An iceberg is a large piece of fresh water ice that breaks from the seaward end of a glacier or polar ice sheet and falls into the sea. Most of the icebergs are formed in spring and summer. At that time, the warmer weather accelerated the speed of the glacier or ice sheet edge splitting. About 10000 icebergs are produced each year from glaciers in western Greenland alone. Where a glacier or ice sheet (shelf) meets the sea, the mutual movement of ice and sea makes the end of glacier or ice sheet break into the sea and become icebergs.

  The Arctic Greenland and the Antarctic continent are covered with snow all year round, and the thickness of snow can be as high as several kilometers. Under the pressure of the thick snow, the soft snowflakes gradually become dense ice, and then slide down the slope of the mountain to form a glacier, and finally meet the sea water. Icebergs are driven by wind and current to drift on the sea.

  The average life span of the icebergs is more than 5000 years. The density of ice is about 0.917 kg / M ~ 3, which is less than the density of sea water about 1.025 kg / M ~ 3. About 90% of the iceberg's volume is below the surface of the sea, and it is very strong. Encountering icebergs is a nightmare of polar ocean transportation. The most famous iceberg collision with a ship was the shipwreck of the Titanic in 1912.

  About 10000 icebergs are produced each year from glaciers in western Greenland alone. Compared with Arctic icebergs, Antarctic icebergs are not only large in number, but also huge in volume. Icebergs with a length of more than 8000 meters are not uncommon. The largest known iceberg is located near the French Antarctic base, covering an area of 160000 square kilometers.

  The life span of an iceberg varies. Long may drift for 10 years, short 1-2 years there will be no trace. Icebergs are extremely valuable freshwater resources, but at present, human beings have no way to use them.

  At present, ice and snow in the Arctic is melting faster than previously thought. From the comparison of the Arctic sea ice area in 1984 and 2012, it can be seen that the reduction of sea ice area is very obvious. Global warming is responsible for the rapid melting of Arctic sea ice.

  What is "icicle of death"?

  in the Antarctic and Arctic seafloor, a very peculiar columnar sea ice is often formed. These slender icicles, which extend from the sea to the bottom of the sea, are like the white fingers of death in fairy tales. As long as it gently touches the life in contact with it, it can freeze each other to death and freeze them in place! In front of it, the life on the sea floor is so fragile and vulnerable! People call it "icicle of death" vividly because of its great lethality to sea creatures

  So, how did such a terrible "icicle of death" come into being? Why do they only appear in the South and the Arctic?