The study found that if the world food system stays on its current growth path, it will produce nearly 1.4 trillion metric tons of greenhouse gases over the next 80 years.
That pollution is expected to come from fertilizers used in agriculture, mismanaged soil, food waste and methane gas released from cows and other animals. Other causes include land-clearing operations and deforestation.
Researchers from the University of Minnesota and the University of Oxford in Britain led the study, which recently appeared in the publication Science.
The researchers predict that even if fossil fuel emissions were halted now, emissions from the world food system would make it impossible to reach current international climate change targets. They say that emissions from food production alone could push world temperatures past 1.5 degrees Celsius by the middle of this century and above 2 degrees Celsius by the end of the century.
A main goal of the 2015 United Nations Paris Agreement on climate change is to keep rises in the Earth's temperature during this century to between 1.5 to 2 degrees Celsius. The U.N. has said that in order to stay below the 1.5 Celsius level, emissions must fall at least 7.6 percent each year through 2030.
The new study calls for immediate "improvements in farming practices, as well as changes in what we eat and how much food we waste," to help reach the Paris Agreement goals.
Jason Hill is a professor of biosystems engineering at the University of Minnesota. He helped lead the study. He said in a statement that the research clearly demonstrates that food has a much greater effect on climate change than is widely known.
Hill also noted that fixing the problem would not require the world's population to completely stop eating meat. "The whole world doesn't have to give up meat for us to meet our climate goals," he told the Associated Press. "We can eat better, healthier foods. We can improve how we grow foods. And we can waste less food."
The researchers say such efforts are achievable and can also lead to many other improvements beyond controlling climate change. These include making humans healthier, reducing water pollution, improving air quality, preventing animal extinctions and improving farm profitability.
The study makes the following predictions:
A nearly complete change to a plant-rich diet around the world could cut nearly 650 billion metric tons of greenhouse gases.
If almost everyone ate the right number of calories based on age - around 2,100 calories a day for many adults - it would reduce emissions by about 410 billion metric tons.
If farming could reduce carbon levels - by using less fertilizer, managing soil better and doing better crop rotation - it would cut greenhouse gases by nearly 540 billion metric tons.
And if people wasted less food - at home, in restaurants or by getting it to people in poorer countries – emissions could be cut by about 360 billion metric tons.
I'm Bryan Lynn.