Agriculture and Forestry

Emissions from industrial, transportation, energy, residential, and commercial sectors are clearly significant sources of greenhouse gases (GHGs). Yet two additional sectors — agriculture and forestry — play a pivotal, dual role as both significant sources of GHGs and significant GHG sinks that sequester GHGs and help regulate climate change. Agricultural lands occupy roughly 40-50% of the Earth’s land surface, and agricultural lands are projected to increase globally by over one billion acres by 2020 to meet the demands of rising populations. Feeding the earth’s ever-growing population and driving a significant part of the global economy does not come without an environmental cost, however. Globally, agriculture accounts for about 10-12% of carbon emissions. Forestlands occupy about one-quarter of the earth’s ice-free land surface, and contain over half of the world’s plant and animal species. On local scales forests provide a wide array of goods and services while on a global scale forests sequester significant amounts of greenhouse gas that would otherwise exacerbate climate change. Even so, deforestation alone accounts for a full one-third of all carbon released into the atmosphere between 1850 and 1998, second only to the energy sector. Over the last two decades, up to 20% of global annual carbon emissions resulted from forest destruction and degradation, more than the global transportation sector. Though the U.S. has long been a stable forest sink, that status is in jeopardy as new threats may lead to significant deforestation over the next 50 years. This chapter discusses both the GHG source and sink potential of the agricultural and forest sectors. It also describes the governance and management frameworks for each sector and the GHG mitigation options available for each. The chapter concludes by highlighting future challenges for U.S. agriculture and forestry related to GHGs and climate