According to the 2006 Food and Agriculture Organization of the United Nations (FAO) report "Livestock's Long Shadow", animal agriculture contributes on a "massive scale" to global warming, air pollution, land degradation, energy use, deforestation, and biodiversity decline. The FAO report estimates that the livestock (including poultry) sector (which provides draft animal power, leather, wool, milk, eggs, fertilizer, pharmaceuticals, etc., in addition to meat) contributes about 18 percent of global GHG emissions expressed as 100-year CO2 equivalents. This estimate was based on life-cycle analysis, including feed production, land use changes, etc., and used GWP (global warming potential) of 23 for methane and 296 for nitrous oxide, to convert emissions of these gases to 100-year CO2 equivalents. The FAO report concluded that "the livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global". The report found that livestock's contribution to greenhouse gas emissions was greater than that of the global transportation sector; this conclusion was criticized in 2010 by Frank Mitloehner of the University of California, Davis, who noted that the authors had not performed a similar life-cycle analysis for transportation, causing the relative contribution of animal agriculture to be overestimated.