Carbon storage overestimated: what the new report means and what to do

Short answer

New research shows reported carbon storage is too high. Reports that count site capacity instead of actual capture rates can overstate stored carbon by about 19–30%. That matters for policy, credits, and investment.

• What changed: Studies like the Imperial College report and a Nature analysis show big gaps between theoretical capacity and real accessible storage.
• Impact: Carbon storage overestimated can lead to poor policy, overissued credits, and bad investment decisions.
• Quick fix: Require reporting of actual capture rates and adopt a 5-step MRV checklist below.

Why numbers are too high

Many reports list how much CO2 a site could hold. They use capacity numbers. They do not always show how much CO2 was actually captured and stored. That difference inflates totals.

Other causes:

• Baseline errors: Forestry and soil projects often use rough estimates. That can overcount storage. See project overestimation cases.
• Accessibility: Not all underground storage is cheap or safe to use. Experts warn accessible geological carbon storage capacity is smaller than theoretical totals (France24 summary).
• Model limits: Soil and forest carbon models miss key details that lower estimates (Stanford study).

Example: how big is a 19–30% error?

Simple math helps. If a project reports 100,000 tCO2 stored based on capacity, a 25% overestimate means real stored CO2 is about 75,000 tCO2. That cuts credits and value by 25%.

Reported_storage = 100000 tCO2
Adjustment = 25% (midpoint of 19–30%)
Actual_storage = Reported_storage * (1 - Adjustment)
Actual_storage = 100000 * 0.75 = 75000 tCO2

5-step MRV checklist to fix claims

1. Require actual capture or injection rates per period, not just capacity.
2. Use site-level monitoring data (flow meters, injection logs) and keep raw files.
3. Compare reported credits to measured capture each year and flag >10% mismatches.
4. Update baselines for land projects with recent field sampling and conservative assumptions.
5. Publish a short public report each year with data, methods, and uncertainty ranges.

For policymakers and funders

Change reporting rules to require capture-rate reporting and independent verification. A short policy brief can help. See the Imperial College summary and the Nature paper for evidence.

Policy tip: Treat geological storage as a scarce resource. Plan on smaller accessible capacity and fund MRV upgrades now.

For project developers and investors

Recalculate claims today using a simple adjustment or your measured capture rates. Investors should ask for capture-rate data and uncertainty ranges before buying credits.

ROI insight: Improving MRV and reporting reduces investor risk and can speed approvals. A clear MRV plan often unlocks finance faster and may lower insurance costs.

Implementation tip: Start with one site. Install flow meters and a basic annual report. That gives reliable data you can scale.

Addressing common pushback

Industry may say economics make some storage inaccessible. That is a fair point. But transparency still matters. Require reporting of what was actually injected or captured. Independent checks can use conservative economic filters when estimating accessible capacity (expert reactions).

Where to learn more

• Imperial College report
• Nature: planetary limit to geologic storage
• CarbonBrief guest post
• Analysis of carbon farming limits

Quick deliverables we recommend

• Downloadable: 5-step MRV checklist (PDF) and spreadsheet calculator to recalculate credits.
• Action: Re-run calculations for active projects and publish corrected annual reports within 2 weeks for high-risk sites.

Bottom line

Carbon storage is a key climate tool, but its size is often overestimated. Require capture-rate reporting, use the 5-step MRV checklist, and recalculate credits now. Small steps bring big clarity.