officialssay

The temperature in central London yesterday reached 35.4C (95.7F) - the hottest on record - with Gravesend in Kent even hotter, at 35.9C (96.6F). Even in Glasgow it was in the 80s Fahrenheit, and the UK record of 37.1C (98.8F) could be broken on Saturday, forecasters said, as all across Europe the merciless sun roasts citizens, sets forests ablaze and makes rivers run dry.

But this heatwave is nothing compared to what global warming has in store, United Nations scientists say - and the international agreement to counter it is now hanging by a thread. Its name is Putin.

If Russia's leader and his government do not soon ratify the Kyoto Protocol - the global warming treaty - the whole agonisingly constructed international mechanism for trying to deal with climate change will fall apart. To the mounting concern of officials in many countries, they show few signs of doing so.

The danger is passing unremarked by most people feeling the heat this summer, a summer whose unusual temperatures and extreme weather events across the world have already been highlighted, and explicitly linked to global warming, by the World Meteorological Organisation.

India, Sri Lanka and the United States have registered record high temperatures, rainfall and tornadoes; continental Europe has seen forest fires like never before and great rivers such as the Po in Italy reduced to a trickle; and now it is Britain's turn.

Yesterday a mass of air with the heat of a desert enveloped southern England, breaking records. And the highest temperature recorded nationally, Gravesend's 35.9C, may be exceeded when even warmer air arrives on Saturday, possibly breaking the UK temperature record of 37.1C (98.8F) set at Cheltenham in 1990.

In central London, which felt to anyone walking its streets like a Turkish bath, the mercury in the thermometer on the roof of the London Weather Centre reached 35.4C at 2.59pm, beating the previous record for the capital of 35C (95F) set in August 1990.

Across the country, train travellers faced a third successive day of delays because of the speed restrictions imposed amid fears that lines could buckle in the heat. Network Rail quoted 11 instances of rails buckling this week and said some rails had been as hot as 50C (122F).

On the roads, drivers were warned by the AA to look out for melting carriageways. London's big wheel, the London Eye, was closed. Otters at a Birmingham aquarium were so hot that managers brought in a supply of snow from an indoor skiing centre.

But if all this heat feels unprecedented, it will feel much hotter in the years to come, according to the scientists of the UN's Intergovernmental Panel on Climate Change, as an atmosphere thickened by increasing amounts of waste gases from industry, energy generation and transport retains more and more of the heat from the sun, like the panes of a greenhouse.

Cutting back on emissions of those greenhouse gases, principally the carbon dioxide (CO2) left after burning coal, gas and oil, is the only realistic option the world has to rein in a runaway global temperature rise that threatens real disaster, with extensive droughts, agricultural failure, more severe storms, and a worldwide rise in sea level predicted as consequences.

The Kyoto Protocol - hammered out in Japan in December 1997 between 180 countries, the whole international community - agreed to begin making those cuts by using renewable energy schemes, improving energy efficiency and developing technologies that do not emit CO2, such as the hydrogen fuel cell to replace the internal combustion engine.

The developed nations took the lead at Kyoto, accepting targets for cutting greenhouse gas emissions to an average of 5 per cent below their 1990 levels, by 2010, as a first step.

But after President George Bush, the oilman son of an oilman father, unilaterally withdrew the US from the treaty in 2001 - saying that the American economy would be damaged by the cuts, and that it was unfair that none were being made by the developing nations such as China and India - the protocol's particular arithmetic means that Russia, the second biggest CO2 emitter after the US, must now ratify it for it to enter into force.

No matter that Britain - last year - and more than 100 other countries have already ratified. Without the Russians, the commitments are no longer binding. The treaty is dead. The world will have to think of something else to try to deal with what is probably the greatest threat it has faced.

And concern is mounting, especially among European governments and environmentalists, that the Russian President, Vladimir Putin, and his government - the only major nation apart from the United States not to have ratified - may never do so.

British officials are constantly analysing Russian pronouncements on Kyoto, and find they usually contain "warmish" words about the treaty - but always stop short of pledging ratification.

It is known there are many people in Washington who hope and believe that Russia will not ratify, and some European governments are suspicious that the Bush administration may be actively pressing the Russians to do nothing.

Tony Blair, on the other hand, has personally pressed Mr Putin to ratify on numerous occasions, as have the German Chancellor Gerhard Schröder and other European Union leaders. British diplomats raise the issue whenever they meet their Russian opposite numbers. They have all got nowhere.

What makes Russia's failure to ratify the treaty potentially calamitous is that it was almost impossible to construct a common position on global warming. Since the initial agreement to act, at the World Climate Conference in Geneva in 1990, reaching that common position has taken exhaustive negotiations by many thousands of officials and politicians from around the world, all of them with different domestic interests and agendas.

Even after the Bush withdrawal, the treaty remained intact and its final technical details were painstakingly put together in a further series of conferences. But a Russian veto means the end of everything. A senior British official said: "It would be absolutely disastrous."

Roger Higman, senior climate campaigner at Friends of the Earth, said: "If Russia doesn't ratify Kyoto, 13 years of negotiations will have been wasted and talks on further cuts in emissions will be stillborn.

"But what's worse is that Russian failure to ratify would be a victory for George Bush and his corporate backers, and a catastrophic blow to European diplomacy. It would demonstrate once and for all that America can dictate the terms of any global agreement - vetoing those that don't suit its interests.

"If Tony Blair's foreign policy is to have an ethical dimension, he must make Russian ratification of Kyoto an absolute priority. We need the same determination to get Kyoto ratified that Mr Blair showed when drumming up support for the war in Iraq."

On 30 September, President Putin will make the opening speech at an international conference on the science of climate change held in Moscow. It would be the perfect stage to announce that Russia will ratify the Kyoto Protocol.

Those feeling this week's heat, who can sense what global warming will be like, should hope and pray that he does.