Introduction: Planet Under Pressure

Planet Under Pressure is a six-part BBC News Online series looking at some of the most pressing environmental issues facing the human race today.

By Alex Kirby BBC News Online environment correspondent

We are a successful breed. Our advance from our hominid origins has brought us near-dominance of the world, and a rapidly accelerating understanding of it.

Scientists now say we are in a new stage of the Earth's history, the Anthropocene Epoch, when we ourselves have become the globe's principal force.

But several eminent scientists are concerned that we have become too successful - that the unprecedented human pressure on the Earth's ecosystems threatens our future as a species.

We confront problems more intractable than any previous generation, some of them at the moment apparently insoluble.

From population to cars to forests - graphs of the increasing pressures on our planet

At-a-glance

BBC News Online's Planet under Pressure series takes a detailed look at six areas where most experts agree that a crisis is brewing:

Food: An estimated 1 in 6 people suffer from hunger and malnutrition while attempts to grow food are damaging swathes of productive land.

Water: By 2025, two-thirds of the world's people are likely to be living in areas of acute water stress.

Energy: Oil production could peak and supplies start to decline by 2010

Climate change: The world's greatest environmental challenge, according to the UK prime minister Tony Blair, with increased storms, floods, drought and species losses predicted.

Biodiversity: Many scientists think the Earth is now entering its sixth great extinction phase.

Pollution: Hazardous chemicals are now found in the bodies of all new-born babies, and an estimated one in four people worldwide are exposed to unhealthy concentrations of air pollutants.

All six problems are linked and urgent, so a list of priorities is little help.

It is pointless to preserve species and habitats, for example, if climate change will destroy them anyway, or to develop novel crops if the water they need is not there.

Air pollution is a serious problem in the world's biggest cities

And underlying all these pressures is a seventh - human population.

There are already more than six billion of us, and on present trends the UN says we shall probably number about 8.9 billion by 2050.

Population growth means something else, too: although the proportion of people living in poverty is continuing to fall, the absolute number goes on rising, because fecundity outstrips our efforts to improve their lives.

Poverty matters because it leaves many people no choice but to exploit the environment, and it fuels frustration.

Above all, it condemns them to stunted lives and early deaths - both avoidable.

Difficult dilemmas

Planet under pressure is more about questions than answers. What sort of lifestyle can the Earth sustain?

Dependence on fossil fuels is pushing up CO2 emissions

How many of us can live at northern consumption levels, and what level should everyone else be expected to settle for?

How can we expect poor people to respect the environment when they need to use it to survive?

Are eco-friendly lives a luxury for the rich or a necessity for everyone?

And how can we act when sizeable and sincere parts of society say we are already overcoming the problems, not being overwhelmed by them?

Species survival

As many see it, we are not doing too badly.

More people are living healthier and longer lives. For increasing numbers, the future offers living standards undreamt of even a generation ago.

But we do have to think through the implications of our success and to realise its weaknesses.

Bangladesh is set to face increased flooding as climate change kicks in

Living within the planet's means need not condemn us to giving up what we now assume we need for a full life, just to sharing it.

The challenge we face is not about feeling guilty for our consumption or virtuous for being "green" - it is about the growing recognition that, as the human race, we stand or fall together.

Ingenuity and technology continue to offer hope of a better world. But they can promise only so much.

You do not need ingenuity and technology to save the roughly 30,000 under-fives who die daily from hunger or easily preventable diseases.

And facing up to the planet's pressure points is about their survival, and ours.