The European Parliament is well known for championing measures to combat global warming, but MEPs themselves are guilty of producing thousands of tonnes of carbon dioxide, unnecessarily, each month.
British MEPs have called for the parliament to stop travelling between Brussels and Strasbourg, arguing that the monthly visits not only waste millions in taxpayers' money, but are damaging the environment.
The 12 trips produce 192,000 tonnes of carbon dioxide a year - enough to fill 49,000 hot-air balloons.
The waste is in addition to the hundreds of flights made to and from Strasbourg each year by the European Union's 732 MEPs.
The figures, compiled by the Tory MEP Chris Heaton-Harris and analysed by the green research organisation Climate Care, will increase pressure for the parliament to stop holding its plenary sessions in Strasbourg. The transfer of documents and staff 12 times a year has been under attack for years.
MEPs have recently come under fresh pressure to stop flying to and from Brussels and their constituencies, and to take the train instead.
"These figures prove that not only does the European Parliament waste over £10m a month moving between Strasbourg and Brussels; but it causes tremendous damage to our environment at the same time," said Mr Heaton-Harris, MEP for the East Midlands. "It's time for common sense to prevail and the parliament to sit in just one place."