Culprits of Climate Change Scientists suggest that climate change in recent decades has been mainly caused by air pollution containing non-carbon dioxide greenhouse gases. Read on at NASA Science News

Picture not only major climatic upheaval -- severe flooding and droughts back to back -- but also changes in the very geography of the planet, with the Everglades national park disappearing off the map and the icy wastes of Alaska giving way to prime agricultural land.

Far from the apocalyptic visions of doom merchants, these are just some of the potential scenarios which emerge from a report entitled "The Climate Change Impacts on the United States", compiled over four years by US scientists under a directive issued by former president George Bush and published in draft form on the Internet in June to invite public comment.

The document suggests that if global warming continues at its current rate, average US temperatures will rise by six degrees Centigrade (10 Fahrenheit) by 2100 and sea-level could rise by over two feet (60 centimetres).

Another report published in June by Britain's Royal Commission on Environmental Pollution recommended a 60 percent reduction in carbon dioxide emissions and a radical reversal of energy policy over the next 50 years in response to the threat posed by global warming.

"The problems are complex and there are no easy answers," said commission chairman Sir Tom Blundell.

"We hope ... our report will begin the wide debate that will be essential if the UK and the whole world community are to rise successfully to the radical challenge that climate change is now posing," he added.

The document envisages a British coastline dominated by wind farms, and with barrages and turbines both on and under the sea to meet the country's 21st century energy demands.

Meantime, global warming may have already killed as many as 100,000 people in the past three years, according to historian David Keys in his book "Catastrophe", which foresees climate change leading to mass migrations, increased disease and poverty and even war.

While the planet has always been prone to severe weather events, a pattern of increasing severity is emerging as exceptional weather conditions have left as many as 300 million people homeless since 1997.

Storms like those that battered France late last year, the worst in living memory, which took 90 lives, destroyed 270 million trees and caused more than 11 billion dollars worth of damage, will become increasingly common.

But while the developed world is the source of most of the atmospheric pollution, it will be the developing world -- countries such as India and Venezuela, where unprecedented floods and mudslides killed tens of thousands last year alone -- which will bear the brunt of global warming.

The precise effects by region are largely unpredictable. But while computer models used to forecast future patterns in the planet's weather, vary in their specific predictions, they agree that the effects will be extreme.

They also present humankind with an uncomfortable conundrum at the onset of the third millennium: the burning of carbon-based fossil fuels (oil, gas and coal) is the principle source of greenhouse gases -- such as carbon dioxide and methane -- which trap solar radiation that enters Earth's atmosphere and so induce global warming.

Fossil fuels are a major driving force behind climate change, but they are also the engine of the global economy and a profligate consumer society.

The debate as to whether the current cycle of global warming is a natural phenomenon or is human-induced is already redundant. It is true the planet has warmed and cooled dramatically on a number of occasions over the geological time change.

But the rate of change, boosted by burning of fossil fuels and other human activity, is higher than ever before. It is estimated that the climate is currently changing between 10 to 50 times faster than in the past 10,000 years.

Scientists recognise this, and governments are beginning to do so too. At the 1997 summit on the global environment in Kyoto, Japan, leaders of the developed world committed themselves to a cut of just over five percent in the emission of industrial gases by 2010. Some nations volunteered cuts of up to 20 percent.

But the United States, by far the world's biggest carbon dioxide polluter, failed to ratify legislation to reduce emissions by a single tonne.

Meantime, global warming is upon us -- deserts are spreading, bringing drought and famine in sub-Saharan Africa while the polar ice cap has thinned by nearly 50 percent in 20 years, and sea levels are rising.

Further extreme change in the coming century may ultimately endanger the survival of the human race itself. Will men decide to hide behind sea walls and radiation filters and wait and see what nature has to bring while continuing their headlong pursuit of short term economic goals?

Or will they direct their ingenuity towards concerns beyond those of the here and now, and do everything possible to reduce their impact on an increasingly unstable and fragile environment to the benefit of future generations?