The head of one of the world's biggest oil companies has admitted that the threat of climate change makes him "really very worried for the planet".
In an interview in today's Guardian Life section, Ron Oxburgh, chairman of Shell, says we urgently need to capture emissions of the greenhouse gas carbon dioxide, which scientists think contribute to global warming, and store them underground - a technique called carbon sequestration.
"Sequestration is difficult, but if we don't have sequestration then I see very little hope for the world," said Lord Oxburgh. "No one can be comfortable at the prospect of continuing to pump out the amounts of carbon dioxide that we are pumping out at present ... with consequences that we really can't predict but are probably not good."
His comments will enrage many in the oil industry, which is targeted by climate change campaigners because the use of its products spews out huge quantities of carbon dioxide, most visibly from vehicle exhausts.
His words follow those of the government's chief science adviser, David King, who said in January that climate change posed a bigger threat to the world than terrorism.
"You can't slip a piece of paper between David King and me on this position," said Lord Oxburgh, a respected geologist who replaced the disgraced Philip Watts as chairman of the British arm of the oil giant in March.
Companies including Shell and BP have previously acknowledged the problem of climate change and pledged to reduce their own emissions, but the issue remains sensitive, and carefully worded public statements often emphasise uncertainties over risks.
Robin Oakley, a climate campaigner with Greenpeace, said: "This is an important statement to make but it does have to come with a commitment to follow through, and that means making the case to his peers in the oil industry who are still sceptical of climate change."
Mr Oakley said a gulf was opening between more progressive oil companies such as Shell, which invests in alternative energy sources including wind and solar power, and ExxonMobil, the biggest and most influential producer, particularly in the US.
In June 2002 ExxonMobil's chairman, Lee Raymond, said: "We in ExxonMobil do not believe that the science required to establish this linkage between fossil fuels and warming has been demonstrated."
Lord Oxburgh's words will also fuel arguments over sequestration. Supporters say it will allow a smoother transition to reduced emissions by allowing us to burn coal, oil and gas for longer. Critics argue that the idea is an expensive and probably unworkable smokescreen for continued reliance on fossil fuels.
Last year the Guardian revealed that ministers were considering plans for a national network of pipelines to carry millions of tonnes of carbon dioxide from power stations to be buried under the North sea.
"You probably have to put it under the sea but there are other possibilities. You may be able to trap it in solids or something like that," said Lord Oxburgh, who claimed even vehicle emissions could be trapped and disposed of. "The timescale might be impossible, in which case I'm really very worried for the planet because I don't see any other approach."
According to a 3,000m (about 10,000ft) ice core from Antarctica revealing the Earth's climate history, carbon dioxide levels are the highest for at least 440,000 years.
Lord Oxburgh said the situation is particularly urgent because many developing countries, including India and China, are sitting on huge untapped stocks of coal, probably the most polluting fossil fuel.
"If they choose to burn their coal, we in the west are not in a very good position to tell them not to, because it's exactly what we did in our industrial revolution."
Bryony Worthington, a climate campaigner with Friends of the Earth, said: "It isn't a responsible attitude to say we're going to pledge to do sequestration but if the plans don't work out then the world's messed up. He's done quite a clever job by making it clear he's concerned but at the same time not pledging to do anything about it."
She called for tougher emission standards for new vehicles, as well as greater investment in energy efficiency measures and renewable sources.
A former non-executive director with Shell, Lord Oxburgh was catapulted into the chairman's role after the company was forced to reveal it had overstated the extent of its reserves. He was widely viewed as a safe pair of hands.
He followed his long-standing academic career with spells as chief science adviser to the Ministry of Defence and rector of Imperial College, London. A crossbench life peer, he still chairs the Lords science and technology select committee, although he must retire from Shell next year.
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