Carbon is the basic building block of forests, which store enormous amounts of it in their trees and soils. When trees die and decompose or are burned, that carbon is released as carbon dioxide (CO2) gas. Forest heath and conditions, management practices, wood harvesting, and use all influence how much carbon is stored and released from forests over time (a.k.a. "carbon flux"). 

The Forest Service produces the authoritative research, analyses, and tools for carbon monitoring and estimation across the nation. The Forest Inventory and Analysis (FIA) program is the foundation for data and models on forest carbon stocks and fluxes at all scales, from farm scale to the National Greenhouse Gas Inventory reporting for the United Nations Framework Convention on Climate Change (UNFCCC), Forest Sustainability Reporting, Resources Planning Assessment,carbon assessment across National Forests and Grasslands, and beyond.

The Forest Service monitors carbon across forests and grasslands because:

• Forests significantly impact the national carbon footprint: forests and associated harvested wood products uptake the equivalent of 10-15 percent of economy-wide CO2 emissions annually. Understanding how land management decisions and land cover changes impact carbon storage and CO2 emissions is critical for formulating and carrying out national strategies to combat climate change.
• Carbon accounting, whether for national greenhouse gas inventories, carbon markets, or private sector sustainability reports, relies upon consistent, high-quality, reliable sources of information. The FIA program provides information of known quality and clearly documented protocols and definitions that has been implemented consistently across the entire country over decades.
• Other organizations, such as universities, NGOs, and private research firms, rely on FIA and related Forest Service Research and Development outputs for baseline data, models and fundamental research in carbon dynamics.
• Harvested wood can store carbon over long time periods and serve as a sustainable substitute for non-renewable materials. Life Cycle Analyses quantify carbon benefits from wood-based products and contribute to more accurate carbon accounting. They also support decision making for businesses, government, and other organizations as they strive to meet sustainability goals and reporting. These analyses rely on data from the FIA Timber Products Output survey.