Now,people realize that as climate change is raising global temperatures,more icebergs are being born.Antarctica creates far more of them than Greenland,the source of bergs in Arctic waters.Antarctica's are also much larger,sometimes reaching the size of small
countries.Recent
data
show
the
average
atmospheric temperature has increased about 4.5 in the western Antarctic Peninsula since the 1940s,making the region,among the fastest warming on earth.This jump has been shown in the recent breaking of major ice shelves along the Antarctic Peninsula.As a result,thousands of new icebergs have broken off,from ice shelves into the Southern Ocean at an accelerated rate.
Even as more icebergs are being created,scientists are learning that they are far from inactive masses of ice.In fact,they strikingly alter their environments biologically,chemically,and physically,making them islands of life in the open sea.Observers at sea have long remarked that they attract seals,and seabirds,and divers have noticed that fish are more numerous near them than in the surrounding sea.Now scientists are learning just what the attraction is all about.
Depending on their size,location,and the season,icebergs can be nurturers (培养者) or destroyers.During their existence—typically years from breaking off from an Antarctic or Greenlandic glacier to their gradual melting as they float into lower altitudes,they support animals on,around,even inside their splendid ice castle.They fertilize the ocean with nutrients,increasing sea creature production.Grounded bergs can shelter areas of the seafloor,protecting
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