Executive Summary

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Agriculture
The Agriculture chapter contains anthropogenic emissions from agricultural activities (except fuel combustion,
which is addressed in the Energy chapter, and agricultural CO 2 fluxes, which are addressed in the Land Use, Land-
Use Change, and Forestry chapter). Agricultural activities contribute directly to emissions of greenhouse gases
through a variety of processes, including the following source categories: enteric fermentation in domestic livestock,
livestock manure management, rice cultivation, agricultural soil management, liming, urea fertilization, and field
burning of agricultural residues. CO 2, CH 4 and N 2O were the primary greenhouse gases emitted by agricultural
activities. CO 2 emissions from the application of crushed limestone and dolomite (i.e., soil liming) and urea
fertilization represented 0.2 percent of total CO 2 emissions from anthropogenic activities. CH 4 emissions from
enteric fermentation and manure management represented 25.4 percent and 10.1 percent of total CH 4 emissions from
anthropogenic activities, respectively, in 2015. Agricultural soil management activities such as fertilizer application
and other cropping practices were the largest source of U.S. N 2O emissions in 2015, accounting for 75.0 percent. In
2015, emission sources accounted for in the Agricultural chapters were responsible for 7.9 percent of total U.S.
greenhouse gas emissions.
Land Use, Land-Use Change, and Forestry
The Land Use, Land-Use Change, and Forestry chapter contains emissions of CH 4 and N 2O, and emissions and
removals of CO 2 from managed lands in the United States. Overall, managed land is a net sink for CO 2 (C
sequestration) in the United States. The drivers of fluxes on managed lands include, for example, forest management
practices, tree planting in urban areas, the management of agricultural soils, the landfilling of yard trimmings and
food scraps, and activities that cause changes in C stocks in coastal wetlands. The main drivers for net forest
sequestration include net forest growth and increasing forest area, as well as a net accumulation of C stocks in
harvested wood pools. The net sequestration in Settlements Remaining Settlements, which occurs predominantly
from urban forests and landfilled yard trimmings and food scraps, is a result of net tree growth and increased urban
forest size, as well as long-term accumulation of yard trimmings and food scraps carbon in landfills.
Forest Land Remaining Forest Land (including vegetation, soils, and harvested wood) represented the largest
carbon sink from LULUCF, accounting for 77 percent of total 2015 negative C fluxes; Settlements Remaining
Settlements (urban trees and landfilled yard trimmings and food scraps) accounted for 12 percent; Land Converted to
Forest Land accounted for 9 percent; and Cropland Remaining Cropland, Wetlands Remaining Wetlands, and Land
Converted to Wetlands accounted for 3 percent of the total negative C fluxes in 2015. Conversely, Land Converted
to Grassland represented the largest carbon source from LULUCF, accounting for 61 percent of total 2015 positive
C fluxes, while Land Converted to Settlements accounted for 31 percent. Land Converted to Cropland accounted for
6 percent. Grassland Remaining Grassland accounted for 2 percent, and settlement soils in Settlements Remaining
Settlements accounted for less than 0.5 percent of the total positive C fluxes in 2015. Overall, positive C fluxes
totaled 481.6 MMT CO 2 Eq. in 2015, while negative C fluxes totaled 868.5 MMT CO 2 Eq. in 2015.
The LULUCF sector in 2015 resulted in a net increase in C stocks (i.e., net CO 2 removals) of 386.8 MMT CO 2 Eq.
(Table ES-5). 22 This represents an offset of 5.9 percent of total (i.e., gross) greenhouse gas emissions in 2015.
Emissions from LULUCF activities in 2015 are 20.4 MMT CO 2 Eq. and represent 0.3 percent of total greenhouse
gas emissions. 23 Between 1990 and 2015, total C sequestration in the LULUCF sector decreased by 16.0 percent,
22 LULUCF C Stock Change is the net C stock change from the following categories: Forest Land Remaining Forest Land, Land
Converted to Forest Land, Cropland Remaining Cropland, Land Converted to Cropland, Grassland Remaining Grassland,
Land Converted to Grassland, Wetlands Remaining Wetlands, Land Converted to Wetlands, Settlements Remaining Settlements,
and Land Converted to Settlements.
23 LULUCF emissions include the CO2, CH4, and N2O emissions from Peatlands Remaining Peatlands; CH4 and N2O emissions
reported for Non-CO2 Emissions from Forest Fires, Non-CO2 Emissions from Grassland Fires, and Coastal Wetlands
Remaining Coastal Wetlands; CH4 emissions from Land Converted to Coastal Wetlands; and N2O Fluxes from Forest Soils and
Settlement Soils.
20 DRAFT Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2015