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Air quality is a serious concern for the protection of human health and our natural environment. The pollutants contributing the most to both local and transboundary air pollution problems are SO2, NOx, NH3, volatile organic compounds (VOCs), and fine particulate matter (PM), and mostly originate from the same sources as greenhouse gases. There are thus strong interactions between strategies designed to improve air quality and those addressing climate change. This article examines these interactions, and the benefits of combined strategies with greater attention to the overall environmental impacts, and finding the 'win-win' solutions. Illustrations are provided from the development of policy in Europe under the UN ECE Convention on Long-Range Transboundary Air Pollution, which is now inextricably linked with strategies to control greenhouse gases. [ABSTRACT FROM AUTHOR]

In 2007 the US Congress began considering a set of bills to implement a cap-and-trade system to limit the nation's greenhouse gas (GHG) emissions. The MIT Integrated Global System Model (IGSM) - and its economic component, the Emissions Prediction and Policy Analysis (EPPA) model - were used to assess these proposals. In the absence of policy, the EPPA model projects a doubling of US greenhouse gas emissions by 2050. Global emissions, driven by growth in developing countries, are projected to increase even more. Unrestrained, these emissions would lead to an increase in global CO2 concentration from a current level of 380 ppmv to about 550 ppmv by 2050 and to near 900 ppmv by 2100, resulting in a year 2100 global temperature 3.5-4.5°C above the current level. The more ambitious of the Congressional proposals could limit this increase to around 2°C, but only if other nations, including developing countries, also strongly controlled greenhouse gas emissions. With these more aggressive reductions, the economic cost measured in terms of changes in total welfare in the United States could range from 1.5% to almost 2% by the 2040-2050 period, with 2015 CO2-equivalent prices between $30 and $55, rising to between $120 and $210 by 2050. This level of cost would not seriously affect US GDP growth but would imply large-scale changes in its energy system. [ABSTRACT FROM AUTHOR]

Much of the debate on climate policy in the USA focuses on the gain or loss to the macroeconomy of alternative policies to reduce greenhouse gas emissions. However, the economy is made up of multiple individuals, not a single representative agent. This article reports the results of alternative ways of distributing emissions allocations across citizens. Macroeconomic effects interact with the policy for distribution, but the distributional weights are more important for the welfare of individual agents than the economy-wide effects of the emissions reductions. Egalitarian distributions of the emissions allowances have the potential to increase the welfare of most people, even if significant emissions reductions are mandated. Focusing on the distribution of emissions allowances (or the revenues generated from an emissions tax) rather than on aggregate GDP may provide guidance in identifying and implementing politically viable solutions to the climate change mitigation problem. [ABSTRACT FROM AUTHOR]