Carbon Budget Remaining Calculator Formula

Understand the math behind the carbon budget remaining calculator. Each variable explained with a worked example.

Use the Carbon Budget Remaining Calculator

Formulas Used

Budget Remaining

remaining_gt = budget_total_gt - used_budget

Years Until Exhausted

years_left = (budget_total_gt - used_budget) / annual_emissions_gt

Budget Already Used

pct_used = used_budget / budget_total_gt * 100

Variables

VariableDescriptionDefault
budget_total_gtTotal Carbon Budget from 2020(Gt CO2)500
annual_emissions_gtCurrent Annual Emissions(Gt CO2/yr)40
years_elapsedYears Elapsed Since 2020(years)6
used_budgetDerived value= annual_emissions_gt * years_elapsedcalculated

How It Works

The Global Carbon Budget

The carbon budget is the total amount of CO2 that can still be emitted while keeping global warming below a specific temperature target.

Formula

Remaining Budget = Total Budget - (Annual Emissions x Years Elapsed)

Years Left = Remaining Budget / Annual Emissions

The IPCC estimates that for a 50% chance of staying below 1.5°C, the remaining budget from 2020 was about 500 Gt CO2. At current rates of ~40 Gt/year, this budget is rapidly shrinking.

Worked Example

Starting budget of 500 Gt CO2 from 2020 with 40 Gt/year emissions, 6 years later.

budget_total_gt = 500annual_emissions_gt = 40years_elapsed = 6
  1. 01CO2 used = 40 x 6 = 240 Gt CO2
  2. 02Remaining = 500 - 240 = 260 Gt CO2
  3. 03Years left = 260 / 40 = 6.5 years
  4. 04Budget used = 240 / 500 x 100 = 48.0%

Ready to run the numbers?

Open Carbon Budget Remaining Calculator