U2's desire to save the planet has been rather undermined by the revelation that the band have a carbon footprint big enough to fly them to Mars and back.

In a speech made in Tokyo last year, Bono said: "“My prayer is that we become better in looking after our planet.”

But according to environmentalist experts from carbonfootprint.com, the band will clock up 70,000 air miles during their 100-date 18-month world tour, not to mention transporting the three 390-tonne stages and 200 crew and backstage staff members who accompany them as well.

Their CO2 emissions are the equivalent of the waste created by 6,500 average British or Irish people in an entire year, or equal to leaving a standard 100 watt lightbulb on for 159,000 years, and are much larger than the carbon footpring left by Madonna during her 2006 world tour when she produced 1,635 tonnes in air transport.

The tour’s carbon footprint can also be measured in space terms, with their colossal emissions of up to 65,000 tonnes of CO2 enough to fly them on a return trip to the planet Mars.

Carbonfootprint.com’s environment consultant Helen Roberts said: “The carbon footprint generated by U2’s 44 concerts this year is equal to carbon created by the four band members travelling the 34.125 million miles from Earth to Mars in a passenger plane.

“You also have to add the carbon emissions from the same number of concerts again next year.

“Just looking at the 44 concerts this year, the band will create enough carbon to fly all 90,000 people attending one of their Wembley concerts to Dublin. To offset this year’s carbon emissions, U2 would need to plant 20,118 trees.”