The UK's Deputy Prime Minister, John Prescott, says the country's recent floods were a warning of further climate change.
Mr Prescott told the UN climate conference in The Hague that the floods had been "a wake-up call".
Mr Prescott began with a reference to an unlikely object which now sits on the podium in the conference hall.
"The sandbag which was placed here yesterday symbolises a lot to people in my country," he said.
"Two weeks ago, much of my country was under water. In the ancient and Roman city of York, hundreds of people worked through many nights to save it from the worst floods and storms since 1625.
"York had extensive new flood protection, tested to the limit where river levels rose over six metres. But it was only the thousands and thousands of these sandbags which saved the city.
"This was a wake-up call that struck home. When people see and experience these ferocious storms, long summer droughts, torrential rains - more extreme and more frequent - they know something is wrong and that climate change now affects them."
Effective action
In many other countries, though, the threat was much worse.
"The Minister of Environment for Nigeria told me that his home town has been engulfed not by water but by the spreading desert," said the deputy prime minister.
"Once-fertile countryside can no longer support farmers who have lived there for many hundreds of years."
Calling for the conference to re-affirm the Kyoto Protocol, the international climate treaty, Mr Prescott said the agreement must be effective.
Its aim of reducing developed countries' emissions of the greenhouse gases, blamed for accelerating natural climate change, to 5.2% below their 1990 levels "may be a small step, but it is a step in the right direction".
And the protocol must be fair, just and equitable, said Mr Prescott.
"We should avoid the temptation in the name of climate change mechanisms to introduce a new form of economic colonialism."
'Global solution'
Developing countries do not have to reduce their greenhouse emissions at this stage, though they will be required to do so later.
Mr Prescott said that was right: "Kyoto is only the first step towards a global solution which will include all nations. But developed countries must lead the way. We created the mess."
There are still wide differences between Europe and the Americans on how countries
should be allowed to achieve their Kyoto targets, with the US arguing that it should be allowed to pay for real or notional reductions in other countries' emissions and then count them towards its own target.
Mr Prescott said the UK's style of living would change as it achieved its own Kyoto reduction targets, but he believed this change could come about "in a way which emphasises gain, not pain".
"But in the long run we must never forget the pain of climate change, if we do nothing."
Mr Prescott said it was the poor countries which had done the least to cause climate change that were "the most vulnerable to catastrophe".
'Positive signs'
He called for more money to help them to cope with it, and for a 50% increase in contributions to the Global Environment Facility. And he ended with a call to delegates to ensure the success of the conference.
"Climate change is already upon us," Mr Prescott told them.
"Unless we join together in agreement this week, we will be throwing away the opportunity of a lifetime.
"There are positive signs behind the scenes of movement towards agreement. We all now need to turn that into an avalanche of support for a good Hague agreement.
"If we do so, we can then leave The Hague knowing we will leave the planet a better place than the one we inherited, and that when the time came we were not found wanting."