WEBVTT 00:00.600 --> 00:04.604 align:left position:10% line:84.67% size:80% (SCIENCE TREK MUSIC) 00:05.372 --> 00:06.406 align:left position:10% line:84.67% size:80% JOAN CARTAN-HANSEN, HOST: 00:06.406 --> 00:07.574 position:10% line:84.67% size:80% Icebergs are chunks of ice that 00:07.574 --> 00:08.808 align:left position:10% line:84.67% size:80% break off glaciers. 00:08.808 --> 00:10.276 position:10% line:84.67% size:80% In the northern hemisphere, most 00:10.276 --> 00:11.444 position:10% line:84.67% size:80% icebergs break off from glaciers 00:11.444 --> 00:12.545 align:left position:10% line:84.67% size:80% in Greenland or Alaska. 00:12.545 --> 00:13.913 position:10% line:84.67% size:80% In the southern hemisphere, most 00:13.913 --> 00:15.181 align:left position:10% line:84.67% size:80% break off from glaciers in 00:15.181 --> 00:16.249 align:left position:10% line:84.67% size:80% Antarctica. 00:16.249 --> 00:17.517 position:12.5% line:84.67% size:77.5% The process of ice falling off 00:17.517 --> 00:18.618 align:left position:10% line:84.67% size:80% is called calving. 00:18.618 --> 00:19.919 align:left position:10% line:84.67% size:80% It can make quite a splash. 00:19.919 --> 00:21.588 align:left position:10% line:84.67% size:80% (splash) Icebergs are made of 00:21.588 --> 00:22.856 align:left position:10% line:84.67% size:80% fresh water and float in the 00:22.856 --> 00:23.890 align:left position:10% line:84.67% size:80% ocean. 00:23.890 --> 00:25.125 align:left position:10% line:84.67% size:80% They eventually drift into 00:25.125 --> 00:26.359 align:left position:10% line:84.67% size:80% warmer waters and melt. 00:26.359 --> 00:27.494 align:left position:10% line:84.67% size:80% Icebergs can be quite small, 00:27.494 --> 00:28.661 align:left position:10% line:84.67% size:80% less than a few feet across. 00:28.661 --> 00:29.863 align:left position:10% line:84.67% size:80% Or they can be very large, 00:29.863 --> 00:31.131 position:10% line:84.67% size:80% sometimes the size of the island 00:31.131 --> 00:32.499 align:left position:10% line:84.67% size:80% of Sicily. 00:32.499 --> 00:34.167 position:10% line:84.67% size:80% Only as little as one-eighth of 00:34.167 --> 00:35.368 align:left position:10% line:84.67% size:80% an iceberg is visible above 00:35.368 --> 00:36.403 align:left position:10% line:84.67% size:80% water. 00:36.403 --> 00:37.637 align:left position:10% line:84.67% size:80% Most of the ice is underwater 00:37.637 --> 00:38.772 align:left position:10% line:84.67% size:80% and that's why they are so 00:38.772 --> 00:39.839 align:left position:10% line:84.67% size:80% dangerous. 00:39.839 --> 00:41.007 align:left position:10% line:84.67% size:80% Ships can't see the sharp, 00:41.007 --> 00:42.242 position:10% line:84.67% size:80% jagged ice underneath the waves. 00:42.242 --> 00:43.943 position:10% line:84.67% size:80% In 1912, the unsinkable British 00:43.943 --> 00:45.545 position:12.5% line:84.67% size:77.5% ocean liner the Titanic hit an 00:45.545 --> 00:46.746 align:left position:10% line:84.67% size:80% iceberg and, well, sunk. 00:46.746 --> 00:48.748 align:left position:10% line:84.67% size:80% More than 15 hundred people 00:48.748 --> 00:50.850 align:left position:10% line:84.67% size:80% drowned. 00:50.850 --> 00:52.052 position:10% line:84.67% size:80% After that, an international ice 00:52.052 --> 00:53.586 position:10% line:84.67% size:80% patrol was established to track 00:53.586 --> 00:55.055 align:left position:10% line:84.67% size:80% icebergs and warn ships. 00:56.122 --> 00:57.624 align:left position:10% line:84.67% size:80% For more information about 00:57.624 --> 00:59.492 position:12.5% line:84.67% size:77.5% glaciers check out the science 00:59.492 --> 01:00.593 align:left position:10% line:84.67% size:80% trek website. 01:00.593 --> 01:01.728 position:12.5% line:84.67% size:77.5% You'll find it at Science Trek 01:01.728 --> 01:03.563 align:left position:10% line:84.67% size:80% dot org