46-square-mile iceberg breaks off in Greenland

This Monday, July 16, 2012, satellite image provided by NASA shows calving, crescent-shaped crack at center, on the Petermann Glacier in northwestern Greenland. / AP Photo/NASA

(AP) An iceberg twice the size of Manhattan tore off one of Greenland's largest glaciers, illustrating another dramatic change to the warming island.

For several years, scientists had been watching a long crack near the tip of the northerly Petermann Glacier. On Monday, NASA satellites showed it had broken completely, freeing an iceberg measuring 46 square miles.

A massive ice sheet covers about four-fifths of Greenland. Petermann Glacier is mostly on land, but a segment sticks out over water like a frozen tongue, and that's where the break occurred.

The same glacier spawned an iceberg twice that size two years ago. Together, the breaks made a large change that's got the attention of researchers.

"It's dramatic. It's disturbing," said University of Delaware professor Andreas Muenchow, who was one of the first researchers to notice the break. "We have data for 150 years and we see changes that we have not seen before."

"It's one of the manifestations that Greenland is changing very fast," he said.

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Researchers suspect global warming is to blame, but can't prove it conclusively yet. Glaciers do calve icebergs naturally, but what's happened in the last three years to Petermann is unprecedented, Muenchow and other scientists say.

"This is not part of natural variations anymore," said NASA glaciologist Eric Rignot, who camped on Petermann 10 years ago.

Ohio State University ice scientist Ian Howat said there is still a chance it could be normal calving, like losing a fingernail that has grown too long, but any further loss would show it's not natural: "We're still in the phase of scratching our heads and figuring out how big a deal this really is."

Many of Greenland's southern glaciers have been melting at an unusually rapid pace. The Petermann break brings large ice loss much farther north than in the past, said Ted Scambos, lead scientist at the National Snow and Ice Data Center in Boulder, Colo.

If it continues, and more of the Petermann is lost, the melting would push up sea levels, he said. The ice lost so far was already floating, so the breaks don't add to global sea levels.

Northern Greenland and Canada have been warming five times faster than the average global temperature, Muenchow said.

Temperatures have increased there by about 4 degrees Fahrenheit in the last 30 years, Scambos said.

The new iceberg is likely to follow the path of the one in 2010, Muenchow said. That broke apart into smaller icebergs headed north, then west and last year started landing in Newfoundland, he said.

It's more than glaciers in Greenland that are melting.

Scientists also reported this week that the Arctic had the largest sea ice loss on record for June.

[Bojax39]

Anybody else want to turn a blind eye to the reality of global warming?

[venusvegasvada]

"We have data for 150 years and we see changes that we have not seen before."

Oh no, there isn't any global warming. No heat wave. No climate change.

All the ice on the polar caps could melt and the deniers would still say that there is no such thing as global warming. Drill baby Drill!

[johngalt_as]

OH MY GOD, THE SKY IS FALLING! Quick venusvegasvada, please tell us what to do?! Yawn! The climate is changing granted, but might it be common sense that the sun has a wee-bit more influence than man? All the planets have warmed (fact). But I guess it's the exhaust fumes from an old Chrysler causing it all, eh?

[ScorpioJax66]

We have information going back much further than 150 years. It is called Greenland because when the Vikings first landed there all they say was green. Then the ice came and chased them off. 150 years ago, what was called the Little Ice Age(approx. 1550-1850 according to NASA) had just ended, so yeah temperatures have been rising since then, but there is no proof that they are warmer before that period began since there were no tools to measure things and little exploration of areas close to the poles. This recent iceberg is half the size of one from 2 years ago and since all the ice lost so far was over water it was floating already and does not cause any increase in sea level. The article also said it could be normal calving. At most it just means water going by the area is warmer. Variations in sea temperature is normal and is the reason for the terms el nimo and la nina. Scientist in the 70s said we were in for a new Ice Age.

[kaylag04]

Uh-oh; now that Greenland's geeting nice, you just KNOW those Vikings'll be coming back. Every time it gets warm, here come the Vikings - but when it's time to shovel snow, not a horned helm to be found!

[Vtechmotor]

46 square miles off a 660,000 square mile ice sheet.

[Vtechmotor]

So a 46 square mile chunk of ice broke off of an icesheet 660235 sq mi in size.
Is there a story here or is this hype?
Oddly enough Carbon dioxide levels were 7,000 part per million in the Cambian perios and the earth did not suffer a runaway greenhouse effect.
Today carbon dioxide levels are 350 parts per million.

Why is man so arrogant to think we can have any effect on climate at all?

Climate is our master not our servant.

Money would be better spent finding ways to deal with climate change than attemt to prevent it.

[jmailbox]

Vtechmotor.

I 100% agree. All these nut job scientists do is talk about the global warming, ok, how about something to do to stop or slow it down.

Or wait, maybe there is nothing that we can do to stop it, because it's going to happen with or without us.

I'm just getting nothing but tired or hearing stupid ramblings of scientists claiming this and that about global warming.

[lesserof2evil]

yeah baby let's burning more coal to run those air conditioners.

[ThomasSense]

The glacier certainly is not growing nor is the exception. Ice is disappearing everywhere.

[knewsteerrrrr]

"We have data for 150 years and we see changes that we have not seen before."

"It's one of the manifestations that Greenland is changing very fast," he said.

Researchers suspect global warming is to blame, but can't prove it conclusively yet. "

Oh brother, I swear you have to stamp GLOBAL CLIMATE CHANGE on these idiot's heads with a metal stamper before they finally GET IT- the climate is changing, it's not long a "is it?" might it be something else?" it's changing rapidly and there's more than enough proof of it.

[Maou_Tsaou]

But even taking the cautious approach here's the first comment at SA on a story on carbon sinking using iron to seed mineral poor oceans.

"Why do we assume less carbon is better? This is just as asinine as the huge scientific gestapo majority who once insisted the Earth must be flat, and discredited all evidence that didn't support their theory. There is a lot of money to be made here, that's the real story."

If they make a strong claim there're damned but even being cautious they get such comments.
So I see why they try not to overstate but I'm agreeing with you. Nothing is going to placate these folks, apparently not even facts.

[johngalt_as]

OH MY GOD, THE SKY IS FALLING! Quick knewsteerrr, please tell us what to do?! Yawn! The climate is changing granted, but might it be common sense that the sun has a wee-bit more influence than man? All the planets have warmed (fact). But I guess it's the exhaust fumes from an old Chrysler causing it all, eh?