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Antarctic Peninsula now almost as warm as 12,000 years ago

Rapid warming of the Antarctic Peninsula is bringing temperatures close to the warmth that followed the end of the last ice age, says lead researcher Richard Mulvaney, a paleoclimatologist with the British Antarctic Survey.

By Wynne ParryLiveScience / August 22, 2012

An Airbus A319 taxis on the runway at McMurdo base in Antarctica. An Australian rescue team swooped into Antarctica nearly two weeks ago to evacuate an American experiencing a medical emergency at a U.S. scientific base. While it is winter in Antarctica, it is one of the fastest warming places on Earth.

(AP Photo/Australian Antarctic Division)

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The Antarctic Peninsula, which juts out about 1,000 miles (1,610 kilometers) from the western flank of the frozen continent, is one of the fastest warming places on Earth.

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In the past 50 years, the air temperature has increased by about 3.6 degrees Fahrenheit (2 degrees Celsius). While this rate of warming is highly unusual, it is not unprecedented, indicates a new study.

The rapid, modern warming is bringing the peninsula's temperatures close to the warmth that followed the end of the last ice age, lead researcher Richard Mulvaney, a paleoclimatologist with the British Antarctic Survey, told LiveScience.

"We are now approaching the temperatures last seen 12,000 years ago," he wrote in an email.

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Mulvaney and colleagues predict continued warming will have serious implications for the ice shelves that jut from the peninsula over the ocean. In recent decades, ice shelves at the northern part have begun collapsing into the sea. Continued warming puts ice shelves further south at risk, they say.

[The Antarctic warming is paralleled by fast-melting ice in the Arctic, as that thaw approaches a new record]

Back in time

To look back at millennia of temperature history for the peninsula, a research team extracted a 1,200-foot (364-meter) ice core from the summit of an island mountain near the northern tip of the peninsula.

Chemical clues in the sections of ice enabled researchers to reconstruct a record of temperature changes going back about 15,000 years, to a time when the last ice age was coming to an end. 

Twice before in the past 2,000 years — around A.D. 400 and A.D. 1500 — the rate of warming has approached the modern one, Mulvaney said. The current warming trend began about 600 years ago, accelerating in the past 50 to 100 years, bringing the peninsula close to its post ice-age highs. 

Warmth means melt

Warming isn't just important for its own sake. While the thick layers of ice that extend from the frozen land have been stable for thousands of years, in the last 30 years rapid collapses, in which the ice shelves disintegrate into the sea, have begun, according to the U.S. Snow and Ice Data Center. [Antarctic Album: An Expedition Into Iceberg Alley]

In 1995, the northernmost portion of the Larsen Ice Shelf, about 770 square miles (2,000 square kilometers) collapsed, forming small icebergs. After retreating for some time, the nearby Prince Gustav Ice Shelf collapsed the same year.  

Scientists have wondered if the loss of ice shelves and rising temperatures on the Antarctic Peninsula are the result of natural cycles or if humans' alterations to the environment, including the ozone hole of Antarctica, are responsible. The results of the study don't provide an answer to this question, but they do offer insight into the pre-Industrial temperature history and how it related to the state of the region's ice shelves.

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