What this calculator does
Kaya identity (CO₂ emissions) works out global CO₂ emissions decomposed into population, wealth, energy and carbon factors. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaF = P × (GDP/P) × (Energy/GDP) × (CO₂/Energy)
The inputs explained
| Field | What to enter |
|---|---|
| Population | A number. Starts at 8000000000. |
| GDP per capita ($/person) | A number, measured in your currency/person. Starts at 12000. |
| Energy intensity of GDP (MJ/$) | A number, measured in MJ/your currency. Starts at 5. |
| Carbon intensity of energy (kg CO₂/MJ) | A number, measured in kg CO₂/MJ. Starts at 0.06. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with population
Every other input is held at the calculator’s starting values while population varies. Select any row to load that scenario into the calculator.
How the answer changes with population
| Population | CO₂ emissions | CO₂ emissions | Emissions per capita |
|---|---|---|---|
| 4,000,000,000 | 14.40 Gt/year | 1.4400e+4 Mt/year | 3.60 t/person/year |
| 6,000,000,000 | 21.60 Gt/year | 2.1600e+4 Mt/year | 3.60 t/person/year |
| 8,000,000,000 | 28.80 Gt/year | 2.8800e+4 Mt/year | 3.60 t/person/year |
| 12,000,000,000 | 43.20 Gt/year | 4.3200e+4 Mt/year | 3.60 t/person/year |
| 16,000,000,000 | 57.60 Gt/year | 5.7600e+4 Mt/year | 3.60 t/person/year |
| 24,000,000,000 | 86.40 Gt/year | 8.6400e+4 Mt/year | 3.60 t/person/year |