We present the organization, instrumentation, datasets, data interpretation, modeling, and accomplishments of the multinational global atmospheric measurement program AGAGE (Advanced Global Atmospheric Gases Experiment). AGAGE is distinguished by its capability to measure globally, at high frequency, and at multiple sites all the important species in the Montreal Protocol and all the important non-carbon-dioxide (non-CO₂) gases assessed by the Intergovernmental Panel on Climate Change (CO₂ is also measured at several sites). The scientific objectives of AGAGE are important in furthering our understanding of global chemical and climatic phenomena. They are the following: (1) to accurately measure the temporal and spatial distributions of anthropogenic gases that contribute the majority of reactive halogen to the stratosphere and/or are strong infrared absorbers (chlorocarbons, chlorofluorocarbons – CFCs, bromocarbons, hydrochlorofluorocarbons – HCFCs, hydrofluorocarbons – HFCs and polyfluorinated compounds (perfluorocarbons – PFCs), nitrogen trifluoride – NF₃, sulfuryl fluoride – SO₂F₂, and sulfur hexafluoride – SF₆) and use these measurements to determine the global rates of their emission and/or destruction (i.e., lifetimes); (2) to accurately measure the global distributions and temporal behaviors and determine the sources and sinks of non-CO₂ biogenic–anthropogenic gases important to climate change and/or ozone depletion (methane – CH₄, nitrous oxide – N₂O, carbon monoxide – CO, molecular hydrogen – H₂, methyl chloride – CH₃Cl, and methyl bromide – CH₃Br); (3) to identify new long-lived greenhouse and ozone-depleting gases (e.g., SO₂F₂, NF₃, heavy PFCs (C₄F₁₀, C₅F₁₂, C₆F₁₄, C₇F₁₆, and C₈F₁₈) and hydrofluoroolefins (HFOs; e.g., CH₂ = CFCF₃) have been identified in AGAGE), initiate the real-time monitoring of these new gases, and reconstruct their past histories from AGAGE, air archive, and firn air measurements; (4) to determine the average concentrations and trends of tropospheric hydroxyl radicals (OH) from the rates of destruction of atmospheric trichloroethane (CH₃CCl₃), HFCs, and HCFCs and estimates of their emissions; (5) to determine from atmospheric observations and estimates of their destruction rates the magnitudes and distributions by region of surface sources and sinks of all measured gases; (6) to provide accurate data on the global accumulation of many of these trace gases that are used to test the synoptic-, regional-, and global-scale circulations predicted by three-dimensional models; and (7) to provide global and regional measurements of methane, carbon monoxide, and molecular hydrogen and estimates of hydroxyl levels to test primary atmospheric oxidation pathways at midlatitudes and the tropics. Network Information and Data Repository: http://agage.mit.edu/data or http://cdiac.ess-dive.lbl.gov/ndps/alegage.html (https://doi.org/10.3334/CDIAC/atg.db1001).

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Despite lawmaker interest in transitioning electricity systems toward renewable energy sources and in mitigating harmful air pollution, the extent to which sub-national renewable energy policies in the U.S. can improve air quality and human health remains unclear. This thesis develops a systemic modeling framework to assess the impacts of future renewable energy policy on air quality, as well as on the economy and on climate change, employing the framework of cost-benefit analysis. To model the chain of policy effects from impacts on the economy to power plant emissions, human health, and climate change, I integrate an economy-wide computable general equilibrium model, an atmospheric chemistry model, and methodologies for the economic valuation of health impacts. I apply this modeling framework to study the potential future impacts of the existing Renewable Portfolio Standards (RPSs) in the U.S. Rust Belt region. This thesis also tests the impacts of alternative RPS stringency levels and assesses RPS impacts compared to carbon pricing, a climate policy favored by many economists.

I estimate that existing RPSs in this region generate health co-benefits that, in economic terms, exceed the climate change mitigation benefits of these policies. Estimated health co-benefits also outweigh the economic costs of the modeled policies, indicating that air quality co-benefits alone may justify RPS implementation. This work further finds that raising RPS stringency in the Rust Belt increases net policy benefits (air quality and climate benefits minus costs). However, I show that air quality co-benefits are highly sensitive to several assumptions such as the economic value assigned to premature mortalities and the magnitude of the health response expected from a given level of pollution. This thesis also estimates that carbon pricing generates greater air quality co-benefits for every ton of CO₂ abated compared to an RPS, suggesting that carbon pricing may be more economically efficient (greater net benefits) relative to an RPS than previously thought. Finally, I show that RPSs have far-reaching economic impacts that have implications for their overall costs and benefits. This finding demonstrates the value of employing economy-wide models to understand the overall economic and environmental impacts of such sector-specific policies, and makes the case for a comprehensive, economy-wide approach for addressing air pollution and climate change.