Climate Change Science: High Quality Greenhouse Gas Emissions Data are a Cornerstone of Programs to Address Climate Change

Elevated levels of greenhouse gases in the atmosphere and the resulting effects on the earth's climate could have significant impacts in the United States and internationally. Potential impacts include a change in sea levels, ecosystems, and ice cover. The United States Congress is considering proposals to limit greenhouse gas emissions using market-based mechanisms that would place a price on emissions. Such programs would create an economic incentive for regulated entities to limit their emissions. Limiting greenhouse gas emissions requires an understanding of existing emissions as well as the development of a program to monitor, report, and verify emissions from entities that might be affected by a future regulatory program. A greenhouse gas mitigation program also requires an understanding of the numerous emissions sources and methods for calculating emissions of six major greenhouse gases--carbon dioxide, methane, nitrous oxide, and several synthetic gases. This testimony focuses on (1) the importance of quality data on emissions in the context of a program intended to limit greenhouse gas emissions, and (2) key considerations in developing reliable data on greenhouse gas emissions. This testimony is based on several prior GAO reports and a review of related literature.