Annual Carbon Emissions from Deforestation in the Amazon Basin between 2000 and 2010.

Sassan S Saatchi,Matthew C Hansen,Xiao-Peng Song,Chengquan Huang,John R Townshend,Bruno Hérault

doi:10.1371/journal.pone.0126754

Abstract

Reducing emissions from deforestation and forest degradation (REDD+) is considered one of the most cost-effective strategies for mitigating climate change. However, historical deforestation and emission rates―critical inputs for setting reference emission levels for REDD+―are poorly understood. Here we use multi-source, time-series satellite data to quantify carbon emissions from deforestation in the Amazon basin on a year-to-year basis between 2000 and 2010. We first derive annual deforestation indicators by using the Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) product. MODIS indicators are calibrated by using a large sample of Landsat data to generate accurate deforestation rates, which are subsequently combined with a spatially explicit biomass dataset to calculate committed annual carbon emissions. Across the study area, the average deforestation and associated carbon emissions were estimated to be 1.59 ± 0.25 M ha•yr−1 and 0.18 ± 0.07 Pg C•yr−1 respectively, with substantially different trends and inter-annual variability in different regions. Deforestation in the Brazilian Amazon increased between 2001 and 2004 and declined substantially afterwards, whereas deforestation in the Bolivian Amazon, the Colombian Amazon, and the Peruvian Amazon increased over the study period. The average carbon density of lost forests after 2005 was 130 Mg C•ha−1, ~11% lower than the average carbon density of remaining forests in year 2010 (144 Mg C•ha−1). Moreover, the average carbon density of cleared forests increased at a rate of 7 Mg C•ha−1•yr−1 from 2005 to 2010, suggesting that deforestation has been progressively encroaching into high-biomass lands in the Amazon basin. Spatially explicit, annual deforestation and emission estimates like the ones derived in this study are useful for setting baselines for REDD+ and other emission mitigation programs, and for evaluating the performance of such efforts.

Highlights

Deforestation is considered the second largest anthropogenic source of carbon dioxide to the atmosphere [1]
We have demonstrated the effective use of satellite data for estimating deforestation and associated carbon emissions on a year-to-year basis
The increased temporal resolution is useful for understanding the global atmospheric CO2 variability and provides important information for emerging policies such as REDD+

Summary

Introduction

Deforestation is considered the second largest anthropogenic source of carbon dioxide to the atmosphere [1]. The large range of emission estimates is due to high uncertainty in quantifying deforestation rates, differences in the definition of forest loss, and the methodology used to estimate emission intensity. The United Nations Food and Agriculture Organization (FAO) provide periodic update on net changes in the area and biomass of the world’s forests at about 5- or 10-year intervals mainly based on country reporting, with supplementary satellite sample analysis. Limitations of FAO’s Global Forest Resource Assessment are discussed in the literature, including primarily the lack of internal consistency due to different definitions of forest among countries and time intervals [2, 13]. Only reporting net changes in forest area, without partition to gross loss and gain, could lead to ambiguous target Only reporting net changes in forest area, without partition to gross loss and gain, could lead to ambiguous target (e.g. “zero deforestation”) for current and future deforestation mitigation programs [15]

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Conclusion