On an observatory 11,000 feet (3,350 metres) high on Mauna Loa, a volcano in Hawaii, a pair of ageing, automated detectors have been churning out details about the make-up of our atmosphere for several decades. In December 2010, they produced their most alarming result to date. They showed that carbon-dioxide levels in the atmosphere have touched 390 parts per million – a 40% increase on pre-industrial levels.
The timing was striking. Just as negotiators were reaching their compromise deal on global warming in Cancún, the Mauna Loa machines showed the problem of greenhouse-gas emissions – left largely unresolved in Mexico – have reached an unprecedented level. Humans have procrastinated while the composition of the air around us has changed remorselessly.
It is a point stressed by Pieter Tans, who heads the US government's carbon-monitoring programme. "I find it shocking," he said after Republican party politicians claimed carbon dioxide posed no threat to earth. "We really are in a predicament here and it's getting worse every year."
Nor is it hard to understand his despair. Humanity was served notice of impending catastrophe 50 years ago when climate scientist Charles David Keeling decided to investigate the fate of the carbon dioxide that was being pumped into the atmosphere from factories and cars. Were the oceans absorbing most of this input, as some scientists said, or was it lingering in the atmosphere? To find out, Keeling installed his detectors on Mauna Loa in March 1958.
At first, he was baffled by his results: carbon-dioxide levels rose to 315.1 in May of that year. Then they fell for the next six months to 310.6. After that, they started to rise again until a new dip started six months later. Then Keeling understood. Those levels were fluctuating as the world's forests and plants – found mostly in the northern hemisphere where earth's land masses are concentrated – drew in carbon dioxide during the growing season in spring and summer and then let it out in winter. Keeling was watching the planet breathe.
But its breathing was troubled, he realised. Those annual cycles did not begin at the same low point each year. "It was higher the second year," Keeling recalled. "Then it was higher the third year. And then the fourth. Then we knew something was going on." In fact, each early winter low in the carbon-dioxide cycle was one to two parts-per-million (ppm) higher compared with the previous year – thanks to rising outputs of industrial carbon dioxide. Keeling started when overall levels were 315ppm. Today they stand at 390 – 391.65 in the first week of January this year -- and will touch 400 around 2015.
This discovery is probably the most important ever made in climate science, say Robert Kunzig and Wallace Broecker in their book, Fixing Climate. "If Keeling had not been so devoted to measuring carbon dioxide, the debate on global warming would be even more mired in polemics than it is now. Instead, the 'Keeling curve' of carbon dioxide at Mauna Loa has become one of the debate's few universally acknowledged truths."
This is a crucial point. Climate-change deniers, as they try to sow doubt about global warming, have attempted to tarnish every meteorological finding they have come across. Hence the furore they created over the leaking of e-mails from the East Anglia Climate Research Unit in the United Kingdom in 2009. However, they have never made a dent in the Keeling curve. As a result, we face the indisputable fact that levels of carbon dioxide, a gas known to warm the atmosphere, is rising relentlessly as we burn the concentrated organic carbon deposited as coal, gas and oil several hundred millions of years ago. In burning this fossil legacy: "Human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future," wrote US scientists Roger Revelle and Hans Suess in 1957.
You get the message. We were warned long ago but have done nothing about the threat of carbon dioxide, such is our dependence on fossil fuel. As a result, the interlude between introducing ecological constraints to halt its increased emission and the onset of the ecological catastrophe that will be triggered if we take no action is now being squeezed alarmingly. We are running out of time.
Indeed, many scientists now believe we passed the point of no return when we breached the 350ppm carbon-dioxide level in 1990. This was the maximum figure our planet could tolerate without suffering some climate change. "We have already seen temperature rises of 0.8 Celsius, thanks mainly to greenhouse-gas emissions," says Bob Ward, policy director at the Grantham Research Institute on Climate Change. "And even if we stopped all these emissions tomorrow, the gases we have already put up there will still produce a further 0.2 C rise in global temperatures by 2030 because of the lag in their effect on the atmosphere and the oceans."
Thus the world cannot avoid becoming at least one degree hotter than it was in the 19th century because of human activities. How much hotter it will get is a more difficult question to answer. Most scientists say increases of at least 2° Celsius above pre-industrial levels by 2100 are now inevitable. That doesn't sound so bad until you note such a rise will expose up to three billion people to the risk of water shortages, says Professor Martin Parry of the UK Met Office, while the UN states global food production will also be disrupted.
In fact, most climate scientists say rises could easily reach 4° C to 6° C, producing global average temperatures not seen on earth for 50 million years. Deserts will spread, ice caps melt, coastal areas flood and millions of people forced from their homes.
Some sceptics deny such changes will occur. Others say it is too costly to abandon the burning of fossil fuels even if this does dump billions of tonnes of carbon dioxide into the atmosphere. They say we should just put up with those spreading deserts and flooded coastlines – a notion of staggering immorality, according to Naomi Oreskes and Erik Conway in their book Merchants of Doubt. "This is the equivalent of medical researchers arguing that they shouldn't try to cure cancer because it is too expensive and that, in any case, people in the future might decide that dying from cancer is not really that bad."
After a year in which climate talks stalled and the “climategate” affair – the East Anglia e-mail leaks – induced near paralysis in dealing with the discussion of global-warming issues, we can see we are in a bad shape. Nothing new there. We have been doing nothing about global warming for 50 years, despite the warnings. Nor do the omens for the next 50 look better, a point highlighted by one US researcher. "When you go to Washington and tell them carbon dioxide will double in 50 years and will have major impacts, what do they say? They ask me to come back in 49 years."
It goes without saying, of course, that in 49 years, it will be too late.
© Copyright Guardian News and Media Limited 2011
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