根據(jù)科學(xué)家的預(yù)測,，由于巴西擴(kuò)張生物燃料種植園從而滿足該國“綠色”燃料生產(chǎn)目標(biāo)帶來的潛在環(huán)境損害可能抵消從使用生物燃料得到的碳減排。
David Lapola及其同事使用了一個(gè)數(shù)學(xué)模型,，以確定增加巴西生物燃料種植園的面積從而滿足政府提出的2020年生物燃料生產(chǎn)目標(biāo)帶來的影響,。
這組科學(xué)家發(fā)現(xiàn),，挪用牧場從而種植滿足未來目標(biāo)的生物燃料作物可能把牲畜推向亞馬遜森林和巴西塞拉多草原，這可能帶來需要大約250年時(shí)間才能通過使用生物燃料而償還的碳債務(wù),。這組作者建議增加現(xiàn)有牧場的牲畜密度作為原棲息地森林砍伐的替代方案,，并提出種植油棕櫚而不是其他常見的生物燃料作物，從而讓碳債務(wù)最小化。
這組作者說,，這項(xiàng)研究可能幫助政府和管理機(jī)構(gòu)建立促進(jìn)可持續(xù)生物燃料制造和使用的標(biāo)準(zhǔn)和項(xiàng)目,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS February 8, 2010, doi: 10.1073/pnas.0907318107
Indirect land-use changes can overcome carbon savings from biofuels in Brazil
David M. Lapolaa,b,1, Ruediger Schaldacha, Joseph Alcamoa,c, Alberte Bondeaud, Jennifer Kocha, Christina Koelkinga, and Joerg A. Priesse
aCenter for Environmental Systems Research, University of Kassel, 34109 Kassel, Germany;
bInternational Max Planck Research School on Earth System Modelling, Max Planck Institute for Meteorology, 20146 Hamburg, Germany;
cUnited Nations Environment Programme, Nairobi, Kenya;
dPotsdam Institute for Climate Impact Research, 14412 Potsdam, Germany; and
eHelmholtz-Centre for Environmental Research, 04318 Leipzig, Germany
The planned expansion of biofuel plantations in Brazil could potentially cause both direct and indirect land-use changes (e.g., biofuel plantations replace rangelands, which replace forests). In this study, we use a spatially explicit model to project land-use changes caused by that expansion in 2020, assuming that ethanol (biodiesel) production increases by 35 (4) x 109 liter in the 2003-2020 period. Our simulations show that direct land-use changes will have a small impact on carbon emissions because most biofuel plantations would replace rangeland areas. However, indirect land-use changes, especially those pushing the rangeland frontier into the Amazonian forests, could offset the carbon savings from biofuels. Sugarcane ethanol and soybean biodiesel each contribute to nearly half of the projected indirect deforestation of 121,970 km2 by 2020, creating a carbon debt that would take about 250 years to be repaid using these biofuels instead of fossil fuels. We also tested different crops that could serve as feedstock to fulfill Brazil’s biodiesel demand and found that oil palm would cause the least land-use changes and associated carbon debt. The modeled livestock density increases by 0.09 head per hectare. But a higher increase of 0.13 head per hectare in the average livestock density throughout the country could avoid the indirect land-use changes caused by biofuels (even with soybean as the biodiesel feedstock), while still fulfilling all food and bioenergy demands. We suggest that a closer collaboration or strengthened institutional link between the biofuel and cattle-ranching sectors in the coming years is crucial for effective carbon savings from biofuels in Brazil.
