Improved estimates of net carbon emissions from land cover change in the tropics for the 1990s

Abstract

[1] Recent figures on net forest cover change rates of the world's tropical forest cover are used for the calculation of carbon fluxes in the global budget. By applying our deforestation findings in the humid tropics, complemented by published deforestation figures in the dry tropics, to refereed data on biomass, we produced new estimates of net carbon emissions. These estimates are supported by recent, independent estimations of net carbon emissions globally, over the Brazilian Amazon, and by observations of atmospheric CO 2 emissions over Southeast Asia. Our best estimate for global net emissions from land-use change in the tropics is at 1.1 ± 0.3 Gt C yr À1 . This estimate includes emissions from conversion of forests (representing 71% of budget) and loss of soil carbon after deforestation (20%), emissions from forest degradation (4.4%), emissions from the 1997-1998 Indonesian exceptional fires (8.3%), and sinks from regrowths (À3.3%).

Reframing the climate change challenge in light of post-2000 emission trends

“…The analysis does not take account of the following: . An earlier estimate based on high-resolution satellite data over areas identified as 'hot spots' of deforestation, estimated the figure at nearer 3.7 GtCO 2 (1 GtC) for 2000 (Achard et al 2004). It is Houghton's more recent estimate that is used in this paper.…”

Fog and rain in the Amazon

“…Hence, the climate of the Amazon is of particular importance for the fate of global CO 2 concentration in the atmosphere (1). Besides the difficulty of estimating carbon pools (1-3), our incapacity to correctly predict CO 2 fluxes in the continental tropics largely results from inaccurate simulation of the tropical climate (1,2,4,5).…”

“…In the more humid Western part of the basin, surface incoming radiation, evapotranspiration, and photosynthesis all tend to peak in the dry season (15-17), whereas GCMs simulate peaks of those fluxes in the wet season (10, 11). Those issues might be related to the representation of convection (1,2,4,5,13,14) and vegetation water stress (6)(7)(8)(15)(16)(17) in GCMs.We here show that we can represent the Amazonian climate using a strategy opposite to GCMs in which we resolve convection and parameterize the large-scale circulation (Methods). The simulations lack many of the biases observed in GCMs and more accurately capture the differences between the dry and wet season of the Amazon in surface heat fluxes and precipitation.…”

“…Hence, the climate of the Amazon is of particular importance for the fate of global CO 2 concentration in the atmosphere (1). Besides the difficulty of estimating carbon pools (1-3), our incapacity to correctly predict CO 2 fluxes in the continental tropics largely results from inaccurate simulation of the tropical climate (1,2,4,5). More frequent and more intense droughts in particular are expected to affect the future health of the Amazon and its capacity to act as a major carbon sink (6)(7)(8).…”

Remote Sensing-Based Estimation of Carbon Sequestration in Hong Kong Country Parks from 1978 to 2004~!2009-05-13~!2009-09-17~!2009-12-30~!

“…These estimates were much higher than those of Milne and Brown [22], who gave annual sequestration rates of 1.05-1.56 tC/ha for conifers in Britain. At the ecosystem level, Achard et al [23] estimated an average regrowth rate of 2.75 tC ha -1 yr -1 for tropical forests; Van Kooten et al [24] found figures for Canada in the range of 0.6 to 0.8 tC ha -1 yr -1 ; while Brainard et al [25] found that British forests sequestered 3.5 tC ha -1 yr -1 . At the global level, Sedjo and Solomon [26] estimated that forests subtract on average 6.24 tC ha -1 yr -1 , while Nordhaus [27] estimated a range of only 0.8 to 1.6 tC ha -1 yr -1 .…”