BOULDER, Colorado, June 29, 2010 (ENS) - Current levels of Earth's atmospheric carbon dioxide may be high enough to bring about "irreversible" shifts in Arctic ecosystems, according to new research published today by scientists from the United States, Canada and The Netherlands.

The Arctic climate system is more sensitive to greenhouse warming than previously known said the researchers, who gathered evidence on what is now Ellesmere Island in Canada's High Arctic from a time period 2.6 to 5.3 million years ago. This period, known as the Pliocene Epoch, occurred shortly before Earth was plunged into an ice age.

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