Q and A from the Guardian.

(Sorry, this is getting a bit dated now)

What is the Climate Change Convention? An agreement made by more than 150 countries at the Earth Summit in Rio in 1992 to limit man-made emissions of greenhouse gases to stop the atmosphere overheating.

What are greenhouse gases? The main ones are carbon dioxide, methane, and nitrous oxide. They prevent the reflected heat of the sun's rays escaping back into space, like the glass in a greenhouse.

Are scientists certain about this? Scientists agree that global warming is taking place and the vast majority believe it is man made. Burning fossil fuels releases carbon dioxide. Intensive agriculture and rubbish tips release methane. The only uncertainty is the scale of the process and whether we can adapt to it.

How quickly is the world warming? An average of up to 5C in 100 years, but more in some areas, notably in the arctic.

How soon will we know? The weather in the UK is already different, but in the arctic some effects are dramatic: some species, such as the polar bear, face extinction owing to melting ice.

What is the Kyoto protocol? An addition to the Rio convention, first agreed in 1997, to give all developed countries legally binding targets for cuts in emissions from the 1990 levels by 2008-12. The EU agreed an overall target of 8%, Japan 7%, and 6% for the US .

Why were the targets different? Some countries found it easier to make cuts than others. The UK had already started the switch to natural gas, Germany had closed many heavy industries, and Japan was already energy efficient. The US found it difficult because of an economic boom in the 90s. The developed world was to cut its emissions by 5.2%, and it was hoped that developing countries would join in later.

How can we keep to the Kyoto targets without cutting domestic emissions? There are three ways. Countries can plant forests to absorb and lock in carbon, or change agricultural practices to cut carbon emissions, such as not ploughing, or keeping fewer farm animals which produce methane. They can install clean technology in other countries and claim carbon credits for themselves. They can buy carbon credits from countries such as Russia, where heavy industry has collapsed and national carbon limits are underused.

But is that enough to solve the problem? Nowhere near. There is already enough additional greenhouse gas in the atmosphere to alter the climate, but we can stave off the worst if we cut man-made greenhouse gas production by 60% to 80% as soon as possible. The temperature will then stabilise at 5C higher than now. Kyoto was meant to be only the beginning, leading to steeper targets by 2020. We need to have cracked the problem by 2050 to avert disaster.

So what went wrong? The rules for how greenhouse gas emissions are measured and how they can be cut were not finalised in Kyoto. It was not agreed to what extent we could rely on planting forests and carbon trading. Years of wrangling ended in angry exchanges at the Hague in November, and things have gone from bad to worse since then. President George Bush repudiated the protocol, fearing that cutting the use of fossil fuel would damage the US economy. A former oil man himself, he has been persuaded by the oil industry to dump the Kyoto deal because it will hurt profits and cost jobs.

What can we do now? The rest of the world could proceed without the US. Most of the EU wants to go it alone and keep to the targets agreed in Kyoto, but the UK and Japan are reluctant without the US. Australia and Canada are against.

Why is there such reluctance? The US emits a quarter of the world's greenhouse gases and unless this is cut, the efforts of others will not make much difference. It will also be impossible to make developing countries such as China take the problem seriously.

Could the EU go it alone, show the lead and then put pressure on Mr Bush? Yes, but it needs partners. Under the Kyoto rules, 55 countries must ratify the protocol - making it law in their own countries - to make it legally binding across the world. A second condition is that they must include enough developed countries to make up 55% of total emissions in 1990, from when all targets are calculated.

How do the figures add up? The US alone was responsible for 36% of developed world emissions in 1990, so all of the EU, eastern Europe, Japan and Russia are needed to reach 55%.

So what will happen? The US will continue to destroy the Kyoto deal and suggest new talks. Others will try to make Kyoto easier for the US to accept. The EU and its allies may forge ahead and ratify it, and challenge Japan to follow suit. Or the talks could collapse.

Who are winners and the losers? The world's poor countries, and poor people who cannot adapt, will suffer first. There will be flooding, drought and famine. There will be millions of environmental refugees in Africa and Asia. Some northern countries gain marginally from a longer growing season in a warmer climate but the gains will not outweigh the losses.

What is the worse-case scenario? Huge tracts of productive land will become submerged, including major cities. Large migrations of people. More natural disasters, triggering a collapse of the insurance market, and a global crash as the world economy collapses.

What is the best-case scenario? That man's ingenuity and technology comes to the rescue with hydrogen and solar power replacing fossil fuels to run transport and create electricity.

Does climate require us to fundamentally change our lifestyles? Not a lot in the electric hi-tech age. We need to cut fuel consumption, stop flying flowers and vegetables round the world when they can be produced locally, and recycle goods. These changes can be achieved without damaging lifestyles.

If Bonn collapses will it be a disaster? Yes, in the diplomatic sense, and environmentally, too. So far no one has come up with a credible alternative.