From the first source within that study.
Within the United States, agriculture is responsible for approximately 6 percentof GHG emissions. Beyond U.S. borders, the links between agriculture and land management and climate change are more striking. On a global scale, agriculture is responsible for 30 percent of GHG emissions, including emissions caused by deforestation and land use change.
Effectively, most Western nations aren't too affected because of of a high mass of available grazing and crop land, as well as extreme efficient farming techniques. Yes, we could sequester more by turning the land that can be changed into forest, but the fact is, much of it is grassland because it can't support forests, we don't have a ton that we could 'reforest', and our logging industry has already grown the forested area of the U.S. a significant amount in the last century, and those "harvestable forests" are an excellent source of long term sequestration by turning the CO2 into long term structures and then planting young forests for new sequestration. (The only argument here is for biodiversity of older forests).
It's third world nations, like I spoke about, where forests are clear cut to grow crops (And feed cows) where the bulk of the green house cycle is actually affected in a negative way--but unlike fossil fuels, it's completely reversible fairly easily--the only issue is telling poor people they can't grow crops.
However, looking at Western beef production as being a primary culprit behind climate change is ridiculous. The issue is removing sequestered long term carbon from the ground and using it for energy--not continuing a cycle of sequestrate/energy that humanities epoch has had stable. The problem is we're changing the cycle with those outside sources, the actual cycle itself isn't the problem. And measuring cow farts, which will cycle back down into grass for more cow farts? Is simply measuring the cycle, that carbon wasn't pulled from a sequestered source.
The biggest issue with livestock, by far, is not carbon emissions--it's water usage. It requires an enormous amount of water that is affected our water tables and the water is subsidized by the government. But the carbon angle is dumb outside of looking at deforestation in third world countries. Sorry to ruin cowspiracy for you.