Core Evidence That Humans Affect Climate Change Ice drilled in Antarctica offers the fullest record of glacial cycles and greenhouse gas levels.The Los Angeles Times, November 25, 2005
The research, published in today's issue of the journal Science, describes the content of the greenhouse gases within the core and shows that carbon dioxide levels today are 27% higher than they have been in the last 650,000 years and levels of methane, an even more powerful greenhouse gas, are 130% higher, said Thomas Stocker, a climate researcher at the University of Bern and senior member of the European team that wrote two papers based on the core.
The work provides more evidence that human activity since the Industrial Revolution has significantly altered the planet's climate system, scientists said. "This is saying, 'Yeah, we had it right.' We can pound on the table harder and say, 'This is real,' " said Richard Alley, a Penn State University geophysicist and expert on ice cores who was not involved with the analysis...
...The Vostok core showed that warm interglacial periods lasted about 10,000 years. Because the current temperate interglacial period has lasted about 12,000 years, many scientists had speculated that the planet was overdue for an ice age.
But the new core shows that the interglacial period of 440,000 years ago, when the Earth's position relative to the sun was similar to what it is today, lasted nearly 30,000 years and was not ended by natural decreases in carbon dioxide, Stocker said. The work suggests that the next ice age is about 15,000 years away.
