In a previous blog (November 5) I wrote about Governor Romney’s response to a direct question from ScienceDebate about his thoughts on Climate Change. The elections are now over, but the issues are still with us. I want to discuss here one important and very relevant aspect of his response. I am quoting it below:
The reality is that the problem is called Global Warming, not America Warming. China long ago passed America as the leading emitter of greenhouse gases. Developed world emissions have leveled off while developing world emissions continue to grow rapidly, and developing nations have no interest in accepting economic constraints to change that dynamic. In this context, the primary effect of unilateral action by the U.S. to impose costs on its own emissions will be to shift industrial activity overseas to nations whose industrial processes are more emissions-intensive and less environmentally friendly. That result may make environmentalists feel better, but it will not better the environment
This statement needs to be analyzed carefully, because it holds the key to offering a solution. A year ago (last October) the World population surpassed 7 billion; when I was born in 1939, the world population was about 2 billion. The median UN estimate for 2050 predicts a global population of 9.2 billion, with about 85% of the people residing in what we identify now as developing and less developed countries (this includes China, as singled out by Governor Romney) (Science 333, 540 (2011)).
Here are the 2008 relevant data for China and the US: Carbon Dioxide emissions (in thousands metric tons) – China – 7.031 million; US – 5.461 million; Carbon Dioxide per person (in metric tons) – China 5.3; US – 18; GDP (in current US $) – China – 4.5 trillion; US – 14.2 trillion; GDP per person (US $) – China – 3,414; US – 46,760; GDP growth (in %) – China – 9.6; US – (- 0.4).
I chose 2008, because this was the latest year that World Bank data was available for all the indicators that I chose to post here (I realize that 2008 was the start of a financial crisis in the US and other countries, but not in China).
There is a useful identity that correlates the environmental impacts (greenhouse gases, in Governor’s Romney statement) with the other indicators. The equation is known as the IPAT equation (or I=PAT), which stands for Impact Population Affluence Technology. The equation was proposed independently by two research teams; one consists of Paul R. Ehrlich and John Holdren (now President Obama’s Science Adviser), while the other is led by Barry Commoner (P.R. Ehrlich and J.P. Holdren; Bulletin of Atmospheric Science 28:16 (1972). B. Commoner; Bulletin of Atmospheric Science 28:42 (1972).)
The identity takes the following form:
Impact = Population x Affluence x Technology
Almost all of the future scenarios for climate change make separate estimates of the indicators in this equation. The difference factor of 15 in GDP/Person (measure of affluence), between the average Chinese and average American makes it clear that the Chinese and the rest of the developing world will do everything they can to try to “even the score” with the developed world. The global challenge is how to do this while at the same time minimizing the environmental impact.
The figure below, taken from my book, shows the dependence of the GDP/Person on Energy Use/Person for 26 countries, including both developing and developed countries. The data for this graph were taken from the 2002 CIA World Factbook.
On superficial observation, the dependence in the graph looks linear. Linear dependence indicates that the energy intensity, defined as the ratio of GDP/Energy Use, is constant and independent of the GDP of a country. The energy intensity is a true measure of the efficiency of energy use. The approximate independence of the energy intensity to GDP, directly contradicts the often-heard perception that developed countries use their energy more efficiently than developing countries.
More careful observation shows (Yevgeniy Ostrovskiy, Michael Cheng and Micha Tomkiewicz; “Intensive and Extensive Parametrization of Energy Use and Income in US States and in Global Environments”; International Conference on Climate Change: Impacts and Responses; 12 – 13 July 2012; Seattle Washington) that the energy intensity is weakly dependent on the GDP (inverse square root dependence), not because developed countries are more efficient in their use of energy, but because service starts to play bigger and bigger roles in developed countries and is considerably less energy dependent as compared to heavy industry.
In the next few blogs I will focus on the difficulties in reaching an international agreement on limiting the use of fossil fuel, what China and other developing countries are doing to change their energy use, and how the USA is reacting to these developments.