He took the first measurement of carbon dioxide in the atmosphere 11,400 feet up on Hawaii's Mauna Loa as a young student in 1958. Every Wednesday and Friday since, he has driven up this, the world's most massive mountain, to take the latest reading of the concentration of the gas that is the main cause of global warming.
Over the years his measurements - all taken on the same instrument - have charted an inexorable climb, at an accelerating rate, as carbon dioxide has been increasingly breathed out by the world, from burning oil, gas and coal. Tomorrow the world's governments meet in Geneva to decide what to do about the resulting changes in the climate.
Last month the Intergovernmental Panel on Climate Change - the official body of more than 2,000 top scientists set up by the world's governments - reported that global warming is already taking place, and that human activities are probably to blame. The climate is already heating up faster than at any time in the last 10,000 years - at twice the maximum rate to which, scientists say, natural systems can adapt - and this is expected severely to disrupt the world's harvests and to raise sea levels to inundate coastal areas.
Last week the Environment Secretary, John Gummer, published a government report concluding that southern England would inherit the climate of the Loire Valley in 25 years and that of the Bordeaux region in 50. This might seem an attractive prospect, particularly in a chilly, wet Wimbledon week but as the report pointed out, it presages massive disturbances of agriculture and industry, and would bring many more storms, droughts and floods, not to mention diseases like malaria, to Britain. Continued warming could eventually sweep even these conditions northwards, bringing harsher climates from the south or even, paradoxically, make the country much colder by diverting the Gulf Stream.
Yet almost every Western country is breaking a commitment made by international treaty to stabilise emissions of carbon dioxide. The conference which opens in Geneva tomorrow will consider strengthening the agreement but this is being strenuously resisted by governments from Australia to Saudi Arabia.
Meanwhile, Mr Chin's measurements continue to tell their ominous story. I caught him on his mobile telephone on Friday, just as he reached the measuring station gouged out of the side of the volcano, whose enormous dome - 75 miles long and 64 miles wide - makes it the bulkiest mountain on earth. Standing in the lunar landscape of its lava flow, looking down on the forests and coast far below, he said the first reading he had taken 38 years ago had revealed 315 parts per million (ppm) of carbon dioxide in the atmosphere: now it had just, for the first time, topped 360ppm. Concentrations are now growing twice as fast as when the measurements began.
"The trend keeps on going up," said Mr Chin. "It makes me a little worried."
It was his twice-weekly trek that first alerted the world. The Swedish scientist, Svente Arrhenius, accurately predicted exactly 100 years ago that carbon dioxide from burning coal would cause global warming, but there was little concern in the middle decades of this century, because the earth's climate appeared to be cooling naturally.
Then Charles Keeling of California's Scripps Institute set up equipment for monitoring the gas on Mauna Loa, recruiting the young Mr Chin to take the readings. It was - and is - an ideal site, in the middle of the Pacific, some 2,000 miles from the nearest land, and protected by freak climatic conditions from pollution from Hawaii below. By the late 1960s, the ever- increasing levels reported from the volcano were beginning to alarm scientists. A decade later, world temperatures started rising, with a vengeance. The ten hottest years in recorded human history have all occurred since 1980. Last year set an all-time high, even though the natural solar energy cycle was at its lowest point.
Another ominous record was also broken last year: worldwide emissions of carbon dioxide were higher than ever, at 6,056 million tons of carbon. The International Energy Agency estimates that by the year 2000 emissions will be 17 per cent higher than in 1990: by 2010 they will have risen 49 per cent.
This was not supposed to happen. Four years ago, at the Earth Summit in Rio, the world's governments signed a treaty to combat global warming. Industrialised nations promised to aim to level off their emissions so that they would be no higher in the year 2000 than in 1990. But almost no Western countries will meet this modest target. The World Energy Council reports that their combined emissions grew by 4 per cent between 1990 and 1995. Only the European Union achieved a slight fall, but this will not last. European environment ministers accept that most individual countries will not fulfil their treaty obligations, but claim the EU as a whole will do so, largely because of big falls in emissions in Britain and Germany. The trouble, as Andrew Warren, director of the Association for the Conservation of Energy puts it, is that "nobody believes it".
Certainly the European Commission does not. It calculates that its members will emit 3 per cent more carbon dioxide in the year 2000 than in 1990: the International Energy Agency puts it at nearly 10 per cent.
Worse, the complacency induced by this false claim is causing governments to scrap energy-conservation measures, which are the best way of curbing the pollution. This year they cut the EU's main energy-saving programme by over two-thirds. Britain which achieved its cut in emissions not by environmental measures, but through the politically-driven decimation of the coal industry and the "dash for gas" following electricity privatisation, has also largely scrapped its programme: the Energy Conservation Trust, set up to spearhead it, has received only a tenth of its planned funding. And the energy minister, Tim Eggar, cites the accidental pollution cuts as justification for opposing other measures.
Emissions have fallen sharply in the former Soviet Union and Eastern Europe, as a result of economic collapse - saving the atmosphere some 500 million tons of carbon - but, as expected, they have greatly increased in the newly industrialising countries of the Far East. In all, says the World Energy Council, they have increased by 3 per cent worldwide since 1990.
Mr Gummer says that he will use the conference opening in Geneva tomorrow to urge "all developed countries to honour their commitments", and will press for a 5 to10 per cent cut in emissions by the year 2010. The 36- country Alliance of Small Island States, some of which are expected to disappear entirely below the waves if global warming continues, will call for a faster and deeper reduction, 20 per cent by 2005. But they face virulent opposition from the industries and countries that make money out of fossil fuels. Australia is leading Western opposition to further controls, while Kuwait and Saudi Arabia have managed even to block the adoption of rules of procedure, threatening the whole process.
Ten days ago at the Royal Institute for International Affairs, in an unusually frank speech from a top diplomat, Eileen Clausen, the US Assistant Secretary of State for environmental issues, said governments were "in disarray" over responding to climate change. There was "no clear policy direction", she said, and "little thought" had been given to implementing and enforcing any policies that were adopted.
Even an energy industry body like the World Energy Council is clamouring for action to conserve fuel and develop renewable sources. Its deputy secretary general, Michael Jefferson, said last week: "Action is required, starting now."
From his mountain top on Friday, Mr Chin was saying much the same. The world cannot abandon fossil fuels, he said, "We cannot all go by bicycle, like in China." But it did urgently need to ensure that the increase of carbon dioxide in the atmosphere did not continue at its present rate.
I asked him for a message for the Geneva meeting. "Slow it down, guys," he said. "Slow it down."Reuse content