• Question: Is melting Arctic ice altering our maps?

    Asked by Mads to Anais, katy, Lauren, Richard, Stuart on 14 Mar 2016.
    • Photo: Anais Kahve

      Anais Kahve answered on 14 Mar 2016:

      Yes it is and it has been for some time now. For example, 20 years ago it would have been impossible for a ship to cross the Arctic Circle. But now because of the melting ice, ships can pass freely through. Also, low-lying land is subject to flooding, so as sea levels rise, land levels decrease, which in turn alter our maps.

    • Photo: Richard Friend

      Richard Friend answered on 14 Mar 2016:

      As the Arctic ice melts and the sea levels rise, some islands will eventually vanish off of our maps entirely! So if you’ve got a burning desire to go and see the Seychelles, it’s probably a good idea to do it sooner rather than later!

    • Photo: Stuart Atkinson

      Stuart Atkinson answered on 15 Mar 2016:

      Good question. If you’ve ever had a glass filled near to the top, and with ice on top, you’ll know that once the ice has all melted the liquid is still contained within the glass. The floating ice displaces its own weight in water and when melted the level drops. As the ice water and the drink are the same density, the liquid level remains the same throughout. The Arctic does not have any land underneath ie it’s just floating ice so you would think the same would be true.

      It’s a little more complicated if the water is more dense than the ice. Unlike artic ice, sea water contains salt and is more dense. This means that when the ice melts, the different densities mean that the level is a little higher. Exactly how much is still open to scientific debate but it is though to contribute a small amount to rising sea levels and therefore the changing shape of coastlines.

      It’s actually ice melting off the land that causes more problems, as when it ends up in the sea it contributes 100% to the water level rise. So ice coming off, say, the Antarctic, or a glacier in Greenland, is of more concern.

    • Photo: Lauren Laing

      Lauren Laing answered on 15 Mar 2016:

      This is a great question! The answer is yes!

      On ordnance survey maps we currently plot the high and low tide marks and land boundaries. As the other scientists have explained, when ice melts it expands, the increased volume of water in the oceans causes sea levels to rise. Therefore in low laying areas like some of our east coast and part of countries like Holland, the land boundaries will change.

      In my office, I sit next to a marine geographer; he also informs me that as the ice caps melt, tectonic plates can shift as the weight of ice decreases. For example, in the UK, Scotland is gradually lifting slowly out of the water, increasing the land mass on the coastal edges, while the South of England is sinking, causing the ocean to take over more of the coastal land.

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