00:00 Sea ice, as in the Arctic, consists of salt water on the surface of the ocean which has
00:14 been frozen.
00:17 When temperatures rise in summer, it melts, or partially melts, before refreezing the
00:21 following winter.
00:22 Just like an ice block melting in a glass of water, the melting of sea ice does not
00:26 raise sea levels, but the reduction of sea ice does amplify the heating of the oceans,
00:31 as the darker water absorbs more sunlight than the more reflective ice, an effect known
00:36 as albedo.
00:38 Land ice, such as glaciers, ice caps and ice sheets, which are immense glaciers, consists
00:43 of fresh water from precipitation, sometimes kilometres thick.
00:47 These glacial ice formations flow towards the sea, pushed by the weight of their ice.
00:52 They can extend into the ocean, forming ice shelves.
00:56 There are two ice sheets on Earth, in Antarctica and Greenland, with the smaller ice caps found
01:02 elsewhere such as Iceland.
01:04 Due to the effect of heat, these ice shelves become thinner until they break off and become
01:09 iceberg, a process known as carving.
01:12 In this case of glacial ice, water is transferred from the land to the oceans, which does raise
01:18 sea levels.
01:19 Ice shelves can also act to retain the ice sheet or glacier and slow its movement.
01:23 If the shelves are sufficiently weakened, the movement of the ice sheet will increase,
01:27 releasing even more fresh water into the oceans.
01:30 According to the scientific group known as the IPCC, just the melting of the Antarctic
01:36 ice sheet would raise sea levels by 10 to 30 centimetres by the end of the century.
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