PARIS (AFX) - Levels of carbon dioxide (CO2), the principal gas that drives global warming, are now 27 pct higher than at any point in the last 650,000 years, according to research into Antarctic ice cores.

The study, adding powerfully to evidence of human interference in the climate system, appears in the run up to a key conference on global warming which opens in Montreal next Monday.

The evidence comes from the world's deepest ice core, drilled at a site called Dome Concordia (Dome C) in East Antarctica by European scientists, Agence France-Presse said.

The core, extracted using a 10-centimeter-wide drill bit in three-meter sections, brought up ice that was deposited by snows up to 650,000 years ago, as determined by estimated layers of annual snowfall.

Analysis of carbon dioxide trapped in bubbles in the ancient ice showed that at no point during this time frame did levels get anywhere close to today's CO2 concentrations of around 380 parts per mln.

Today's rising CO2 concentrations are 27 pct higher than at the highest level seen over the 650,000-year time scale, according to the study, which appears in the weekly US journal Science. In the past five years, the average global temperature has risen by 0.2 C -- 100 times higher than is normal for such a short time scale -- and 2005 is on course for being the hottest year on record.

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