Key highlights from December 2025 in the sustainability space.
1- Swiss court declares climate case Asmania et al. vs Holcim admissible
On December 17, the Cantonal Court of Zug declared admissible a civil claim filed by Indonesian islanders against the cement company Holcim. The complaint, filed in 2023, alleges that as one of the main CO2 emitters, Holcim is neglecting its climate obligations and therefore contributing to recent flooding of low lying Indonesian islands.
The ruling rejects the company’s argument that climate protection should remain within the ambit of policy and that companies should not be subject to justiciable accountability. In doing so, the court echoes the logic of the ICJ’s July 2025 advisory opinion which established that the tangible harm induced by unchecked environmental degradation necessitates substantive and enforceable climate obligations. By affirming the admissibility of climate cases brought by civil society on grounds of objective and avoidable harm, the decision paves the way for climate justice that holds major polluters directly accountable.
2-New York announces new GHG emissions disclosure regulations
On December 1, 2025, the New York State Department of Environmental Conservation (DEC) announced new regulations for mandatory greenhouse gas (GHG) emissions disclosure, to take effect in 2027. This decision enacts part 253 pursuant to the state’s Climate Leadership and Community Protection Act, which implemented state-wide 60% reduction of GHG emissions by 2030.
The DEC’s regulations require certain entities that emit 10,000 metric tons of CO2 annually, including fuel suppliers, waste disposal, and petroleum and natural gas facilities, to provide GHG emission data reflecting the previous year’s emissions.
This advancement represents a further step towards efforts by several states, including California, Washington, Minnesota, Illinois and New York, to harmonize their disclosure legislation and thereby reinforce climate obligations for major emitters. While these states account for approximately 7% of national emissions based on 2023 data, their combined economies represented roughly 30% of U.S. GDP in 2024, making this multistate group a significant economic force in incentivizing climate action.
3- European Commission unveils pilot action for plastics
On December 24, the European Commission announced a set of pilot actions aiming to optimize plastics recycling. The implementing act, which establishes end-of-waste criteria and quality management systems to be implemented by producers, is published for public feedback until January 26 before its final adoption.
These measures are part of the upcoming Circular Economy Act, to be proposed in 2026, which will address legal certainty for chemical recycling, the implementation of the Single Use Plastics Directive, and harmonization of rules for the calculation, verification and reporting of chemically recycled plastics.
4- UK regulator bans ads over greenwashing
On December 3, the UK Advertising Standards Authority (ASA) published three rulings banning ads from Nike, Lacoste and Superdry over misleading environmental claims. In each case, the ASA found that companies’ advertising of products as sustainable were likely to mislead consumers and violated the Committees of Advertising Practice (CAP) code, which requires businesses to provide a high level of substantiation for all environmental claims.
Significantly, in the cases of Nike and Lacoste, the sole factor of products containing mainly recycled materials or certified fabrics did not constitute sufficient claim to sustainability, as the companies had not provided evidence that their products had no detrimental environmental effects when taking into account their entire life cycle.
5- Bank of England announces new climate risk policy
On December 3, the Bank of England’s Prudential Regulation Authority published Supervisory statement 5/25 that put forth updated expectations for firms’ climate risk management approaches. The statement outlines the operational and financial risks inherent to climate change and the transition to a net-zero economy, as well as strategies for a strategic management approach. Chapters include new guidelines for governance, risk management, climate scenario analysis, data and disclosures, as well as two sector-specific chapters for banking and insurance firms.
Firms are expected to conduct an internal review of their current status in meeting these expectations by June 2026, as well as to regularly update their risk assessments and climate actions. The new expectations underscore the role of financial institutions in incentivizing and facilitating climate action, not only as social responsibility, but as a long-term investment in resilience and sustainable growth.
- Content prepared with the help of Amanda Alden.