Former SNP climate minister Stewart Stevenson says the economic value of oil and gas can pay for environmental policies.

Speaking to Scotland Tonight, the MSP said fewer fossil fuels should be burned and should instead be used as a "chemical feed-stock".

He also called on efforts to build on the carbon-capture and storage approach.

During her keynote speech at the SNP spring conference on Sunday, the First Minister Nicola Sturgeon declared climate change as a national emergency. It followed days of disruption by the campaign group Extinction Rebellion.

Earlier this year the SNP welcomed the discovery of new oil fields in the North Sea, producing some 11.9 billion barrels of oil by 2050 according to the Oil and Gas Authority.

However, the Scottish Greens co-convener Patrick Harvie says we need to leave the vast majority of fossil fuels untouched in order to have a chance to reduce the effects of climate change.

They debated the subject on Scotland Tonight on Monday.

Stevenson:  "Extracting oil and gas from the North Sea is not an issue. It's what you do with that.

"We've got to burn less of it.

"We've got to use more of it as a chemical feedstock.

"We've got to build on the carbon-capture and storage approach to using that fuel because it's an economic value that will pay for the climate change agenda. In other policy areas."

Harvie: "No, we cannot burn fossil fuel in order to get ourselves out of a climate crisis.

"Mike Russell a senior member of the cabinet, just the other day, said on television that they want to continue seeing licences issued for new exploration and new extraction.

"We know very clearly the world knows that we have to leave the vast bulk of fossil fuel in the ground unburned if we're going to have a chance. We have far more in existing fossil fuel reserves than we can afford to use.

"[Stewart] also knows that if we if we're not going to burn it, it will not be financially viable to extract it merely for other chemical feed-stock. So we've got a huge opportunity to retool our economy to use non-hydrocarbon, non-oil and gas chemical feed-stocks and to innovate there.

"But, I really disagree with Stewart about two points.

"This is about the politics. We can't say take the politics out of this. This is deeply political. We have to reject the idea that continued free market capitalism for example is a way out of this.

"That's the economic paradigm that brought us to the point of crisis, and I also disagree that we should be trying to achieve the same thing with the new climate change bill that we did with the last one. I think we need to recognise the mistakes we made with the last one.

"We all patted ourselves on the back for consensus about targets and we had reached no consensus about how to reach those targets."