The Green Alliance, a environmental think-tank, asked this question at its annual debate in London last night. Below are selections from the speeches of the four participants.

Caroline Lucas, Green Party MP for Brighton Pavilion

“Exploitation of finite resources can never be sustainable.“

“The question of whether it [shale gas] can be sustainable must rest on whether it is compatible with saving our climate and I think it is not.”

“It is reckless and irresponsible to be using public resources and giving tax breaks to help companies find a new source of carbon [shale gas] when we have more proven reserves than we can safely burn and when there is a small and shrinking window that we can do anything about it [global warming]. If we go down the road of fracking we are locking ourselves into a very centralised system in the hands of the big energy companies.“

“There are local environmental risks [to fracking]. There are very real concerns about water and air pollution. Despite what the minister [Michael Fallon] said at the weekend, Water UK is actually pretty concerned about water pollution.”

Michael Liebreich, Chief Executive Officer of Bloomberg New Energy Finance

“The local impacts are going to be very considerable, despite what the onshore and PR companies are trying to have us believe. You cannot do 100 truck movements a day in a small British village and somehow make that disappear locally.”

[Depletion rate of shale gas] “Two years after fracking, the flow rate has declined by 85 per cent so you have to re-frack – which means more truck movements – or you have to move onto the next village. It is a self-licking ice cream once you get started. People living near some of these operations will not like that. It will be very hard to do this without some very serious local disruption.”

“We are going to be using gas for next 100 years because [it is used for] electricity, transport, heating and industrial uses. There are some things that we can do, such as decarbonisation of transport, but heating is going to very difficult to get off gas.”

“Our domestic resources are declining and declining fast. Where are we going to get this gas from? If it is possible to extract shale gas in the UK and mitigate these local problems then I think we have a responsibility to explore.

David Kennedy, Chief Executive of the Committee on Climate Change, the statutory advisor to the government on low carbon technology

“We need to worry about the carbon footprint [of shale gas]. There is a big issue about putting those measures [to prevent fugitive methane emissions] into place. If you look at the evidence from the States, the best practices are not in place across the piece. That is the challenge for the government, the Environment Agency and the industry, to manage the carbon footprint of shale gas in an appropriate way.”

“There are big profits which can benefit all of us from tax revenues as long as the government does not give all those tax revenues away as tax breaks to get the industry going.”

“It is very tempting for politicians to look at the situation in the United States and the depressed gas price and think this is the answer to our affordability issues and we’ve heard politicians say it is the main benefit. ‘We can have an industrial revolution in this country attracting energy-intensive industries from all over the world because of shale gas.’ There is no evidence to support that claim.”

“Shale gas offers an opportunity not to import more and more but to meet demand by a sovereign source.”

“There is a role for shale gas but let’s be very careful what that role is: to meet on-going demand for heat. It doesn’t change the story of power sector decarbonisation or our carbon budgets or what we should commit to [on targets to tackle climate change].“

Lord Smith, Chair of the Environment Agency

“It [shale gas] is absolutely no substitute for the real work of increasing energy efficiency and developing renewables, which has to be our focus of energy policy.”

“In the short-to-medium term, whilst we are moving towards decarbonisation, it could provide, providing it is done properly, a useful bit of an answer to our energy needs. It is not going to be the all-singing-all-dancing answer that some people claim that it might be.”

“Can it be done locally sustainably? Yes provided that the regulation and monitoring of what is happening is as rigorous as it possibly can be.”

“There are some in the industry that claim [the requirements of European environmental directives] is too complex a system of regulation. Actually having firm regulation in place, and having all these requirements, is our guarantee that it can, and must, happen sustainably.”