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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Environment and Resources 24 (1999), S. 571-605 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A total of 176 countries have ratified the United Nations Framework Convention on Climate Change, thereby agreeing to limit emissions of greenhouse gases that threaten to interfere with the Earth's climate. While compliance procedures are being developed, the best indicators of implementation of the Convention are the emissions inventories of greenhouse gases that member countries must submit to the Convention as part of their national communications. We review some of the first emissions inventories from non-Annex I (developing) countries. We focus on land-use change and forestry because these activities are responsible for the major emissions of carbon in many non-Annex I parties, and because they are the only activities with the potential to remove carbon from the atmosphere and sequester it on land. The review shows first, that some developing countries have already begun to reduce emissions and second, that there are significant discrepancies between the data used in the emissions inventories and the data available in international surveys. Conceptual uncertainties also exist, such as distinguishing anthropogenic from nonanthropogenic sinks of carbon, and these will require political rather than scientific resolution. We discuss several options for counting terrestrial sources and sinks of carbon in light of the Kyoto Protocol.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Environment and Resources 21 (1996), S. 293-310 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The CO2 concentration of the atmosphere has increased by almost 30% since 1800. This increase is due largely to two factors: the combustion of fossil fuel and deforestation to create croplands and pastures. Deforestation results in a net flux of carbon to the atmosphere because forests contain 20-50 times more carbon per unit area than agricultural lands. In recent decades, the tropics have been the primary region of deforestation. The annual rate of CO2 released due to tropical deforestation during the early 1990s has been estimated at between 1.2 and 2.3 gigatons C. The range represents uncertainties about both the rates of deforestation and the amounts of carbon stored in different types of tropical forests at the time of cutting. An evaluation of the role of tropical regions in the global carbon budget must include both the carbon flux to the atmosphere due to deforestation and carbon accumulation, if any, in intact forests. In the early 1990s, the release of CO2 from tropical deforestation appears to have been mostly offset by CO2 uptake occurring elsewhere in the tropics, according to an analysis of recent trends in the atmospheric concentrations of O2 and N2. Interannual variations in climate and/or CO2 fertilization may have been responsible for the CO2 uptake in intact forests. These mechanisms are consistent with site-specific measurements of net carbon fluxes between tropical forests and the atmosphere, and with regional and global simulations using process-based biogeochemistry models.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Global change biology 1 (1995), S. 0 
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Changes in land use between 1850 and 1980 are estimated to have increased the global areas in croplands, pastures, and shifting cultivation by 891, 1308, and 30 × 106 ha, respectively, reducing the area of forests by about 600 × 106 ha, releasing about 100 PgC to the atmosphere, and transferring about 23 PgC from live vegetation to dead plant material and wood products. Another 1069 × 106 ha are estimated to have been logged during this period, and the net release of carbon from the combined processes of logging and regrowth contributed 23 PgC to the 100-PgC release. Annual rates of land-use change and associated emissions of carbon have decreased over the last several decades in temperate and boreal zones and have increased in the tropics. The average release of carbon from global changes in land use over the decade of the 1980s Is estimated to have been 1.6 ± 0.7 PgC y−1 almost entirely from the tropics. This estimate of carbon flux is higher than estimates reported in recent summaries because it is limited here to studies concerned only with changes in land use. Other recent analyses, based on data from forest inventories, have reported net accumulations of carbon as high as 1.1 PgC y−1 in temperate and boreal zones. Because the accumulation of carbon in forests may result from natural processes unrelated to land-use change, estimates based on these inventories should be distinguished from estimates based on changes in land use. Both approaches identify terrestrial sinks of carbon. The argument is made here, however, that differences between the two approaches may help identify the location and magnitude of heretofore ‘missing’ sinks. Before different estimates can be used in this way, analyses must consider similar geographical regions and dates, and they must account for the accumulation and loss of carbon in forest products in a consistent fashion.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Global change biology 5 (1999), S. 0 
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The net emissions of carbon from forestry and changes in land use in south and southeast Asia were calculated here with a book-keeping model that used rates of land-use change and associated per hectare changes in vegetation and soil to calculate changes in the amount of carbon held in terrestrial ecosystems and wood products. The total release of carbon to the atmosphere over the period 1850–1995 was 43.5 PgC. The clearing of forests for permanent croplands released 33.5 PgC, about 75% of the total. The reduction of biomass in the remaining forests, as a result of shifting cultivation, logging, fuelwood extraction, and associated regrowth, was responsible for a net loss of 11.5 PgC, and the establishment of plantations withdrew from the atmosphere 1.5 PgC, most of it since 1980. Based on comparisons with other estimates, the uncertainty of this long-term flux is estimated to be within ±30%. Reducing this uncertainty will be difficult because of the difficulty of documenting the biomass of forests in existence 〉40 years ago. For the 15-y period 1981–1995, annual emissions averaged 1.07 PgC y–1, about 50% higher than reported for the 1980s in an earlier study. The uncertainty of recent emissions is probably within ± 50% but could be reduced significantly with systematic use of satellite data on changes in forest area. In tropical Asia, the emissions of carbon from land-use change in the 1980s accounted for approximately 75% of the region’s total carbon emissions. Since 1990 rates of deforestation and their associated emissions have declined, while emissions of carbon from combustion of fossil fuels have increased. The net effect has been a reduction in emissions of CO2 from this region since 1990.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Climatic change 40 (1998), S. 495-518 
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A positive correlation exists between temperature and atmospheric concentrations of carbon dioxide and methane over the last 220,000 years of glacial history, including two glacial and three interglacial periods. A similar correlation exists for the Little Ice Age and for contemporary data. Although the dominant processes responsible may be different over the three time periods, a warming trend, once established, appears to be consistently reinforced through the further accumulation of heat-trapping gases in the atmosphere; a cooling trend is reinforced by a reduction in the release of heat-trapping gases. Over relatively short periods of years to decades, the correspondence between temperature and greenhouse gas concentrations may be due largely to changes in the metabolism of terrestrial ecosystems, whose respiration, including microbial respiration in soils, responds more sensitively, and with a greater total effect, to changes in temperature than does gross photosynthesis. Despite the importance of positive feedbacks and the recent rise in surface temperatures, terrestrial ecosystems seem to have been accumulating carbon over the last decades. The mechanisms responsible are thought to include increased nitrogen mobilization as a result of human activities, and two negative feedbacks: CO2 fertilization and the warming of the earth, itself, which is thought to lead to an accumulation of carbon on land through increased mineralization of nutrients and, as a result, increased plant growth. The relative importance of these mechanisms is unknown, but collectively they appear to have been more important over the last century than a positive feedback through warming-enhanced respiration. The recent rate of increase in temperature, however, leads to concern that we are entering a new phase in climate, one in which the enhanced greenhouse effect is emerging as the dominant influence on the temperature of the earth. Two observations support this concern. One is the negative correlation between temperature and global uptake of carbon by terrestrial ecosystems. The second is the positive correlation between temperature and the heat-trapping gas content of the atmosphere. While CO2 fertilization or nitrogen mobilization (either directly or through a warming-enhanced mineralization) may partially counter the effects of a warming-enhanced respiration, the effect of temperature on the metabolism of terrestrial ecosystems suggests that these processes will not entirely compensate for emissions of carbon resulting directly from industrial and land-use practices and indirectly from the warming itself. The magnitude of the positive feedback, releasing additional CO2, CH4, and N2O, is potentially large enough to affect the rate of warming significantly.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Climatic change 19 (1991), S. 99-118 
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Recent estimates of the net release of carbon to the atmosphere from deforestation in the tropics have ranged between 0.4 and 2.5 × 1015 g yr−1. Two things have happened to require a revision of these estimates. First, refinements of the methods used to estimate the stocks of carbon in the vegetation of tropical forests have produced new estimates that are intermediate between the previous high and low estimates of carbon stocks. When these revised estimates were used here to calculate the emissions of carbon from deforestation, the new range was 1.0–2.0 × 1015 g C. Second, the previous range of estimates of flux was based on rates of deforestation in 1980. Myers' recent estimate of the rates of tropical deforestation in 1989 is about 90% higher than the rates just 10 years ago. When these recent rates were used to calculate the current net flux of carbon to the atmosphere, the range was between 1.6 and 2.7 × 1015 g C. Other uncertainties expanded this range, however, to 1.1–3.6 × 1015 g C yr−1. Three factors contributed about equally to the expanded range: rates of deforestation, the fate of deforested lands (permanent or temporary clearing), and carbon stocks of forests, including anthropogenic reductions of carbon stocks within forests (thinning or degradation).
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 1991-01-01
    Description: The net annual flux of carbon from south and southeast Asia as a result of changes in the area of forests was calculated for the period 1850 to 1985. The total net flux ranged from 14.4 to 24.0 Pg of carbon, depending on the estimates of biomass used in the calculations. High estimates of biomass, based on direct measurement of a few stands, and low estimates of biomass, based on volumes of merchantable wood surveyed over large areas, differ by a factor of almost 2. These and previous estimates of the release of carbon from terrestrial ecosystems to the atmosphere have been based on changes in the area of forests, or rates of deforestation. Recent studies have shown, however, that the loss of carbon from forests in tropical Asia is greater than would be expected on the basis of deforestation alone. This loss of carbon from within forests (degradation) also releases carbon to the atmosphere when the products removed from the forest burn or decay. Thus, degradation should be included in analyses of the net flux of carbon from terrestrial ecosystems. Degradation may also explain some of the difference between estimates of tropical forest biomass if the higher estimates are based on undisturbed forests and the lower estimates are more representative of the region. The implication of degradation for estimates of the release of carbon from terrestrial ecosystems is explored. When degradation was included in the analyses, the net flux of carbon between 1850 and 1985 was 30.2 Pg of carbon, about 25% above that calculated on the basis of deforestation alone (with high estimates of biomass), and about 110% above that calculated with low estimates of biomass. Thus, lower estimates of biomass for contemporary tropical forests do not necessarily result in lower estimates of flux.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
    Publication Date: 1991-01-01
    Description: Determining how land-use change effects atmospheric CO2 concentrations requires new approaches to research because of the large area and the long period of time involved. This special issue of the CanadianJournalofForestResearch presents a series of papers that demonstrate one approach to the problem. Estimates of the flux of carbon to the atmosphere are based on site-specific information concerning the effects of land-use change on the carbon content of terrestrial vegetation. This spatially explicit approach combines historical and current information on land-use change for a specific area. South and southeast Asia was chosen for the study because the region is undergoing major land-use changes and makes a significant contribution to atmospheric CO2. The results of the study have assisted in reducing the uncertainty about the magnitude of carbon release while providing new constraints to the analysis.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
    Publication Date: 1994-08-14
    Print ISSN: 0953-4075
    Electronic ISSN: 1361-6455
    Topics: Physics
    Published by Institute of Physics
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  • 10
    Publication Date: 1999-07-23
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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