Milk poured down kitchen sinks every year creates a carbon footprint equivalent to thousands of car exhaust emissions, according to a new study.
Scientists say 360,000 tonnes of milk are wasted in the UK each year, creating greenhouse gas emissions amounting to 100,000 tonnes of carbon dioxide.
The University of Edinburgh study said this is the same number emitted by about 20,000 cars annually.
Researchers looking into the environmental impact of food production said eating less meat and cutting down on food waste would save significant greenhouse gas emissions.
They also suggest the food industry could reduce emissions by seeking more efficient ways to use fertilisers.
Dr David Reay, of the university's School of GeoSciences, who led the study, said: "Eating less meat and wasting less food can play a big part in helping to keep a lid on greenhouse gas emissions as the world's population increases."
Researchers also said halving the amount of chicken consumed in the UK and other developed countries to levels eaten in Japan could cut greenhouse gas emissions equivalent to taking 10 million cars off the road.
The research team said figures show if average chicken consumption in developed countries fell from the current level of 26kg each every year to the Japanese average of about 12kg each by 2020, global emissions from poultry would fall below current levels, despite increased output from the developing world.
This would cut the predicted global output of nitrous oxide, a key greenhouse gas, from this source by almost 20%, based on current growth rates, they said.
The study, carried out in collaboration with the University of Aberdeen and partners in Europe and America, was published in Nature Climate Change.
The team arrived at their findings by examining data for global agricultural production of greenhouse gases together with consumption of food in various regions of the world.
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