Intensified meat production in response to climate change would bring short-term rewards, long-term risks

Much of this current and anticipated "intensification" of agriculture centers on increasing meat production through more efficient means, including factory farming, which keeps animals in closely confined environments and raises the risk of the spread of zoonotic diseases, such as avian influenza.

"As long as meat consumption continues to rise globally, both climate change, from deforestation and methane, and pandemics will likely continue to rise," says Matthew Hayek, an assistant professor in New York University's Department of Environmental Studies and the author of the analysis, which reviews more than 100 articles studying the effects of intensifying animal agriculture on the environment and on zoonotic diseases -- infectious diseases that come from animals.

As the climate warms, researchers have concluded that countries will need to produce more food, and more efficiently, than ever before. To address these current and future needs, the agriculture industry has adopted "intensification" practices: adding more "inputs," such as machinery, hormones, and antibiotics, while increasing production.

Hayek's Science Advances analysis shows that intensification can, in the short term, reduce animal feed requirements and land use because animals are sedentary and gaining weight as fast as possible when placed in intensive facilities -- rather than grazing on open land. This can decrease deforestation, helping to maintain wild animal habitats and buffering against diseases that come from those wild animals by keeping them far from regular human contact.

However, intensification can accelerate diseases that come from domestically farmed animals.

"This is because intensive production facilities confine animals close to each other," explains Hayek. "This confinement, most typically used for pigs and chickens, allows diseases to quickly spread and mutate rapidly between many thousands of animals in one facility."

More specifically, the Science Advances examination revealed that raising chickens requires three times more antibiotics and 170 times more animals to produce the same quantity of meat as raising cattle, raising risks of diseases such as avian influenza ("bird flu") and antibiotic-resistant bacteria. Therefore, although shifting meat consumption from beef to chicken can benefit the climate, Hayek says, it could hasten the spread of costly, potentially pandemic diseases.

"Meat consumption creates a 'trap' of disease risks: extensive 'free-range' production that requires wildlife habitat clearing on one hand or intensive animal confinement on the other," concludes Hayek. "To prevent both climate change and costly pandemics in tandem, we should rapidly reduce meat consumption as well as support forest protections and better farmed animal health through veterinary services. Policies can help accelerate the shift to plant-rich options by changing our food landscape: making plant-based choices easier to access, more affordable, and more appealing."