The "big 10" global food and drink companies together emit more greenhouse gases than the Nordic countries and would rank as the 25th most polluting country in the world if grouped together, Oxfam claims in a report.
In a highly critical overview of their climate change policies, the international charity warns the companies that they are risking financial ruin if they do not do more to use their clout and size to tackle the climate crisis.
The companies are Associated British Foods, Coca-Cola, Danone, General Mills, Kellogg, Mars, Mondelez International, Nestlé, PepsiCo and Unilever.
The new report, titled "Standing on the Sidelines", says together they churn out more than Finland, Sweden, Denmark, Norway and Iceland's annual total of 250 million tonnes of greenhouse gases, according to its analysis of the Carbon Disclosure Project for company emissions and the most recent data for country emissions.
Oxfam insists the companies are capable of cutting their combined emissions by 80 million tonnes by 2020. It says they are not doing enough collectively despite the threat climate change poses to the sustained supply of ingredients needed for their products, their economic might and the need to feed a growing population.
Between the companies, they generate US$1.1 billion a day in revenues, equivalent to the total GDP of all the world's lower-income countries.
Oxfam singled out Kellogg and General Mills as two of the worst on climate change policies and is calling on these "clear laggards'' to lead the sector towards more responsible policies and practices.
The agency urged them to disclose their agricultural emissions and biggest polluting suppliers, and set targets to cut emissions from their supply chains.
Climate change is linked to storms, floods, droughts and shifting weather patterns, which affect food supplies and put pressure on prices, causing more hunger and poverty. Oxfam projects that the price of products such as corn flakes could rise sharply by up to 44 per cent in 15 years because of climate change.
Oxfam's director of UK campaigns and policy, Sally Copley, said: "By failing to cut emissions adequately the 'big 10' are putting short-term profits ahead of the long-term interests of both themselves and the rest of us.
"Their influence and wealth are the perfect ingredients to stop putting their businesses at risk and making climate change worse."
A statement from Kellogg said: "Kellogg is committed to doing what's right for the environment and society. As part of this commitment, we are working to reduce greenhouse gas emissions - along with energy use and water use - by 15 to 20 per cent at our manufacturing facilities by 2015.
"Oxfam has recognised our commitment to working with global palm oil suppliers to source fully traceable palm oil, produced in a manner that's environmentally responsible, socially beneficial, and economically viable."
General Mills said climate change "is a serious issue, and as a food company we are very aware of the impact that climate change could have on agriculture and the world's food supply".
The company said it had been actively engaged in positively influencing climate policy and had been taking steps to reduce greenhouse gas emissions in its operations for many years.