In recent weeks, scientists have released two separate findings that indicate the consequences of global warming due to the emission of “greenhouse gases” — primarily carbon dioxide (CO2) from the industrial burning of fossil fuels — may be far greater than previously estimated.
The new findings underscore the need for governments around the world, in particular the industrialised
Rajendra Pachauri, chairperson of the United Nationsâ€™ Intergovernmental Panel on Climate Change (IPCC), which pools the expertise of more than 2000 of the worldâ€™s climate scientists, warned on October 25 that the greenhouse gas emission reduction targets established in the 1997 Kyoto agreement do not go far enough and far more radical solutions must be found.
Pachauri welcomed the Russian parliamentâ€™s October 22 ratification of the
The new evidence on the pace of global warming suggests that world governments may have even less time to act than previously estimated. The October 11 British Guardian reported that CO2 in the atmosphere is at record levels and increasing at an accelerating rate, while the September 23 edition of Science revealed that glaciers in western Antarctica flowing into sea are speeding up, indicating an increased level of melting.
The scientists who make up the IPCC estimate that unless levels of greenhouse gases in the atmosphere are stabilised by mid-century, Earthâ€™s average temperature will rise by up to 5.8°C by 2100. According to the IPCC figures, if unchecked, CO2 levels in the air will be between 650 and 970 parts per million (ppm). However, these estimates may be too conservative.
According to the October 11 Guardian, measurements of average atmospheric CO2 levels in 2002 and 2003 may confirm that the rate of CO2 accumulation is now increasing at an alarming rate. Scientists at
Associated Press reported earlier this year, on March 20, that scientists at Mauna Loa Observatory had recorded the CO2 level in the atmosphere peaking at a record of 379 ppm, compared to 376 ppm a year earlier and 373 ppm in 2002.
The increase has raised the spectre of a “runaway” greenhouse effect already underway. Previous increases of CO2 levels of above 2 ppm — 1973, 1988, 1994 and 1998 — have coincided with the El Nino weather pattern in the Pacific. However, this cannot explain the latest rises.
Weather scientist Charles Keeling, who began measuring atmospheric CO2 at Mauna Loa in 1958, told the Guardian that “it is possible that this is merely a reflection of natural events like previous peaks in the rate, but it is also possible that it is the beginning of a natural process unprecedented in the record … [The rise] could be a weakening of the Earthâ€™s carbon sinks, associated with world warming, as part of a climate change feedback mechanism. It is cause for concern.”
Piers Forster, senior research fellow at the
Friends of the Earthâ€™s
Predictions about the rate of CO2 accumulating in the atmosphere might not be the only estimates that have to be revised. Based on the IPCCâ€™s present forecasts, global warming triggered by unchecked greenhouse gas emissions will cause a sea level rise of between 20 centimetres and almost 1 metre by the end of the century. However, the IPCCâ€™s prediction is based on an assumption that the polar ice caps will not melt significantly.
However, according the September 23 journal Science, NASA researchers have found that six vast glaciers in the west Antarctic are flowing into the
According to Eric Rignot, a glaciologist at NASAâ€™s Jet Propulsion Laboratory, should the six glaciers completely melt, they alone will cause the worldâ€™s sea level to rise by more than a metre. Researchers using ice-penetrating radar also found that the glaciers are on average 430 metres thicker than previously thought, meaning they are dumping considerably more fresh water into the ocean.
One reason why Antarctic glaciers are entering the sea at a much faster rate is because floating 500-metre ice shelves, which significantly slow the entry of the glaciers into the sea, have begun to collapse and melt.
The Larsen A ice shelf suddenly collapsed in 1995. The Wilkins Ice Shelf is shrinking. In 2002, the 3400- square kilometre Larsen B shelf — at least 12,000 years old and up to 70 storeys thick — disintegrated into the
The calving of monster icebergs is now common. Ted Scambos, an expert from the
According to NASAâ€™s Robert Thomas, the ice shelves are melting rapidly and have been thinning at the rate of 10 to 15 metres a year since the 1990s. The rate of thinning today is double that in the 1990s, he added.
The Larsen and Wilkins ice shelves are relatively insignificant in Antarctic terms, but their demise may indicate that similar processes may be underway on the massive Ross and the Filchner-Ronne ice shelves. “Ice- shelf thinning could be happening elsewhere in the Antarctic, but we just donâ€™t know”, Scambos told Science.
The Ross and the Filchner-Ronne ice shelves prevent the gigantic land-based Western Antarctic Ice Sheet from rapidly entering the ocean and melting. The Western Antarctic Ice Sheet, the smaller of Antarcticaâ€™s two vast ice sheets, contains a mind-boggling 3.2 million cubic kilometres of ice, about 10% of the worldâ€™s total ice — enough to raise the sea level six metres. (If the more secure Eastern Antarctic Ice Sheet melted, the sea would rise more than 60 metres!)
Within the western sheet are five ice streams — enormous glaciers more than 50 kilometres wide and one kilometre thick. The Ross Ice Shelf — floating ice nearly the size of New South Wales — and the similarly sized Filchner-Ronne Ice Shelf prevent them sliding into the sea where they would rapidly melt.
The West Antarctic Ice Sheet may have melted at least once before, between 110,000 and 130,000 years ago, causing the sea level to rise about five metres higher than todayâ€™s level. An article in the August 1995 Scientific American pointed out that the five-metre rise was followed by a 10-metre decrease — all in the space of 100 or so years!
The May 2002 edition of Science reported that researchers from the