Fast-Track Shrinking of Baffin Island Ice

Fast-Track Shrinking of Baffin Island Ice

Feb, 2008  - Icy Baffin Island in the 
Canadian Arctic is not half as icy as it was just 50 years ago. Ice caps 
on the island's northern plateau are 50 percent smaller in area than they 
were in 1950 due to warming temperatures and are expected to vanish by the 
middle of the century, according to new research from the University of 
Colorado at Boulder. 
Radiocarbon dating of dead plant material emerging from beneath the 
receding ice show the Baffin Island ice caps are now smaller in area than 
at any time in at least the last 1,600 years, said geological sciences 
Professor Gifford Miller of CU-Boulder's Institute of Arctic and Alpine 
Research. 
"Even with no additional warming, our study indicates these ice caps will 
be gone in 50 years or less," he said. 
Located just west of Greenland, the 196,000 square mile Baffin Island is 
the fifth largest island in the world. Most of it lies above the Arctic 
Circle. 
The study also showed two distinct bursts of Baffin Island ice cap growth 
beginning about 1280 A.D. and 1450 A.D., each coinciding with ice core 
records of increases in stratospheric aerosols tied to major tropical 
volcanic eruptions, Miller said. 
The unexpected findings "provide tantalizing evidence that the eruptions 
were the trigger for the Little Ice Age," a period of Northern Hemisphere 
cooling that lasted from roughly 1250 to 1850, he said. 

The researchers also used satellite data and aerial photos beginning in 
1949 to document the shrinkage of more than 20 ice caps on the northern 
plateau of Baffin Island, which are up to four miles long, generally less 
than 100 yards thick and frozen to their beds. 
"The ice is so cold and thin that it doesn't flow, so the ancient 
landscape on which they formed is preserved pretty much intact," said 
Miller. 
In addition to carbon-dating plant material from the ice edges, the 
researchers extracted and analyzed carbon 14 that formed inside the Baffin 
Island rocks as a result of ongoing cosmic radiation bombardment, 
revealing the amount of time the rocks have been exposed, he said. 
The analysis of carbon 14 in quartz crystals indicated that for several 
thousand years prior to the last century, there had been more ice cover on 
Baffin Island, Miller said. 
The increase of ice extent across the Arctic in recent millennia is 
thought to be due in large part to decreasing summer solar radiation there 
as a result of a long-term, cyclic wobble in Earth's axis, said Miller. 
"This makes the recent ice cap reduction on Baffin Island even more 
striking," he said. 
Funded primarily by the National Science Foundation, the study is among 
the first to use radiocarbon samples from rocks for dating purposes, 
Miller said. The radiocarbon portion of the study was conducted at INSTAAR 
and the University of Arizona. 
Temperatures across the Arctic have been rising substantially in recent 
decades as a result of the build up of greenhouse gases in Earth's 
atmosphere. Studies by CU-Boulder researchers in Greenland indicate 
temperatures on the ice sheet have climbed seven degrees Fahrenheit since 
1991. 
The paper was published online in Geophysical Research Letters and 
featured in today's edition of the American Geophysical Union journal 
highlights. 
Authors on the study included Miller, graduate students Rebecca Anderson 
and Stephen DeVogel of the Institute of Arctic and Alpine Research at 
CU-Boulder, Jason Briner of the State University of New York at Buffalo, 
and Nathaniel Lifton of the University of Arizona. 

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