The chart illustrates how the climate impact of beef and lamb dwarfs that of other foods. This is partly down to the biology of how these animals digest food, explains
Prof Sir Charles Godfray, a population biologist and head of the
Oxford Martin School at the
University of Oxford. He tells Carbon Brief:
“In a very broad-brush approach, the products from ruminant animals – sheep, cows and their relatives, animals with four stomachs – they tend to have greater greenhouse gas effects. Part of that is because digestion by ruminants produces a lot of methane.”
Cows and sheep are “ruminants” – meaning that their stomachs contain specialised bacteria capable of digesting tough and fibrous material, such as grass. The digestive process causes the animals to
belch out
methane, a greenhouse gas that is around
28-34 times (pdf) more powerful than CO2 over a 100-year period.
However, the chart illustrates that producing beef is more than twice as carbon intensive as producing lamb.