A CENTURY ago the world population was 1.6 billion. By 1974 it had reached four billion. This year, it passed the seven billion mark and by 2050, it is expected there will be another two billion of us.

Meanwhile, we are encouraged to consume more, not least in the very short term to make Christmas a success ... not for religious or spiritual reasons, but for the sake of company bottom lines.

It is estimated that already, at the developed world’s rate of consumption, it would take the resources of one and a half planets to cope.

So how do nine billion people, consumption and sustainability fit into the same equation?

This is the very big question which Dr Peter White will be tackling at a free public lecture at Newcastle University on Tuesday.

Based in the North East, he is director of global sustainability for Procter & Gamble.

And P&G is certainly global. It has 300 brands, ranging from household care to beauty and grooming products, and from Pringles snacks to pet foods.

In the North East, the company employs 1,700 at its Longbenton research centre, Seaton Delaval production plant and Cobalt Business Park services centre, which provides back office support for the company’s Europe, Middle East and Africa operations.

That’s the regional perspective. Globally P&G reaches 4.4 billion consumers, aims to make that five billion by 2015, and ideally all nine billion by 2050.

So it is very much part of the population/ consumption/ sustainability debate.

“How do we make sure that nine billion people have an adequate standard of living within the limits of the planet and which will not lead to environmental degradation and resource depletion?” asks Peter White.

He answers his own question: “It is about delivering a better quality of life for everybody through the efficient use of resources.”

Much turns on wringing more from less. As P&G has grown, its environmental impact has lessened, he says.

Since 2002, the company’s energy use per product has been reduced by 52%, carbon emissions, water usage and waste for disposal have been halved.

One approach has been to make use of what was waste from the production process.

Waste oil from Pringle production is now converted into biodiesel; waste from the Oil of Olay beauty product is now used in leather conditioning; fibre sludge from paper production is used to make roof tiles; soapy water from cleaning detergent plant lines goes to car washes.