November 24, 2005

Greenhouse gases are at 'unprecedented' levels.

The current levels of carbon dioxide and other greenhouse gases in the atmosphere are at their highest point in the last 650,000 years, according to new data from scientists studying Antarctic ice. They've also found that, during the past 50 years, carbon dioxide levels have risen 200 times faster than during any other time over the last eight ice ages.

These disturbing new findings come from ice cores taken from the Antarctic, which go back 210,000 years further into the past than any cores previously available. Air bubbles preserved in these cores give snapshots of what the earth's atmosphere was like when the ice formed.

Scientists with Antarctice ice core

Scientists extracting an ice core from inside a drill in East Antarctica.
[Photo: British Antarctic Survey]

What's causing the jump in greenhouse gas levels?

According to Thomas Stocker of the University of Bern [Switzerland], the burning of fossil fuels by industry is the culprit, raising the levels of greenhouse gases far higher than anything that could be accounted for by natural causes. Says Stocker, who led the team that analyzed the Antarctic ice: "This is really something unprecedented."

After searching ice spanning the period of 390,000?650,000 years before present, Stocker's team has discovered that carbon dioxide levels in the atmosphere did not exceed 290 parts per million during that time. Today, that figure is around 375 parts per million.

The situation is similar for methane: during this period, levels hovered around 600 parts per billion. Today's atmospheric methane concentration is well over 1,700.


Posted by Magpie at November 24, 2005 03:55 PM | Environment | Technorati links |