Wednesday, April 24, 2013

Earth Day Warning: 1,600 Years of Ice in Andes Melted in 25 Years

Quelccaya Ice capGlacial ice in the Peruvian Andes that took some 1,600 years to form has melted in just 25 years, according to studies of tropical ice cores made by scientists.
The study, which was released earlier this month and published in the journal Science Express, focused on the Quelccaya ice cap, located in the Canchis region of Cusco, in the Vilcanota of the Cordillera Oriental section of the Andes. According to the report, an increase in temperature has melted an important part of the ice, and uncovered plants that were frozen for over a millennium.
The research was carried out by a team led by Lonnie Thompson, an Ohio State University glaciologist and distinguished professor of earth sciences who has been studying the Andes glacial ice caps for decades.
Thompson’s team retrieved ice cores from the Quelccaya ice cap in 2003, and noticed startling similarities to other ice cores they had taken from Tibet and the Himalayas.  Patterns in the chemical composition of certain layers matched up, even though the cores were taken from opposite sides of the planet.
Thompsons-Ice cap researchThe team — which includes Thompson’s wife, Ellen Mosley-Thompson, distinguished professor of geography at Ohio State and director of the university’s Byrd Polar Research Center—  describes these tropical ice cores as 1,800 year old “Rosetta stones,” providing the most complete history of low-latitude climate.
According to a press release, these cores are allowing scientists to compare other climate histories from the Earth’s tropical and subtropical regions over the last two millennia.
“These ice cores provide the longest and highest-resolution tropical ice core record to date,” Thompson said.
Quelccaya 1978The Quelccaya Ice Cap sits on a volcanic plane some 18,000 feet above sea level in the Andean altiplano and spans an area of some 44 square kilometers.
Qori Kalis, the ice cap’s major outlet glacier, has seen significant reduction in the past decades. Pictures taken by Thompson in 1978 and 2011 show the changes at the glacier.
Quelccaya 2011The new cores, drilled from Peru’s Quelccaya Ice Cap, are special because most of their 1,800-year history exists as clearly defined layers of light and dark: light from the accumulated snow of the wet season, and dark from the accumulated dust of the dry season.
Pictures, right, taken by Thompson, show the retreat of the ice cap at Quelccaya in 1978 (above) and 2011.
The ice cores taken in 2003 clearly show layers of light and dark between accumulated snow in the wet season and accumulated dust in the dry season.  Most of the moisture in the area on the high Andean altiplano comes from the east, in snowstorms fueled by moist air rising from the Amazon Basin.  But these ice core records also show the impact from the west, specifically from the El Niño climate change, when warm temperatures rise in the tropical Pacific.
Ice cap - ThompsonSeveral years ago, the team found plants that had been exposed due to melting ice. Chemical analysis showed the plants to be around 4,700 years old, which means the ice cap had reached its smallest extent in nearly five millenniums.
“If any time in the last 6,000 years these plants had been exposed for any five-year period, they would have decayed,” Thompson said. “That tells us the ice cap had to be there 6,000 years ago.”
In the past, Thompson has been outspoken about the dangers of global climate change. In 2010 Thompson argued that virtually all climatologists were convinced that “global warming poses a clear and present danger to civilization.”

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