4月20日 世界最大冰川之一已融化

Scientists say one of the world's largest icebergs has melted away.

The so-called A68 iceberg had a surface area of nearly 6000 square kilometers and weighed approximately 1 billion tons after it broke away from Antarctica in 2017.

Its drift towards the island of South Georgia in the southern Atlantic raised fears for wildlife there but satellites show the formation is now virtually gone, broken into countless small fragments.

To understand all this I'm joined now by Huw Griffiths. He is a marine biogeographer who has conducted research on iceberg A68.

Thank you for joining us, could you tell us about the dramatic pictures we just saw, a little bit about the life and times of A68, what happened?

So A68 started off as part of a massive floating ice shelf called Larsen C and that's deep into the Weddell sea in Antarctica, and part of it broke away forming this new iceberg which is was twice the size of Luxembourg. It's the biggest one existing in the world at that time.

For a little while it just sat where it was, and then eventually over time it started moving northwards with the currents.

And for a long time it stayed really big, which is quite surprising to many people because normally when icebergs start moving they start to break up just because of the movement of the waves and things like, that but over the next two years it moved further and further north and into warmer water but also rougher seas.

And the combination of rough seas and warmer water basically was its doom in the end, it's what killed it essentially and it broke up into much smaller pieces but still those pieces have been around for months, so it's lasted a long time.

Did it also die because of global warming, is global warming part of the story here?

So A68 story really isn't part of global warming. Icebergs naturally melt as they move further away from Antarctica, otherwise we'd have them kind of floating up the Atlantic and all over the place

But actually, it's a good warning to us of what could happen to ice shelves in the future.

So Larsen C, the ice shelf that A68 broke away from, it was 12 percent of the ice shelf that was lost when this iceberg broke off.

But that's a normal process where more ice is coming off the land and replaces what's breaking off into the sea, but Larson C is also one of the ice shelves that's most at risk from climate change in the next hundred years.

And as its name suggests there were used to be a Larson A and a Larsen B, which were two smaller ice shelves further north and both of them have disintegrated in my lifetime and have had links to climate change in their demise.

Okay so climate change i guess still an issue although not in the demise of A68.

Huw Griffiths in Cambridge thank you so much for that insight.