Russell Vale mine approved as Sussan Ley says it won't cause world temperatures to rise

Ms Ley said while she had appealed against the Federal Court's finding, she had considered the duty of care.

But she decided the greenhouse gas emissions (GHG) from the mine - estimated by the court at 100 million tonnes of CO2 - would not increase world temperatures.

"I have accepted the department's recommendation on the available evidence, that a decision to approve the proposed action would be unlikely to lead to an increase in global average surface temperatures," she said.

"The proposed action is not likely to cause more coal to be consumed globally (and therefore more GHG emissions) than if the proposed action was not approved."

Lock the Gate spokesman Nic Clyde slammed the decision as "terrible for Australian children".

"Wollongong Coal's dire financial situation and rotten environmental history were grounds enough to reject this project - but instead Sussan Ley has rolled out the red carpet for this company," he said.

"She approved this mine even while acknowledging that the Federal Court found 'there was a real risk that even an infinitesimal increase in global average surface temperature may trigger a tipping point or a 4°C Future World'.

"Sussan Ley has knowingly subjected Australian children to catastrophic climate risks."

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