Climate change in the High Court of Australia: Will a coal mine’s contribution to climate change cause likely environmental impacts ‘in the locality’?

Nick Scott, Harj Narulla, Nicholas Young, Michael Burger, Harro van Asselt, Jessica Wentz and Maria Antonia Tigre

In May, the High Court of Australia (HCA) will hear MACH Energy Australia v Denman Aberdeen Muswellbrook Scone Healthy Environment Group & Anor (“Denman”), the first climate case to reach Australia’s apex court. The case concerns the New South Wales Independent Planning Commission’s (IPC) decision to approve the continued and expanded operation of a coal mine. At issue is whether the environmental impact assessment for the project was required to consider downstream greenhouse gas (GHG) emissions from the burning of coal from the mine. In that respect, the case adds to a growing body of climate jurisprudence in which courts consider whether and how climate impacts must be integrated into environmental impact assessments However, the Denman case raises a further question: whether the GHG emissions associated with a coal mine can be understood as being likely to cause climate and environmental impacts in a particular ‘locality’. The HCA’s treatment of this question is likely to be scrutinised in courts within Australia and beyond, with the case potentially having global implications given Australia’s position as a major fossil fuel exporter.

The Sabin Center and the Centre for Climate Engagement (“CCE”) at Hughes Hall, University of Cambridge, represented by Counsel Frank Clarke SC and Harj Narulla, jointly filed a submission to the HCA as amici curiae, arguing that climate-related impacts stemming from the development’s GHG emissions can be considered likely impacts in the locality. The HCA granted the Sabin Center and CCE leave to appear as amici curiae in April 2026. This blog post outlines key aspects of the submission and considers how the questions raised in the case fit into the broader global climate litigation landscape.

Background

In 2016, MACH Energy purchased a coal mine in Mount Pleasant in the Hunter Valley, a region in the Australian state of New South Wales (NSW). The mine was initially permitted to operate until December 2026 and extract up to 10.5 million tonnes of coal per annum. In January 2021, MACH Energy applied to the IPC to significantly expand operations, seeking to extend the life of the mine by 22 years and double its annual extraction rate. In December 2022, the IPC approved the application.

Denman Aberdeen Muswellbrook Scone Healthy Environment Group and Anor (“Denman”) challenged the IPC’s decision on multiple grounds, including that the IPC had not complied with section 4.15(1)(b) of the Environmental Planning and Assessment Act 1979 (EPA Act). That provision requires the IPC to consider “the significant likely impacts of that development, including environmental impacts on both the natural and built environments, and social and economic impacts in the locality.” Denman argued that the IPC had failed to consider the impact of the mine’s Scope 3 emissions “in the locality.” Denman’s application was initially dismissed by the NSW Land and Environment Court but allowed on appeal by the Court of Appeal of the New South Wales Supreme Court. MACH Energy appealed the decision to the HCA, Australia’s highest court. And now here we are.

MACH Energy requested that the HCA consider three questions: (1) Must environmental impacts in the locality be considered under section 4.15(1)(b) of the EPA Act? (2) Does the requirement to consider environmental impacts require a decision-maker to consider the impacts of climate change? (3) Are climate impacts “capable of being considered an environmental impact of a development ‘in the locality’ within the meaning of section 4.15(1)(b)”? The submission filed by the Sabin Center and CCE addresses the third question.

Linking specific developments to local climate impacts in Australian courts

MACH Energy’s core argument in relation to Ground 3 is that environmental impacts are not capable of being considered “likely impacts” of the development “in the locality.” MACH Energy claims that it is not challenging the general link between climate change and negative environmental impacts, but the more specific link between emissions from a given source and impacts in a particular place. We argue that climate attribution science and the law are now sufficiently developed such that certain local climate impacts can reasonably be understood as a likely consequence of the Mount Pleasant coal mine’s Scope 3 emissions.

Importantly, for the purposes of the EPA Act, “likely impacts” do not need to be evidenced through a definitive causal relationship or meet a specific empirical threshold. In Gray v Minister for Planning and Others, the NSW Land and Environment Court held that the fact that the local impacts of a coal mine’s contribution to climate change were not, in its view, measurable “d[id] not suggest that the link to causation of an environmental impact is insufficient” Similarly, the Federal Court of Australia’s climate-related decision in Pabai v Commonwealth recognised that while it may well be “that it is not possible to measure or quantify the precise extent to which” Australia’s GHG emissions “incrementally contributed to the impacts of climate change on the Torres Strait Islands,” it does not “necessarily follow…that there was no such impact”. The key question is whether there is a “real chance or possibility” of impacts, a notably lower threshold than that which is required under, for example, many private law frameworks of causation.

Australian courts have consistently recognised the links between GHG emissions, climate change, and localised environmental harms. In Pabai, the Federal Court noted a “near linear relationship” between emissions and global warming, and a “near or approximately linear relationship” between this warming and climate impacts “at both the global and local or regional level”. State and federal courts have made similar observations in the context of fossil fuel extraction, and when considering specific environmental impacts, such as bushfires and heatwaves. These decisions rely on a vast amount of scientific evidence prepared by institutions such as the Intergovernmental Panel on Climate Change and suggest that climate-related harms facing the Hunter Valley (where the Mount Pleasant mine is located), such as rising temperatures and increased precipitation, can be scientifically, and legally, linked to fossil fuel extraction.

Other Australian decisions are consistent with this view, such as the determination in Sharma by her litigation representative Sister Marie Brigid Arthur v Minister for the Environment that “science is likely capable” of linking increased temperatures to measurable risks, and the NSW Land and Environment Court’s decision in Gloucester Resources v Minister for Planning, which used climate attribution science to link GHG emissions from a coal mining project to “both direct and indirect environmental impacts” occurring in specific localities, including in the context of coal mining and in instances where a project made up “a small fraction of the global total of GHG emissions”.

In short, the submission by the Sabin Center and CCE demonstrates that climate attribution science can link localised climate impacts to specific developments and that this has been recognised by Australian and (as discussed further below) international and other domestic courts. It follows, then, that climate-related impacts stemming from the Mount Pleasant coal mine should be considered “likely impacts” of the development under s 4.15(1)(b) of the EPA Act.

Denman in an international context

Many international and domestic courts across the world have heard climate-related cases. Many of these courts’ decisions support the notion that climate attribution science can demonstrate relationships between specific local climate harms and specific emitters in a range of contexts. This includes the European Court of Human Rights’ decision in Verein KlimaSeniorinnen and Others v Switzerland, which found a causal relationship between Swiss climate policy and heat-related risks in Switzerland, such that the government’s failure to implement sufficient measures to reduce emissions violated fundamental rights. In a domestic context, the Supreme Court of the United States’ opinion in Massachusetts v EPA concluded that GHG emissions from motor vehicles in the U.S. were sufficiently causally connected to localized impacts, such as sea level rise in the state of Massachusetts, to confer standing on the state plaintiffs. Courts in Belgium, Germany, and Colombia have found that government decisions on climate change can violate human rights and breach duties of care, confirming that these decisions caused harm to specific individuals within their respective countries in determining that individual plaintiffs had standing to bring each claim.

As noted, anticipated impacts do not need to meet the causal threshold generally required under private law principles to be considered “likely impacts” under section 4.15(1)(b). Nonetheless, even within private law contexts, courts in some jurisdictions have acknowledged the possibility that localised climate impacts may plausibly be attributed to specific emitters. This is evident in the German High Court of Hamm’s decision in Lliuya v RWE, which regarded a claim targeting a firm for its cumulative and substantial historical share of GHG emissions. While the claim was dismissed for other reasons, the court in Lliuya indicated that it was theoretically feasible for emitters to be held liable for climate-related harms. In upholding the admissibility of another claim targeting a company’s historical emissions, a Swiss cantonal court in Asmania v Holcim accepted that climate science can establish “known differences in causal contributions amongst emitters”. The Supreme Court of New Zealand made similar indications in Smith v Fonterra.

International courts have also supported the idea that it is possible to establish causal links between GHG emissions and climate damages. In its Advisory Opinion on the Obligations of States in respect of Climate Change, the International Court of Justice observed that establishing such links is “not impossible in the climate change context”. The Inter-American Court of Human Rights expressed a similar view in its Advisory Opinion on the Climate Emergency and Human Rights, as did the International Tribunal for the Law of the Sea in its Advisory Opinion on Climate Change and International Law.

Conclusion

If the HCA engages with the third ground of appeal in Denman, the Court will have an opportunity to affirm climate attribution science’s ability to trace GHG emissions from specific developments to specific local climate impacts. We argue that doing so would align with climate science, previous decisions in Australian and foreign courts, and recent Advisory Opinions delivered by international courts. Affirming that climate science can establish these links may help ensure that public decision making in Australia, a major fossil fuel producer and one of the world’s highest per-capita GHG emitters, reflects the best available science and matches the country’s climate ambitions. More broadly, the case may build on global trends in climate litigation, as climate attribution science continues to inform claims across the world.