(Reuters) -- Air from the oldest ice core confirms human activity has increased the greenhouse gas carbon dioxide (CO2) in the atmosphere to levels not seen for hundreds of thousands of years, scientists said Monday.
Bubbles of air in the 800,000-year-old ice, drilled in the Antarctic, show levels of CO2 changing with the climate. But the present levels are out of the previous range.
"It is from air bubbles that we know for sure that carbon dioxide has increased by about 35 percent in the last 200 years," said Dr Eric Wolff of the British Antarctic Survey and the leader of the science team for the 10-nation European Project for Ice Coring in Antarctica.
"Before the last 200 years, which man has been influencing, it was pretty steady," he added.
The natural level of CO2 over most of the past 800,000 years has been 180-300 parts per million by volume (ppmv) of air. But today it is at 380 ppmv.
"The most scary thing is that carbon dioxide today is not just out of the range of what happened in the last 650,000 years but already up 100 percent out of the range," Wolff said at the British Association Festival of Science in Norwich, eastern England.