KAREN Eberhardt-Shelton is absolutely right.

(‘The picture is absolutely obvious’, April 6).

Population is possibly the basic problem, and consideration of it is long overdue.

In 1800, the population of the world was about one billion.

It is now 7.313 billion, and increasing by a billion every12twelve years.

A billion is a thousand thousand thousand.

To give you some idea of the vastness of this number, a thousand seconds is just over a quarter of an hour, a million is 11 and a half days, and a billion is 31 and three quarter years.

Will growth level out?

No one really knows.

UN projections are based on assumptions about future fertility, and are often revised (usually upwards).

Medium projections for 2050 and 2100 are 9.6 and 10.9 billion, but 2050 figures could be anywhere between 8.3 and 10.9 billion, and 2100 between 6.7 and 16.6 billion.

Except at the low end of this range, growth is not expected to peak.

This is important because we are already about fifty per cent over the Earth’s biocapacity, even with the very low consumption levels of many of the world’s poor.

If we all consumed at the average rate of the developed world, we would need three-and-a-half Earths.

Not only that, but our actions threaten the Earth’s ability to continue even at the present level.

Climate change is going to produce many unpleasant surprises.

Sea levels are rising and threatening much low-lying land and many of the great cities: if these areas are overwhelmed, the number of migrants and refugees in the world will grow to totally dwarf present numbers, and famine and violence will result.

A recent paper issued by the Royal Society, called ‘Can the collapse of global civilisation be avoided?’, on tinyurl.com/p74757v states emphatically that ‘The human predicament is driven by overpopulation, overconsumption of natural resources and... (inappropriate) technology’.

It seems there is a taboo about this subject, but we must discuss it.

Our survival depends on it.

Roger Plenty

Rodborough Hill