Article 17 of the Kyoto Protocol allows Annex B parties to meet their commitments by trading greenhouse gas emissions reductions "supplemental" to domestic emissions control. We demonstrate that implementing supplementarity by imposing concrete ceilings on imports of allowances in a market for tradable emissions rights gives rise to monopsonistic effects, even with price-taking behavior by both buyers and sellers. We assess the importance of this finding for Annex B emissions trading, in the context of the import and export provisions of the recent EU Proposal on supplementarity. Our results show that the proposal would reduce efficiency, and could significantly alter the distribution of the gains from trade in an Annex B tradable permits market.

Since the introduction of motorized transportation systems, economic growth and advancing technology have allowed people and goods to travel farther and faster, steadily increasing the use of energy for transportation. Modern transportation systems are overwhelmingly powered by internal combustion engines fueled by petroleum. Emissions of carbon dioxide (CO₂), the principal greenhouse gas (GHG) produced by the transportation sector, have steadily increased along with travel, energy use, and oil imports. In the absence of any constraint or effective countermeasures, transportation energy use and GHG emissions will continue to increase.

In the U.S. economy, transportation is second only to electricity generation in terms of the volume and rate of growth of GHG emissions. In terms of carbon dioxide, which accounts for 95 percent of transportation's GHG emissions, transportation is the largest and fastest growing end-use sector.¹  Today, the U.S. transportation sector accounts for one-third of all U.S. end-use sector CO₂ emissions, and if projections hold, this share will rise to 36 percent by 2020. U.S. transportation is also a major emitter on a global scale. Each year it produces more CO₂ emissions than any other nation's entire economy, except China. Given its size and rate of growth, any serious GHG mitigation strategy must include the transportation sector.

This report evaluates potential CO₂ emission reductions from transportation in the United States. Measures considered include energy efficiency improvements, low-carbon alternative fuels, increasing the operating efficiency of the transportation system, and reducing travel. Highway vehicles should be the primary focus of policies to control GHG emissions, since they account for 72 percent of total transportation emissions. Passenger cars and light trucks together account for more than half of total sectoral emissions.

This paper compares major mobility variables from about 30 travel surveys in more than 10 countries. The analysis of cross-sectional and longitudinal data broadly confirms earlier findings of regularities in time and money expenditure shares for passenger travel (travel budgets). Despite the rather rough stability, travel demand characteristics, influenced by the two travel budgets, show strong regularities across space and time for all countries examined.

The response of the ocean's meridional overturning circulation (MOC) to increased greenhouse gas forcing is examined using a coupled model of intermediate complexity, including a dynamic 3D ocean subcomponent. Parameters are the increase in CO2 forcing (with stabilization after a specified time interval) and the model's climate sensitivity. In this model, the cessation of deep sinking in the north "Atlantic" (hereinafter, a "collapse"), as indicated by changes in the MOC, behaves like a simple bifurcation. The final surface air temperature (SAT) change, which is closely predicted by the product of the radiative forcing and the climate sensitivity, determines whether a collapse occurs. The initial transient response in SAT is largely a function of the forcing increase, with higher sensitivity runs exhibiting delayed behavior; accordingly, high CO2-low sensitivity scenarios can be assessed as a recovering or collapsing circulation shortly after stabilization, whereas low CO2-high sensitivity scenarios require several hundred additional years to make such a determination. We also systemically examine how the rate of forcing, for a given CO2 stabilization, affects the ocean response. In contrast with previous studies based on results using simpler ocean models, we find that except for a narrow range of marginally stable to marginally unstable scenarios, the forcing rate has little impact on whether the run collapses or recovers. In this narrow range, however, forcing increases on a time scale of slow ocean advective processes results in weaker declines in overturning strength and can permit a run to recover that would otherwise collapse.

© 2007 Springer