What is the Current Remaining Carbon Budget and Trajectory?

The Current Remaining Carbon Budget is the amount of CO₂ expressed in Gigatonnes that can be emitted in the future to keep human-induced warming below 1.5 °C (2.7 °F).

Likelihood

The Remaining Carbon Budget is not just a single number. Scientists calculate budgets for a range of likelihoods to keep warming below 1.5 °C (2.7 °F). Policy makers must choose and commit to a carbon budget to stay below 1.5 °C (2.7 °F).

You can inspect the likelihood and the corresponding budget of limiting human-induced warming to 1.5 °C (2.7 °F) by adjusting the likelihood slider in the widget. A higher likelihood of limiting warming (67% or 83%) corresponds to a lower remaining carbon budget and a lower likelihood (17% or 33%) to a higher budget.

Trajectory till exhaustion

The number exhausted in is an estimate of the year when the remaining carbon budget will be exhausted based on a chosen likelihood and on the latest given exhaustion rate of 41 Gt CO₂ per year.

Only for CO2 emissions

The remaining carbon budget is only for CO₂ emissions, and not to be confused with CO₂-equivalent emissions. However, the budget calculations take into account that other human factors also influence the human-induced warming, for example methane CH₄, N₂O and sulfur dioxide. Unexpected changes in these factors also change the Remaining Carbon Budget, which is recalculated yearly by the IGCC.

Units and measures

The Remaining Carbon Budget is expressed in gigatonnes of CO₂.

Insights from this chart

The current 2023 budget for a likelihood of 50% to stay under 1.5 °C (2.7 °F) is 250 gigatonnes CO₂, with estimated exhaustion in 2029.

The current 2023 budget for a likelihood of 83% to stay under 1.5 °C (2.7 °F) is 100 gigatonnes CO₂, with estimated exhaustion in 2025.

With current CO₂ emissions (exhaustion rate), the budget will be exhausted within the next 12 years for all likelihoods. There could not be a clearer message that this decade is crucial for reducing carbon emissions.

More about remaining carbon budgets in the Indicators of Global Climate Change 2022 paper.

About the data

Climate Change Tracker is part of the Indicators of Global Climate Change (IGCC) initiative to spread indicators of climate change that are consistent with the IPCC Assessment Report 6. The IGCC produces estimates for key climate indicators: emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, surface temperature changes, the Earth’s energy imbalance, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes.

Comparison with IPCC Assessment Report 6

The remaining carbon budget for the 50% likelihood of limiting warming to 1.5 °C (2.7 °F) was estimated in IPCC AR6 to be 500 Gt CO₂ from the start of 2020. The updated assessment has reduced that budget to 250 Gt CO₂ from the start of 2023. Various factors in the update caused the budget to be reduced by more than the 122 Gt CO₂ emissions in that 3-year period.

Data sources

IGCC Indicators of Global Climate Change 2022
Credits: Chris Smith, Tristram Walsh, Alex Borger, Piers Forster, Nathan Gillett, Mathias Hauser, Willam Lamb, Robin Lamboll, Matthew Palmer, Aurélien Ribes, Dominik Schumacher, Sonia Seneviratne, Blair Trewin, & Karina von Schuckmann. (2023). Indicators of Global Climate Change 2022 (v2023.06.02). Zenodo. https://doi.org/10.5281/zenodo.8000192Update cycle: yearlyDelay: mixed