Hello and welcome to More or Less on the BBC World Service, the programme which analyzes

the numbers in the news with clever investigative skills like counting. I'm Kate Lownball.

Loyal listener Dave wrote in to More or Less at BBC.co.uk with the following question.

In recent reports about the rate in which one glacier in the Antarctic is melting,

I think I heard someone say that if the whole of the Antarctic guys melted,

then sea level would rise by something like 70 metres. This seems an awful lot.

Is it right? A 70 metre sea level rise would certainly be worrying.

The familiar shapes of continents would have to be entirely redrawn with much of Australia,

India and South America underwater. So to answer the question, I turn to Dr Bethan Davies,

a senior lecturer at Royal Holloway University in London, where she studies Antarctic glaciers.

She wants us to start by imagining a big block of ice.

One kilometer down, one kilometer long and one kilometer deep.

It's a pretty big block. We can convert that volume of ice into a massive ice.

So for seawater it would be one gigaton, one billion tonnes in one kilometer cubed.

So we've got a giant ice cube equal to one gigaton of seawater. How many cubes would you need

to raise the world's sea level? It takes 361 gigaton, 361 billion tonnes of ice to raise global

sea levels by one millimeter. The world is a big place, so it would take an astonishing

amount of melted ice to even impact sea levels slightly, which raises the question,

how many of those blocks are there in Antarctica? Oh, correctly. Hang on, let me lift it up.

Okay, here we go. I've got the data. I've got the data. Right. So in Antarctica, there are

three ice sheets, the Eastern Antarctica sheet, the West Antarctic Ocean, and the Antarctic Peninsula

ice sheet. So in Eastern Antarctica, there are 22.4 million cubic kilometres of ice.

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