Populations of mussels, clams and oysters produce “ridiculous” levels of climate-warming gasses on a par with herds of cattle, a new study shows.

Scientists have warned the ocean creatures are producing large amounts of the strongest greenhouse gases - methane and nitrous oxides - from the bacteria in their guts.

This methane bubbles out of the water contributing to global warming as it as 28 times greater warming potential than carbon dioxide.