World population and GDP per capita from year 1 to 2010 AD. The total human impact is their product. The inset shows the relative annual change of each between 1950 and 2010 [Maddison, 2001; Bolt and van Zanden, 2014; United Nations, 2013b]. Their averages were 1.69% and 2.21%, respectively, out of a total of ~4% (average annual change in GDP). Therefore, growth in population and consumption per capita have both played comparably important roles in the remarkable increase of human impact on planet Earth. This ~4% total growth corresponds to doubling the total impact every 17 years. Note that the contribution from population growth has been relatively steady, while the contribution from the relative change in GDP per capita has been much more variable from year to year (even negative for some years). See Endnote 2 for a description of the mathematical formula used to generate the inset and sources of data.