WEBVTT FILE 1 00:00:00.680 --> 00:00:02.450 The sheet of ice that covers Greenland 2 00:00:02.450 --> 00:00:06.400 contains enough frozen water to raise oceans by 25 feet 3 00:00:06.400 --> 00:00:07.700 across the globe 4 00:00:07.700 --> 00:00:10.370 As the planet warms, glaciers melt 5 00:00:10.370 --> 00:00:12.520 causing sea levels to rise 6 00:00:12.520 --> 00:00:15.740 But not all of that melt happens at the surface 7 00:00:15.740 --> 00:00:19.380 In the summertime, rivers and pools of meltwater 8 00:00:19.380 --> 00:00:21.890 find their way down through the glacier 9 00:00:21.890 --> 00:00:23.060 to the bed below. 10 00:00:23.060 --> 00:00:25.760 From there, the water runs beneath the glacier 11 00:00:25.760 --> 00:00:27.180 until it reaches the ocean. 12 00:00:27.180 --> 00:00:29.650 Because meltwater contains no salt, 13 00:00:29.650 --> 00:00:31.630 it weighs less than ocean water 14 00:00:31.630 --> 00:00:33.620 and rises up the front of the glacier 15 00:00:33.620 --> 00:00:36.050 in what scientists call a plume. 16 00:00:36.050 --> 00:00:40.070 Around Greenland, oceans are cold and fresh near the surface 17 00:00:40.070 --> 00:00:42.110 and warm and salty at depth 18 00:00:42.110 --> 00:00:46.430 As the plume rises, it draws in the warm, salty water 19 00:00:46.430 --> 00:00:48.960 metling the glacier face from the bottom up. 20 00:00:48.960 --> 00:00:53.200 Eventually, a piece of the glacier breaks off 21 00:00:53.200 --> 00:00:57.310 making an iceberg in a process known as calving. 22 00:00:57.310 --> 00:01:00.300 As the oceans warm, 23 00:01:00.300 --> 00:01:03.330 calving speeds up, causing glaciers to retreat 24 00:01:03.330 --> 00:01:04.560 and flow faster. 25 00:01:04.560 --> 00:01:07.450 Faster glaciers dump more ice into the oceans 26 00:01:07.450 --> 00:01:10.760 and drive sea levels higher across the globe. 27 00:01:10.760 --> 00:00:00.000