Leave as much in the ground as possible but gas will continue to have to be burnt during a transition to cleaner fuels, says former UK Environment Agency chief

Significant quantities of known coal and tar sands reserves will need to be kept in the ground to avoid the worst climate change impacts, the former chief of the UK Environment Agency has said.

But he said that lower carbon fuels such as gas would need to be extracted and burned while the world economy moves away from fossil fuels.

Chris (now Lord) Smith, a former Labour MP and minister, said: “We will have to leave carbon in the ground, but leaving all fossil fuels in the ground is for the fairies.”

“Leave as much coal in the ground as possible. Leave as much tar sands [oil] in the ground as possible. But there will be a long transition to [lower-carbon] fuels and we will need gas at least for some time,” he said.

A growing body of scientific studies show that only a minority of the world’s remaining reserves of fossil fuels can be burned if global warming is to be held to less than 2C, regarded as the limit of safety beyond which the effects of climate change are likely to become catastrophic and irreversible. The Guardian is currently running a Keep it in the Ground campaign to encourage the world’s two largest charitable foundations – the Bill and Melinda Gates Foundation and the Wellcome Trust – to divest their endowments from fossil fuel assets. The campaign has so far attracted over 145,000 signatures.

Lord Smith pointed out that the use of coal for the UK’s electricity generation has recently been about 40%, as the price has fallen and the European carbon price cap failed to bite. “It’s the highest for 25 years,” he said. “If I were to start an environmental campaign now, it would be focused on that.”

Lord Smith was shadow secretary of state for the environment under the then Labour leader John Smith from 1992 to 1994, before becoming culture secretary in Tony Blair’s first term. He is currently chairman of the taskforce on shale gas, an independent body funded by businesses that operate in the shale gas industry.

His views were echoed by Caroline Flint, currently Labour’s shadow secretary of state for energy and climate change, and the current Lib Dem energy and climate change secretary, Ed Davey.

Last week, Caroline Flint said she would “look into” the issue of whether the MPs pension fund should divest from fossil fuel companies but added that the debate over divestment should be about setting the right conditions for long-term investment in environmental sustainability.

Her office later expanded on this, saying that she did not support divestment from fossil fuels, but wanted to encourage investment in clean energy through a decarbonisation target, adding: “We will need fossil fuels as a transition to a lower carbon energy mix and even then as a back-up to deal with intermittency [of renewables].”

Ed Davey, the Lib Dem energy and climate change secretary has said that investors should consider moving their money from “very risky” coal assets but that gas would continue to be needed.

At an election hustings last week he said: “The way pension funds are going, they are interested in placing their money in what they see as sustainable forms of investment. To give incentives we need decarbonisation targets. I would make a distinction between coal and oil and gas.”

He also called for more transparency for investors. “You need to ensure investors have real disclosure about the assets of the companies they are investing in, [to see whether they are] building assets or long-term liabilities. Investor disclosure is one thing we can push through.”

Liz Truss, the Conservative environment secretary, said she did not support divestment.

The coal industry has responded to the portrayal of gas as a cleaner and transitional fuel that will aid the world to move to a lower-carbon energy mix.

Andrew Mackenzie, chief executive of the BHP Billiton mining group, told the Financial Times this week: “I think there is a marketing ploy, which is ‘give up coal and burn more gas’. I am not against the trend, but come on — the last time I looked there was plenty of carbon in methane and there is huge amounts of carbon in oil, and the carbon emissions from transport are just as much a problem as the carbon emissions from coal-fired power stations.”

He said developing countries would continue to need coal as many did not have access to indigenous gas resources, and that the key to helping them reduce greenhouse gas emissions would be to continue to develop technology to burn coal more efficiently and more cleanly. He called on all fossil fuel industries to work together on technologies for capturing and storing carbon dioxide.