A "virtually locked-in" population growth that will not even be dented by a global pandemic or a prolonged conflict implies that any efforts towards sustainability have to be directed to curbing consumption, says a new study.

The world must focus on policies and technologies that reduce our impact as much as possible through technological and social innovation, say the University of Adelaide scientists.

Global population has risen so fast that roughly 14% of all human beings that have ever existed are alive today, notes Professor Corey Bradshaw, Director of Ecological Modelling in the Environment Institute and School of Earth and Environmental Sciences.

The team examined various scenarios for the human population to reduce by the end of the century and found that neither a world-wide one-child policy like China's nor a global conflict mimicking the combined effects of both the world wars would make much of a difference.

There will still be around 5-10 billion people by 2100.

Most estimates predict around 11 billion by end of the century.

Population vs Consumption
Population scientists have been stressing on this fact when they say that rising per capita incomes have outstripped head counts several times over, leading to galloping consumption as the greater threat to sustainability.

The Royal Society came out some time back to warn against rising consumption and emissions while also calling for the need to lift the 1.3 billion people living in absolute poverty to an adequate standard of living.

It called upon developed and the emerging economies to reduce material consumption levels through resource use efficiency, reducing waste and investing in sustainable technologies.

That consumption beats population as the main environmental threat has been the refrain of many who call attention to the fact that the ecological footprint of the world's rich overwhelms that of a majority of the poor.

An extra child in the United States today will produce an eventual carbon footprint seven times that of an extra Chinese child, 55 times that of an Indian child and 86 times that of a Nigerian child, calculated Paul Murtaugh, a statistician at Oregon State University.