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Land Use Issues
Overview Land use change and forestry issues are important to national and global inventories of greenhouse gases in two ways:
Land use issues are of particular interest to the United States because U.S. forests and soils annually sequester large amounts of carbon dioxide. Much of the forest land in the United States was cleared for agriculture, lumber, or fuel in the hundred years prior to 1920. Since then, much agricultural and pastureland has reverted to forest land and is now covered with relatively young, rapidly growing trees. The amount of carbon being sequestered annually is uncertain, in part because of an absence of data and because of difficulties in measuring sequestration. Moreover, in addition to technical uncertainties, there is also policy or accounting ambiguity about which aspects of the biological carbon cycle ought to be included in national inventories as anthropogenic emissions and removals. The revised guidelines for national emissions inventories published in 1997 by the Intergovernmental Panel on Climate Change (IPCC) pursuant to the Framework Convention on Climate Change contain a set of rules governing the inclusion of carbon sequestration and land use in national inventories.90 The U.S. Environmental Protection Agency (EPA), relying heavily on the work of U.S. Forest Service researchers Richard Birdsey and Linda Heath, estimates annual U.S. carbon sequestration (generally defined according to the IPCC guidelines) at 211 million metric tons carbon equivalent (Table 32).91 Under the IPCC guidelines, this quantity would be treated as an offset to gross greenhouse gas emissions from other sources. Table 32. Net Carbon Flux from Land Use Change and Forestry, 1990-1998 EPA’s carbon flux estimates are based on surveys of U.S. forest lands carried out at 5-year intervals by the U.S. Forest Service, U.S. Department of Agriculture. Annual estimates of carbon fluxes between survey years are interpolated and, therefore, change little from year to year, except when a new assessment is made. In this year’s report, for the first time, landfilled yard trimmings are included in the EPA’s carbon flux estimates. The estimates for carbon fluxes from landfilled yard trimmings trend downward over time, based on EPA projections. Total forestry carbon fluxes have fallen from 316 million metric tons carbon equivalent in 1990 to 211 million metric tons carbon equivalent in 1998. The decrease is due mainly to maturation and slowing in the spread of forest cover, as well as a reduction in landfilled yard trimmings. The dramatic drop between 1992 and 1993 is due, in part, to methodological changes that incorporated periodic activity data rather than annual stock estimates. As can be seen from the estimates, the vast majority of the carbon fluxes are from forests and soil (171 million metric tons carbon equivalent or 81 percent of total forestry carbon fluxes), followed by harvested wood (37 million metric tons carbon equivalent or 18 percent) and landfilled trimmings (2.3 million metric tons carbon equivalent or 1 percent). To put these figures in perspective, carbon fluxes from forestry offset 14.1 percent of energy-related carbon dioxide emissions, which totaled 1,495 million metric tons carbon equivalent in 1998. The 211 million metric tons carbon equivalent sequestered through land use and forestry activities in 1998 would also act to offset total U.S. emissions of greenhouse gases by 11.6 percent. If the EPA’s estimate of 211 million metric tons carbon equivalent sequestered through carbon fluxes from forestry holds for 1999, then sequestration will offset a little less than 14 percent of the 1,511 million metric tons of carbon dioxide emitted through the burning of fossil fuels in 1999. Land Use and the Kyoto Protocol The United States and many other countries participating in the Kyoto Protocol believed that it was important to include Land Use, Land Use Change and Forestry (LULUCF) activities in a binding treaty limiting greenhouse gas emissions; however, the issues of whether and how terrestrial carbon sequestration would be accepted for meeting commitments were the subject of complex and difficult negotiations at Kyoto. While LULUCF activities were ultimately included in the Kyoto Protocol, controversial issues in its implementation remain.92 Under Article 3 of the Kyoto Protocol, countries must count both sequestration and emissions from a limited set of LULUCF activities toward meeting their Kyoto Protocol target commitments. Parties must identify and examine all activities that release a greenhouse gas into the atmosphere (a source) and enhance reservoirs that sequester carbon (sinks).93 Articles 3.3, 3.4, and 3.7 provide the framework for the accounting of sources and sinks for compliance purposes under the Kyoto Protocol:
Implementation of these articles is complicated by a lack of clear definitions for words such as “reforestation” and “forest.” Further, the LULUCF provisions in the Kyoto Protocol cannot be effectively implemented until the accounting rules have been determined. The fact that the commitments have been agreed to, but agreement on rules for meeting those commitments has not yet been negotiated, is problematic. According to researchers at the Pew Center on Global Climate Change,98 implementation of the LULUCF provisions of the Protocol raises at least six principal issues for domestic LULUCF activities:
A well-designed carbon accounting system would provide verifiable and accurate reporting of changes in carbon stocks resulting from LULUCF practices. Such data are necessary to measure compliance with commitments under the Kyoto Protocol. It should be recognized, however, that accounting for LULUCF activities under Articles 3.3 and 3.4 involves a number of uncertainties, including measurement uncertainty, uncertainty in identification of lands under Article 3.3 or 3.4, and uncertainty in determining and quantifying baselines.99 The IPCC’s 2000 report on Land Use, Land-Use Change, and Forestry presents two possible accounting approaches that may be adopted for solitary or combined use in meeting these requirements: (1) the “land-based” approach and (2) the “activity-based” approach. A “land-based” approach to accounting would consider changes in carbon stocks on lands where activities accepted under Article 3.3 or 3.4 are occurring. First, applicable activities would be defined, and lands on which the activities are occurring would be identified. Changes in global carbon stocks on such lands during a determined period of time would be calculated. Changes in carbon stocks over all land units over the specified time period would be summed for the total account of carbon dioxide emissions and removals.100 An “activity-based” approach to accounting would consider the changes in carbon stocks in applicable carbon pools and/or emissions and removal of greenhouse gases resulting from LULUCF activities. Under this approach, each relevant activity’s impact on global carbon stocks would be determined per unit of area and unit of time. The activity’s impact would be multiplied by the area on which the activity occurs and by either the number of years it is applied or the number of years of the commitment period. All activities would be summed for the total account of emissions and removals.101 Current Global Carbon Sequestration LULUCF is a term that refers to human activities that alter land use or affect the amount of carbon in existing forest or soil stocks. This sector involves both emissions of greenhouse gases (sources) and removal of gases from the atmosphere via carbon sequestration (sinks). Global vegetation and soils, which contain about three times as much carbon as the Earth’s atmosphere, provide an opportunity to sequester a considerable amount of carbon dioxide from the atmosphere. LULUCF practices are of particular interest to the United States, because forest land constitutes 33 percent (737 million acres) of the total U.S. land area. The United States has experienced a low rate of change in forest land area over the past 20 years, with average fluctuations of only about 0.1 percent per year since 1977. Thus, intensified management of U.S. forests has the potential to increase the growth rate and, eventually, the biomass density of the forests, thereby increasing the uptake of carbon.102 The IPCC reports that current carbon stocks are much larger in soils than in vegetation, particularly in non-forested ecosystems in middle and high latitudes (Table 33).103 Table 33. Global Carbon Stocks in Vegetation and Soil Carbon Pools Down to a Depth of 1 Meter The enhancement of carbon sequestration through LULUCF activities differs from fossil fuel emission reductions in a number of ways. The potential of LULUCF activities is limited by land availability as well as the amount of carbon that can be stored per unit of land (“saturation”). Further, carbon offsets that occur as a result of land use or forestry practices are at risk of being lost at a later time. In contrast, emission reductions from fossil fuels not burned in one year do not generally result in greater emissions in a subsequent year (“permanence”).104 Accounting for the amount of carbon being sequestered annually involves a high degree of uncertainty due to lack of data and to difficulties in measuring sequestration. Further, policy or accounting uncertainties regarding which aspects of the biological carbon cycle should be included in national inventories as anthropogenic emissions and removals also abound. The IPCC’s 2000 report on LULUCF details values for carbon sequestration as a result of LULUCF activities in a different manner. According to the IPCC, from 1850 to 1998, combined carbon dioxide emissions resulting from fossil fuel burning, industrial processes, and land-use change led to an increase in the atmospheric content of carbon dioxide of 176±10 billion metric tons carbon equivalent. Atmospheric carbon dioxide concentrations increased from approximately 285 to 366 parts per million. About 43 percent of the carbon dioxide emitted from 1850 to 1998 remains in the atmosphere. The remainder, about 230±60 billion metric tons carbon equivalent, has likely been taken up in approximately equal amounts in the oceans and in terrestrial ecosystems.105 The average annual global carbon budgets for 1980-1989 and 1989-1998 are shown in Table 34. During these two decades, terrestrial ecosystems may have served as a carbon sink despite the estimate that emissions as a result of land-use change, primarily in the tropics, were 1.7±0.8 billion metric tons carbon equivalent per year and 1.6±0.8 billion metric tons carbon equivalent per year, respectively, during the two decades.106 Table 34. Average Annual Global Carbon Dioxide Budget, 1980-1989 and 1989-1998 Estimates for Future Global Carbon Sequestration Researchers at the Pew Center on Global Climate Change maintain that, over the next 50 years, LULUCF management practices could result in the sequestration of 60 to 87 billion metric tons carbon equivalent in the world’s forests and another 23 to 44 billion metric tons carbon equivalent in the world’s agricultural soils. Those estimates account for carbon that either has already been released to the atmosphere or is expected to be released. The annual carbon gain in the world’s forests may reach an estimated 2.2 billion metric tons carbon equivalent by 2050.107 The IPCC’s 2000 report offers further estimates for future terrestrial carbon sequestration (although it should be noted that different definitions and accounting approaches under Article 3.3 of the Kyoto Protocol result in different estimates of carbon stock change). Table 35 illustrates the estimated carbon stock changes resulting from afforestation, reforestation, and deforestation activities under the IPCC guidelines and, alternatively, under three United Nations Food and Agriculture Organization (FAO) “definitional scenarios” based on different accounting methods (assuming area conversion rates remain constant and excluding carbon in soils and wood products). The FAO scenarios include the harvest/regeneration cycle, because regeneration is defined as reforestation. Three accounting approaches are distinguished:
The IPCC definitional scenario involves transitions between forest and non-forest land uses under Article 3.3 and assumes that not only planting but also other forms of stand establishment (e.g., natural establishment) are considered to be afforestation or reforestation activities. The IPCC definitional scenario results in estimated Annex I emissions of 44 to 83 million metric tons carbon equivalent per year.108 Both the FAO activity-based accounting scenario and the IPCC definitional scenario indicate that for Annex I countries, including the United States, afforestation and reforestation will function to offset a portion of carbon emissions. As shown in Table 35, however, the effects of deforestation under the FAO Activity-Based Scenario and the IPCC Definitional Accounting Scenario can greatly diminish the positive carbon sequestration effects of afforestation and reforestation activities. In its 2000 report, the IPCC also provides estimates of carbon sequestration and avoided emissions from carbon stocks via selected Activities Implemented Jointly (AIJ) and other LULUCF projects (Table 36). A LULUCF project is defined as “a planned set of activities aimed at reducing greenhouse gas emissions or enhancing carbon stocks that is confined to one or more geographic locations in the same country and specified time period and institutional frameworks such as to allow net greenhouse gas emissions or enhancing carbon stocks to be monitored and verified.”109 Currently, experience is being acquired through AIJ and other LULUCF projects that are being implemented in at least 19 countries.110 Included in Table 36 are 10 projects focused on decreasing emissions through avoiding deforestation and improving forest management, and 11 projects focused on increasing carbon sequestration—mostly forest projects based in tropical countries.111 Uncertainty is involved in the assessment of these projects for a number of reasons. First, there currently exist only a limited number of projects and project types. Geographic distribution of projects is uneven, and there have been limited field operations to date. Further, there is an absence of an internationally agreed-upon set of guidelines and methods to establish baselines and to quantify emissions and sequestration. The projects do not report all greenhouse gas emissions or estimate leakage, and few have undergone independent review.112 If you would like to receive any information relating to any of our greenhouse gas reports via e-mail, click here and subscribe by entering your e-mail address.
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