WEBVTT - What  would happen if the polar ice caps melted?

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<v Speaker 1>from house stuff works dot com, where smart happens. Hi

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<v Speaker 1>am our brain with today's question. If the polar ice

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<v Speaker 1>caps melted, how much would the oceans actually rise? You

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<v Speaker 1>may have heard about global warming. It seems that in

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<v Speaker 1>the last hundred years, the Earth's temperature has increased by

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<v Speaker 1>about half a degree celsius. This may not sound like much,

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<v Speaker 1>but even half a degree can have an effect on

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<v Speaker 1>our planet. According to the US Environmental Protection Agency, the

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<v Speaker 1>sea lave All has risen six to eight inches in

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<v Speaker 1>the last one hundred years. This higher temperature may be

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<v Speaker 1>causing some floating icebergs to melt, but this will not

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<v Speaker 1>make the oceans rise. Icebergs are floating chunks of ice.

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<v Speaker 1>In order to float, the iceberg displaces a volume of

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<v Speaker 1>water that has a weight equal to that of the iceberg.

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<v Speaker 1>So when an iceberg melts, nothing happens to sea level,

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<v Speaker 1>but the rising temperature and icebergs could play a small

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<v Speaker 1>role in the rising ocean level. Icebergs are chunks of

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<v Speaker 1>frozen glaciers that break off from land masses and fall

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<v Speaker 1>into the ocean. The rising temperature may be causing more

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<v Speaker 1>icebergs to form by weakening the glaciers, causing more cracks

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<v Speaker 1>and making ice more likely to break off. As soon

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<v Speaker 1>as the ice falls into the ocean, the ocean rises

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<v Speaker 1>a little bit. If the rising temperature affects glaciers and icebergs,

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<v Speaker 1>could the polar ice caps be in danger of melting

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<v Speaker 1>and causing the oceans to rise even more. This could happen,

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<v Speaker 1>but no one knows when. The main ice covered land

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<v Speaker 1>mass is Antarctica at the South Pole, with about nine

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<v Speaker 1>of the world's ice. Antarctica is covered with ice and

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<v Speaker 1>average of two thousand, one hundred thirty three meters or

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<v Speaker 1>seven thousand feet thick, more than a mile. In other words,

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<v Speaker 1>if all of the Antarctic ice melted, sea levels around

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<v Speaker 1>the world would rise about sixty one or two hundred feet,

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<v Speaker 1>but The average temperature in Antarctica is minus thirty seven

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<v Speaker 1>degrees celsius, so the ice there is in no danger

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<v Speaker 1>of melting. In fact, in most parts of the continent

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<v Speaker 1>it never gets above freezing any time during the year.

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<v Speaker 1>At the other end of the world, the North Pole,

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<v Speaker 1>the ice is not nearly as thick as at the

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<v Speaker 1>South Pole. The ice floats on the Arctic Ocean. If

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<v Speaker 1>it melted, sea levels wouldn't really be affected. There is

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<v Speaker 1>a significant amount of ice covering Greenland, which would add

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<v Speaker 1>another seven meters or twenty feet to the oceans if

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<v Speaker 1>it melted. Because Greenland is closer to the equator than Antarctica,

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<v Speaker 1>the temperatures there are higher, so the ice is more

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<v Speaker 1>likely to melt, but there might be a less dramatic

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<v Speaker 1>reason than the polar ice caps melting. For the higher

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<v Speaker 1>ocean levels. The higher temperature of the water is actually

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<v Speaker 1>having an effect. Water is most dense at four degrees celsius.

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<v Speaker 1>Above and below this temperature, the density of water decreases.

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<v Speaker 1>The same weight of water occupies a bigger space, so

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<v Speaker 1>as the overall temperature of the water increases, it naturally

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<v Speaker 1>expands a little, making the oceans rise. Scientists have tried

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<v Speaker 1>to predict what the sea level will be in the year.

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<v Speaker 1>Different scientists come up with different predictions, but in general

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<v Speaker 1>they estimate that the sea will rise fifty centimeters or

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<v Speaker 1>twenty inches, with the lowest estimates in the fifteen centimeter

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<v Speaker 1>or six inch range and the higher in the centimeter

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<v Speaker 1>or thirty seven inch range. The rise will come from

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<v Speaker 1>thermal expansion of the ocean and from melting glaciers and

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<v Speaker 1>ice sheets. Twenty inches is no small amount. It could

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<v Speaker 1>have a big effect on coastal cities, especially during storm

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