Sharing a stage with the former US vice president at the annual gathering of world movers and shakers in the Swiss ski resort of Davos, the U2 frontman joked that their friendship was a source of pressure on the domestic front.

"He's been round my house and it's like... here's the recycler Al, you know... I've got a posh car, but it runs on ethanol Al," Bono said.

Acknowledging that a career in rock music was not always conducive to a green lifestyle, Bono compared a conversation with Gore to an act of religious contrition.

"It's like being with an Irish priest. You start to confess your sins," he said. "Father Al, I am not just a noise polluter, I am a noise-polluting, diesel-soaking, gulfstream-flying rock star.

"I'm going to kick the habit. I'm trying father Al, but oil has been very good for me -- those convoys of articulated lorries, petrochemical products, hair gel."

Bono and Gore were in Davos to push their respective campaigns for poverty alleviation and reducing carbon emissions.