The authors of this report address previous estimates of climate change due to livestock. They argue that previous estimates produced by the United nations (UN) left out some key data and has therefore underestimated the effects of livestock on climate change. They estimate that livestock and their byproducts account for at least 32.6 billion tons of carbon dioxide per year, which is 51% of annual worldwide greenhouse gas (GHG) emissions.

The authors speak mainly to Livestock’s Long Shadow, a 2006 report by the United Nations’ Food and Agriculture Organization. The authors argue that the report underestimates the amount of GHG emissions in a few major ways and then discussing in detail their revised calculations. They argue that the biggest mistakes were made in terms of overlooking respiration and land use by livestock, as well as leaving some methane production unaccounted for. In all, they their estimate is 55% higher than the previous UN estimate.