By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM and Maps.com
CONSEQUENCES OF GREENLAND’S ERRATIC WEATHER
A recent BBC (May 1, 2013) article reported the death of the leader of a team attempting to hike across Greenland. Although Greenland authorities were able to rescue the remainder of the party by helicopter, 31-year-old Philip Goodeve-Docker died while trying to trek 400 miles (644 km) across Greenland’s ice sheet.
This trek across Greenland’s expansive glacier was to be a tribute to Goodeve-Docker’s late grandfather. On his Facebook page, Goodeve-Docker said the trek would take as many as 35 days and would be “one of the great polar challenges.” He anticipated “such dangers as polar bears…, crevasses up to 500 meters deep, polar winds, (and) temperatures of 5 C to -50 C…”
Only two days into their trip, beginning at Angmagsslik (Tasiilaq) on Greenland’s east coast, 70 miles (113 km) south of the Arctic Circle, the explorers’ single tent blew apart in a massive storm called a “Piteraq,” leaving them exposed to subfreezing temperatures. A Piteraq is a cold, heavy high-velocity katabatic wind that flows by gravity down the east side of the Greenland ice sheet.
The Greenland ice sheet is a remnant of the Pleistocene epoch, a geologic period occurring between 2 million years and 10,000 years ago. Beginning about a million years prior to the Pleistocene, huge ice sheets periodically covered large parts of North America, Europe and Asia.
The ice age occurred because the earth’s atmosphere cooled in one of many warming and cooling cycles. At the peak of the last North American ice sheet about 18,000 years ago, the global climate was 5 to 8 degrees F (3 to 5 degrees C) lower than today.
Glaciers begin when snow accumulates year after year without completely melting during the warm season. The snow turns to firn, a granular ice, which is compressed by the weight of additional snow and transformed into crystalline ice. The weight of the ice causes plastic deformation of the lower layers and the glacier begins to flow outward. As the ice accumulates to greater and greater depths, the glacier expands its geographic area.
The thickness of the North American ice sheet reached more than 10,000 feet (3,048 m), literally standing as a high ice plateau and creating its own polar climate.
Toward the end of the Pleistocene, about 10,000 years ago, all of the great continental glaciers in the northern hemisphere were in full retreat (melting). Greenland’s icecap alone remains today as a magnificent remnant of the great ice age, covering 80 percent of the island’s 840,004 square miles (2,175,610 sq. km).
The Greenland ice sheet is a dome of ice more than 10,000 feet (3,048 m) thick, sloping away from the center in all directions. The weight of the glacier at its greatest depth is more than 285 tons per square foot (2,850 tons per square meter), depressing the bedrock below sea level in places.
The outer edge of Greenland consists of a ring of low hills and mountains. The glacier has sliced valleys through the mountains that are now filled with seawater. At the upper ends of many of these fjords, the tongues of glacial ice periodically calve off, creating icebergs. It was this sort of iceberg that sank the Titanic.
The Greenland ice cap is considerably smaller today than during the Pleistocene, when it extended much farther to the west and was connected to the North American ice sheet. It continues to diminish in size.
January temperatures near the center of Greenland’s ice cap average -53 degrees F (-47 C), while July temperatures are 12 degrees F (-11 C). The warmest part of the island is along the southwest coast where some summer temperatures in the 50s F (30s C) occur. The east side of the island is always colder as the frigid wind spills off the glacier. Average annual snowfall is surprisingly low over most of the island, averaging fewer than 10 inches (25 cm) annually over the glacier.
Until recently, the cold, dense air over the high ice plateau has kept warmer, moist air at bay. Now, however, warm Atlantic air is increasingly penetrating the interior, raising temperatures. Since the mid-1500s, Greenland’s climate has gradually been warming.
Tragically, Philip Goodeve-Docker and his party suffered the loss of their only protection from the high winds when their tent blew away. With no backup shelter and a storm initially too severe for helicopter rescue, they had to huddle on the open glacier in -31 degrees F (-35 degrees C) for nearly 24 hours until the winds subsided. By then, it was just too late for Goodeve-Docker.
This tragic event demonstrates the wind and temperature extremes found on Greenland’s high ice dome, even toward the end of April.
And that is Geography in the NewsTM.
Sources: GITN #1200 Death on Greenland, May 31, 2013; GITN #823 Greening of Greenland, April 21, 1995; http://nsidc.org/news/press/20021207_seaice.html; http://www.nasa.gov/vision/earth/lookingatearth/greenland-20060216.html; http://www.bbc.co.uk/news/uk-22363216; and http://www.thesun.co.uk/sol/homepage/news/4910687/north-pole-explorer-freezes-to-death-as-trek-is-struck-by-snow-storm.html?OTC-RSS&ATTR=News
Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor.
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