International comparison of natural capital use: A three-dimensional model optimization of ecological footprint

Humanity can be considered sustainable only if the natural capital stocks remain constant.The basic concepts and methodologies of a three-dimensional model of ecological footprint were introduced by this paper.Then much emphasis was put on the derivation and calculation of two indicators-regional footprint depth and regional footprint size so as to optimize the model.Taking this as the basis,an assessment and comparison of natural capital use in 11 major countries in 2007 were performed.Moreover,the fact was provided that results differed before and after optimization.The results demonstrated the following.First,the world-average appropriation of natural capital flows per capita was 1.71 ha,and more than one and a half planets were necessary to support the resource consumption of world's inhabitants.Fossil-fuel carbon emissions were the dominant pattern of natural capital use and the major driver of ecological overshoot on the globe.Second,the descending order of countries that occupy the capital flows was Canada,Russia,USA,Brazil,France,Germany,the world-average,Italy,China,UK,Japan and India.Conversely,the ascending order of countries that deplete capital stocks was Canada,Brazil,Russia(the three of them almost deplete nothing),the world-average,France,India,China,USA,Germany,UK,Italy and Japan.Third,some developed countries like the USA,France and Germany were obligated to pay compensation to developing countries,as the capital flows and stocks they used are both much more than the world average.Fourth,the world-average footprint size per capita decreased by 0.09 ha while the footprint depth increased by 0.05 comparing models with or without optimization.In particular,the optimized model offered a more conservative estimate on the sustainability of developed countries and thus a relatively optimistic estimate on that of developing countries.This was in accordance with the real situation of the natural capital use and ecological deficit in different countries.And the last,how to increase national income and control ecological deficit would be dual challenges for China.It is suggested that a priority for lands that support the use of natural capital should be given to grassland,and it is necessary to put constraint on the accelerating urban expansion.