Understanding, quantifying, and tracking atmospheric methane and emissions is essential for addressing concerns and informing decisions that affect the climate, economy, and human health and safety. Atmospheric methane is a potent greenhouse gas (GHG) that contributes to global warming. While carbon dioxide is by far the dominant cause of the rise in global average temperatures, methane also plays a significant role because it absorbs more energy per unit mass than carbon dioxide does, giving it a disproportionately large effect on global radiative forcing. In addition to contributing to climate change, methane also affects human health as a precursor to ozone pollution in the lower atmosphere. Improving Characterization of Anthropogenic Methane Emissions in the United States summarizes the current state of understanding of methane emissions sources and the measurement approaches and evaluates opportunities for methodological and inventory development improvements. This report will inform future research agendas of various U.S. agencies, including NOAA, the EPA, the DOE, NASA, the U.S. Department of Agriculture (USDA), and the National Science Foundation (NSF).

Is the climate warming? Is the hydrological cycle intensifying? Is the climate becoming more variable or extreme? Is the chemical composition of the atmosphere changing? Is the solar irradiance constant? Answers to these questions are fundamental to understanding, predicting, and assessing climate on time scales ranging from weeks to a century. Atmospheric, oceanic, and environmental scientists have primarily relied on an ad-hoc collection of disparate environmental observational and data management systems to address these problems. But these systems were not designed to measure climate variations and, as a result, changes and variations of the earth system during the instrumental climate record is far from unequivocal. This book develops a framework from which a Global Climate Observing System, currently being discussed in international forums, can be implemented to monitor changes and variations of climate. Audience: Administrators, policy makers, professionals, graduate students, and others interested in learning how we can ensure a long-term climate record for application to national economic development and understanding ecosystem dynamics.