The classic I.P.A.T. (Ecological Impact = Population * Affluence * Technology) equation very succinctly sums up the problem that humanity faces. Growth in both the number of people on the planet, and the level of affluence per person (I use GDP per capita as a measure if this), combine to drive increased levels of ecological impact. Technology may provide ways of reducing that impact per unit of growth (population * affluence), but cannot offset the 3%+ growth rate currently assumed as normal[i]. As measured by the Ecological Footprint, humanity’s resource usage reached the capacity of the Earth in the early 1970’s and is now assessed to be have reached the level of 1.6 Earths, and will rise to two planets by 2030[ii].

In the late 1970’s, China implemented policies limiting couples to one child in order to limit its’ population growth (there were many exceptions, e.g. for agricultural families where the first child was a girl). It has been estimated that the current Chinese population would otherwise be about 400 million more than the current 1.36 billion[iii] (compared to the approximately 1 billion population in 1980). The policy most probably accelerated the reduction in birth rates generally associated with increasing levels of affluence. The end result has been a relatively rapid ageing of the population, an imbalance between male and female children driven by social pressures for male infants, and increasing social discontent. These issues have combined to push the Chinese government to loosen the restrictions.

China Ecological Footprint

China Ecological Footprint

Source : Ecological Footprint Network,

Since the late 1970’s, China experienced average growth rates of over 10%, reducing to 7% only recently, driven primarily by increasing levels of per capita affluence that greatly overwhelmed any reductions in the population growth rate. It is estimated that China’s economy now equals the size of that of the United States, compared to being only a tiny fraction of it in 1980. Given China’s much larger population, its’ per capita GDP is still far behind that of the United States, at US$12,880 versus US$54,597[iv].

Technology-driven increases in resource usage efficiency were unable to offset such rapid growth, with China’s Ecological Footprint increasing from being equal to its’ bio-capacity in 1970 to 2.5 times that capacity in 2011. With its economy set to double every 12 years for the foreseeable future, this imbalance can only increase. Even with a stable population, China’s economy would need to more than quadruple in size for the average Chinese to have a level of affluence equal to that of current citizens of the United States. The scale of the resulting ecological disaster is difficult to comprehend.

To simply stabilize the global Ecological Footprint, both issues of population and average affluence need to be addressed – but the far larger one is the growth in per capita levels of affluence rather than that of population growth. The U.N. (United Nations) estimates that the global population will by about 33%, to 9.7 billion, between now and 2050[v]. Growth of only 2% per annum in per capita affluence would produce a 100% increase in the global economy in the same period, assuming zero population growth. The latest U.N. development goals call for 7% per annum growth in the least developed countries, to help reduce poverty, which would double the size of those country’s economies every 10 years.

A general assumption for ongoing global economic growth rates is that of 3%, which would result in a doubling of the global economy every 24 years. There has been no historical case of increases in resource efficiency being able to offset such rapid growth, let alone exceed it to allow for a return to a level within the Earth’s bio-capacity.

The only logical solution is the proposed Contraction and Convergence approach, under which the richer nations reduce affluence to make room for the less-rich ones, but this has gained little or no traction at the international level. One of the biggest problems with this approach is the inevitable rebalancing of the relative scale of individual nations’ economies, and therefore their relative power positions. The tensions that such changes cause can be seen in the recent geopolitical issues between the United States and China, as the latter has rapidly gained on the former in economic terms. The geopolitical reality is a fundamental hurdle to real progress in stabilizing and reversing humanity’s ecological overshoot.


[i] Abdul A. Erumban (2015), Global Economic Output 2015 – Key Findings, The Conference Board. Accessed at

[ii] Emma Howard (2015), Humans have already used up 2015′s supply of Earth’s resources – analysis, The Guardian. Accessed at

[iii] BBC (2015), China to end one-child policy and allow two, British Broadcasting Company. Accessed at

[iv] Wayne M. Morrison (2015), China’s Economic Rise: History, Trends, Challenges, and Implications for the United States, Congressional Research Service. Accessed at

[v] John Wilmoth (2015), Press briefing for the publication of World Population Prospects: The 2015 Revision, The United Nations. Accessed at