A cap-and-trade program, as is used in the European Trading Scheme, is currently the most widely discussed method in the US for reducing greenhouse gases. A basic cap-and-trade program operates by mandating a fixed level of emissions for a given period, issuing permits, and then allowing a market for those permits to develop. The resulting market price for emissions permits, and hence the economic impacts of the chosen policy, can only be estimated in advance with a high degree of uncertainty. Many of the current US cap-and-trade proposals contain provisions for cost-containment instruments which reduce the possible range of emissions prices. This paper analyzes the relative effectiveness of three such cost-containment instruments, including a safety valve, an intensity target, and banking and borrowing. The results presented rely on two computable general equilibrium models developed at the Massachusetts Institute of Technology, and show the predicted performance of these instruments under a simulated range of economic outcomes.

Development of regional policies to reduce net emissions of carbon dioxide (CO2) would benefit from the quantification of the major components of the region’s carbon balance fossil fuel CO2 emissions and net fluxes between land ecosystems and the atmosphere. Through spatially detailed inventories of fossil fuel CO2 emissions and a terrestrial biogeochemistry model, we produce the first estimate of regional carbon balance for the Northeast United States between 2001 and 2005. Our analysis reveals that the region was a net carbon source of 259 Tg C/yr over this period. Carbon sequestration by land ecosystems across the region, mainly forests, compensated for about 6% of the region’s fossil fuel emissions. Actions that reduce fossil fuel CO2 emissions are key to improving the region’s carbon balance. Careful management of forested lands will be required to protect their role as a net carbon sink and a provider of important ecosystem services such as water purification, erosion control, wildlife habitat and diversity, and scenic landscapes.

© 2013 American Chemical Society

A three-dimensional ocean model with an idealized global geometry and coarse resolution coupled to a two-dimensional (zonal-mean) statistical-dynamical atmospheric model is used to investigate the response to the increasing CO2 concentration in the atmosphere. Long-term present-day climate simulations with and without asynchronous integration in the ocean have been carried out with and without flux adjustments, and with either the Gent-McWilliams (GM) parameterization scheme or horizontal diffusion (HD). The results show that a moderate degree of asynchronous coupling between the ocean's momentum and tracer fields still allows an accurate simulation of transient behavior, including the seasonal cycle. The use of the GM scheme significantly weakens the Deacon Cell and eliminates convection in the Southern Ocean. The deep ocean temperatures systematically decrease in the runs without flux adjustment. We demonstrate that the mismatch between heat transports in the uncoupled states of two models is the main cause for the systematic drift.
        The global warming experiments are sensitive to the parameterization of the sub-grid mixing. The penetration of anomalous heat in the Southern Ocean is noticeably weaker in the case with the GM scheme. As a result, the transient surface response exhibits less inter-hemispheric asymmetry than in the HD case. The equilibrium surface warming of the Southern Hemisphere is noticeably larger than that of the Northern Hemisphere in the GM case; the equilibrium warming is more uniform in the HD case. Use of the GM parameterization also leads to smaller decrease and faster recovery of the sinking in the North Atlantic. The increase in the surface heat fluxes is shown to be the dominant factor causing the weakening of the circulation. Results of the simulation with different rates of increase in the forcing are also presented.

This study links a multisectoral, regionalized, dynamic, computable general equilibrium (CGE) model of Ethiopia with a system country-specific hydrology, crop, road, and hydropower engineering models to simulate the economic impacts of climate change scenarios from global circulation models (GCMs) to 2050. In the absence of externally funded, policy-driven adaptation investments, Ethiopia's GDP in 2050 will be up to 10% below the counterfactual no climate change (historical climate) baseline. Suitably designed adaptation investments could restore aggregate welfare to baseline levels at a cost that is substantially lower than the welfare losses as a result of climate change. Such investments, even if funded from domestic resources, have benefits that greatly exceed their costs, and are largely consistent with Ethiopia's long-run development strategy.

© 2012 Blackwell Publishing Ltd.