Given that the Arctic ice sheet is melting why aren t we seeing a corresponding rise in sea levels

A.� Although the Arctic ice sheet is melting and breaking up the majority of the ice is still frozen at the moment. But more importantly as the Arctic ice sheet is already in the sea it is displacing its own volume in water and therefore contributes to the current level of the sea.

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Q.� How much has the Arctic ice sheet thinned by

A.� According to research, it's been reduced by around 40% over the last 40 years or so.

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Q.� So why the panic over sea levels

A.� Although the melting of the Arctic ice sheet isn't going to raise sea levels dramatically, it's a different story in the south. Antarctica holds the majority of the earth's water, around 70% of it, locked up in ice.

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If this were to melt and contribute to the volume of the world's oceans, then we're in trouble.

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Q.� Why would Antarctic ice raise sea levels

A.� Because unlike the Arctic, Antarctica's ice lies on land, rather than in the sea, and so it would make a significant contribution to the volume of water if it became liquid. If all of Antarctica's ice melted it would raise global sea levels by about 200 feet.

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Q.� So should we care about the Arctic ice sheet

A.� Yes indeed. As always with nature everything is interconnected: the Arctic ice sheet might not affect sea levels but it would have a profound effect on the earth's weather system.

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This huge sheet of ice reflects back large amounts of the suns rays, acting as a natural refrigerator for the planet: without this deflection things could get dangerously hot.

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Also ice and melt water from the Arctic Ocean play a significant part in ocean circulation patterns on the North Atlantic, along with other climate systems over the entire planet.

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Q.� At the current rate, how much longer will the Arctic ice last

A.� It may be ice free by as early as the end of this century.

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Have you got a question about our changing environment Click here to ask.

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by Lisa Cardy