Urbanization imposes complicated and heterogeneous impacts on ecosystems. With the purpose of reflecting the comprehensive influence of urbanization on the ecosystem, we choose the ecological footprint to represent the ecosystem's integrated change and distinguish low-income, middle-income and high-income countries to reflect the nonlinear impact. This paper uses both static and dynamic STIRPAT (Stochastic Impacts by Regression on Population, Affluence and Technology) models to analyze 72 countries at different income levels during the 1980-2008 period. The results show that the overall ecological elasticity of urbanization at the global level is negative. Specifically, results suggest urbanization, associated to increased income, to have eco-friendly potential in terms of decreased ecological footprint. To explain such results, this paper answers two questions: Why does urbanization show ecological protection effects? Why does a more pronounced protection effect seem associated to increased income levels? Improved market mechanism, increased resource use efficiency as well as increased environmental awareness in urban areas associated to increased income levels are likely to support an eco-friendly urbanization process. Burden-shift to low-income countries also needs to be taken into account, in order to avoid policies that increase wellbeing locally at the expenses of far-away areas. (C) 2016 Elsevier Ltd. All rights reserved.