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Tiptoe through the icebergs

Updated Wednesday 7th March 2007

Mark Brandon continues his research into the Antarctic ice shelves.

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After a bouncy voyage across Drake Passage we finally reached the ice and have started our scientific program. I am going to write more about our science in future posts when we have some exciting results - but first I have to say a little more about why I am here.

It is all to do with ice shelves

Almost all of Antarctica is covered with ice and in some places this is a few kilometers thick. At the edge of the continent the ice reaches the sea and one of two things can happen: The first is that the ice can break off into relatively small bits called icebergs, which float away from Antarctica to melt in the sea. (In the Arctic it was one of these things that sank the Titanic). The second thing that can happen is that where many glaciers flow into an enclosed bay, they can form what is called an ice shelf.

Ice shelves come in a range of sizes, from small ones like the Ward Hunt ice shelf in the Arctic to the Ross Ice Shelf, Antarctica which is about the size of Spain. They have been in the news over the last few years as some commentators have linked their break up and collapse to global warming. But is only very recently that scientists at the British Antarctic Survey have provided direct evidence that global warming is responsible at least one ice shelf collapse.

From my point of view the most interesting thing about an ice shelf is that it floats. Yup - even that Spain sized ice shelf is floating on seawater. Now seawater is relatively warm compared with the ice, so when warm ocean currents flow beneath an ice shelf, then the shelf actually melts from below. It doesn't seem fair does it - the ice shelf gets it at the surface from global warming, and also at the bottom  from the sea.

Which brings me to where I am as I type this over a satellite link: sailing around the edge of the Wilkins Ice Shelf.

The Wilkins is a relatively small ice shelf at the base of the Antarctic Peninsula and is well on its way to collapse. We think the warm water flowing beneath it could be responsible. On this trip we want to measure how much warm water is flowing beneath the ice shelf, and what the 'damage' is.

Our trip around Alexander Island Copyrighted image Icon Copyright: Used with permission This excellent map is open source and I have added the red lines which show the places we are going to take our ship and make measurements.

I love Antarctic names! Most of Antarctica has only been named in the last hundred years and I know quite a few people who have had the odd mountain range named after them. (Of course all naming these days is done by committee).

You can see that in our area music lovers were in control. It's a personal thing but I'm sad that in a hundred years Bach's ice shelf will be gone, but Beethoven will still have his Peninsula.

Unfortunately there are two obvious problems with the map. The first is that 'Wilkins' is misspelt, and the second is that the coastlines of all the islands are rubbish!

 

A vague mapHere is an example of the dodgy coastlines taken from one of the ships paper navigation charts. The land is wrong by at least 5 miles.

Just get your head around that. In this age of satellites, we don't know the  coastline of Antarctica to the same level of accuracy that we already know the topography of Mars  and Venus.

Of course the reason that the coastline is so poor is that they were mostly mapped out by people on sailing ships and husky-drawn sledges decades before the satellites were launched.

Whilst this is a bit disappointing from my point of view as it makes it a little harder, it does mean we get the odd comedy moment.

Our ship some miles inland! Copyrighted image Icon Copyright: Used with permission The picture on the right is a photo I took a few hours ago of the ships computer navigation display. Charcot Island is in brown and our ship track is in red. I assure you that we never hit land. It's odd asking the Captain to take our ship into areas that are genuinely unexplored. We don't know the coastline, we don't know the water depth - in fact all we do know is we are going to be surrounded by icebergs. It's a big responsibility.

I am not sure how many unexplored areas there left on our planet, but I am glad I have the chance to visit and study this one.

In my next entry I will tell you about some of the measurements we are making here.

 

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