Koichi Kaya, a Japanese engineer, noticed that carbon emissions (C) or greenhouse gasses (GHG) equal the product of emissions per energy unit (C/E), energy use per unit of economic output (E/Y), per capita income (Y/P) and population (P). C = C/E*E/Y*Y/P*P

During 2000-2010 the percent changes in these four factors have been roughly:

C (+2%) = C/E (+0.5%) +E/Y (-1.5%) + Y/P (+2%) + P (+1%)

Economic growth and population growth more than cancelled out efficiency improvements (falling E/Y), while energy sources actually have been getting “dirtier” as shown by the rising C/E ratio. The main strategy the world has been counting on to solve the Greenhouse problem, reducing C/E by shifting to renewable energy, is still going in the wrong direction due to more burning of dirty tar sands and coal.

To date, policy attention focusses on installing new technology for cleaner energy and more energy efficiency. But a 3% rate of growth doubles the size of the economy every 23 years. That means even if emissions could be cut to 1/2 of present levels per dollar of output in just 23 years, output will double in that time and grow eight times bigger in a century. Halving emissions per unit of output while doubling output leaves emissions unchanged. Even if C/E decreases, so long as Y increases the world will remain in a “carbon trap” much like the “poverty trap” that afflicts countries with high birth rates and fast growing populations.

A successful climate stabilization strategy would attack every term on the right hand side of the Kaya Equation as part of the climate solution. If both emissions and demand were cut in half in 25 years. 1/2/ x 1/2 = 0.25, the result would be a 75% reduction in emissions.

We will need to re-vision humanity’s goals to aim towards a steady state economy and lower global population. That’s a positive vision, by the way. Reversing growth offers an opportunity for future generations to live on a green uncrowded earth with a steady state economy of abundance and shared with other animals, birds, trees, flowers, fish and butterflies. The problems caused by growth can only be ended by reversing growth. Continued growth heads us towards collapse and miserable rat race lives on a damaged planet.