Failure to make our farms more efficient would leave us unable to feed the growing world population and potentially lead to an ecological disaster with ever more dangerous levels of carbon dioxide in the atmosphere, they said.
Drawing up models of how changes in our diet could impact on farming by 2050, the Exeter University team found that a "high-meat, low-efficiency" situation would increase the amount of carbon dioxide in the atmosphere by 55 parts in a million.
In contrast, a "low-meat, high-efficiency" scenario would lower carbon dioxide levels by 25 ppm – enough to keep the rise in global temperature below the two-degree threshold which is seen by climate experts as the maximum "safe" increase.
In practice this would mean reducing the average worldwide meat consumption down from 16.6 per cent to 15 per cent of our daily intake of calories, which in a typical western diet equates to about half of the meat we currently eat.
This would mean that despite the expected global population increase to 9.3 billion by 2050, less farmland would be required for livestock and more could be used for the growth of bio-energy crops.
Although they are not as efficient energy sources as fossil fuels, plants absorb carbon from the atmosphere meaning they would have an overall benefit in tackling global warming, according to the study in the Energy and Environmental Science journal.
Tom Powell, a PhD student who led the project, said: "Our global agricultural system is so inefficient that we harvest about a quarter of everything that grows on the land, but only about seven to eight per cent of what we harvest ends up as food, so there are huge losses there.
"By focusing on making agriculture more efficient and encouraging people to reduce the amount of meat they eat, we could keep global temperatures within the two degrees threshold."
Co-author Professor Tim Lenton added: "With livestock production accounting for 78 per cent of agricultural land use today, this is the area where change could have a significant impact."
