What is the factor for 2050?

Back to Environmental Vision 2050

Ideal situation in 2050

This section discusses the Factor that will be achieved if the ideal situation is realized in 2050.

Professor Emeritus Yoichi Kaya of the University of Tokyo, the Director-General of the Research Institute of Innovative Technology for the Earth, has put forward what he calls the “Kaya Identity,” which represents the relationship between human activities and CO₂ emissions as shown in the figure below*. The Kaya Identity was reported to the Intergovernmental Panel on Climate Change (IPCC) in 1990 as an equation that indicates the effects of reductions in CO₂ emissions on GDP growth and was referred to in the IPCC's Fourth Assessment Report as well.

According to this formula, “CO₂ emissions resulting from human activities” is expressed as the product of “lduqo;CO₂ emissions per unit energy consumption,” the “energy efficiency of economic activities” (ratio of energy consumption to GDP), the “economic level per capita,” and the “population.”

Eco-efficiency is obtained by dividing “value” by “environmental impacts,” but if this is simplified, “value” can be symbolized by GDP, an index of economic affluence, and “environmental impacts” by CO₂ emissions. In other words, if eco-efficiency is considered to be equal to “GDP/CO₂ emissions,” it can be expressed as the product of “GDP per capita (G/P),” the “population (P),” and the reciprocal of CO₂ emissions(1/CO₂ emissions) using the Kaya Identity.

In this section, let us consider the degree of improvement in eco-efficiency for the world based on forecasts and goals for 2050.

First, according to the Organization for Economic Cooperation and Development (OECD), “GDP per capita” (i.e. “value”) is expected to grow by an average of 3.4 times for the whole world though it varies from one country to another.
Next, in order to prevent environmental impacts from increasing as the world population is projected to grow by 1.5 times, it is necessary to heighten eco-efficiency by 1.5 times.
And at the G8 Summit in L'Aquila in July 2009, the leaders of advanced countries agreed to reduce greenhouse gas emissions by 80% by 2050, but at COP15 in Copenhagen in December 2009, participants will discuss the common goal of halving CO₂ emissions for the whole world by the same year. In order to achieve this goal, it is necessary to increase eco-efficiency by at least two times.

Multiplying the above figures indicates that the Factor must be increased to 10 (3.4×1.5×2=10) in order to improve the average eco-efficiency for the whole world. Incidentally, specific reduction targets for 2020 are being discussed mainly by advanced countries as part of the medium-term CO₂ emission reduction plans. If the growth rate for the population and GDP during the period up to 2020 is taken into account as described above, the Factor will be 2.6 if CO₂ emissions are reduced by 15% and 3.2 if they are reduced by 30%.

*: Kaya, Y.; Impact of carbon dioxide emission control on GNP growth: Interpretation of proposed scenarios, Paper presented to the IPCC Energy and Industry Subgroup, Response Strategies Working Group, Paris, (mimeo), (1990).
: IPCC 2000; Special report on emissions scenarios, Cambridge University Press, (2000).