High Court rules on greenhouse gas emissions and the impacts of climate change, but what does this actually mean for Western Australia?

The High Court of Australia has made a rare foray into the world of planning and environmental law, in the decision of MACH Energy Australia Pty Ltd v Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc [2026] HCA 35.  Specifically, the High Court has considered the relevance of downstream greenhouse gas emissions and the impacts of climate change in the context of assessing resource extraction proposals.

The immediate media reaction has painted this High Court decision as being a win for environmentalists and a loss for the resources industry.  But what (if anything) does this High Court decision actually mean for the undisputed home of the resources industry, Western Australia?

Arguably, not much.

The facts

The underlying subject matter before the High Court was a development approval to extend the operational life of an existing coal mine in the Hunter region, by a period of 22 years.  The extension would have resulted in an estimated 406 million tons of coal being extracted and the project would have accounted for an estimated 0.065% of total global greenhouse gas emissions.

A community group sought a judicial review of the development approval decision.  This legal challenge was unsuccessful at first instance, but was then successful in the intermediate appeal.  The mine operator was then granted special leave to appeal to the High Court.

The appeal in the High Court was centered on section 4.15(1) of the Environmental Planning and Assessment Act 1979 (NSW) (EPA Act), which outlines the considerations that a consent authority must take into account in assessing and determining a development application.  One limb of this provision requires regard to be given to any environmental planning instrument, for which the relevant instrument was the State Environmental Planning Policy (Resources and Energy) 2021 (NSW) (Resources SEPP).  Another limb of this provision requires regard to be given to “environmental impacts of development”.

Section 2.20 of the Resources SEPP provides that prior to granting a development approval for a mining project, the consent authority must consider whether conditions should be imposed to ensure that “greenhouse gas emissions are minimised to the greatest extent practicable”.  The High Court construed this provision as encompassing what are known as “Scope 3” emissions, which is a concept that includes downstream third-party emissions from the combustion of coal extracted from the relevant mine.  The evidence was that about 98% of the greenhouse gas emissions from the project would be Scope 3 emissions and that these would largely be associated with coal being exported overseas before being used.

The decision

One of the issues before the High Court was whether the consent authority had properly followed the Resources SEPP by considering whether conditions should be imposed in respect of Scope 3 emissions.  The consent authority had referred briefly to Scope 3 emissions in its statement of reasons for its decision, but there was no direct discussion about whether conditions should be imposed.  By a majority of 3 to 2 on this particular issue, the High Court held that the consent authority failed to consider whether Scope 3 emissions should be conditioned, which was contrary to the Resources SEPP and section 4.15(1) of the EPA Act.

The High Court accordingly dismissed the appeal, with the result being that the development approval for the coal mine extension remains quashed.

The High Court separately considered whether the other requirement in section 4.15(1) of the EPA Act, to consider environmental impacts of development, specifically required the consent authority to consider local-level environmental impacts associated with climate change.  On this issue, all justices of the High Court found that there is no specific requirement for the consent authority to consider local-level environmental impacts and the requirement within section 4.15(1) of the EPA Act is broader and is simply to consider “environmental impacts of development”.  Such impacts may well include local-level impacts or impacts associated with climate change, but a development approval decision will not be invalidated owing to a failure of the consent authority to specifically consider some particular local-level aspect of the environment.

According to the reasons of the High Court, the only legal error made by the consent authority related to its failure to consider imposing conditions on Scope 3 emissions.  Importantly, the High Court did not say that a consent authority in future must impose such conditions and the requirement will instead be to properly consider whether or not they should be imposed.  It therefore seems quite possible that the same coal mine extension project could end up receiving a new development approval, if the consent authority makes a new decision where it gives proper consideration to whether or not conditions should be imposed on the topic of Scope 3 emissions.  When viewed in this light, it is arguable that the High Court decision is not actually a significant win for the environment and does not signal the demise of coal mining in Australia.

Relevance to Western Australia

Put simply, the High Court decision has no direct relevance to Western Australia.  That is fundamentally because the EPA Act is New South Wales legislation and the Resources SEPP is a New South Wales planning instrument.  Further, there are no direct equivalents in Western Australian legislation or planning policies.

The standard list of relevant considerations for the determination of a development application in Western Australia is set out in clause 67 in Schedule 2 of the Planning and Development (Local Planning Schemes) Regulations 2015 (WA) (Clause 67).

Clause 67 refers to State planning policies, but the relevant State planning policy on the environment and natural resources (being Statement of Planning Policy No 2 – Environmental and Natural Resources Policy) is over 20 years old, and whilst it does refer to greenhouse gas emissions, it does not contain any content that could be construed as a requirement for planning decision-makers to consider climate change impacts of conditioning Scope 3 emissions.

Clause 67 refers to environmental protection policies approved under section 31(d) of the Environmental Protection Act 1986 (WA) (EP Act), but there is not currently any environmental protection policy in place under the EP Act that deals specifically with the topics of greenhouse gas emissions or climate change.

Clause 67 refers to the environmental impacts of development, but in the specific context of considering the amenity of a locality, so this would presumably need to be read as referring only to environmental impacts that may impact upon local amenity.  Clause 67 then separately refers to “the likely effect of the development on the natural environment…and any means that are proposed to protect or mitigate impacts on the natural environment”.  These provisions could arguably enable a planning decision-maker to consider impacts of a development through its contribution to climate change, if there is a sound factual basis upon which to contend such an impact.  These provisions could not however be said to compel a planning decision-maker to condition Scope 3 emissions associated with a proposal.

On the basis of the above, the differences between the legislative and planning regimes in New South Wales and Western Australia respectively are such that the High Court decision does not set any precedent that will bind future decision-making within Western Australia.  It can otherwise be observed that there is not currently any State-level requirement in Western Australia for the conditioning of greenhouse gas emissions or for the impacts of climate change to be specifically considered in the context of planning decision-making.

Other considerations

Importantly, unlike the position in New South Wales where a development approval is needed for a mining project, in Western Australia, works associated with a mining project will ordinarily be exempt from the need for a development approval.  That is as a consequence of section 120 of the Mining Act 1978 (WA), which says that the provisions of a planning scheme shall not prohibit or affect the carrying out of any properly authorised mining operations.  Similarly, in the context of oil and gas extraction, section 15 of the Petroleum, Geothermal Energy and Greenhouse Gas Storage Act 1967 (WA) provides that the authority behind various permits granted under that regime may be exercised in the relevant area “despite any other Act or law”, which effectively stands as a development approval exemption.  The High Court decision is about a planning law in New South Wales, but the resources industry in Western Australia is largely immune from the application of planning laws.

It should however be observed that greenhouse gas emissions and climate change are considered in Western Australia as part of the environmental impact assessment process under Part IV of the EP Act.  This was indeed the case prior to the High Court decision and will continue unaffected by the High Court decision.  In particular, the Environmental Protection Authority in Western Australia has a guideline in place, which states that its environmental impact assessment considerations will include: “whether reasonably practicable measures have been considered to reduce scope 3 emissions, such as entering into arrangements with third parties to reduce emissions”.  The core issue in the High Court matter is accordingly already a feature of major projects in Western Australia, albeit under the EP Act environmental assessment regime and not under planning laws.

Whilst the High Court decision does not set any legal precedent to this effect, the High Court decision could potentially draw greater attention to both upstream and downstream greenhouse gas emissions and climate change impacts in the context of non-resource industry proposals that nevertheless have a significant carbon footprint.  It is however unclear whether a submission from an objector referring to potential indirect environmental impact, through a contribution to global climate change, would be likely to influence a planning decision-maker, in the absence of adopted planning policies providing direct guidance on this topic.

If you have any questions in relation to this High Court decisions, please contact Lavan’s planning, environment and land compensation team.

Disclaimer

The information contained in this publication does not constitute legal advice and should not be relied upon as such. You should seek legal advice in relation to any particular matter you may have before relying or acting on this information. The Lavan team are here to assist.