Previous studies on the impact of the UK's diet on the environment had failed to factor in deforestation and other land use changes across the world, the report said, so the sector's environmental impact had been underestimated.
The WWF revised its estimate of the UK's food and drink emissions from 152 million tonnes a year of CO2 to a massive 253 million an increase of more than 65%.
Though the figures are not directly comparable, the Department of Transport estimates that all UK transport, including air travel, accounts for 173 million tonnes of CO2, while the total amount of CO2 pumped out by all the country's power stations is 177 million tonnes both considerably less than the new food sector estimates.
"These new findings show it's going to be even harder for food companies to achieve the cuts needed to prevent climate change but they also show it's even more important," said WWF head of business relations Dax Lovegrove. "We believe food-related emissions need to be cut 70% by 2050, and you can't escape that this will involve consumers needing to change their habits, especially with regard to meat and dairy.
"Retailers need to persuade customers to change their habits."