Scientists drilling ice cores in Antarctica have produced the world’s deepest sample and discovered definitive evidence that human activity since the Industrial Revolution has radically altered the planet’s atmosphere.
The 650,000-year-old ice, determined by estimated average annual snowfall levels, was extracted from the Dome Concordia (Dome C) in east Antarctica by a European team.
The research by the 10-country European Project for Ice Coring in Antarctica (EPICA) outstripped a previous drilling record 0f 210,000 years, set at the Vostok Antarctic site.
Contained in the ice sample are tiny bubbles of trapped carbon dioxide.
Analysis has revealed that in the millennia leading up to the mid-19th century CO2 concentrations stayed well below today’s level of 380 parts per million (380 ppm).
In pre-industrial times, the CO2 concentration was around 278 ppm.
“We have added another piece of information showing that the time scales on which humans have changed the composition of the atmosphere are extremely short compared to the natural time cycles of the climate system,” said the study’s lead author Thomas Stocker of the University of Bern’s Physics Institute in Switzerland.
Natural events such as volcanic eruptions release massive amounts of greenhouse gases such as carbon dioxide, methane and nitrous oxide into the air and impact on the Earth’s surface temperature.
But the intensive coal-burning that has fuelled development since the Industrial Revolution has produced unprecedented amounts of CO2 emissions.
Evidence is continuing to mount that never before have temperature rises increased at such a rapid and advanced rate.
In the past five years, the average global temperature has jumped by 0.2 degrees centigrade – 100 times higher than usually seen over such a brief time span.
Ocean levels rising
Not only is the world getting hotter, with 2005 on track to become the hottest year on record, but ocean levels are also rising twice as quickly.
Glaciers in the Alps, Greenland and the Himalayas are melting faster than ever and ominous cracks have appeared in Antarctic ice shelves.
A research team led by Professor Kenneth Miller, from Rutgers University in the US, has released disturbing new findings based on drillings off the New Jersey coastline.
Sediment samples showed a steady one millimetre a year increase in ocean level from 5,000 years ago to about 200 years ago.
Sea level measurements from 1850, taken from tidal gauges, and more recently from satellite images, have recorded a two-millimetre annual rise.
“Without reliable information on how sea levels had changed before we had our new measures, we couldn’t be sure the current rate wasn’t happening all along,” Professor Miller said.
“Now with solid historical data, we know it is definitely a recent phenomenon.”
The studies have been published days before members of the United Nations’ Framework on Climate Change are due to meet in Montreal, Canada.
Scientists are hoping the research will sharpen international resolve to strengthen commitments on curbing carbon pollution.
In particular, focus is on the future of the Kyoto Protocol which is set to expire in 2012.