BEIJING, Jan. 30 (Xinhuanet) -- Ice fields on an Arctic island larger than the U.S. state of California -- the fifth largest in the world -- have shrunk 50 percent in the last 50 years and will be gone in another 50 years, scientists said this week.

A study published in the Jan. 28 issue of the journal Geophysical Research Letters reveals the expanses of ice blanketing Baffin Island's northern plateau in the Canadian Arctic are smaller than at any time in at least the last 1,600 years.

"Even with no additional warming, our study indicates these ice caps will be gone in 50 years or less," said study researcher Gifford Miller of the University of Colorado, Boulder's Institute of Arctic and Alpine Research.

Temperatures across the Arctic have been rising dramatically in recent decades as a result of the buildup of greenhouse gases in Earth's atmosphere, say the researchers. It's this warming trend they say is behind Baffin's meltdown.

Baffin's ice caps, which are domes of ice too small to be labeled ice sheets as those on Greenland are, span just four miles (about six kilometers) long. What makes the ice fields such great study sites is the fact that they are very thin, generally less than 300 feet (91 meters) thick, and they're very cold, so they don't flow and erode the landscape beneath as most glaciers do.

Miller and his colleagues analyzed radioactive carbon in dead plant material emerging from beneath the receding ice margins, which would tell them the last time these plants had been exposed to the atmosphere.

The oldest dates are from about 1,600 years ago, suggesting the ice fields have remained intact for that long, that is, until 2005 when the scientists sampled the now-exposed plant material. In addition, they extrapolated other radiocarbon data along with satellite imagery to calculate the historical ice-cover and ice-free area in the same area.

Some of the ice fields studied formed in pre-Medieval times, Miller said, and persisted until now. "That tells us right there that the warming of the 20th century is the warmest sustained period of warming in that time," Miller said. "It clearly says we're now warmer than we were in Medieval times."