Roughly 200 experts in disciplines from nutrition to animal welfare are calling on the World Health Organization to take a more serious look at the impact of industrial livestock production on human health and the climate.

In a letter sent Monday, the group—which includes former New York Times food writer Mark Bittman and environmentalist Bill McKibben—appealed to the WHO, asking that its next director-general work “to reduce the size and number of factory farms.” The WHO’s World Health Assembly got underway Monday, and the body will elect a new leader this week.

“As the global health community acknowledges the intertwined nature of planetary and human health, it must also confront the role that factory farming plays in climate change,” the letter says.

The group points to predictions that, without a reduction in meat consumption, agriculture—including livestock production and growing grain to feed livestock—is on track to gobble up half the world’s carbon budget if countries expect to meet the 2050 target of limiting global temperature rise to less than 2 degrees Celsius. The livestock industry’s contribution to greenhouse gases come from direct sources, including methane emitted from the animals belching and their manure, but also from indirect sources, including land conversion and deforestation linked to growing feed.