By Gabriel Labbate and Ruben Lubowski
As the UNFCCC’s Methodological Expert Panel (MEP) and Supervisory Body prepare to make a pivotal decision on permanence under Article 6.4 in the coming months, the stakes could not be higher.
The permanence question is central to the credibility and practicality of an international carbon market. Get it right, and Article 6.4 can become a cornerstone of the global mitigation architecture, enabling countries and the private sector to achieve higher ambition at lower cost. Get it wrong, and the result will be a mechanism that either fails to assure environmental integrity or erects barriers so burdensome that participation dwindles.
Integrity without scale is failure. If done correctly, moreover, greater scale will enhance integrity. The task is to craft permanence rules that are practical, broadly applicable, and politically viable.
What is permanence?
Net emissions reductions are at risk of non-permanence if they risk future rebounds above business-as-usual levels, thus reversing climate gains over time. The MEP draft standard considers this an inherent risk for activities that increase carbon stocks or avoid loss of carbon stocks from biological reservoirs, while ignoring the case of reduced fossil emissions, where risks also exist (an example is the post-Fukushima spike in fossil emissions following reduced nuclear power use in Japan). Unless carbon stocks are chemically transformed, the only guarantee of permanence is systemic change that reduces economic and social drivers of risk—whether fossil or biological (Schwarzman et al. 2021). Article 6.4 should enable projects and programmes to demonstrate reversal risk mitigation by addressing fundamental economic drivers while reducing emissions and increasing removals across both fossil and nature-based opportunities.
Permanence is not a binary variable
The treatment of permanence in the MEP’s draft standard appears to embrace a binary approach: a tonne of CO2 is either stored ‘permanently’ or it is not. This binary framing oversimplifies what science tells us. The IPCC’s Sixth Assessment Report (2023) notes that CO2 has multiple atmospheric lifetimes. Joos et al. (2013) show that while 40% of an initial atmospheric CO2 perturbation is on model-average removed from the atmosphere within 20 years, it takes an additional 80 years to mitigate the next 19% of the perturbation. At year 1000, more than 25 % of the perturbation is still airborne. This reflects a decay curve, not a binary threshold. If Article 6.4 seeks ‘like-for-like,’ it should follow that curve rather than impose arbitrary cut-offs.
Should every asset be risk-free?
One important consideration is how integrity is safeguarded across the system, rather than at the scale of each individual project. Many discussions default to the assumption that no individual project should receive more credits than it is due. This approach may sound intuitively correct, but it is limited in efficacy and unnecessarily restrictive, such that it can marginalise Article 6.4 in the global climate response.
Instead, integrity can often be more effectively ensured at the portfolio level. Under such an approach, risk is managed collectively, and the overall pool of activities maintains environmental performance through mechanisms such as jurisdictional-scale accounting, pooled buffer reserves, and insurance solutions, among others. This can ensure that the collective whole is robust, while acknowledging that it is likely impossible to get every single project right. As decades of experience on diversified investment portfolios show, not every asset is risk‑free, but diversification and prudent management can deliver strong performance at the aggregate level.
Cost reduction helps keep climate policy alive
The global net‑zero transition will require unprecedented investment, and if mitigation costs become excessive, political support will erode. One of Article 6.4’s core roles is to lower the cost of global climate targets by enabling mitigation where it is most efficient.
Well-designed international markets are mission-critical for the Paris Agreement, with the potential to double climate ambition for the same cost as current NDCs without cooperation. This will require billions of tonnes of emissions transfers, particularly to scale financing across the Global South and to halt and reverse tropical deforestation in the coming decade (UNEP 2021; Piris-Cabezas et al. 2023).
Rules that are too rigid or that selectively burden nature-based projects risk narrowing participation, reducing liquidity, and raising prices, which in turn could weaken both demand and supply. A balanced approach – combining credible safeguards with reasonable flexibility – will preserve the inclusivity and cost‑effectiveness needed to enable increasing ambition over the long term.
The case for near-term carbon storage
Recognising permanence as a continuum rather than a binary state would allow Article 6.4 policymakers to differentiate between storage that lasts for a few decades and storage that persists for centuries, without dismissing the former as inconsequential.
The timing of storage matters because the climate system contains potential tipping points. If crossed, these thresholds could trigger large and irreversible changes, such as the dieback of the Amazon rainforest or the destabilisation of polar ice sheets. In such a context, storing carbon today can deliver greater marginal value than storing it decades from now. By delaying thresholds and reducing the rate of warming, early storage helps preserve the natural systems underpinning climate stability. Limiting Article 6 participation and market volume solely to projects with permanent carbon storage is a riskier policy than explicitly allowing shorter storage periods – if the latter helps prevent runaway climate change and its global consequences.
A pivotal choice for Article 6
The forthcoming decisions on permanence under Article 6.4 offer a chance to build a framework that is grounded in scientific evidence yet flexible and pragmatic. Portfolio‑level integrity management, recognition of permanence as a continuum, incorporation of the value of carbon across different timeframes, commitment to cost effectiveness, and support for innovation together form a robust approach, and one we can improve over time.
Let’s abandon false dichotomies and instead ensure Article 6.4 retains integrity while delivering the ambition the climate effort urgently requires.
Gabriel Labbate is Head of the Climate Mitigation Unit at the UN Environment Programme.
Ruben Lubowski is Chief Carbon & Environmental Markets Strategist at Lombard Odier Investment Managers, and Adjunct Professor at Columbia University’s School of International and Public Affairs.
Any opinions expressed in this commentary reflect the views of the authors and not of Carbon Pulse.