On Christmas Eve 1968, after moon transit Apollo 8 astronauts Anders and Boorman recorded by hand-held camera the first photographs of Planet Earth as a solitary system with clear boundaries. Such images have become iconic, and have coincided with a growing understanding of the limits of a system within which human activity must source its resource needs. Over the subsequent 45 years, world population doubled from 3.5 to 7 billion, and the size of the world economy grew by 3.8 fold from US $11.2 trillion (at constant 2000 US $) to $42.5 trillion in 2011. GDP per capita has thus almost doubled. Mean life expectancy has risen from 56 to 69.6 years, driven strongly by a sharp global fall in under-5 mortality rates from 153 to 51 per 1000 live births. Yet these advances in income and health indicators have also brought depletion of natural capital and threats to ecosystem services, have been spread unevenly across and within countries, and have left a substantial proportion of the world’s population in hunger and poverty.
A number of global metrics have been developed to demonstrate the impact of human activities on finite Earth. These include the Human Development Index of UNDP, Genuine Progress Indicator, Ecological Footprints using global hectare equivalents, the Happy Planet Index, and planetary boundaries. No single approach has captured all source and sink resource use and impact, nor necessarily satisfactorily resolve complexities back to a single metric (such as global earths, hectares or sector boundaries). However, all conclude that i) the Earth has already exceeded its capacity to supply source and sink resources without resulting in negative feedback loops that reduce the supply of both, and ii) consumption and population drivers continue to rise, suggesting that the impacts on both environment and economy will also continue to grow. Overshoot has already begun to occur, in which more resources are being used than can be regenerated each year. Yet conventional economic growth is still a primary political goal in most countries.
The Royal Society (2012) concluded that indefinite growth is impossible in a finite world. Overshoots of consumption will provoke crashes when finite limits are reached.
- Royal Society report: People and the Planet
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- The consumption of a finite planet: well-being, convergence, divergence, and the nascent green economy. Pretty J. 2013. Environ. Resource Econ. 55 (4), 475-499