100-Sq.-Mile Ice Island Breaks Off Greenland Glacier

suraj.sun sends word of a 100-sq.-mile (260-sq.-km) ice island that broke off of a Greenland glacier on Thursday. "The block of ice separated from the Petermann Glacier, on the north-west coast of Greenland. It is the largest Arctic iceberg to calve since 1962... The ice could become frozen in place over winter or escape into the waters between Greenland and Canada. ... [NASA satellite] images showed that Petermann Glacier lost about one-quarter of its 70-km-long (43-mile) floating ice shelf. There was enough fresh water locked up in the ice island to 'keep all US public tap water flowing for 120 days,' said Prof Muenchow." The Montreal Gazette has more details and implications for Canadian shipping and oil exploration, along with this telling detail: "the ice island’s thickness [is] more than 200 metres in some places... [or] half the height of the Empire State Building." The NY Times has a good satellite photo of the situation.

Comments

Re:Clearly a sign of AGW

[Rei]

Right, because global warming predicts that all weather will cease to exist, right?

Seriously, what sort of idiot thinks that there will be no randomness from year to year? Climate is about *averages*. And the trends are clear.

Re:landlocked

[ls671]

From TFA:

http://dotearth.blogs.nytimes.com/2010/08/07/vast-ice-island-breaks-free-of-greenland-glacier/

> Petermann is a sleeping giant that is slowly awakening.
> Removing flow resistance leads to flow acceleration.

Basically, this means flow acceleration would speed up erosion of the corners that "landlock" it relatively quickly. Pressure caused by the increasing flow on the parts that do the "landlocking" could also lead to the iceberg breaking into smaller parts thus making it easier to make it to the open water.

Re:GISS

[mysidia]

Global warming refers to a general trend. Even if there is global warming, it can still be colder one year than the other, even though the trend is upwards.

The fact that the temperature was warmer on average for several years in the past, could mean that there was more melting, causing ice to be more brittle, or more likely to break when ice re-froze.

In other words, damage could have happened to the glacier over time that caused certain regions to be less stable or less sustainable, even if the pattern for a later year had been colder.

It's not 2010 that matters alone, it's the group of large number of years.... 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

You can't just take one year out of all those, and use temperature or other changes during that one year to show that there IS or IS NOT atmospheric gas pollution causing global warming, or if global warming did or did not result in an event.

The mass might break off due to past global warming, even if it happened to be colder this year.

The mass might break off even if there is no global warming at all.

Global warming might effect the probability that large pieces break off of glaciers over time, rather than being a single cause of any deteoriation event.

So anyways, the fact temps cooled alone is no proof that global warming did not result in this.

Re:In terms of rum & cokes,

[Sovetskysoyuz]

Volume of a 15 x 2 x 3 cm chocolate bar: 9e-5 cubic metres
Volume of an Olympic swimming pool: 2.5e3 cubic metres
Volume ratio is 1 : 2.78e7
Total volume of the oceans is 1.3e18 cubic metres
Iceberg volume, in the same ratio as chocolate bar : swimming pool, would be 4.68e10 cubic metres
If the iceberg is 200 m thick, then the area is 234 square kilometres.
The area of the iceberg, according to the article, is 260 square kilometres
O.o
You, sir, have astounding powers of estimation.

Re:Just one question for the Algoreithm experts..

[Rei]

As a reference:

The author, of course, conflates finding crops growing in modern Greenland to assuming that they could have grown back then, but notes the strong evidence that little, if anything, was ever successfully grown back then but hay and possibly limited amounts of flax (and the only evidence for that is pollen studies, which failed to turn up traditional food crops). Contemporary writings noted that most Greenlanders lived their whole life without ever seeing wheat, a piece of bread, or a mug of barley beer. The earliest settlers reportedly tried growing barley, but there was virtually no success.

Re:Clearly a sign of AGW

[theshowmecanuck]

And, BTW, ice cover has increased since 2007... is that a sign of Global Cooling?

The extent of the ice cap is not the only way to measure the ice cover in the arctic. Probably more important is the quality and the volume of the ice at the polar cap.

By the way, ice 'extent' is different than the 'area' covered by ice. 'Extent' is what is often quoted, not 'area'. Extent is measured like this: If a grid square being examined has more than 15% ice then it is considered ice covered. So if you had two grids being examined of say 10 sq km each, one being covered 80% by ice and the other being 16% covered by ice, the measurements would say that the ice extent or extent of ice coverage is 20 sq km, when the area would be more like 9.6 sq km. Because this is measured by satellite, grids for study are normally more like 25 or more sq km. Argument can be made to use extent over area since sometimes melt water over ice can be interpreted by the analysis software as being open water. Not always but sometimes; so they use extent to be on the safe side.

What many leave out is analysis of data from satellites that provide measurement of ice thickness. The linked web site addresses this somewhat. I have read about and seen information mentioned more and more on this for at least the last five or six years (and to be sure, the real experts have been looking at this for years). It looks like even if the ice extent is greater this year than in 2007, it is still about 1.6 million sq km less than the 1979 to 2000 average; and more importantly, the current volume of arctic ice is the lowest on record.

Re:Clearly a sign of AGW

[Rei]

If it's about averages, then you have to set the bar for the average. You can say a 30 year average is significant, or a 60 year average, or a 600 year average, or a 6,000 year average.

No, that would be called "making things up". Statistical significance requires statistical evidence. And we have ample evidence that the planet's temperature is dominated on the inter-annual scale by ENSO, and to a lesser extent, by other factors, but is dominated by AGW on the multi-decadal scale.

We have tons of data on ice extent. Most people know that, back to 1979, we have a beautiful record of satellite readings with only small holes. But there's a lot more.

Before that, we have sailing logs and logs from Arctic cities for the arrival and departure of ice. A particularly good source of data is the records from the US and Soviet navies' submarine fleets, which has been made available to researchers. There's direct written records from sailors all the way back to the dark ages, although these progressively become much patchier and are usually only good for localized ice extent.

From coastal records, the data dates back as far. Starting in the late 1800s, it becomes very good, and is near complete starting in the 1950s. Iceland has a good 1,200 year record.

Probably the best long-term record we have is that of sediment cores, and just recently we've started getting an increasingly number of papers on the subject (due to the hostility of the region, only readily have many cores become available). Here's a good review. There are several types of sediment proxies.

The first includes the deposition of ice-rafted debris. Large grains of minerals don't just appear in the middle of the ocean. They're too big to blow and too heavy to float. We observe the process of ice rafted debris being deposited in present day. The debris comes in two types: smaller grains from coastal margins, and larger grains from icebergs. The size, shapes, chemical signatures, and surface characteristics of the grains bear hallmarks of their origins and of the type of ice conditions at the time.

A second source of data in sediment cores is that of microfossils. Different types of plankton have different habitats in which they can live (i.e., some can live under ice, others can't) and known sedimentation and preservation rates. A third, and similar, technique involves the fossils of bottom-dwelling organisms. This may seem odd, as they're not directly affected by the ice -- but they're *hugely* indirectly affected. Very little organic matter, which such organisms eat, is deposited beneath the ice sheet; however, vast quantities are deposited around the edges of the ice, and a normal amount beyond it. Their populations are shown to well correlate with ice cover.

A fourth technique, like the above, involves the amount of organic matter itself deposited. Beyond just quantity, you can look at chemistry -- for example, there are chemical biomarkers for diatoms that live in sea ice.

At the coasts, you have a lot more data, as sea ice has significant affects on the land when it touches. This affects everything from whalebone to large mollusks to driftwood to plant matter and so forth. Even arctic tree records provide significant data, as arctic trees do not survive along coasts perennially lined with ice.

Concerning driftwood: wood cannot pass through ice. Driftwood floats, becomes waterlogged, and sinks in open water. Driftwood entrained in sea ice collects in quantity at the ice margin, and corresondingly sinks in quantity at such locations. Massive quantities of driftwood fossils are available.

Various types of sea mammals closely correspond with the ice margins -- polar bears, various species of seals, walrus, narwhal, beluga, and bowhead. T

Re:Clearly a sign of AGW

[Rei]

Which would be a valid argument if that's what scientists were actually doing. The early 20th century warming is a combination of several factors -- first, a strong shift in the PDO, and then followed by not only a decline in PDO, but a rapid increase in global industrialization. The latter might seem like it would have just the opposite effect, but you have to remember that until the 1960s/1970s, there was very little regulations on power plant emissions. While CO2 causes warming, it has to accumulate for this to happen. Far more rapid is the cooling effects of chemicals like sulfur dioxide, which were emitted en masse until the first world started mandating scrubbers on its power plants. While SOx has a relatively short (compared to CO2) residency, so it's really just a masking of the real climate, its affects are quite powerful.

Re:Clearly a sign of AGW

[Rei]

It's not true. The Earth warmed this much, and this fast, from 1900 to 1945

No, today's warming is faster.

The early 20th century warming is a combination of several factors -- first, a strong shift in the PDO, and then followed by not only a decline in PDO, but a rapid increase in global industrialization. The latter might seem like it would have just the opposite effect, but you have to remember that until the 1960s/1970s, there was very little regulations on power plant emissions. While CO2 causes warming, it has to accumulate for this to happen. Far more rapid is the cooling effects of chemicals like sulfur dioxide, which were emitted en masse until the first world started mandating scrubbers on its power plants. While SOx has a relatively short (compared to CO2) residency, so it's really just a masking of the real climate, its affects are quite powerful.