A major report on land use and climate change says the West's high consumption of meat and dairy produce is fuelling global warming.
But scientists and officials stopped short of explicitly calling on everyone to become vegan or vegetarian.
They said that more people could be fed using less land if individuals cut down on eating meat.
The document, prepared by 107 scientists for the UN's Intergovernmental Panel on Climate Change (IPCC), says that if land is used more effectively, it can store more of the carbon emitted by humans.
It was finalised following discussions held here in Geneva, Switzerland.
The report calls for vigorous action to halt soil damage and desertification - both of which contribute to climate change.
It also warns that plans by some governments to grow trees and burn them to generate electricity will compete with food production unless carried out on a limited scale.
The Earth's land surface, and the way it is used, forms the basis for human society and the global economy.