Greenland’s meltdown

[neufer]

Click to view full size image

<<2010 was an exceptional year for Greenland’s ice cap. Melting started early and stretched later in the year than usual. Little snow fell to replenish the losses. By the end of the season, much of southern Greenland had set a new record, with melting that lasted 50 days longer than average.

This image was assembled from microwave data from the Special Sensor Microwave/Imager (SSM/I) of the Defense Meteorological Satellites Program. Snow and ice emit microwaves, but the signal is different for wet, melting snow than for dry. Marco Tedesco, a professor at the City College of New York, uses this difference to chart the number of days that snow is melting every year. This image above shows 2010 compared to the average number of melt days per year between 1979 and 2009.

The long melt season primarily affected southern and western Greenland, where communities experienced their warmest year on record. After a warm, dry winter, temperatures were particularly high in the spring, getting the melt season off to a strong start. The early melting set the tone for the rest of the season, leading to more melting all the way into mid-September.

When snow melts, the fine, bright powder turns to larger-grained, gravely snow. These large grains reflect less light, which means that they can absorb more energy and melt even faster. When the annual snow is melted away, parts of the ice cap are exposed. The surface of the ice is also darker than snow. Since dark ice was exposed earlier and longer in 2010, it absorbed more energy, leading to a longer melt season. A fresh coat of summer snow would have protected the ice sheet, but little snow fell.

Melting ice in Greenland freshens the seas near the Arctic and contributes to rising sea levels around the world. It is unclear just how much melting ice from Greenland will push sea levels up, largely because the melting is occurring much more quickly than scientists predicted. Current estimates call for an increase of up to 0.6 meters by 2100.>>

[BMAONE23]

This is likely caused by a strongly Negative Arctic Oscillation

Click to view full size image

In the negative phase, changes in the circulation pattern bring drier weather to Alaska, Scotland and Scandinavia, as well as wetter conditions to the western United States and the Mediterranean. In the negative phase, frigid winter air extends far into the middle of North America. This keeps much of the United States east of the Rocky Mountains colder than normal, but has the opposite effect on Greenland and Newfoundland leaving them warmer than usual.

Longer and later melting in Greenland is expected under a Negative Arctic Oscillation condition as is a generally lower snow fall rate
Current conditions (as of the date of this posting) indicate 80% of the Greenaland area to be below normal temperatures with only 10% at about 12deg F above normal and about 20% at 24deg F below normal.

Click to view full size image

Fortunately the blocking high that was situated over Greenland keeping the region warmer than normal for much of the winter seems to have subsided but the Negative Arctic Oscillation is still keeping the region drier than normal and limiting the ammount of seasonal snowfall

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The Greenland high or “Greenland Block” causes the jet stream to ‘buckle’ or drop drastically far south unleashing arctic air into the continental United States. The trough, or ‘buckle’ in the jet stream (U-shaped dip) causes cold air to clash with the warmer Gulf Stream off the southeast US coast. These ingredients along with disturbances riding the jet stream (river of fast-moving air) produce the powerful Nor’easters that give the Washington Area its snow storms.

[neufer]

This is likely caused by a strongly Negative Arctic Oscillation

But is the strong Negative Arctic Oscillation a result of Global Arctic Warming?

[Chris Peterson]

But is the strong Negative Arctic Oscillation a result of Global Arctic Warming?

The models certainly seem to support that assertion, don't they?

[BMAONE23]

But is the strong Negative Arctic Oscillation a result of Global Arctic Warming?

The models certainly seem to support that assertion, don't they?

But models have been wrong many times before as they are only models, simulations, probabilities.
While "Models" may support a certain point of view (it is with this point of view in mind that they are written and rewritten) the lack of direct correlation between the AO and the supposed source of AGW (CO2) is clear in the real world.
Since 1950, CO2 has advanced from just above 310ppm to 390ppm today

Click to view full size image

source
with an average annual variance of about 6ppm

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source
While the trend of CO2 increase is well established and measured, there is no direct or indirect correlation between the levels of the demonized gas proported to be responsible for global climate change (global warming) and positive or negative trends in the Arctic Oscillation pattern

Click to view full size image

source

[Chris Peterson]

But models have been wrong many times before as they are only models, simulations, probabilities.
While "Models" may support a certain point of view (it is with this point of view in mind that they are written and rewritten) the lack of direct correlation between the AO and the supposed source of AGW (CO2) is clear in the real world.

I would argue that you completely and totally misunderstand what a model is. They are not written from some "point of view". They are simply numerical simulations of interacting physical systems- with those systems described by generally well understood physics.

In climatology, most models developed in the last twenty years appear to have been largely accurate. I think there is little doubt that models now in use are highly predictive and very useful for understanding things like how arctic sea surface temperature modulates the Arctic Oscillation. (Nobody is trying to connect atmospheric CO2 levels directly to the Arctic Oscillation; CO2 levels are definitively implicated in global warming, and global warming is definitively implicated in rising sea surface temperatures, so there's a connection... but hardly something that would make sense to consider quantitatively.)

[bystander]

Satellites See Unprecedented Greenland Ice Sheet Surface Melt
NASA Science News | JPL-Caltech | GSFC | 2012 July 24

[img3="Extent of surface melt over Greenland's ice sheet on July 8, 2012 (left) and July 12, 2012 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as "probable melt" (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as "melt" (dark pink) correspond to sites where two or three satellites detected surface melting. (Image credit: Jesse Allen (NASA Earth Observatory) and Nicolo E. DiGirolamo (SSAI/GSFC/Cryospheric Sciences Laboratory))"]http://www.nasa.gov/images/content/6703 ... 94-673.jpg[/img3]

---

For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

"The Greenland ice sheet is a vast area with a varied history of change. This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story," said Tom Wagner, NASA's cryosphere program manager in Washington. "Satellite observations are helping us understand how events like these may relate to one another as well as to the broader climate system."

Son Nghiem of NASA's Jet Propulsion Laboratory in Pasadena, Calif., was analyzing radar data from the Indian Space Research Organisation's (ISRO) Oceansat-2 satellite last week when he noticed that most of Greenland appeared to have undergone surface melting on July 12. Nghiem said, "This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?"

Nghiem consulted with Dorothy Hall at NASA's Goddard Space Flight Center in Greenbelt, Md. Hall studies the surface temperature of Greenland using the Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites. She confirmed that MODIS showed unusually high temperatures and that melt was extensive over the ice sheet surface.

Thomas Mote, a climatologist at the University of Georgia, Athens, Ga; and Marco Tedesco of City University of New York also confirmed the melt seen by Oceansat-2 and MODIS with passive-microwave satellite data from the Special Sensor Microwave Imager/Sounder on a U.S. Air Force meteorological satellite.

The melting spread quickly. Melt maps derived from the three satellites showed that on July 8, about 40 percent of the ice sheet's surface had melted. By July 12, 97 percent had melted.

This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May. "Each successive ridge has been stronger than the previous one," said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate.

Even the area around Summit Station in central Greenland, which at 2 miles above sea level is near the highest point of the ice sheet, showed signs of melting. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores analyzed by Kaitlin Keegan at Dartmouth College in Hanover, N.H. A National Oceanic and Atmospheric Administration weather station at Summit confirmed air temperatures hovered above or within a degree of freezing for several hours July 11-12.

"Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. "But if we continue to observe melting events like this in upcoming years, it will be worrisome."

Satellites Observe Widespread Melting Event on Greenland
NASA Earth Observatory | 2012 July 24

Greenland seeing unprecedented melting
Discover Blogs | Bad Astronomy | 2012 July 24

[bystander]

Closeup of the Ice Island from Petermann Glacier
NASA Earth Observatory | 2012 July 23

[i]Credit: Jesse Allen and Robert Simmon[/i]

---

In July 2012, a massive ice island broke free of the Petermann Glacier in northwestern Greenland. On July 16, the giant iceberg could be seen drifting down the fjord, away from the floating ice tongue from which it calved.

On July 21, 2012, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite captured this image of the iceberg’s continuing journey. This image has been rotated and north is toward the right. This detailed image reveals that the iceberg covers an area of about 32.3 square kilometers (12.5 square miles).

ASTER combines infrared, red, and green wavelengths of light to make false-color images that help to distinguish between water and land. Water is blue, ice and snow vary in color from pale blue to white, and land areas appear brick red and brown. Clouds in the scene cast dark shadows onto the iceberg surface. Similar surface cracks appear on both the Petermann Glacier and the newly formed ice island.

Nearly two years ago in July 2010, another large iceberg calved from the Petermann Glacier. That iceberg was estimated at roughly 97 square miles (251 square kilometers). This latest calving occurred farther upstream on the Petermann, but nevertheless occurred along a rift that appeared in satellite imagery in 2001.

Ted Scambos of the National Snow and Ice Data Center observed melt ponds on the iceberg surface, but stated that the Petermann calving was likely associated with ocean currents rather than surface melt.

Greenland Glacier Calves Another Huge Ice Island
Universe Today | Jason Major | 2012 July 24

Huge glacier calves off Greenland
Discover Blogs | Bad Astronomy | 2012 July 19

More Ice Breaks off of Petermann Glacier
NASA Earth Observatory | 2012 July 17

[neufer]

http://asterisk.apod.com/viewtopic.php? ... 29#p179929

[neufer]

[img3="Plankton from equatorial waters found in the Arctic Ocean in 2010,
from left to right: Dictyocoryne truncatum & Didymocyrtis tetrathalamus.

(Frank Costanza: "How can I go on a cruise with out my cabana wear?")
"]http://www.csmonitor.com/var/ezflow_sit ... ll_600.jpg[/img3]

What is subtropical plankton doing in Arctic waters?
C.S. Monitor LiveScience Staff / July 25, 2012

<<Samples of plankton collected in the Arctic Ocean near Norway revealed something surprising: single-celled creatures that belonged thousands of miles to the south where the conditions are balmier.

This may sound like a story about the surprising effects of global warming, but it isn't. At least not entirely. That's because the researchers believe these warm-water invaders, called Radiolaria, are likely the result of an isolated pulse of water that carried them beyond the usual extent of the northbound Gulf Stream, a current that travels from the Gulf of Mexico into the northern Atlantic Ocean. Radiolaria have ornate, glassy shells, and they eat algae and other microscopic organisms. Different species live in different temperature ranges. [Spectacular Photos of Sea Creatures]

In 2010, a ship operated by the Norwegian Polar Institute collected plankton samples northwest of the Norwegian archipelago of Svalbard in the Arctic Ocean. Of the 145 types of organisms in these samples, 98 came from farther south, as far as the tropics. The discovery of living organisms like these in the northern waters was unprecedented, but the quirk in ocean circulation that scientists believe carried them this far north is not. Pulses of warm water have reached along the Norwegian coast and into the Arctic basin several times in the 20th century. What's more fossil evidence suggests warm-water plankton may have become temporarily established in the Arctic multiple times during past millennia. "This doesn't happen continuously — but it happens," lead researcher Kjell Bjørklund, of the University of Oslo Natural History Museum, said in a statement.

While researchers don't think this particular incursion is the direct result of global warming, ocean scientists generally expect changes in ocean circulation to bring more southern water, and the organisms it contains, farther north. For instance, warming is expected to weaken a current, the North Atlantic Polar Gyre, that prevents the Gulf Stream from penetrating farther north. Changing wind patterns and the influx of freshwater from melting sea ice and glaciers could also result in more southern water being drawn north, said Arnold Gordon, head of Lamont-Doherty Earth Observatory's division of ocean and climate physics at Columbia University, in a statement. Gordon was not involved in this research. "When we suddenly find tropical plankton in the Arctic, the issue of global warming comes right up," study researcher O. Roger Anderson, a specialist in one-celled organisms at Lamont-Doherty, said in a statement. So, it's important to critically examine evidence that may explain observations like this one, Anderson said. A description of the radiolaria discovery appears in the July issue of the journal Micropaleontology.>>

[BMAONE23]

Satellites See Unprecedented Greenland Ice Sheet Surface Melt
NASA Science News | JPL-Caltech | GSFC | 2012 July 24

[img3="Extent of surface melt over Greenland's ice sheet on July 8, 2012 (left) and July 12, 2012 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as "probable melt" (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as "melt" (dark pink) correspond to sites where two or three satellites detected surface melting. (Image credit: Jesse Allen (NASA Earth Observatory) and Nicolo E. DiGirolamo (SSAI/GSFC/Cryospheric Sciences Laboratory))"]http://www.nasa.gov/images/content/6703 ... 94-673.jpg[/img3]

---

For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

"The Greenland ice sheet is a vast area with a varied history of change. This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story," said Tom Wagner, NASA's cryosphere program manager in Washington. "Satellite observations are helping us understand how events like these may relate to one another as well as to the broader climate system."

Son Nghiem of NASA's Jet Propulsion Laboratory in Pasadena, Calif., was analyzing radar data from the Indian Space Research Organisation's (ISRO) Oceansat-2 satellite last week when he noticed that most of Greenland appeared to have undergone surface melting on July 12. Nghiem said, "This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?"

Nghiem consulted with Dorothy Hall at NASA's Goddard Space Flight Center in Greenbelt, Md. Hall studies the surface temperature of Greenland using the Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites. She confirmed that MODIS showed unusually high temperatures and that melt was extensive over the ice sheet surface.

Thomas Mote, a climatologist at the University of Georgia, Athens, Ga; and Marco Tedesco of City University of New York also confirmed the melt seen by Oceansat-2 and MODIS with passive-microwave satellite data from the Special Sensor Microwave Imager/Sounder on a U.S. Air Force meteorological satellite.

The melting spread quickly. Melt maps derived from the three satellites showed that on July 8, about 40 percent of the ice sheet's surface had melted. By July 12, 97 percent had melted.

This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May. "Each successive ridge has been stronger than the previous one," said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate.

Even the area around Summit Station in central Greenland, which at 2 miles above sea level is near the highest point of the ice sheet, showed signs of melting. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores analyzed by Kaitlin Keegan at Dartmouth College in Hanover, N.H. A National Oceanic and Atmospheric Administration weather station at Summit confirmed air temperatures hovered above or within a degree of freezing for several hours July 11-12.

"Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. "But if we continue to observe melting events like this in upcoming years, it will be worrisome."

Satellites Observe Widespread Melting Event on Greenland
NASA Earth Observatory | 2012 July 24

Greenland seeing unprecedented melting
Discover Blogs | Bad Astronomy | 2012 July 24

Interesting but is it really unprecedented?

un·prec·e·dent·ed    [uhn-pres-i-den-tid]

adjective
without previous instance; never before known or experienced; unexampled or unparalleled:

The article itself states

Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data.

If it happens about once every 150 years or so and last in 1889 (123 years ago) like Goddard Geologist Lora Koenig stated then it can't really be unprecedented

[Beyond]

I think the "unprecedented" refers to the fact that they've never -seen- such a fast melt before. The last one happened too long ago for any eye-witnesses to still be around. So even though it's sort of a scheduled happening, it's the first time anyone now-a-days has seen it. Therefore it is unprecedented.

[BMAONE23]

Given that no one lives for 150 years, it could likely always be viewed as unprecedented provided it happens on a similar timescale in 2140-2160
According to this paper titled Analysis of Ice Layers in the NEEM Firn Column

(snip)physical properties of the firn have been analyzed. In the 81m of analyzed firn core, two regions containing ice layers were identified at depths of 29m and 46m. Isotopic analysis provides a depth-age scale that dates these layers to be from 1935 and 1879, respectively. These years were in the two warmest decades of the instrumental temperature record for Greenland.

The 1879 date is closer to the 150 year periodic surface melting events than the 1889 date mentioned in the quoted article

[bystander]

I think the reason for "unprecedented" can be found in the first two paragraphs:

For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.