A conspiracy theory that grows more implausible by the day

It is appropriate that in the week in which the Kyoto Protocol finally came into effect, we have been given irrefutable proof that the earth is heating up at an unnatural rate - and that is being caused by human actions. Dr Tim Barnett, of the Scripps Institution of Oceanography, presented a paper to a prestigious scientific conference in Washington this week that ought to dispel any lingering doubts over mankind's responsibility for climate change.

It is appropriate that in the week in which the Kyoto Protocol finally came into effect, we have been given irrefutable proof that the earth is heating up at an unnatural rate - and that is being caused by human actions. Dr Tim Barnett, of the Scripps Institution of Oceanography, presented a paper to a prestigious scientific conference in Washington this week that ought to dispel any lingering doubts over mankind's responsibility for climate change.

Dr Barnett argues that climate models based on air temperatures are not always reliable. The real place to look for evidence of global warming, he says, is in the oceans. Having analysed millions of temperature readings made by the US National Oceanic and Atmospheric Administration, Dr Barnett has discovered that, over the past 40 years, the world's oceans have been steadily warming up. This cannot be explained by natural phenomena such as changes in solar activity, volcanic eruptions or long-term, cyclical, changes in our climate.

The only explanation for the rise is the massive increase in greenhouse emissions produced by humans over the past four decades. Dr Barnett's conclusion leaves no room for doubt: "The debate over whether or not there is a global warming signal is now over, at least for rational people."

Another presentation to the conference spelt out, once again, the dangers of global warming. Ruth Curry of the Woods Hole Oceanographic Institution points out that ice is receding everywhere. For humans, this will mean drought where major water sources are fed by snow or glacial melt. In the Andes and western China, millions will be left without adequate water during the summer. For animal life, the consequences will be even more severe. Seals, walruses and polar bears - their natural habitats shrinking fast - are on the road to extinction.

It is somewhat ironic that such compelling evidence for the existence and dangers of manmade climate change should have been presented in the capital of the United States. That nation's government, alone among developed countries, still stubbornly refuses to accept the international scientific consensus on global warming. Many prominent figures in Washington have convinced themselves that "global warming" is a fiction, and that international attempts to control emissions are secretly aimed at sabotaging the American economy. This, of course, is a conspiracy theory that suits vested business interests in the US.

The main responsibility of our own Government now is to exert intense pressure on the US to wake up to the reality of climate change. It was encouraging that Sir Emyr Jones Parry, the British ambassador to the UN, made no bones about America's duty when he spoke out this week. But will Mr Blair be so candid with his friend George Bush, when the Prime Minister chairs meetings of the G8 later this year? We will have to wait to find out. But as this latest research confirms beyond doubt, global warming will soon drastically change our way of life for the worse. If we wait too long, we will bitterly regret it.