Determination of tropical deforestation rates and related carbon losses from 1990 to 2010 (original) (raw)
Related papers
Proceedings of the National Academy of Sciences, 2002
Carbon fluxes from tropical deforestation and regrowth are highly uncertain components of the contemporary carbon budget, due in part to the lack of spatially explicit and consistent information on changes in forest area. We estimate fluxes for the 1980s and 1990s using subpixel estimates of percent tree cover derived from coarse (National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer) satellite data in combination with a terrestrial carbon model. The satellite-derived estimates of change in forest area are lower than national reports and remotesensing surveys from the United Nations Food and Agriculture Organization Forest Resource Assessment (FRA) in all tropical regions, especially for the 1980s. However, our results indicate that the net rate of tropical forest clearing increased Ϸ10% from the 1980s to 1990s, most notably in southeast Asia, in contrast to an 11% reduction reported by the FRA. We estimate net mean annual carbon fluxes from tropical deforestation and regrowth to average 0.6 (0.3-0.8) and 0.9 (0.5-1.4) petagrams (Pg)⅐yr ؊1 for the 1980s and 1990s, respectively. Compared with previous estimates of 1.9 (0.6-2.5) Pg⅐yr ؊1 based on FRA national statistics of changes in forest area, this alternative estimate suggests less ''missing'' carbon from the global carbon budget but increasing emissions from tropical land-use change.
Accelerated deforestation in the humid tropics from the 1990s to the 2000s
Geophysical Research Letters, 2015
Using a consistent, 20 year series of high-(30 m) resolution, satellite-based maps of forest cover, we estimate forest area and its changes from 1990 to 2010 in 34 tropical countries that account for the majority of the global area of humid tropical forests. Our estimates indicate a 62% acceleration in net deforestation in the humid tropics from the 1990s to the 2000s, contradicting a 25% reduction reported by the United Nations Food and Agriculture Organization Forest Resource Assessment. Net loss of forest cover peaked
Tropical deforestation and the global carbon budget
1996
The CO 2 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 CO 2 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 CO 2 from tropical deforestation appears to have been mostly offset by CO 2 uptake occurring elsewhere in the tropics, according to an analysis of recent trends in the atmospheric concentrations of O 2 and N 2 . Interannual 293 1056-3466/96/1022-0293$08.00 variations in climate and/or CO 2 fertilization may have been responsible for the CO 2 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.
Estimated carbon dioxide emissions from tropical deforestation improved by carbon-density maps
Deforestation contributes 6–17% of global anthropogenic CO2 emissions to the atmosphere1. Large uncertainties in emission estimates arise from inadequate data on the carbon density of forests2 and the regional rates of deforestation. Consequently there is an urgent need for improved data sets that characterize the global distribution of aboveground biomass, especially in the tropics. Here we use multi-sensor satellite data to estimate aboveground live woody vegetation carbon density for pan-tropical ecosystems with unprecedented accuracy and spatial resolution. Results indicate that the total amount of carbon held in tropical woody vegetation is 228.7 Pg C, which is 21% higher than the amount reported in the Global Forest Resources Assessment 2010 (ref. 3). At the national level, Brazil and Indonesia contain 35% of the total carbon stored in tropical forests and produce the largest emissions from forest loss. Combining estimates of aboveground carbon stocks with regional deforestation rates4 we estimate the total net emission of carbon from tropical deforestation and land use to be 1.0 Pg C yr−1 over the period 2000–2010—based on the carbon bookkeeping model. These new data sets of aboveground carbon stocks will enable tropical nations to meet their emissions reporting requirements (that is, United Nations Framework Convention on Climate Change Tier 3) with greater accuracy.
Challenges to estimating carbon emissions from tropical deforestation
Global Change Biology, 2007
An accurate estimate of carbon fluxes associated with tropical deforestation from the last two decades is needed to balance the global carbon budget. Several studies have already estimated carbon emissions from tropical deforestation, but the estimates vary greatly and are difficult to compare due to differences in data sources, assumptions, and methodologies. In this paper, we review the different estimates and datasets, and the various challenges associated with comparing them and with accurately estimating carbon emissions from deforestation. We performed a simulation study over legal Amazonia to illustrate some of these major issues. Our analysis demonstrates the importance of considering land-cover dynamics following deforestation, including the fluxes from reclearing of secondary vegetation, the decay of product and slash pools, and the fluxes from regrowing forest. It also suggests that accurate carbon-flux estimates will need to consider historical land-cover changes for at least the previous 20 years. However, this result is highly sensitive to estimates of the partitioning of cleared carbon into instantaneous burning vs. long-timescale slash pools. We also show that carbon flux estimates based on ‘committed flux’ calculations, as used by a few studies, are not comparable with the ‘annual balance’ calculation method used by other studies.
Tropical deforestation and climate change
2005
Tropical deforestation, including both the permanent conversion of forests to croplands and pastures and the temporary or partial removal of forests for shifting cultivation and selective logging, is estimated to have released on the order of 1-2 PgC/yr (15-35% of annual fossil fuel emissions) during the 1990s. The magnitude of emissions depends on the rates of deforestation, the biomass of the forests deforested, and other reductions in biomass that result from forest use. If, in addition to carbon dioxide, one considers the emissions of methane, nitrous oxide, and other chemically reactive gases that result from deforestation and subsequent uses of the land, annual emissions during the 1990s accounted for about 25% of the total anthropogenic emissions of greenhouse gases. Trends in the rates of tropical deforestation are difficult to predict, but at today’s rates, another 85 to 130 PgC will be released over the next 100 years, the emissions declining only as tropical forests are e...
Reporting carbon losses from tropical deforestation with Pan-tropical biomass maps
Environmental Research Letters, 2015
The 'Reduction of Emissions from deforestation and forest degradation' (REDD+) activities under the United Nations Framework Convention on Climate Change (UNFCCC) are expected to offer results-based payments to developing countries for reducing greenhouse gas emissions from forested lands. It is necessary to determine reference data on forest carbon losses against which future rates of change can be evaluated, and to have reliable methods for monitoring, reporting and verification of such changes. Advances in satellite remote sensing approaches and techniques for measuring purposes are therefore of tremendous interest. A robust example advancing such approaches, applied on the full tropical belt, is provided in the recent paper of Tyukavina et al 2015 (Environ. Res. Lett. 10 074002). Data and methods are no longer an obstacle to the inclusion of REDD+ in a new climate agreement.
Comment on "Determination of deforestation rates of the world's humid tropical forests
Science (New York, N.Y.), 2003
estimated tropical deforestation and atmospheric carbon emissions from 1990-1997 and concluded that both were substantially lower than found in previous studies. However, we assert that they markedly underestimated carbon emissions, by omitting key factors and making some invalid assumptions. The net effect is a potentially large underestimate of the impact of tropical deforestation on global warming. Achard et al.