U2's world tour might make an enormous impression with its giant claw, but the environmental impact is reportedly just as staggering. According to an environmental group, the band's 44 concert dates this year have the equivalent carbon footprint of a return flight to Mars. And U2 have the same number of shows planned for 2010.

"Looking at the 44 concerts, U2 will create enough carbon to fly all 90,000 people attending one of their Wembley dates (in London) to Dublin," Helen Roberts, an environmental consultant for carbonfootprint.com, told the Belfast Telegraph. Put another way, U2's CO2 emissions are reportedly the equivalent to the average annual waste produced by 6,500 British people, or the same as leaving a lightbulb running for 159,000 years.

Environmentalists' criticism of U2 comes within a year of Bono's "prayer" that "we become better in looking after our planet". The band could cut their emissions by almost 75% by using sea, not air, to ship their three 390-tonne stages to North America. Even then, their emissions would be three times higher than Madonna's 2006 world tour, according to the Belfast Telegraph.

Though U2 may yet announce that they are paying to carbon offset their world tour – they would need to plant 20,118 trees a year, according to Roberts – at least one fan has argued that the environmental damage is worth the price. "The carbon footprint of this might be quite large, but the spiritual rewards to the audience of this are those that enhance a life," Mark Reed wrote in a review for the Final Word website. "If all life were bread and water, then there would be nothing to lift mankind above the amoeba."

And amoebas can't listen to Where the Streets Have No Name.