as well as carbon release in the atmosphere." Beef is also the primary driver of deforestation in the Amazon, with around 80% of all converted land being used to rear cattle. 91% of Amazon land deforested since 1970 has been converted to cattle ranching. 41% of global deforestation from 2005 to 2013 has been attributed to the expansion of beef production. This is due to the higher ratio of net energy of gain to net energy of maintenance where metabolizable energy intake is higher. The ratio of feed required to produce an equivalent amount of beef (live weight) has been estimated at 7:1 to 43:1, compared with about 2:1 for chicken. However, assumptions about feed quality are implicit in such generalizations. For example, production of a kilogram of beef cattle live weight may require between 4 and 5 kilograms of feed high in protein and metabolizable energy content, or more than 20 kilograms of feed of much lower quality. A simple exchange of beef to soy beans (a common feed source for cattle) in Americans' diets would, according to one estimate, result in meeting between 46 and 74 percent of the reductions needed to meet the 2020 greenhouse gas emission goals of the United States as pledged in 2009. A 2021 CSIRO trial concluded that feeding cattle a 3% diet of the seaweed Asparagopsis taxiformis could reduce the methane component of their emissions by 80%. While such feed options are still experimental, even when looking at the most widely used feeds around the globe, there is high variability in efficiency. One study found that shifting compositions of current feeds, production areas, and informed land restoration could enable greenhouse gas emissions reductions of 34–85% annually (612–1,506 MtCO2e yr−1) without increasing costs to global beef production. Some scientists claim that the demand for beef is contributing to significant biodiversity loss as it is a significant driver of deforestation and habitat destruction; species-rich habitats, such as significant portions of the Amazon region, are being converted to agriculture for meat production. The 2019 IPBES Global Assessment Report on Biodiversity and Ecosystem Services also concurs that the beef industry plays a significant role in biodiversity loss. Around 25% to nearly 40% of global land surface is being used for livestock farming, which is mostly cattle. Certifications Some kinds of beef may receive special certifications or designations based on criteria including their breed (Certified Angus Beef,