nearly three times its 2010 level. However, these effects come with a reduction in total primary energy as the policy is introduced, and large costs economy-wide. Chinese national and municipal policies include objectives of promoting vehicle ownership and mobility on the one hand, and of reducing dependence on carbon-intensive refined oil on the other. My findings illustrate that 3 these goals are at odds, and offer inputs to policy design related to vehicle sales, public transit, congestion, pollution and energy security.

Per-capita income, consumption patterns and CO2 emissions

This paper investigates the importance of per-capita income and the sectoral composition of consumption as determinants for the level and evolution of carbon dioxide (CO2) emissions across countries. It is based on the model and estimation strategy in Caron, Fally and Markusen (2012) which allows the identification of the income elasticity of consumption by controlling for cross-country price differences which are inferred from bilateral trade flows.

At the sector-level, we find a statistically significant negative correlation between income elasticity and the total CO2 intensity of production. At the country-level, the data exhibits an inverted-U relationship between per-capita income and the average CO2 content of both consumption and production. The relationship holds when evaluated using average production intensities and is thus partially generated by differences in consumption patterns. In turn, we find these differences to be explained by per-capita income levels. Importantly, the link is much weaker for the total CO2 content of consumption than for the direct content, as total energy demand is more income-elastic than direct household consumption.

This finding implies a modest scope for per-capita income growth to reduce aggregate CO2 emission intensity purely through its impact on consumption shares. We estimate the elasticity of the average total CO2 content of worldwide consumption (which equals that of production) to per-capita income to be only -0.06, with, however, larger reductions in rich countries.

Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback

Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, we examine the degradation of near-surface permafrost, temporal dynamics of inundation (lakes and wetlands) induced by hydro-climatic change, subsequent methane emission, and potential climate feedback. We find that increases in atmospheric CH4 and its radiative forcing, which result from the thawed, inundated emission sources, are small, particularly when weighed against human emissions. The additional warming, across the range of climate policy and uncertainties in the climate-system response, would be no greater than 0.1 ° C by 2100. Further, for this temperature feedback to be doubled (to approximately 0.2 ° C) by 2100, at least a 25-fold increase in the methane emission that results from the estimated permafrost degradation would be required. Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions.

© 2013 the authors

Permafrost, Lakes, and Climate-Warming Methane Feedback: What is the Worst We Can Expect?

Permafrost degradation is likely enhanced by climate warming. Subsequent landscape subsidence and hydrologic changes support expansion of lakes and wetlands. Their anaerobic environments can act as strong emission sources of methane and thus represent a positive feedback to climate warming. Using an integrated earth-system model framework, which considers the range of policy and uncertainty in climatechange projections, we examine the influence of near-surface permafrost thaw on the prevalence of lakes, its subsequent methane emission, and potential feedback under climate warming. We find that increases in atmospheric CH4 and radiative forcing from increased lake CH4 emissions are small, particularly when weighed against unconstrained human emissions. The additional warming from these methane sources, across the range of climate policy and response, is no greater than 0.1C by 2100. Further, for this temperature feedback to be discernable by 2100 would require at least an order of magnitude larger methaneemission response. Overall, the biogeochemical climate-warming feedback from boreal and Arctic lake emissions is relatively small whether or not humans choose to constrain global emissions.

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