The voluntary carbon offset market sold roughly 200 million tons of CO2 credits in 2023. Investigations published the same year by The Guardian, ProPublica, and Berkeley Law concluded that the largest credit type — Verra-certified REDD+ forest credits — was over-credited by an average of 90%+. Many "1 ton offset" credits represented zero tons of actual avoided emissions.
This isn't niche. REDD+ was the most common offset type. Most corporate "net zero" claims relied on it. The market is now in correction.
A carbon credit is whatever the registry says it is
There is no single global definition of "1 ton of CO2 offset". There are competing registries (Verra/VCS, Gold Standard, American Carbon Registry, Climate Action Reserve, Puro.earth, CDR registries) each with their own methodology for what counts as 1 ton.
A REDD+ credit from Verra and a biochar credit from Puro both nominally represent "1 ton". They are not the same thing. The REDD+ credit promises avoided deforestation that may or may not have happened anyway. The biochar credit represents carbon that has been physically removed from the atmosphere and converted to a stable solid.
Permanence varies from years to geological
Reforestation: 30–80 years until the forest matures, but vulnerable to fire (a single wildfire reverses decades of sequestration).
Soil carbon: 10–50 years, vulnerable to land-use changes.
Biochar: 100s of years (charcoal in soil is biologically stable).
Direct air capture (DAC) with geological storage: 1,000+ years (CO2 is mineralized into rock).
The price reflects this. Verra REDD+ credits were $5/ton at peak. Biochar is $80–150/ton. DAC is $250–500/ton. The 100x price spread is not "cheaper is the same".
A "100% carbon neutral" claim made with $5/ton REDD+ credits is meaningfully different from the same claim made with $200/ton DAC credits. Both are technically valid under voluntary market rules. They are not equivalent.
Verification standards rank as A+/A/B/F
Puro.earth (durable removals) is the strongest verification standard for biochar/DAC/enhanced weathering — A+ tier.
Gold Standard is moderate — A tier — with rigorous additionality requirements but mostly avoidance/reduction credits.
Verra/VCS is the largest registry but post-2023 scandal credibility — B tier for new credits, F tier for the legacy REDD+ inventory still on the market.
Anything from a registry you've never heard of, or a "carbon offset" sold by a non-registry intermediary without a public methodology — assume it's fiction unless you can find the methodology document.
"Reduce first, offset last" is the only honest framing
Even high-quality offsets are not a substitute for emissions reduction. The hierarchy:
- Eliminate the emission entirely (electrify, switch to renewables, change behavior)
- Reduce the emission as much as possible
- Offset only the residual that genuinely cannot be eliminated, with high-permanence removals (not avoidance credits)
Our carbon offset calculator compares 10 offset types (REDD+, reforestation, methane capture, biochar, DAC, soil carbon, ocean alkalinity, blue carbon, and more) by quality grade (A–F), permanence, verification standard, and price. Three pre-built portfolios — budget (mostly avoidance), balanced (mix), high-durability removals (only durable carbon removal). Honest framing throughout: this is the last line of defense, not a substitute for reduction.