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Thursday, July 24, 2025

The Kaya Identity Formula for Carbon Emissions Drivers: Human Population, GDP Per Capita, Energy Intensity, and Carbon Emissions Intensity

     According to Wikipedia, the Kaya identity is defined as follows:

The Kaya identity is a mathematical identity stating that the total emission level of the greenhouse gas carbon dioxide can be expressed as the product of four factors: human population, GDP per capita, energy intensity (per unit of GDP), and carbon intensity (emissions per unit of energy consumed). It is a concrete form of the more general I = PAT equation relating factors that determine the level of human impact on climate.”

     The Kaya identity was developed by Japanese energy economist Yoichi Kaya. The I=PAT formula for environmental impact was developed by biologist Paul Ehrlich and John Holdren, both of whom can be regarded as catastrophists based on their wildly wrong predictions about population and climate refugees, respectively.  

I = P × A × T

The expression equates human impact on the environment to a function of three factors: population (P), affluence (A) and technology (T). It is similar in form to the Kaya identity, which applies specifically to emissions of the greenhouse gas carbon dioxide.”

     The Kaya identity is expressed in the form:

 


Where:

F is global CO2 emissions from human sources

P is global population

G is world GDP

E is global energy consumption

And:

G/P is the GDP per capita

E/G is the energy intensity of the GDP

F/E is the emission intensity of energy

 

     The global population is expected to peak at around 10.3 billion people in the 2080s, according to the latest estimates, although there are some predictions of a peak as early as 2064. GDP per capita continues to rise every year. Both energy intensity and carbon emissions intensity have continued to drop steadily every year.

     Below is a graph of the parameters from 1965 through 2023, followed by the same graph run for the past 25 years, from 1998 through 2023.

   

 


Source: Our World in Data




Source: Our World in Data



References:

 

Kaya identity. Wikipedia. Kaya identity - Wikipedia

I=PAT. Wikipedia. I = PAT - Wikipedia

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