akar.earthReversal: Definition
What is a reversal in carbon credits? Avoidable and unavoidable reversals, how buffer pools compensate, and the main reversal risks in Indonesian forests.
A reversal is a loss of carbon that a project previously claimed as an emission reduction or removal, for example when credited trees burn, are felled or die. After a reversal, the net climate benefit of the project falls below what was credited.
Why it matters
Reversals are the practical face of permanence risk. Without a system to compensate for them, buyers would hold credits backed by carbon that is back in the atmosphere. Standards design buffer pools, monitoring rules and penalties around reversals, and buyers increasingly check a project’s reversal history before buying.
How reversals are detected and handled
Reversals are detected through monitoring: field re-measurement, satellite alerts and event reports such as fires. Standards distinguish:
- Unavoidable reversals: fire, drought, storms, pests. Buffer credits are cancelled to cover the loss.
- Avoidable reversals: caused by the proponent, such as harvesting beyond plan or land conversion. The proponent usually has to compensate by retiring replacement credits.
- Loss events: many programmes require a loss event report within a set time after the event is identified.
Verra’s buffer pool rules set out how cancellation and replenishment work. Our page on permanence and reversals compares programmes.
Indonesia angle
The largest reversal risk for Indonesian forest and peat projects is fire, especially in drained peatland in Sumatra and Kalimantan during dry El Niño years. Other risks include encroachment, illegal logging and permit changes. Smallholder ARR projects face farmers removing trees for crops or income, which is why agreements, benefit sharing and timely satellite deforestation alerts matter.
Common mistakes
- Not reporting a loss event quickly, which can trigger penalties.
- Treating a planned timber harvest as a reversal when it was already accounted for in long-term average carbon stock.
- Assuming small, scattered losses are not reversals; cumulative losses count.
Related terms
See buffer pool, permanence and non-permanence risk, or browse the carbon standards hub.
Frequently asked questions
What is the difference between avoidable and unavoidable reversals?
Avoidable reversals come from the proponent's negligence or decisions, such as clearing trees. Unavoidable reversals come from events outside its control, such as wildfire or storms. Standards treat them differently when compensating.
What happens to buyers' credits after a reversal?
Under pooled buffer systems, already-issued credits stay valid. Buffer credits equal to the loss are cancelled instead, and the project may have to replenish the buffer.