Article 6.4's 40% Haircut & The CORSIA Supply Shock: A Market Bifurcation

The voluntary carbon market is bifurcating in real time, and the fault line is becoming impossible to ignore.

On February 26, the UN's Article 6.4 Supervisory Body authorized its first-ever issuance—a Myanmar cookstove project. The headline isn't the milestone; it's the math. Due to brutally conservative new methodologies, the project received roughly 41% fewer credits than it would have under legacy Clean Development Mechanism (CDM) rules.

Meanwhile, CORSIA-eligible credit prices have been sliding since late 2025, driven by a sudden flood of newly tagged supply that nearly doubled the eligible pool in a matter of weeks. And today, Boeing signed its second major carbon removal deal in four months—a 40,000-tonne biochar purchase from Carbonfuture, following a 100,000-tonne offtake with Charm Industrial in November—completely bypassing the traditional compliance credit supply chain.

For professionals navigating this market, the signal is deafening: The era of volume-based crediting is over. The market is splitting into shrinking compliance assets—technically eligible but hemorrhaging volume and confidence—and high-durability removals commanding premium capital.

Here is why the convergence of a UN haircut, a supply-driven price slide, and a corporate flight to CDR defines the future of carbon trading.

The 40% Haircut: A Systemic Shock to Supply Models

As we analyzed in our initial coverage of the Myanmar issuance, the transition from the CDM to the Paris Agreement's Article 6.4 mechanism was never going to be 1:1. However, the severity of the reduction has caught developers and financiers off guard.

The culprit was the fraction of non-renewable biomass (fNRB) calculation—the metric that determines what share of household biomass use is assumed to cause deforestation. Under the CDM, the Myanmar project used an fNRB of 0.90. Under Article 6.4's standardized default values, that number was slashed to 0.36—a 60% reduction in the key emission factor that drives cookstove credit generation.

The net result: approximately 41% fewer credits issued than the CDM baseline would have produced.

This is not an isolated case; it is a precedent. At least 165 projects are moving from the CDM to Article 6.4, and many are cookstove or energy efficiency projects relying on similarly generous baselines. The Supervisory Body has signaled that conservative default values and downward baseline adjustments will be the norm, not the exception.

The Commercial Implication: If you are holding or financing legacy CDM projects expecting a smooth transition to Article 6.4 to feed CORSIA demand, you must stress-test your expected inventory with a 30-50% volume discount. The regulatory direction is clear: tighter baselines, fewer credits, less room for generous assumptions.

The CORSIA Price Slide

The logical economic response to a 40% supply shock should be a price spike. Instead, CORSIA-eligible credit prices have been falling steadily since late 2025.

Fastmarkets assessed CORSIA Phase 1 (CP1) spot prices at $19/tCO2e in late January 2026, down from $23.20 in October 2025 and continuing to slide below $18.30 by early February. ICE CP1 December 2026 futures have traded as low as $14.50/tCO2e. The driver is not weak demand—it is a sudden flood of newly eligible supply:

• Hestian's Malawi cookstove project brought 1.5 million tCO2e of freshly tagged CP1-eligible credits in November 2025.
• Verra tagged 4.78 million tCO2e from DelAgua's clean cooking projects in Rwanda, Sierra Leone, and The Gambia.
• Guyana's ART TREES project added 9.09 million tCO2e of vintage 2023 credits.
• Total CP1-eligible supply nearly doubled from 17.5 million to over 32 million tCO2e in a matter of weeks.

The Article 6.4 haircut adds a devastating new dimension to this picture: even the supply pipeline that was supposed to flow from transitioning CDM projects is now deeply uncertain. Aviation buyers face both a flood of existing supply AND shrinking confidence in future supply quality. The market is pricing in a grim reality: credits that lose 40% of their volume upon regulatory review carry too much headline risk for a Fortune 500 balance sheet.

The Corporate Flight to Durable CDR

If the CORSIA slide is the market's vote of no confidence in legacy compliance credits, the corporate pivot to durable carbon removal is the alternative manifesto—and no company illustrates this more clearly than Boeing.

In November 2025, Boeing signed an offtake agreement with Charm Industrial to purchase up to 100,000 tonnes of permanent carbon removal. Charm converts agricultural and forest residues into carbon-rich bio-oil through pyrolysis, then injects it into EPA-regulated underground wells where it solidifies permanently. The process also produces biochar as a co-product, returned to farmland as a soil amendment. Bio-oil CDR runs roughly $600/tonne—multiples above CORSIA spot prices near $19.

Then today, Boeing doubled down. The aerospace giant signed a multi-year deal with Carbonfuture for at least 40,000 tonnes of biochar carbon removal credits, sourced from four projects in the Global South. Carbonfuture tracks carbon removal from production to end use and records legal ownership—exactly the kind of chain-of-custody transparency that compliance credits lack. Boeing can also acquire additional credits under the agreement, with the deal believed to be one of the largest CDR purchases in aviation.

Two major CDR deals in four months. Boeing is targeting Scope 3 business travel emissions—the exact "hard-to-abate" sector that CORSIA was designed to cover—and is systematically building a diversified removal portfolio rather than relying on the traditional compliance supply chain. Biochar credits trade around $150/tonne, still multiples above CORSIA spot, but Boeing is clearly willing to pay for permanence and traceability.

Boeing is not alone. These deals are part of a broader corporate surge into durable CDR:

• In August 2025, the ICVCM approved three biochar methodologies (CAR, Isometric, and Verra) as meeting the Core Carbon Principles—opening the floodgates for institutional buyers.
• Carbon Direct's 2026 State of the VCM report found that fewer than 10% of CDR projects meet rigorous quality standards, underscoring critical supply scarcity.
• Charm's customers already include Google, JPMorgan Chase, and the Frontier corporate consortium. Boeing's double-down signals that aviation—CORSIA's core constituency—is systematically abandoning the mechanism's own supply chain.

The "So What?" for the Market

We are watching the death of the "ton-is-a-ton" commodity model. The market is splitting into two distinct asset classes with divergent economics:

1. The Compliance/Legacy Tier: Dominated by transitioning CDM projects and CORSIA demand.

   • Outlook: Bearish. Regulatory haircuts will destroy volume. A supply flood is crashing prices. Buyers are hesitant as integrity concerns persist.
   • Action: Traders should hedge heavily. Developers must re-model project finance assuming a 30-50% revenue cut.

2. The Durable/Integrity Tier: Dominated by biochar, bio-oil injection, enhanced weathering, and high-quality removals.

   • Outlook: Bullish. Supply is the only constraint. Demand is anchored by deep-pocketed corporates (Microsoft, Boeing, Google) who view price as secondary to defensibility. Boeing's two deals in four months tell you everything about the trajectory.
   • Action: This is where the smart capital is deploying. The ICVCM approvals have opened the floodgates for institutional buyers to treat durable CDR as a bankable asset.

What to Watch

• ICAO's Technical Advisory Body (TAB): Will ICAO accept Article 6.4 credits for CORSIA without further caveats? If they hesitate due to volume and methodology volatility, CORSIA could face a complete credibility crisis.
• The "Transition Pipeline" Exodus: Watch for CDM project developers withdrawing from the Article 6.4 transition process. If the 40% haircut makes their projects insolvent, we will see a wave of project abandonments in Q2 2026.
• Biochar Issuance Volumes: With 25 projects registered under Isometric's now-CCP-approved protocol expecting 500,000 credits in 2026, watch if issuance speed can keep pace with surging corporate demand. If delays occur, CDR prices will spike further.

The message is clear: The UN just popped the volume bubble. The future belongs to those building for permanence, not those optimizing for a baseline that no longer exists.