The Americans...are very much the villains of the piece

Sir Crispin Tickell, former British ambassador to the UN

A meeting in the Japanese city of Kyoto three years ago sought to limit the amount of the so-called "greenhouse gases" each country could emit, in order to check the trend towards global warming. But the protocol agreed there has yet to come into force.

The Sixth Session of the Conference of the Parties (Cop6) to the UN Framework Convention on Climate Change (UNFCCC) will attempt to move the signatories closer to final approval and implementation of the Kyoto action plan.

Opening the meeting, the conference head, Dutch Environment Minister Jan Pronk, told delegates the evidence of climate change was mounting.

"The greenhouse gases we produce are having a visible impact on the environment," he told them.

"We need to bring negotiations to a successful close, so that we can ratify the Kyoto Protocol and start putting it into practice.

"This will take an enormous effort, since rich countries' emissions would otherwise increase by around 20% over the same period."

Responsible

The chairman of the Intergovernmental Panel on Climate Change, Dr Robert Watson, said greenhouse gases were to blame.

"The weight of the evidence is that we humans are at least partially responsible for climate change," he said.

The Earth's surface temperature was now higher than for 1,000 years, and new forecasts put the expected temperature rises until 2100 at between 1.5 and 6.0C - double the previous estimates, he said.

The convention's executive secretary, Michael Zammit Cutajar, said The Hague meeting was "a make-or-break opportunity for climate change treaties".

It will be next week before Cop6 can come to any conclusions. Only in the last few days will ministers meet to finalise decisions.

Fuel costs

Sir Crispin Tickell, the former British ambassador to the UN, told BBC News Online's special climate change webcast that success or otherwise at The Hague would depend on the attitude taken by the US.

"We have a real problem in so far as the biggest industrial country in the world has not even submitted the agreement to congress," he said.

The UK is struggling to cope with heavy rainfall and floods

"The Americans in this area are very much the villains of the piece. They've not gone along with Kyoto and yet they are unquestionably the largest polluter with 4% of the world's population and 25% of greenhouse gas emissions."

But the pressure is on to reach an agreement, with several countries now experiencing their worst weather conditions in recent memory.

Many scientists and environmental groups argue these storms are the direct result of years of carbon dioxide emissions resulting from the burning of fossil fuels.

 Click here to watch Alex Kirby present our webcast from the Thames barrier in London

The problem for Cop6 delegates is that cutting emissions will not be painless.

The Kyoto Protocol requires the world to burn less oil, gas and coal, which means making heating, power and transport more expensive for consumers.

'Flexibility mechanisms'

The Hague conference is a make-or-break opportunity for climate change treaties

Michael Zammit Cutajar, executive secretary

Kyoto calls for a cut in the six main greenhouse gases to 5.2% below their 1990 level by no later than 2012.

To make the targets easier and cheaper to meet, Kyoto put up the idea of "flexibility mechanisms".

These would allow nations to buy and sell the right to emit gases, plant forests to soak up carbon dioxide, and invest in pollution control measures in other countries. But the detail of how these mechanisms should work has led to deep divisions.

Lobby groups

So far, only about 30 countries have ratified the protocol, mostly developing nations that are not being asked to make many sacrifices yet.

Some countries which are being asked to make cuts say they will not ratify until they know the details of how the protocol will work, and that is what has to be hammered out now in The Hague.

Oil-producing nations are calling for compensation for the impact of reduced oil consumption on their economies.

Police arrested 20 banner-waving demonstrators outside the conference hall, but said there were no injuries.