Geoscience Reference
In-Depth Information
no longer be colonized. The George River herd has a particularly limited summer range, restricted to the tun-
dra plateaus along the Labrador Sea, 150 kilometers (90 miles) inland from Nain. These are the traditional
calving grounds, and caribou concentrate there in part because the dominant winds reduce insect harassment.
This summer refuge constitutes only 15 percent of their annual range, and the growing herd has likely dam-
aged this restricted habitat, essentially eating itself out of house and home and partially accounting for the
most recent plunge in population.
But caribou numbers around the globe have plummeted by half in recent decades. These drastic declines
may be related to global warming, which has boosted temperatures twice as much in the north as elsewhere.
As a result, unusual freezing rains in autumn lock away winter forage under ice, the summer plague of flies
and insect parasites has increased, and the Arctic “green-up” occurs two weeks earlier, out of phase with the
evolved timing of the migration to the calving grounds.
BERGS TO BITS
ICEBERGS IN
Newfoundland waters are a dramatic feature of the marine environment and a reminder of the is-
land's northerly affiliations. In Labrador waters, there is ice all months of the year. In late August I have seen
large icebergs drifting imperiously along the mountainous, island-studded coast as if summer did not exist.
Mountains of lucent, frozen freshwater, icebergs have been compared to floating cathedrals—Ice Age
Chartres adrift in the North Atlantic. Icebergs themselves vary a great deal in shape and mass. Large icebergs
can be two football fields long, whereas “bergy bits” and “growlers” are a mere 5 to 15 meters (16 to 49 feet)
in length. As we know, much of the mass of the iceberg—some 90 percent—is underwater. Large icebergs can
weigh more than 10 million tonnes; the smallest bergy bits still tip the scale at over 100 tonnes. The visible sil-
houettes of icebergs also vary greatly, from round topped “dome” type to the “picturesque Greenland” type,
sporting one or more spires.
Most icebergs are calved from the glaciers of west Greenland; others originate in the glaciers of east Green-
land and the islands of the Canadian High Arctic, namely Devon, Ellesmere, Bylot, and Baffin Island. It is es-
timated that the 2-kilometer (1-mile) thick Greenland ice cap produces between 10,000 and 40,000 icebergs
every year. In any given year, 500 to 2,500 icebergs drift by the Labrador coast, and of these only several hun-
dred reach the Grand Banks of Newfoundland. Fewer still make it further south. The seabird biologist and
writer Richard Brown, in his classic Voyage of the Iceberg, observed that from an historical perspective, “there
has only been one iceberg.” When it ripped a devastating hole in the side of the world's largest ship, the Titan-
ic, on April 14, 1912, it was far south—41 degrees north—of where most icebergs ever occur.
