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Antarctic Journal

January 31, 2003

Home Away From Home

Giant petrel
Dan inside the hut.
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I've been sleeping in a one-room shelter called "the hut" lately. It's a charming building with wooden walls, three windows and a tin roof a couple hundred yards from the labs and sleeping quarters. It's about the size and shape of an outhouse on its side. People stay there for privacy, solitude or, as in my case, to be more in tune with this little corner of Antarctica. I'm anxious to make high quality audio recordings of all the sounds around me here. Some of them require great patience to obtain. Elephant seals, for example, don't make their weird grunts and groans all the time: only every once in a while. So each night, on the way to the hut, I visit a seal wallow and sit for an hour or so listening and recording. I also want to record the popping sound that certain kinds of glacier ice makes when it floats in water (its been described as sounding like the "snap, crackle and pop" of Rice Krispies) and the dramatic boom of glaciers calving (which never seems to occurs when I'm waiting for it). The hut is a good place staging area for getting all of these sounds.

Earlier this week I was awakened in my hideaway by two loud reports, the sort of sound I'd love to record. I was later told that what we concluded must have been the glacier calving woke up many others and shook Palmer's buildings. The rumble of breaking ice is the most obvious sign that glaciers are alive with movement, not static and eternal as they appear from afar. In fact the ice in the Marr ice piedmont that covers most of Anvers Island is flowing from the center toward the sea at 30 to 600 feet a year, a typical rate for glacier flow (however, the most recent study of the glacier's characteristics is thirty years old and may no longer be accurate). That means that ice falling off the 300-foot ice cliff face (about 180 feet above the water and 120 feet below) into Palmer's Arthur Harbor could be thousands of years old. The ice inside all glaciers flows from high points to low areas. But that doesn't mean glaciers are necessarily growing. In fact sometimes glaciers contract, or retreat, even while the ice inside keeps flowing outward. The edge of a glacier is a little bit like a waterfall. The river keeps flowing even though the fall remains in the same place. When more water in the form of precipitation falls on a glacier than is removed by melting and calving, a glacier grows, or advances. If removal exceeds accumulation a glacier recedes. If accumulation and removal of ice are exactly in balance, a glacier's edge is static. The Marr ice piedmont (an ice piedmont is a flat plain of glacier ice fed by a group of mountain glaciers) is shrinking, as it has been for at least about 40 years, at a rate of 30 feet a year. Old aerial photos of Palmer station show the glacier's retreat dramatically. When the station was built, the glacier edge, or tongue, reached right up to where one of the station's laboratories now stands. Where my cozy hut is located was under ice in 1963.

Researchers say global warming is probably causing the Marr, as well as glaciers throughout the Antarctic Peninsula, to shrink. The Antarctic Peninsula has warmed as much as, and possibly more than, any other place on Earth. In the last 50 years, the average winter temperature here has climbed by 9 degrees Fahrenheit. Ironically, this warming has caused increased snowfall. That's because the amount of sea ice, ocean topped by an ice cover, has declined. Sea ice prevents moisture from escaping from the ocean into the air. Less sea ice means more moisture, which falls back to Earth as rain and snow. However, this added precipitation has probably been more than balanced by increased melting caused by higher temperatures. Apart from Greenland and the Antarctic Ice Cap, the world's two biggest glaciers, most of the world's glaciers are retreating rapidly. Last year glaciologist Loni Thompson at Ohio State University announced research showing that the glacier atop Mount Kilimanjaro in Tanzania has shrunk to just one-fifth its size at the beginning of the last century. It will be gone in 15 or 20 years. Mark Meier a geologist at the University of Colorado says that almost all such glaciers have been melting for decades. In the last 40 years about 1,000 cubic miles of water has melted from the world's glaciers. And the rate of melting is increasing.

Just yesterday I finally succeeded in getting the sound of Arthur harbor's glacier face calving. I got it by leaving an audio recorder on by itself for several hours not far from the hut. When I listen back, it's amazing to hear how much ice is actually falling. Punctuating stretches of silence, with only bird calls and the sound of swells breaking on rocks, there is a steady series of crackles when small amounts of ice fall and the thunder of bus-size chunks breaking off, followed by loud splashes. It's the sound of Antarctica warming up. I'll be writing later about the impact of this warming on penguins. Also, look for a gallery of Antarctic sounds in the coming days.

In the Teacher Guide section, look for these related projects:

  •  Journal Jeopardy
  •  Global Warming
  •  Antarctic Symphony

  • Read the January 27th entry
    Read the January 22nd entry
    Read the January 17th entry
    Read the January 14th entry
    Read the January 13th entry
    Read the January 9th entry
    Read the December 29th entry
    Read the December 23rd entry