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The document identifies four U.S. federal tax expenditures, each causing an annual revenue loss exceeding $1 billion, that contribute to greenhouse gas emissions by promoting fossil fuel use. These include the expensing of exploration and development costs, percentage depletion, the alternative fuel production credit, and the exemption of qualified parking expenses. While removing these provisions would improve economic efficiency and reduce the budget deficit, the author notes that the resulting impact on greenhouse gas emissions would be small, meaning such reforms must be part of a larger climate strategy.

The document argues that current NDCs insufficiently address transport emissions, with only 29 countries specifying quantitative targets. It proposes three primary areas for enhancement: accelerating electrification and fuel economy, amplifying 'avoid and shift' measures like public transport and urban planning, and addressing freight emissions through clean fuels and information technology.

The study evaluates transport interventions in Porto Alegre, Brazil, finding that a BRT system could reduce annual CO2 emissions by 25-31 thousand tonnes compared to a business-as-usual scenario with fare integration, whereas fare integration alone might increase emissions.

The paper examines the complexities of developing citywide transportation GHG emissions inventories, highlighting that results vary based on decisions regarding boundaries, trip inclusion, and data collection. It reviews diverse methodologies—including those from the World Bank, the European Commission, San Francisco, and Lisbon—and argues that accurate inventories are essential for climate action plans and performance-based funding.

The World Resources Institute argues that while biofuels can serve as a domestic substitute for petroleum and offer lower emissions than fossil fuels, their actual impact on emissions and the environment depends on the specific feedstocks and conversion processes used. Consequently, the WRI emphasizes that US policies promoting the biofuels industry must be carefully designed to minimize negative environmental and economic impacts.

The U.S. GHG Emissions Flow Chart provides a detailed breakdown of 2003 emissions totaling 6,978 MtCO2 equivalent. The largest contributing sectors are Electricity & Heat (32.4%) and Transportation (27.2%), with Carbon Dioxide (CO2) accounting for 85% of the total gas composition.