Boosted carbon emissions from Amazon deforestation

Standing biomass is a major, often poorly quantified determinate of carbon losses from land clearing. We analyzed maps from the 2001–2007 PRODES deforestation time series with recent regional pre‐deforestation aboveground biomass estimates to calculate carbon emission trends for the Brazilian Amazon basin. Although the annual rate of deforestation has not changed significantly since the 1990s (ANOVA, p = 0.3), the aboveground biomass lost per unit of forest cleared increased from 2001 to 2007 (183 to 201 Mg C ha −1 ; slope of regression significant: p < 0.01). Remaining unprotected forests harbor significantly higher aboveground biomass still, averaging 231 Mg C ha −1 . This difference is large enough that, even if the annual area deforested remains unchanged, future clearing will increase regional emissions by ∼0.04 Pg C yr −1 – a ∼25% increase over 2001–2007 annual carbon emissions. These results suggest increased climate risk from future deforestation, but highlight opportunities through reductions in deforestation and forest degradation (REDD).