The British Environment Minister, Michael Meacher, has no doubt that the severe flooding in England in the last month must be counted as one of the early impacts of global climate change, caused by humanity pumping more and more greenhouse gases into the atmosphere.

Friends of the Earth International is even more convinced, which is why hundreds of its supporters including a busload of university students from Limerick will today start building a one-kilometre dyke around the Netherlands Congress Centre in The Hague.

After five days of talks on technicalities, the sixth Conference of the Parties to the United Nations Climate Change Convention - or COP6, as it's known in shorthand - will move into high gear this weekend as diplomats are joined by government ministers from all over the world.

According to Michael Zammit Cutajar, the convention's executive secretary, the Hague conference is "a make-or-break opportunity" for the whole process of trying to cut back greenhouse gas emissions in line with the landmark Kyoto Protocol, agreed at COP3 in December 1997.

"Unless governments of developed countries take the hard decisions that lead to real and meaningful cuts in emissions and to greater support for developing countries, global action on climate change will lose momentum," he warned. That's why the talks in The Hague are seen as so crucial.

"With scientists increasingly convinced that we are already witnessing the effects of global warming, we must ensure that the next decade produces real progress on lowering emissions and moving economic growth on to climate-friendly paths," Mr Cutajar said. In other words, it's crunch time.

Last month UN member-states received a draft of the latest report from the Intergovernmental Panel on Climate Change (IPCC), made up of the world's leading climate scientists, which warned that the Earth is going to get a lot warmer in the next 100 years than previously predicted.

The report, obtained by the Guardian of London, suggests that average global temperatures could rise by 6(, twice as high as the IPCC's "worst-case scenario" figure quoted in its 1995 assessment, which also found there was "a discernible human influence" on the climate.

That tentative conclusion has been hardened by the latest assessment, which baldly states that the burning of fossil fuels - coal, oil and gas - and the emission of chemicals such as chlorofluorocarbons (CFCs) have contributed substantially to global warming in the past 50 years.

Robert T. Watson, the IPCC's chairman, is on record as saying: "It is no longer a question of whether the Earth's climate will change, but rather when, where and by how much". Even small changes in the climate could "produce relatively large changes in the frequency of extreme events".

And although there are still uncertainties about the regional impacts of this trend, IPCC members say the draft now being studied in world capitals represents a scientific consensus. Their only fear is that some governments may try to water down the text before it is published next May.

Most governments have still not ratified the Kyoto Protocol, which means that its emissions targets for developed countries, which add up to an overall 5 per cent reduction on 1990 levels by 2010, are not yet in effect; they want to see how it will work in practice before signing up.

The crucial task facing the Hague Climate Summit is to decide these details in a way that maintains environmental credibility, something the EU is insisting on. "The meeting's success will be measured by the early entry into force of the Kyoto Protocol, I hope by 2002," Mr Cutajar said.

Developed countries are concerned that this rapid transition to a lower-emissions economy could have short-term economic implications, including a potential impact on trade competitiveness, both among themselves and affecting those developing countries that are industrialising fast.

The US, which is responsible for 23 per cent of global carbon emissions, has been the most recalcitrant. In 1998 its Senate decided by 95 votes to nil against adopting the Kyoto Protocol, at least until rapidly developing countries such as China and India also agree to cut their emissions.

The Protocol will enter into force after it has been ratified by 55 parties to the Climate Change Convention, including OECD countries representing at least 55 per cent of this group's total 1990 carbon dioxide emissions. So far only 30 countries, all from the developing world, have ratified it.

Key issues that need to be decided revolve around the Protocol's "flexibility mechanisms", known to insiders as "flexmechs", including rules for emissions trading, "joint implementation" of reduction targets and a "clean development mechanism" for assisting developing countries.

"Sinks" are another sticking point. The term refers to the capacity of trees to absorb carbon dioxide from the atmosphere, but what's at issue is the extent to which developed countries can obtain "credits" to offset their own emissions by planting new forests either at home or abroad.

Ireland is relying on doubling its tree cover to provide sinks for the carbon dioxide from its overheated economy. It has grown so rapidly in recent years that we have already exceeded the agreed target of capping increases in emissions at 13 per cent above their 1990 levels by 2010.

And although the Government's climate change strategy, published on November 1st, ostensibly aims to ensure equity in bearing the burden of cuts, it still provides cushions or hedges for some of the more powerful vested interests, such as agriculture and the cement industry. Take cement. The production of every tonne of it releases another tonne of carbon dioxide into the atmosphere from the pulverising of limestone. Yet carbon dioxide emissions are not a material consideration in deciding whether to license or grant planning permission for a new cement plant.

According to the Sunday Tribune, the Tanaiste, Ms Harney, expressed concern that even a single new plant could add 2 per cent to national carbon-dioxide emissions. But the Minister for the Environment, Mr Dempsey, was more anxious to protect the industry's competitiveness.

The Government's climate strategy merely pledges that officials will "negotiate" with the cement manufacturers to ensure emissions are in line with the global benchmark for industry best practice. No wonder it is relying on tree-planting and such "big hits" as closing Moneypoint. The EU's common position, agreed on November 7th by environment ministers in Brussels, is that sinks and flex-mechs must not be used as a clever dodge by developed countries, notably the US, to evade "significant, real, domestic abatement measures" on carbon emissions.

EU ministers at the summit will be arguing for a firm ceiling on the use of flex-mechs to make sure that all developed countries take steps to achieve the Kyoto targets. They will be pressing for a political agreement on the key points, leaving details to be worked out over the next year.

At their Brussels meeting, the EU environment ministers also drafted a letter to the US president-elect underlining the importance of making serious commitments to tackle climate change. European parliamentarians have made a similar appeal to sceptical members of the US Congress.

THERE is also a marked difference between Al Gore and George W. Bush on climate change. Gore knows a lot about it; in his 1992 book, Earth In The Balance, he identified it as the biggest environmental threat facing humanity. Bush, on the other hand, is a mouthpiece for the oil lobby.

The EU is desperately anxious for the US to adopt the Kyoto Protocol. But whether it's led by Bush or Gore, progress will be painfully slow. For a start, the Republicans will have a slim majority in both houses of Congress. But many Democrats also remain to be convinced.

Even if Al Gore succeeds in capturing what he sees as his birthright, he would face the challenge of persuading Americans to buy the kind of package that would make a difference, because there is little stomach for the type of societal changes implied even by a 7 per cent cut in emissions.

If the US and other developed countries do not sign up for Kyoto, implementing the protocol in good faith, there is almost no hope of reversing human-induced climate change, especially when a 70 per cent cut in greenhouse gas emissions is needed to avoid the worst effects.

Even if agreement is reached in The Hague, Friends of the Earth has warned that climate change will become "a disastrous reality" for millions of the world's poorest and most vulnerable people. And it blamed the US, in particular, for delaying effective international action to tackle the crisis.

Frank McDonald will be reporting from The Hague throughout next week