Public Carbon Debt Ledger

What Is Carbon Debt?

Carbon debt is the cumulative total of unremediated greenhouse gas emissions attributable to a company. Unlike annual reporting that resets each year, carbon debt persists — because CO₂ in the atmosphere persists. Each tonne emitted adds to the outstanding balance.

The word “debt” is not a metaphor — it reflects the physics. CO₂ is a stock pollutant: once emitted, a significant fraction remains in the atmosphere for centuries, continuing to trap heat and drive warming regardless of whether annual emissions fall. Reducing the rate of new emissions is necessary but does not address the cumulative burden already aloft. That burden is the debt.

Virtually every other form of industrial pollution is regulated on the principle that the polluter bears responsibility for cleanup. Sulphur dioxide, mercury, asbestos, oil spills — in each case, the entity that created the contamination is expected to remediate it. Carbon dioxide is the glaring exception. No jurisdiction currently requires emitters to remove the CO₂ they have already placed in the atmosphere. The Carbon Debt Ledger applies the same accountability logic: emissions accumulate as obligations until the emitter demonstrably removes an equivalent quantity through durable carbon dioxide removal.

The Ledger tracks two baseline periods. Since 1992 captures emissions from the moment governments formally recognised climate change as a crisis. Since 2015 captures emissions from when the world agreed on a temperature target.

Why 1992 and 2015?

1992 — The Earth Summit: The United Nations Framework Convention on Climate Change (UNFCCC) was adopted at the Earth Summit in Rio de Janeiro. This marked the first time governments formally recognised that climate change was a serious problem requiring international cooperation.

2015 — The Paris Agreement: The Paris Agreement was signed by 196 nations, committing to limiting global warming to well below 2°C above pre-industrial levels. This is widely considered the point at which the world agreed on a clear temperature target.

Scope 1+2 vs Scope 3

Scope 1+2 (Operational Emissions): Direct emissions from company operations (Scope 1) plus indirect emissions from purchased energy (Scope 2). These are emissions the company directly controls.

Scope 3 (Product Emissions): Emissions from the use of sold products — primarily the combustion of fossil fuels by end users. For oil, gas, and coal companies, Scope 3 typically accounts for 80–95% of total emissions.

The leaderboard ranks companies by Scope 1+2 debt only, as these are the emissions most directly attributable. Company profiles show both S1+2 and full S1+2+3 figures.

What Carbon Debt Is NOT

• Not reduced by avoided emissions or efficiency improvements — these slow the rate of new debt but don't remediate existing stock
• Not offset by temporary carbon credits — short-lived sequestration does not address atmospheric persistence
• Not diminished by renewable energy investments — these reduce future emissions, not past ones
• Not zeroed by net-zero pledges — only verified, durable carbon dioxide removal retires debt

How Is It Calculated?

Carbon debt is computed as the running sum of annual emissions from a baseline year (1992 or 2015) to the present, minus any verified durable carbon dioxide removal (CDR) retirements.

Currently, two companies have CDR activity: Petrobras (1,154 tCO₂e confirmed) and Equinor (330,000 tCO₂e committed, not yet delivered). Both represent a fraction of a percent of their total debt — underscoring the scale challenge.

Only high-quality durable carbon removal retires carbon debt: direct air capture, mineralization, enhanced weathering, ocean-based removal, and long-lived biochar with verified permanence. Temporary offsets, traditional emissions avoidance projects, reforestation, and efficiency gains do not address carbon dioxide that is already in the atmosphere.

What Is Carbon Dioxide Removal (CDR)?

Carbon Dioxide Removal (CDR) is the process of capturing CO₂ directly from the atmosphere and storing it durably — in geological formations, mineralised materials, or other long-lived reservoirs. CDR is the only mechanism that can address the stock of historical emissions already in the atmosphere.

The IPCC Sixth Assessment Report states that CDR deployment is required in all modelled pathways that limit global warming to 2°C or below by 2100. It cannot substitute for immediate emissions reductions, but it is essential for balancing residual emissions and, over time, drawing down the cumulative CO₂ burden.

CDR methods vary widely in maturity, cost, and permanence. Technological approaches include Direct Air Capture with Carbon Storage (DACCS), Bioenergy with Carbon Capture and Storage (BECCS), enhanced weathering, and biochar. Natural approaches include afforestation and soil carbon sequestration, though these generally offer less permanence. For the purposes of the Carbon Debt Ledger, only durable CDR with verified permanence counts toward retiring carbon debt.

The durable CDR market is still nascent. CDR.fyi tracks purchases and deliveries across the durable carbon removal market and is an excellent resource for understanding the current state of CDR deployment. For a broader overview of CDR science and methods, see Carbon Gap's CDR 101.

Data Sources

About This Platform

The Public Carbon Debt Ledger is an independent, ratings-style accounting platform. It was not commissioned by any company, government, or NGO. Its purpose is to make visible what corporate accounting conventions obscure: the cumulative, unresolved carbon obligations of the world's largest emitters.