Why do carbon offsets have a credibility problem?
Carbon offsets have been plagued by failures because they often rely on projected future reductions that are never realized. A 2025 study in Nature Sustainability explains that project developers create 'ex ante' scenarios—estimates of what would have happened without the offset project—and scientists' 'ex post' evaluations frequently show that these scenarios overestimate actual emission reductions, leading to overcrediting [3]. This means companies buy offsets that don't represent real climate benefits.
A 2021 interview-based study of carbon market practitioners found that even industry insiders only partially believe in offsets; they sustain their involvement through 'disavowal'—knowing the problems but ignoring them—and through trust in authority figures rather than in the offsets themselves [5]. This psychological dynamic explains why flawed offsets persist despite widespread criticism.
How does durable carbon removal fix this?
The critical difference is storage duration. A 2024 modeling study in Communications Earth & Environment tested what happens when carbon is stored for different lengths of time under a net-zero scenario with 6 billion tons of residual CO₂ emissions per year. They found that storing carbon for only 100 years—the typical offset duration—would cause an additional 0.8°C of warming by the year 2500 compared to permanent storage, putting the Paris Agreement temperature limits at risk [2]. Their conclusion: credible neutralization requires storage for at least 1,000 years, matching the atmospheric residence time of fossil CO₂ [2].
This means durable removal—like injecting CO₂ into geological formations or growing biomass that locks carbon in deep ocean sediments for millennia—can avoid the 'temporary storage' problem that makes offsets unreliable. The same study emphasizes that removal must be paired with storage in a reservoir that matches the emission source, e.g., geological storage for fossil emissions [2].
But is durable removal automatically credible? No—verification is still hard.
Even durable methods face verification hurdles. A 2023 study on seaweed-based carbon removal explains that simply growing seaweed and storing its biomass does not guarantee that CO₂ was removed from the atmosphere. The process requires proving 'air-sea CO₂ equilibrium'—the time it takes for the ocean to release the CO₂ that seaweed absorbed, which ranges from weeks to years depending on the ecosystem [1]. Without quantifying this, seaweed offsets cannot be verified as real removal [1].
The 2025 Nature Sustainability study offers a solution: systematic ex-post evaluations—measuring actual outcomes after a project is implemented—can restore credibility by catching overcrediting that ex-ante projections miss [3]. This applies to both durable and non-durable methods, but for durable removal, it ensures the promised long-term storage actually occurs.
Do consumers trust durable removal more than offsets?
Consumer preferences suggest that how a company uses removal matters. A 2023 survey and choice experiment found that consumers strongly prefer companies to reduce their own controllable emissions internally rather than buy offsets for those same emissions—and this preference is especially strong among eco-conscious consumers [4]. However, consumers value internal reductions and offsets equally when the offsets cover emissions the company cannot control [4].
This implies that durable removal used to neutralize unavoidable emissions (e.g., from aviation) may be accepted, but using it as a substitute for cutting direct emissions would still face consumer skepticism. The credibility of durable removal depends not just on storage duration but on how it is framed within a company's overall climate strategy.
About These Sources
This answer is built on 5 peer-reviewed studies — published from 2021 to 2025, 2 from 2024 or later, 5 in Q1 journals, collectively cited 205 times — selected as the most relevant from 5 studies that passed quality screening, drawn from 27 papers retrieved from a database of over 500 million.
Sources used in this answer
Air‐sea carbon dioxide equilibrium: Will it be possible to use seaweeds for carbon removal offsets?
Seaweed carbon removal requires proving air-sea CO₂ equilibrium (weeks to years) to verify actual atmospheric CO₂ drawdown; storage pools alone do not equate to removal [1].
Durability of carbon dioxide removal is critical for Paris climate goals
Using a climate model, the study shows that storing CO₂ for only 100 years under net-zero emissions causes 0.8°C additional warming by 2500 vs. permanent storage; storage must last at least 1,000 years to neutralize fossil emissions [2].
Restoring credibility in carbon offsets through systematic ex post evaluation
Systematic ex-post evaluations can restore credibility in carbon offsets by catching overcrediting that ex-ante projections miss; this applies to all offset types [3].
Offset or reduce: How should firms implement carbon footprint reduction initiatives?
Consumers prefer companies to internally reduce controllable emissions rather than buy offsets, but value offsets equally for uncontrollable emissions; eco-conscious consumers show the strongest preference [4].
The fantasy of carbon offsetting
Interviews with offset market practitioners reveal that their support is sustained through disavowal of problems, trust in authority, and desire for offsets' unrealizable promises [5].