Global warming is set to accelerate alarmingly because of a sharp jump in the amount of carbon dioxide in the atmosphere.

Preliminary figures, exclusively obtained by The Independent on Sunday, show that levels of the gas - the main cause of climate change - have risen abruptly in the past four years. Scientists fear that warming is entering a new phase, and may accelerate further.

But a summit of the most polluting countries, convened by the Bush administration, last week refused to set targets for reducing their carbon dioxide emissions. Set up in competition to the Kyoto Protocol, the summit, held in Sydney and attended by Australia, China, India, Japan and South Korea as well as the United States, instead pledged to develop cleaner technologies - which some experts believe will not arrive in time.

The climb in carbon dioxide content showed up in readings from the US government's National Oceanic and Atmospheric Administration, taken at the summit of Mauna Loa, Hawaii. The measurements have been taken regularly since 1958 in the 11,400ft peak's pristine conditions, 2,000 miles from the nearest landmass and protected by unusual climatic conditions from the pollution of Hawaii, two miles below.

Through most of the past half-century, levels of the gas rose by an average of 1.3 parts per million a year; in the late 1990s, this figure rose to 1.6 ppm, and again to 2ppm in 2002 and 2003. But unpublished figures for the first 10 months of this year show a rise of 2.2ppm.

Scientists believe this may be the first evidence that climate change is starting to produce itself, as rising temperatures so alter natural systems that the Earth itself releases more gas, driving the thermometer ever higher.

© Copyright 2006 Independent News and Media Limited

###