Weighing the Evidence: Although Levels of Atmospheric Carbon Dioxide Have Increased Dramatically since the 19th Century, Some Still Doubt That Climate Change Is Man Made
This summer, researchers working north of the Arctic Circle were treated to balmy temperatures of 19[degrees]C. Many of the glaciers that stretched across the fjords of Svalbard a few decades ago have retreated to the point where they barely reach the ocean and the area has become something of a tourist destination. Solid evidence of the effect of human-induced global warming? Not so, according to Gareth Rees, a scientist studying there. "I could discuss what is happening to glaciers in a particular bit of the Arctic," he says, "but although they are melting back, at least some of this, if not most, is probably as a result of natural climate fluctuation."
The more experts to whom you speak, the more you realise that global climate is difficult to pin down. Although it's clear we're seeing significant changes in global temperatures and weather patterns, there is still debate over whether or not these changes are human induced. "At parties, a scientist could say that global warming caused by humans is definite, but in layman's terms, it isn't," says David Stainforth of the Oxford-based research group Climateprediction.net (CPDN).
In 1860, the atmospheric concentration of C[O.sub.2] was around 280 parts per million (ppm). By 2001, the concentration had risen to 360 ppm, and today it's around 380 ppm. Not only have C[O.sub.2] levels in the atmosphere risen by more than 30 per cent from where they were before humans began burning fossil fuels in earnest, but they are expected to be double pre-industrial levels in around 50 years.
According to a 2001 Intergovernmental Panel on Climate Change (IPCC) report, when the atmospheric C[O.sub.2] concentration doubles, global temperatures will rise by between 1.5[degrees]C and 4.5[degrees]C. As potentially disastrous as such a rise will almost certainly be, things could get a lot worse. CPDN has enlisted more than 100,000 people around the world (or rather, their computers) to run a variety of complex climate models. According to Stainforth, the results suggest that the rise could be as high as 11[degrees]C.
And it's clear that we're already experiencing the effects of a warming world. In the summer of 1987, a Russian ice-breaker became the first surface ship to reach the North Pole. Tourists have since sailed there. In August, data from satellites monitoring the Arctic showed that the extent of the sea ice was the lowest on record. The Met Office has forecast an ice-free North Pole by the summer of 2080.
US photographer Bruce Molnia is gathering further evidence of warming by taking 'after' shots of glaciers around the world--photographing them from the precise spots used by 19th-century photographers. One such comparison involves photographs taken when John Muir discovered Glacier Bay in 1879. Molnia's images show the bay's glaciers in retreat; however, the retreat was underway when Muir first visited.
Sceptics pounce on discrepancies such as Glacier Bay as evidence that human activity isn't the issue, suggesting that the climate change that we're currently experiencing is primarily natural in origin. Dr Benny Peiser, a social anthropologist at Liverpool John Moores University believes that our emissions are a short-term issue. "There is a bias of pessimistic prognosis in the scientific community," he says. "Fossil fuels will run out soon. And glaciers are melting, as they would do in a warming trend. …