A report on land use and climate change finalised after discussions in Geneva, Switzerland, says that the high consumption of meat and dairy produce is fuelling global warming.
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 says that rising temperatures, increased rain and more extreme weather events will all have an impact on crops and livestock.
But food production also contributes to global warming. Agriculture - together with forestry - accounts for about a quarter of greenhouse gas emissions. Livestock rearing contributes to global warming through the methane gas the animals produce, but also via deforestation to expand pastures, for example.
The authors of the report encourage action to stop wasting food - either before or after its sale to consumers.
Waste food can sometimes be used as animal feed or, if suitable, redirected to charities to feed people in need.
The report has also called 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.
It says that how the land responds to human-induced climate change is a ‘vital concern’ for the future.