An attempt to prevent the expansion of an open-cut coal mine has been rejected despite its expected contribution to global emissions.
A group representing communities in the coal-rich NSW Hunter region took the operators of the Mount Pleasant mine near Muswellbrook to the state's Land and Environment Court in a bid to invalidate the 2022 decision allowing it to expand..
They argued the planning commission's consent failed to consider the global impact of emissions from coal to be mined there, among other grounds relating to biosecurity, air quality, health and social impacts, which were all dismissed.
NSW Land and Environment Court Justice John Robson said the court could only review whether the commission correctly carried out its required functions.
"Although these proceedings raise matters of the utmost public interest, and while there is no doubt that the continuation of coal mining will contribute to the global total of greenhouse gas concentrations which affects the climate system and causes climate change impacts ... it is not the function of this court to undertake merits review of the commission's findings," he said in a decision published on Monday.
Operator MACH Energy applied to deepen the mine and double its output, extending its life to 2048 in a bid to extract an additional 406 megatonnes of coal.
The NSW Independent Planning Commission consented, subject to conditions, in September 2022.
Tony Lonergan, treasurer of the Denman Aberdeen Muswellbrook Scone Healthy Environment Group which brought the court action, said the decision was extremely disappointing.
"But also a devastating blow to anyone who cares about a safe climate," he said in a statement following the court's decision.
The decision demonstrated planning laws were not ready to address global warming, he added.
MACH Energy has three weeks to decide whether it will seek costs, and was contacted for comment.
