Carbon Clock Calculator

A carbon budget is the total amount of CO₂ that can be released into the atmosphere while still keeping global warming below a chosen threshold — typically 1.5°C or 2°C above pre-industrial levels. Once this cumulative emissions limit is exceeded, that temperature target is effectively breached. The IPCC regularly updates these estimates based on the latest climate science.

According to the IPCC Sixth Assessment Report (AR6), as of early 2020 there were approximately 400–500 Gt CO₂ remaining for a 50% chance of limiting warming to 1.5°C, and around 1150 Gt CO₂ for a 67% chance of staying under 2°C. These budgets decrease every year as global emissions continue. The figures used in this calculator reflect those IPCC estimates adjusted for emissions since that publication.

Global CO₂ emissions are currently around 37–40 billion tonnes (Gt) per year, or roughly 1.2–1.3 tonnes per second. This includes emissions from fossil fuels, industry, and land-use change. The exact figure varies year to year and is tracked by organisations such as the Global Carbon Project and the IEA.

If global emissions continue to grow each year (as they broadly have historically), the carbon budget depletes faster than a flat-rate calculation suggests. Selecting 'current growth' applies a compound annual growth rate to future emissions. Choosing 'no growth' assumes emissions stay constant — a more optimistic but still challenging scenario.

The calculator divides the remaining global carbon budget equally by the world population to estimate each person's fair share. It then divides that share by your personal annual footprint to show how many years your own emissions are sustainable within the remaining budget. This is a simplified equity-based calculation and does not account for income, geography, or historical responsibility.

The 1.5°C target is the more ambitious goal set by the Paris Agreement, associated with significantly lower risks of extreme weather, sea level rise, and ecosystem collapse. The 2°C target is a fallback threshold, offering more time but also more severe climate impacts. The remaining carbon budget for 2°C is roughly 2–3 times larger than for 1.5°C.

Your carbon footprint is the total greenhouse gas emissions caused by your activities — including home energy use, transport, diet, and shopping. The global average is about 4.7 tonnes per person per year, though US residents average around 14–15 tonnes. You can use the EPA's Carbon Footprint Calculator or similar tools to get a more precise estimate based on your lifestyle.

Individual actions — reducing flying, eating less meat, switching to renewable energy, and driving less — can collectively reduce global emissions. However, systemic change through policy, corporate action, and infrastructure is essential at scale. The climate clock is primarily a tool to visualise urgency; meaningful change requires both personal and political action.