Something unusual happens in the carbon market on 1 September each year, and this autumn it happens again. Auctioneers quietly withdraw a slice of supply and park it in a reserve nobody trades. Between now and 31 August 2027 that slice runs to 190,494,202 allowances, and the figure lands just as legislators argue over what should eventually happen to the pile.
The Market Stability Reserve exists because the emissions trading system spent most of the last decade drowning in permits issued before the financial crisis wrecked industrial demand. Prices collapsed, the price signal stopped signalling, and the reserve absorbs the excess automatically rather than through political negotiation. It runs on a formula. When allowances in circulation exceed a threshold, the mechanism swallows a share of the following year’s auction volume.
A second rule went further. Since 2023, Article 1(5a) has invalidated every allowance held in the reserve above 400 million, permanently deleting the surplus rather than storing it. That provision has erased roughly 3.2 billion allowances, an amount comfortably larger than the Union’s entire annual emissions under the system. Supply and demand came back into balance, which is precisely what the drafters wanted.
The Commission now argues that the deletion has done its job and should stop. Its proposal of 1 April 2026 would end the invalidation mechanism and keep the reserve intact as a buffer available for future market stress. The reasoning is straightforward. A reserve that destroys what it holds cannot release anything when prices spike, and the second trading system covering buildings and road transport will price carbon for households in a way that makes spikes politically dangerous.
Parliament and Council must now co-decide the text, filed as procedure 2026/0085(COD), and the environment committee has been working through it during a week in which MEPs also take positions on trans-European energy networks and on relations with China. The committee voted a negotiating mandate in April on the reserve covering the newer sectors, where centre-coalition groups converged on a phased cancellation rather than an abrupt end to deletions.
That compromise reveals the real dispute. Environmental campaigners see a stored buffer as a promise of future looseness, a pile of paper emissions that governments can release the moment industry complains about costs. Manufacturers see the same buffer as insurance against a price shock they cannot hedge. Both readings hold, which is why the file will not resolve quickly.
Traders have already priced part of the answer. Ending invalidation raises long-term supply expectations without changing a single tonne of near-term compliance demand, and the legislative record on the reserve shows how often the mechanism has been retuned since 2015. Each retune shifted expectations more than volumes.
The precedent deserves attention. Officials sold automatic instruments to governments as insulation from lobbying, machinery that would tighten a market without ministers voting to raise costs. The Union now amends that machinery by ordinary legislative procedure, with amendments, trilogues and national industrial interests fully in the room. The reserve may keep working. The claim that it works without politics no longer holds.
