Screwcaps produce the largest carbon footprint compared to synthetic closures and corks says research conducted for a French closure company.
The production of screwcaps gives off over 10kg of CO2 per tonne compared with 2.5kg of CO2 per tonne for corks, according to tests conducted by Cairn Environment for Oeneo Bouchage in France.
The composite DIAM closure fell between the two, with a carbon footprint of 4.3kg of CO2 per tonne.
All the closures are produced by Oeneo, and production of the PVC capsule to go with the cork and DIAM closures was taken account in recording the data.
Oeneo Bouchage, which makes the DIAM composite and treated cork closure, said the tests had been ratified by the French Environmental Agency.
Carbon footprint is the measure of the amount of CO2 a greenhouse gas released into the atmosphere through the combustion of fossil fuels and other sources.
One recent environmental study found that an individual cheeseburger has a carbon footprint of 3.06kg of CO2, including transportation of the raw materials and carbon emitted during the cooking process.