Greenhouse Effect At All-Time High

Study Finds Carbon Dioxide Levels Now Exceed That Of Any Era

(AP) 
The team, which included scientists from France and Germany, found similar results for methane, another greenhouse gas.

Researchers also compared the gas levels to the Antarctic temperature over that time period, covering eight cycles of alternating glacial or ice ages and warm periods. They found a stable pattern: Lower levels of gases during cold periods and higher levels during warm periods.

The bottom line: "There's no natural condition that we know about in a really long time where the greenhouse gas levels were anywhere near what they are now. And these studies tell us that there's a strong relationship between temperature and greenhouse gases," said Oregon State's Brook. "Which logically leads you to the conclusion that maybe we should worry about temperature change in the future."

A lengthening history of greenhouse gas concentrations should help climate specialists build better models about what the future might bring, Stocker said. It also may help answer additional questions such as how long ago humans started influencing greenhouse gas accumulations, and what impact other factors such as ocean currents play in the complexities of climate change.

Just a decade ago, scientists weren't sure it was possible to trace greenhouse gas concentrations back so far in ice. Now, Brook is part of another international research team preparing to hunt an ice-core sample dating back a million years or more, hoping to reach eras when Earth's temperature was significantly warmer.