Fargione, et al, "Land Clearing and the Biofuel Carbon Debt," Science, February 2008.
"Biofuels are a potential low-carbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food crop–based biofuels in Brazil, Southeast Asia, and the United States creates a 'biofuel carbon debt' by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions that these biofuels would provide by displacing fossil fuels."
Searchinger et al, "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change," Science, February 2008.
"By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years."
Hill, et al, "Climate change and health costs of air emissions from biofuels and gasoline," Proceedings of the National Academy of Sciences of the USA, February 2009.
"For each billion ethanol-equivalent gallons of fuel produced and combusted in the US, the combined climate-change and health costs are $469 million for gasoline, $472–952 million for corn ethanol depending on biorefinery heat source (natural gas, corn stover, or coal) and technology, but only $123–208 million for cellulosic ethanol depending on feedstock (prairie biomass, Miscanthus, corn stover, or switchgrass)."
Searchinger, et al, "Fixing a Critical Climate Accounting Error," Science, October 2009.
"The accounting now used for assessing compliance with carbon limits in the Kyoto Protocol and in climate legislation contains a far-reaching but fixable flaw that will severely undermine greenhouse gas reduction goals. It does not count CO2 emitted from tailpipes and smokestacks when bioenergy is being used, but it also does not count changes in emissions from land use when biomass for energy is harvested or grown. This accounting erroneously treats all bioenergy as carbon neutral regardless of the source of the biomass, which may cause large differences in net emissions. For example, the clearing of long-established forests to burn wood or to grow energy crops is counted as a 100% reduction in energy emissions despite causing large releases of carbon."
Empa, et al, "Harmonisation and extension of the bioenergy inventories and assessment," for the Swiss Federal Office of Energy, August 2012.
Page 81 "Table 33: ILCD Midpoint results of the biofuel and fossil fuel value chains per v.km." (vehicle*kilometer) - Chart shows that "Ozone depletion" is the only category in which biofuels consistently rank much better than gasoline. The "Climate change" category shows that only 15 of the 27 listed biofuel sources ranked much better; one, Brazilian soy, even ranked much worse.
Liska, et al, "Biofuels from crop residue can reduce soil carbon and increase CO2 emissions," Nature Climate Change, April 2014.
"Removal of corn residue for biofuels can decrease soil organic carbon (SOC) and increase CO2 emissions because residue C in biofuels is oxidized to CO2 at a faster rate than when added to soil."