Key Takeaways - 39 Essex Chambers Climate Change Half Day Seminar

Introduction

With the 2025 UN Climate Change Conference (COP30) underway in Brazil, 39 Essex Chambers hosted a half-day seminar on the latest developments in climate law. This paper summarises the key takeaways from the day.

Stephen Tromans KC and Nigel Pleming KC opened the day by noting that, despite the world experiencing one of the warmest Novembers on record, there are widespread attempts to roll back the scientific consensus on the anthropogenic causes of climate change. They highlighted Donald Trump’s decision to defund climate science and the Environmental Protection Agency’s (EPA) proposal to rescind its endangerment finding on greenhouse gases, which has underpinned US federal climate regulation for more than fifteen years.

Whilst the political environment looks bleak, there have been several significant and positive developments in climate law. The first discussed during the seminar was the International Court of Justice’s landmark advisory opinion on the obligations of states on climate change.

Flora Curtis and Ella Grozinski - ICJ advisory opinion on Climate Change

Flora Curtis began by outlining the origins of the ICJ’s advisory opinion. It started as a grassroots campaign by students from the Pacific Island nations, before being picked up and proposed as a resolution at the UN General Assembly by the Republic of Vanuatu. In March 2023, the Assembly adopted the resolution by consensus and the Court delivered its unanimous Opinion in July 2025.

The first notable aspect of the decision Flora highlighted was the breadth of international law which the Court held are relevant to states’ climate obligations. Several states had attempted to argue that the Paris Agreement and other climate treaties formed a lex specialis which displaced general international obligations. The Court rejected this suggestion, explaining that duties relating to the climate arise across international law, including human rights law and the law of the sea.

The Court also interpreted states’ obligations under the Paris Agreement. The ICJ’s decision was clear that, under Article 2, the primary obligation is to keep temperature levels to 1.5°C rather than the upper 2°C limit. Additionally, the ICJ emphasised that when determining what contribution each state should make to achieving this aim, under Article 4, historical contributions to climate change should be taken into account such that developed countries who have greater historic emissions should bear more of the burden.

Ella Grodzinski then addressed the Court’s findings on the consequences of breaching these obligations. The Court rejected arguments from some states that it is impossible to attribute the harms of climate change because of the cumulative nature of emissions. Rather, it accepted that states’ contributions can be scientifically quantified and that a failure to take appropriate protective action may amount to an unlawful act. Importantly, the Court characterised many of the key obligations relating to climate as erga omnes, meaning all states have a legal interest in them and may take action against an offending state.

Camilla ter Haar and Grace Cheng - International investment treaty arbitrations and climate change

In the next session, Camilla ter Haar and Grace Cheng examined how international investment treaty arbitrations are increasingly intersecting with climate policy. Camilla explained that Investor State Dispute Settlement (ISDS) clauses were originally designed to promote investment by protecting investors from expropriation, safeguarding legitimate expectations and ensuring fair and equitable treatment. In the climate context, these protections can be engaged when States introduce regulatory measures aimed at mitigation or adaptation. Whilst ISDS mechanisms can potentially stymie such measures, they can also help attract investment into low carbon technologies by providing commercial certainty.

Grace described recent arbitral institutional reforms aimed at making arbitral processes more environmentally sustainable. Building on the shift to virtual hearings during the Covid-19 pandemic, arbitral tribunal’s rules – such as those in Hong Kong and Singapore – increasingly require tribunals to consider the environmental impact of their procedures. Specialist frameworks, including the Permanent Court of Arbitration’s Optional Rules for Natural Resources and Environment Disputes, also offer tailored procedures, expert arbitrator lists and the possibility of interim measures to prevent serious environmental harm.

Camilla and Grace also discussed the recent ICSID claim Woodhouse Investment Pte Ltd and West Cumbria Mining (Holdings) Ltd v United Kingdom, filed on 8 August 2025 under the 1975 UK Singapore Bilateral Investment Treaty (BIT). This case follows the High Court’s quashing of the planning permission for the proposed West Cumbria coal mine in Friends of the Earth Ltd v Secretary of State for Levelling Up, Housing and Communities [2024] EWHC 2349 (Admin), a consequence of the Supreme Court’s decision in R (Finch) v Surrey County Council [2024] UKSC 20. The investors allege breaches of fair and equitable treatment and unlawful expropriation, raising questions about the impact of ICSID on the UK’s approach to scope 3 emissions.

Stephanie David and Daniel Kozelko: Consenting for solar farms: patterns and challenges

We then heard from Stephanie David who highlighted the significant policy emphasis on building solar in the UK Solar Roadmap and the new Carbon Budget and Growth Delivery Plan. Given that emphasis with ambitions to accelerate solar deployment from over 18GW to 45-47GW by2030 with scope to exceed 47GW through a ‘rooftop revolution’. Daniel Kozelko analysed two routes[1] for applicants seeking consent for solar development: (i) locally under the Town and Country Planning Act 1990 (for which applications must be 49.9MW or less); and (ii) the route for a Nationally Significant Infrastructure Project (NSIP) under the Planning Act 2008 (for which, in England, applications must be 50MW with an increased threshold of 100MW from 31 December 2025; and in Wales the threshold is 350MW).

The general perception is that the NSIP regime is more onerous for applicants, but the speakers considered how the National Policy Statements (NPS) under the Planning Act 2008 might in fact be more favourable to such developments. Stephanie then explained how the NPSs had identified solar as Critical National Priority (CNP) infrastructure. She considered paragraph 4.2.16 of NPS EN-1 which sets out various presumptions for CNP infrastructure, namely the Secretary of State will take as the starting point that it “is to be treated as if it has met any tests in [planning policy] which requires a clear outweighing of harm, exceptionality or very special circumstances”. Daniel then went on to consider the Stonestreet Solar DCO which demonstrated the strength of the NSIP route: the Stonestreet Solar DCO was granted consent notwithstanding harm to a nearby Grade 1 listed heritage asset, whereas a solar development next door was refused planning permission by a planning inspector under the TCPA 1990 for harm to the same asset.

Stephanie then considered the recent case of R (Boswell) v Secretary of State for Energy Security and Net Zero [2025] EWCA Civ 669 where it was argued that such a policy approach could lead to predetermination. In Boswell, the Court of Appeal upheld Lieven J’s approach in the High Court, had rejected the argument based upon predetermination and agreed that paragraph 5.2.2 NPS (2011) EN-1 (whereby CO2 emissions “are not reasons to prohibit the consenting of projects […] or to impose more restrictions on them”) encapsulates both the assessment of significance for the purpose of the environmental impact assessment as well as the weight to be given to that assessment as part of the planning balance.

Daniel then looked at NPS EN-1 which directs the decision maker’s attention to whether the impact of the development on heritage or landscape is temporary or permanent. In Anesco Ltd v SSLUHC [2025] EWHC 1177 (Admin) the court upheld the Secretary of State’s refusal of permission for a 49.72MW solar scheme, finding that although national policy was relevant as a material consideration in respect of the temporary nature of the development, this did not bypass conflict with the local development plan. This serves as a reminder of how considerations under both routes will interact in the decision-making process.

Looking forwards, the picture may change again with the introduction of the Planning and Infrastructure Bill which currently awaits Royal Assent and introduces reforms to the Planning Act 2008, although various amendments proposed in the House of Lords, such as a requirement that solar development only the best and most versatile land be consented at the local level, did not make it into the final draft.

Scarlett Milligan and Alan Payne KC: Investigating climate change and air quality in inquests & related civil claims for damage

Scarlett Milligan and Alan Payne KC began their presentation by explaining the key issues that arose in the inquest touching on the death of Ella Adoo-Kissi-Debrah. Ella, a child, lived on one of the busiest and most polluted routes in Lewisham and suffered repeated asthma attacks, a severe seizure and died, tragically, of cardiac arrest. Significantly, air pollution was found to be a key contributory factor to both the induction and exacerbation of her asthma (especially where Ella’s house was located, within 30m of the road).

Alan discussed the key areas of evidence that are likely to be elicited in inquests that consider air quality and air pollution, including whether any pollutants are subject to EU and domestic limits applicable to the area in question. He also suggested that companies faced with potential claims should consider the following: distance of pollutants from people who live nearby; mitigating steps that can be taken; recording key information including the identified risks, steps taken and engagement with people who live nearby; the steps that people can take to limit their exposure to pollution; warning people and monitoring the evidence of any spikes in pollution; and engagement with the local authority as well as licencing authorities to ensure that they are aware of the pollution evidence and associated risks to local people.

Scarlett then analysed potential causes of action for individuals affected by poor air quality, with a particular focus on the causes of action that were relied upon by Ella’s family in their civil claim, brought against central government departments. She explained that there were other causes of action, such as nuisance, as well as regulatory regimes (including potential criminal liability) that were beyond the scope of the talk.

In Ella’s case, it was argued that Article 2(1) ECHR (right to life), Article 3 ECHR (the prohibition on inhuman and degrading treatment) and Article 8 ECHR (right to private/family life) were engaged and that there had been a breach of the Human Rights Act 1998. Previous decisions of the European Court of Human Rights (ECtHR) had highlighted the importance of information sharing so that people can be made aware of the specific and identifiable pollution risks in their area. Scarlett outlined the change in approach which has followed the ECtHR case of Verein KlimaSeniorinnen Schweiz & Ors v Switzerland (Application No. 53600/20), which was the first to deal with climate change (including air quality and pollution) generally, rather than from a specific source or hazard. That case demonstrated that member states will be afforded a wide margin of appreciation in the targets and measures adopted to tackle air pollution, but that failures in abiding by those targets or progressing measures (as well as failures to provide risk-related information and adaptation measures in response to climate change) were justiciable and may found to be breaches of Article 8, and potentially Article 2 and 3.

Scarlett then outlined possible claims in negligence, including difficulties that may arise in terms of identifying a duty of care, the SAAMCO scope of duty, and causation.

Finally, and as claimed in Ella’s case, breaches of retained EU law and Francovich damages were considered. Importantly, under Article 23 of EU Directive 2008/50/EC (transported into domestic law by the Air Quality Standards Regulations 2010), where air quality levels are assessed to be above limit values, an Air Quality Plan needs to be prepared to address the responsible sources with a view to bringing the zone(s) into compliance as soon as possible. However, there is no provision in the EU Directive or the 2010 Regulations conferring an entitlement to damages in the event of a breach.

Conclusion

To conclude the seminar, Stephen Tromans KC, Nigel Pleming KC and Gethin Thomas invited questions from the audience and discussed a number of pressing issues across a broad range of topics including the challenge to reduce demand for high emitting activities (both existing demand and demand growth), rising insurance claims, and the question of whether a new international environmental court should be established to deal with the growing legal issues relating to climate change.