Arctic Sea Ice

[sinimod]

Here is a nice set of maps from Climate HQ comparing the extent of multi-year ice in the Arctic Ocean from 1988 to 2010. The decline is very striking. There is, of course, a pronounced vulnerability of young ice to climate variation. If, for example, warm winds persist accompanying a prolonged summer Arctic Dipole Anomaly, it is possible that in the coming years most, or even all young ice could melt leaving only a strip of multi-year ice. Once the multi-year ice is gone, an ice-free summer Arctic Ocean is possible, something climatologists and oceanographers were not predicting until some time between 2040 and 2050. Now there is a likelihood of that happening before 2020.

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http://www.nasa.gov/topics/earth/fea...aice-melt.html

NASA Study Quantifies Role of Melt in Loss of Old Arctic Sea Ice Nov 9 2010
Since the start of the satellite record in 1979, scientists have observed the continued disappearance of older "multiyear" sea ice that survives more than one summer melt season. Some scientists suspected that this loss was due entirely to wind pushing the ice out of the Arctic Basin -- a process that scientists refer to as "export." In this study, Ron Kwok and Glenn Cunningham at NASA's Jet Propulsion Laboratory in Pasadena, Calif., used a suite of satellite data to clarify the relative role of export versus melt within the Arctic Ocean.

Kwok and Cunningham show that between 1993 and 2009, a significant amount of multiyear ice -- 1,400 cubic kilometers (336 cubic miles -- was lost due to melt, not export.

...Kwok said. "The story is always more complicated -- there is melt as well as export -- but this is a another step in calculating the mass and area balance of the Arctic ice cover."

But multiyear ice that survives more than one season has also been declining, as noted in previous work by Joey Comiso of NASA's Goddard Space Flight Center in Greenbelt, Md., who shows a loss of about 10 percent per decade since the beginning of the satellite record in 1979. Scientists want to know where this loss is occurring.

Not all of the multiyear ice loss is accounted for, however. Ice loss through Fram Strait and from melt from 2005 to 2008 accounts for just 52 percent of total ice loss. The team suggests that melt in other Arctic regions and outflow through other passages besides Fram Strait could account for the difference.

Ice extent, The latest value : 9,473,438 km2 (November 21, 2010) JAXA
Almost a record low for this date. Particularly noticable is Hudson Bay

http://blog.nwf.org/wildlifepromise/...y-polar-bears/

As we reported yesterday, Hudson Bay polar bears are eagerly awaiting the sea ice to freeze up so they can break their fast, return to the ice and start hunting for seals, their primary food source. Historically, Hudson Bay should have ice by now and the bears should be long gone. However, climate change is causing dramatic declines in sea ice. As a result, these bears are stuck on land, living off their fat reserves, and waiting. For some, the longer wait could mean starvation and death.

A little late
http://nsidc.org/arcticseaicenews/index.html
From Nov 2

Even with the rapid ice growth at the beginning of the month, October 2010 had the third-lowest ice extent for the month in the satellite record. The linear trend for October steepened slightly from -5.9% per decade to -6.2% per decade.

The Freezups used to make everything look normal for a while, this does not appear to true any longer. Even Autumn does not look good.

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http://psc.apl.washington.edu/zhang/...10GL044988.pdf
Arctic sea ice response to atmospheric forcings with varying levels
of anthropogenic warming and climate variability
Jinlun Zhang, Michael Steele, and Axel Schweiger

Numerical experiments are conducted to project arctic sea ice responses to varying levels of future anthropogenic warming and climate variability over 2010–2050. A summer ice‐free Arctic Ocean is likely by the mid‐2040s if arctic surface air temperature (SAT) increases 4°C by 2050 and climate variability is similar to the past relatively warm two decades. If such a SAT increase is reduced by one‐half or if a future Arctic experiences a range of SAT fluctuation similar to the past five decades, a summer ice‐free Arctic
Ocean would be unlikely before 2050

When I first read 2050 as the date of ice free summers I was thinking what planet are they on. But they do have a point, there is a significant difference between an ice free moment, an ice free September, ice free all summer for a summer, and ice free all summer every summer. What they are saying is not that the Arctic will not have an ice free moment before 2050 but that not every summer will be ice free before 2050.

It is entirely possible some remnant ice will hang around a lot longer than the rest of the sea ice. It is entirely possible a few cold winters and summers will see sea ice into summer long after we are used to seeing ice free summers.

We have now got to the stage where what we mean by ice free must be clearly defined.

A reliable, commercially navigable, Arctic Sea in summer is not far away. How will the increase in maritime traffic affect the models?

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http://nsidc.org/arcticseaicenews/index.html
December 6, 2010
Slow ice growth leads to low November ice extent

Arctic sea ice extent averaged over November 2010 was 9.89 million square kilometers (3.82 million square miles). This is the second-lowest November ice extent recorded over the period of satellite observations from 1979 to 2010, 50,000 square kilometers (19,300 square miles) above the previous record low of 9.84 million square kilometers (3.80 million square miles) set in 2006.

Ice extent was unusually low in both the Atlantic and Pacific sectors of the Arctic and in Hudson Bay. Typically by the end of November, nearly half of Hudson Bay has iced over. But on November 30, only 17% of the bay was covered by sea ice. Compared to the 1979 to 2000 average, the ice extent was 12.4% below average for the Arctic as a whole.

The linear rate of decline for the month is –4.7 % per decade.

Recent research from scientists at the NASA Jet Propulsion Laboratory shows that summer melt of old, thick ice in the Beaufort Sea has contributed substantially to the overall loss of thick multiyear ice in the Arctic. Using data from the QuikSCAT satellite, researchers Ron Kwok and Glenn Cunningham found that the Beaufort Sea lost 947,000 square kilometers (366,000 square miles) of multiyear ice during the summers of 1993 to 2009.

The study also showed that multiyear ice loss increased in the last few years. From 2005 to 2008, the Beaufort Sea lost 490,000 square kilometers (189,000 square miles) of multiyear ice, 32% of the total loss of multiyear ice in the Arctic Ocean during that time period.

Many animals in the Arctic depend on the sea ice cover. A new study by researchers from the University of Virginia and NOAA suggests that seals and walrus rely on certain types of sea ice, called seascapes, for resting and reproduction. The character of these seascapes depends on local and regional weather and ocean conditions, and is changing in conjunction with the long-term downward trend in sea ice extent, cover, and structure.

Just the interesting bits was almost the whole page. It is fairly clear that we are seeing a non linear response from the ice.
http://arctic.atmos.uiuc.edu/cryosph...region.13.html
Hudson Bay
Cryosphere Today shows the last 12 months ice area and anomalies, you can see the earlier melt and later freeze most clearly on the anomalies chart.

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The latest value : 11,382,813 km2 (December 21, 2010)

Another record low for date

The freeze up of Hudson Bay has temporarily stalled
http://arctic.atmos.uiuc.edu/cryosph...region.13.html

Hudson Bay is an interesting case study earlier thaw, later freeze up. By now it should be almost totally frozen. The saw tooth pattern is becoming sinal at the top of the freeze.

A comment from Climate Progress on last weeks article in Nature.
http://climateprogress.org/2010/12/2...e-cover-story/

Joe Romm is more pessimistic than Nature, I am more pessimistic than Joe.
As I see it the fate of the summer sea ice is pretty much sealed already.

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The latest value : 11,614,063 km2 (December 27, 2010) JAXA

Lowest ever for date, by a significant margin.
Where has all the cold gone? NY!

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The latest value : 12,243,594 km2 (January 4, 2011) JAXA extent
Still a record low for date.

Hudson Bay: still not completely frozen.

http://nsidc.org/arcticseaicenews/index.html
January 5, 2011
Repeat of a negative Arctic Oscillation leads to warm Arctic, low sea ice extent

Arctic sea ice extent averaged over December 2010 was 12.00 million square kilometers (4.63 million square miles). This is the lowest December ice extent recorded in satellite observations from 1979 to 2010, 270,000 square kilometers (104,000 square miles) below the previous record low of 12.27 million square kilometers (4.74 million square miles) set in 2006 and 1.35 million square kilometers (521,000 square miles) below the 1979 to 2000 average.

The warm temperatures in December came from two sources: unfrozen areas of the ocean continued to release heat to the atmosphere, and an unusual circulation pattern brought warm air into the Arctic from the south. Although the air temperatures were still below freezing on average, the additional ocean and atmospheric heat slowed ice growth.

A note on Antarctica

While sea ice is growing in the Arctic, it is early summer in the Antarctic and sea ice is melting. For the past four months, Antarctic sea ice extent has remained well above average. The high ice extent around Antarctica appears to relate to a persistently positive phase of the Southern Annular Mode—an Antarctic counterpart to the Arctic Oscillation—and to the mild La Niña conditions in the Pacific. In December 2010, the monthly mean Southern Annular Mode index was lower, and Antarctic sea ice extent had dropped back to within about standard deviation of the mean.

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The latest value : 12,362,031 km2 (January 11, 2011) JAXA

Still the lowest ever for date. Hudson Bay is still not frozen over.
The freeze up is not supposed to be interesting, but it is.

(Now the Arctic's missing cold has gone down as far as Atlanta, wont be long before we have snow in Pensacola)

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http://arctic.atmos.uiuc.edu/cryosph...region.13.html

Hudson Bay ice area is a little over 1 million sq kilometers, about 200,000 sq km less than the 1979-2008 mean. The freeze up is awful late, late to freeze will probably mean early to thaw, subject to that Arctic Dipole.

The latest JAXA
The latest value : 12,741,719 km2 (January 21, 2011)
No longer the lowest for date.

The next few months could be interesting. Said that before haven't I, but never this early.

Next to watch: The Barents Sea, the period of "almost ice free" next summer plus spring and autumn. (Prediction: more than 4 months with less than 10%) The Kara Sea has an area of about 850,000 sq km expect 3 months to have less than 50,000 sq km. Laptev: 6 weeks at about 10%.

Anyone else want to look the fool next September?

Skeptical Science has a piece also
http://www.skepticalscience.com/Monc...l-Sea-Ice.html

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http://climateprogress.org/2011/01/2...lobal-warming/
The year the sea forgot to freeze
Climate Progress has a blog on the slow freeze up

Surface temperature anomalies for the period 17 December 2010 to 15 January 2011 show impressive warmth across the Canadian Arctic….

The largest anomalies here exceed 21°C (37.8°F) above average, which are very large values to be sustained for an entire month.

and the comments at Nevin's are very informative
http://neven1.typepad.com/blog/2011/...-thread-4.html

Fings is diff'ent. And more people are noticing.

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http://rabett.blogspot.com/2011/01/w...neer-drop.html

Today, NCAR reports on how northern Canada is enjoying a balmy winter, and the ice freeze is way behind schedule, but, dear bunnies, we all know that the global ice cover is very high because of the large ice pack around the Antarctic, or, as the images below from 2003 and 2011 show, maybe not.

Prof Rabett has noticed too.

In the comments

Not looking good for the seal pupping season along the Labrador coast. Dead seals already washing up.

http://www.cbc.ca/canada/newfoundlan...seals-117.html

The NCAR link Eli provided
http://www2.ucar.edu/currents/cold-c...shing-mildness

JAXA Arctic Sea Ice Extent-The latest value : 12,847,813 km2 (January 24, 2011) Second lowest for date.

And a bit from Skeptical Sciece on the albedo effect
http://www.skepticalscience.com/Flanner2011.html

Perhaps the first snow and ice melted more quickly than expected and eventually we’ll run out of the easy to melt bits, or maybe the decline in Arctic sea ice will halt for ~30 years to bring it back in line with models. However, if the current pattern holds then this would boost the best estimate of global warming temperature rises by about 20% - here’s hoping it’s just a blip!

[sinimod]

Warming North Atlantic Water Tied to Heating Arctic

Led by Robert Spielhagen of the Academy of Sciences, Humanities and Literature in Mainz, Germany, the study showed that water from the Fram Strait that runs between Greenland and Svalbard -- an archipelago constituting the northernmost part of Norway -- has warmed roughly 3.5 degrees Fahrenheit in the past century. The Fram Strait water temperatures today are about 2.5 degrees F warmer than during the Medieval Warm Period, which heated the North Atlantic from roughly 900 to 1300 and affected the climate in Northern Europe and northern North America.

"We know that the Arctic is the most sensitive region on the Earth when it comes to warming, but there has been some question about how unusual the current Arctic warming is compared to the natural variability of the last thousand years," said Marchitto, also an associate professor in CU-Boulder's geological sciences department. "We found that modern Fram Strait water temperatures are well outside the natural bounds."

The rate of Arctic sea ice decline appears to be accelerating due to positive feedbacks between the ice, the Arctic Ocean and the atmosphere, Marchitto said. As Arctic temperatures rise, summer ice cover declines, more solar heat is absorbed by the ocean and additional ice melts. Warmer water may delay freezing in the fall, leading to thinner ice cover in winter and spring, making the sea ice more vulnerable to melting during the next summer.

Air temperatures in Greenland have risen roughly 7 degrees F in the past several decades, thought to be due primarily to an increase in Earth's greenhouse gases, according to CU-Boulder scientists.

"We must assume that the accelerated decrease of the Arctic sea ice cover and the warming of the ocean and atmosphere of the Arctic measured in recent decades are in part related to an increased heat transfer from the Atlantic," said Spielhagen.

[sinimod]

Polyak et al., 2010 published the highly informative article “History of sea ice in the Arctic” last year in Quaternary Science Reviews. Numerous facts and projections about the Arctic sea ice were included in their article. Leonid Polyak, a research scientist at Byrd Polar Research Center at Ohio State University and lead author of a study completing the first comprehensive history of Arctic ice has been quoted by Science Daily as saying

The ice loss that we see today -- the ice loss that started in the early 20th Century and sped up during the last 30 years -- appears to be unmatched over at least the last few thousand years

.
Below are some observations from the introduction and background sections of the article, mostly from work by other researchers (with links provided):

A reduction of sea ice promotes strong arctic warming through the ice-albedo feedback mechanism, probably influencing weather systems beyond the Arctic (Francis et al., 2009).

Changes in ice cover and freshwater flux out of the Arctic Ocean may also affect circulation in the North Atlantic, which has profound influence on climate in Northern Europe and North America (Segar et al., 2002; Holland et al., 2006).

Continued ice retreat will accelerate coastal erosion from increased wave action (Jones et al., 2009), and will have cascading effects on the Arctic Ocean food web including top predators, such as polar bears and seals (Derocher et al., 2004; Durner et al., 2009).

Recent years have witnessed the intrusion of exotic planktonic biota into the high Arctic (Hegseth and Sundfjord, 2008).

Reduced ice allows enhanced marine access to the Arctic Ocean providing opportunities for commercial shipping and natural-resource exploitation.

Arctic sea ice attains its maximum seasonal extent in March and minimum extent in September.

For the period of reliable satellite observations (1979 onwards), extremes in Northern Hemisphere ice extent, defined as the ocean region with at least 15% ice cover, are 16.44 x 10^6 km^2 for March 1979, and 4.28 x 10^6 km^2 for September 2007 (Stroeve et al., 2008).

The ice cover can be broadly divided into a perennial ice zone, where ice is present throughout the year, and a seasonal ice zone, where ice is present only seasonally (Weeks and Ackley, 1986; Wadhams, 2000). A considerable fraction of Arctic sea ice is perennial, which differs strongly from Antarctic sea ice, which is nearly all seasonal.

Ice concentrations in the perennial ice zone typically exceed 97% in winter but fall to 85-95% in summer. Sea-ice concentrations in the seasonal ice zone are highly variable, and in general (but not always) decrease toward the southern sea-ice margin.

Thickness of sea ice, which varies markedly in both time and space, can be described by a probability distribution. The peak of this distribution for the Arctic Ocean as a whole is about 3 meters (Williams et al., 1975; Wadhams, 1980), but there is growing evidence that shrinking ice extent over recent decades has been attended by substantial thinning.

Although there are many different types of sea ice, the two basic categories are: (1) first-year ice, which represents a single year’s growth, and (2) multi-year ice, which has survived one or more melt seasons (Weeks and Ackley, 1986).

New ice forms during autumn in seasonally open water, mostly over continental shelves, and is then transported into the central Arctic basin, and can thicken through bottom growth. Undeformed first-year ice can reach as much as 1.5-2 m in thickness. Although multi-year ice is generally thicker, first-year ice that undergoes convergence and/or shear can produce ridges as thick as 20-30 m.

Under the influence of wind and ocean currents, the Arctic sea-ice cover is in nearly constant motion. The large-scale circulation mainly consists of the Beaufort Gyre in the western Arctic Ocean, and the Transpolar Drift, the movement of ice from the coast of Siberia eastward across the pole and into the North Atlantic by way of the Fram Strait. About 20% of the total ice area of the Arctic Ocean and nearly all of the annual ice export is discharged each year through the Fram Strait, the majority of which is multi-year ice.

The composite historical record of Arctic ice margins shows a general retreat of both seasonal and annual ice during the last 5 decades (Kinnard et al., 2008), with the most reliable observations since 1979 onwards corresponding to the satellite era. The overall trend of ice retreat is clearly larger than decadal-scale variability.

The severity of present ice loss can be highlighted by the breakup of ice shelves at the northern coast of Ellesmere Island (Mueller et al., 2008), which have been stable until recently for at least several thousand years based on geological data (England et al., 2008).

On the basis of satellite records, negative trends in sea-ice extent encompass all months, with the strongest trend in September, which, according to the NSIDC has had a decline rate of 11% per decade.

Many factors have contributed to this sea-ice loss (Serreze et al., 2007), such as general Arctic warming (Rothrock and Zhang, 2005), extended summer melt season (Stroeve et al., 2006), and the effects of the changing phase of large-scale atmospheric patterns such as the Northern Annular Mode and the Dipole Anomaly (Wang et al., 2009). These atmospheric forcings have flushed some thicker multi-year ice out of the Arctic and left thinner first-year ice that is more easily melted out in summer (Rigor and Wallace, 2004; Rothrock and Zhang, 2005; Maslanik et al., 2007), changed ocean heat transport (Polyakov et al., 2005; Shimada et al., 2006), and increased recent spring cloud cover that augments long-wave radiation flux to the surface (Francis and Hunter, 2006).

An ice-tracking algorithm applied to satellite and buoy data suggest that the amount of the oldest and thickest ice within the multi-year pack has declined significantly (Maslanik et al., 2007). The area of the Arctic Ocean covered by predominantly older ice (5 or more years old) decreased by 56% between 1982 and 2007. Within the central Arctic Ocean the coverage of old ice has declined by 88% and ice that is at least 9 years old has essentially disappeared.

The decrease in mean thickness for the Arctic has been from 2.6 m in March 1987 to 2.0 m in 2007 (Maslanik et al., 2007).

Natural variability has contributed to the trend, but evidence is strong that greenhouse gas forcing has played a major role (Stroeve et al., 2007).

And from the article summary a conclusion drawn from reviewed geological data indicate that the history of Arctic sea ice is closely linked with climate changes driven primarily by greenhouse and orbital forcings and associated feedbacks.

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JAXA sea ice extent: The latest value : 13,372,344 km2 (February 3, 2011)
For a few weeks it has not been lowest for date, still very low historically.

NSIDC Monthly report came out a few days ago
http://nsidc.org/arcticseaicenews/index.html
Arctic Oscillation brings record low January extent, unusual mid-latitude weather

Arctic sea ice extent averaged over January 2011 was 13.55 million square kilometers (5.23 million square miles). This was the lowest January ice extent recorded since satellite records began in 1979. It was 50,000 square kilometers (19,300 square miles) below the record low of 13.60 million square kilometers (5.25 million square miles), set in 2006, and 1.27 million square kilometers (490,000 square miles) below the 1979 to 2000 average.

January 2011 had the lowest ice extent for the month since the beginning of satellite records. The linear rate of decline for the month is –3.3% per decade.

While the Arctic has been warm, cold and stormy weather has affected much of the Northeast U.S. and Europe. Last winter also paired an anomalously warm Arctic with cold and snowy weather for the eastern U.S. and northern Europe. Is there a connection?

The new normal?

[sinimod]

In the January 28 issue of Science Magazine, Spielhagen et al. published the paper Enhanced Modern Heat Transfer to the Arctic by Warm Atlantic Water. In their study, which presented a multidecadal-scale record of ocean temperature variations during the past 2000 years, they find “that early-21-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.”

According to an article entitled Recent Warming Reverses Long-Term Arctic Cooling by Kaufman et al., 2009, proxy temperature records from poleward of 60° N indicate pervasive cooling in the Arctic from 2000 years ago, through the Medieval Climate Anomaly, the Little Ice Age, and into the Industrial Revolution. Arctic waters experienced this cooling trend until the recent reversal evidenced by rising air temperatures and a decline of the sea ice cover. This cooling trend reversed during the 20th century, with 4 of the 5 warmest decades of their 2000-year reconstruction occurring between 1950 and 2000.

The warming in the 20th Century contrasts sharply with the preceding cooling trend (the Kaufman et al., 2009 study covered from 2000 years ago to the present), which if projected into the 20th century, Arctic summers would have been expected to be -0.5° C cooler than the average temperature for the years 1961-1990. This cooling corresponds to the slow reduction in summer insolation at high latitudes, in turn corresponding to the slow decrease in the earth’s tilt relative to the plane of the orbit of the earth around the sun. Today the tilt is 23.5° and slowly “straightening up,” and should reach its minimum tilt of about 22° in 8,000 years. The less the tilt, the less summer heating the high latitudes get, thus increasing the chances of northern ice surviving during the summer. If ice survives the summer, then ice sheets can build up, possibly advancing southward and causing another ice age.

In addition, the current eccentricity of the earth’s orbit around the sun is only about 1.7%, so the its insolation effect is quite small. The eccentricity of the earth’s orbit around the sun varies from nearly zero to almost 6%. The eccentricity of earth’s orbit is currently increasing, thus nudging earth toward building ice sheets in the northern hemisphere. Therefore, both the obliquity and eccentricity insolation effects are pushing earth toward the next natural ice age.

So, to summarize, we should be heading into another ice age, but that process has been interrupted by anthropogenic global warming.

Water from the Atlantic Ocean moves into the Arctic Ocean through the Fram Strait. Spielhagen et al. investigated planktic foraminifers in a sediment core from western Svalbard continental margin, strategically situated in the path of Atlantic Water inflow to the Arctic Ocean. Two methods of temperature reconstruction were implemented: one using the SIMMAX modern analog technique applied on planktic foraminifer species counts to calculate temperatures at 50-m water depth, and the other using Mg/Ca measurements on the species Neogloboquadrina pachyderma (sinistral).

In sediments in the core dated before 100 years ago, 10 to 40% of all planktic foraminifers were subpolar species. However, in the youngest sediments reflecting the past ~100 years, there has been a steep increase in subpolar species and an unprecedented inversion of the subpolar/polar species ratio, reaching 66% subpolar specimens in the surface sample. The high percentage of subpolar species indicates a strongly increased influence of warm Atlantic water moving laterally from the Norwegian Sea.

Results from the SIMMAX and the Mg/Ca measurements allowed for the quantification of temperatures for the last 2000 years. Both methods reveal a warming of approximately 2° C in the uppermost Atlantic waters of the Fram Strait (Arctic Gateway) since about 120 years ago over the highest temperatures of the preceding 2000 years.

Along with the increased heat influx from the Bering Strait, the inflow of warm water from the Atlantic has increased the melt season for Arctic sea ice, aided in the warming of the atmosphere above the Arctic Ocean, and helped cause the atmospheric circulation patterns in the Arctic to change, engendering the meridional flow the Arctic Dipole anomaly (Overland and Wang, 2010) to form, which provides positive feedback for melting Arctic ice. Overland et al., 2010 explain that the recent increased sea ice mobility, loss of multi-year sea ice, and extended open water areas at the end of summer lead to enhanced heat storage in newly sea-ice-free ocean areas, which is in turn released to the atmosphere in the following autumn. As he described in discussion in Jeff Masters’ Wunderblog

the Arctic is normally dominated by low pressure in winter, and a “Polar Vortex” of counter-clockwise circulating winds develops surrounding the North Pole. However, during the winter of 2009-2010, high pressure replaced low pressure over the Arctic, and the Polar Vortex weakened and even reversed at times, with a clockwise flow of air replacing the usual counter-clockwise flow of air around the pole. This unusual flow pattern allowed cold air to spill southwards and be replaced by warm air moving poleward. This pattern is kind of like leaving the refrigerator door ajar--the refrigerator warms up, but all of the cold air spills out into the house.

This pattern has caused a decrease in the pressure differential between the Icelandic Low and Azores High (North Atlantic Oscillation or NAO). A positive NAO leads to increased westerly winds and mild and wet winters in Europe. Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America more readily. Negative NAO winters tend to bring cold winters to Europe and the U.S. East Coast, but leads to very warm conditions in the Arctic, since all the cold air spilling out of the Arctic gets replaced by warm air flowing poleward. (Wunderblog).

What all of this suggests to me is that after a century of an increasingly intense reversal of the natural state of orbitally-induced Arctic temperature decline, the Arctic polar vortex is becoming increasingly unstable, and may be edging toward a climate regime shift in which the Arctic Dipole becomes the norm. Initially, the regime shift will result in what we have been seeing the last couple of years, an increased likelihood of extremely negative NAO values with warm Arctic winters and cold North American, European, and east Asian winters. But I believe that as the earth continues to warm due to the energy imbalance caused by increased greenhouse gases, the warming trend in mid-latitude Northern Hemisphere winters will be re-established in these areas.

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http://nsidc.org/arcticseaicenews/index.html
March 2, 2011
February Arctic ice extent ties 2005 for record low; extensive snow cover persists

Sea ice extent averaged over the month of February 2011 was 14.36 million square kilometers (5.54 million square miles). This was a tie with the previous record low for the month, set in 2005. February ice extent remained below normal in both the Atlantic and Pacific sectors, particularly in the Labrador Sea and the Gulf of St. Lawrence.

...the February trend is now at -3.0 percent per decade.

This winter also saw a relatively strong negative AO index during December and January. However, as we discussed in our January 5, 2011 post, the positive sea level pressure anomalies were centered near Iceland. This led to a more extensive anticyclonic (clockwise) transport pattern than last winter. This may help keep a more extensive distribution of multiyear ice cover as summer approaches.

SNOW

Sea ice extent is only one of a number of data sets scientists use to understand how climate is changing. Rutgers University and NOAA have compiled a 45-year record of Northern Hemisphere snow cover extent from NOAA snow charts. These data show that much of northern North America, Scandinavia and northern Eurasia are snow covered between 90 and 100 percent of the time in January and February. High elevation plains and mountains at lower latitudes, such as the southern Rocky Mountains in the U.S. and Hindu Kush in Asia, also have extensive snow cover.

An interesting historical perspective
http://www.science20.com/chatter_box...cientist-76675

... those infinite Islands of ice were ingendred and congealed in time of Winter, and now by the great heat of Summer were thawed, and then by ebs, flouds, winds, and currents, were driuen to and fro, and troubled the fleet; so that this is an argument to proue the heat in Summer there to be great, that was able to thaw so monstrous mountaines of ice.

It is clear that Best broadly understood that sea ice advance in winter and retreat in summer is only possible due to the great heat input during polar summers and the loss of that heat during polar winters.

http://www.science20.com/chatter_box...#comment-61283

The main reason for that so few people ever have visited this land (east coast) is that 90% of the pack ice in the north pole basin have its outlet to the open sea here. This means that there is a hundreds of miles wide barrier of continuos slowly southwards drifting multi-year pack ice present here near all year around. The ice barrier stretches along all of Greenlands east coast except for 2-3 months in late summer and autumn when only the southeastern part is ice free.
The barrier have for all times before 1800 century prevented any ship to reach the coast of North East Greenland.

Per Michelsen

A little different nowdays

[sinimod]

I decided to post this where I meant to post it in the first place. (I accidentally posted this in the sea level rise thread. It belongs here where it would be expected. I guess it doesn't hurt to post it twice.)

Shifting spring: Arctic plankton blooming up to 50 days earlier now

Each summer, an explosion of tiny ocean-dwelling plants and algae, called phytoplankton, anchors the Arctic food web.

But these vital annual blooms of phytoplankton are now peaking up to 50 days earlier than they did 14 years ago, satellite data show.

"The ice is retreating earlier in the Arctic, and the phytoplankton blooms are also starting earlier," said study leader Mati Kahru, an oceanographer at the Scripps Institution of Oceanography in San Diego.

In the late 1990s, phytoplankton blooms in these areas hit their peak in September, only after a summer's worth of relative warmth had melted the edges of the polar ice cap. But by 2009 the blooms' peaks had shifted to early July.

"The trend is obvious and significant, and in my mind there is no doubt it is related to the retreat of the ice," said Kahru, who published the work in the journal Global Change Biology.

Ecologists worry that the early blooms could unravel the region's ecosystem and "lead to crashes of the food web," said William Sydeman, who studies ocean ecology as president of the nonprofit Farallon Institute in Petaluma, Calif.

When phytoplankton explode in population during the blooms, tiny animals called zooplankton - which include krill and other small crustaceans - likewise expand in number as they harvest the phytoplankton. Fish, shellfish and whales feed on the zooplankton, seabirds snatch the fish and shellfish, and polar bears and seals subsist on those species.

The timing of this sequential harvest is programmed into the reproductive cycles of many animals, Sydeman said. "It's all about when food is available." So the disrupted phytoplankton blooms could "have cascading effects up the food web all the way to marine mammals."

...research has shown that northern Atlantic cod populations crash when plankton blooms in that region shift in time.

Last week, the National Snow and Ice Data Center, in Boulder, Colo., reported that in February, Arctic sea ice covered a smaller area than ever seen in that month, tying with February 2005 as the most ice-free February since satellites began tracking Arctic ice in 1979.

This post could just as well have gone in Tony's "Food" thread since it appears very possible that fish populations, upon which millions of people depend on for one of their primary food sources, could collapse due to changes in phytoplankton phenology.

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Time for the melt season to begin, if it hasn't already. Again I will end up predicting a record low and hopefully end up being wrong.

Nevin has a nice animation of the Bering Sea showing the ice looking more like slush. Comparing it with 2007 and 2004. Not quite sure how the rest of the Arctic looks, but given the late freeze up of Hudson Bay it will probably be early to melt.
http://neven1.typepad.com/blog/2011/...ering-sea.html

The JAXA (IJIS) site shows
The latest value : 13,818,281 km2 (March 16, 2011)
Third lowest for date (subject to revision, it is an early figure).

Nevin has put all the common Arctic ice graphs on one page, so if you are an Ice tragic you can get your fix on one site. Or click through.
http://sites.google.com/site/arcticseaicegraphs/

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JAXA The latest value : 13,601,406 km2 (March 22, 2011)
http://nsidc.org/arcticseaicenews/index.html
March 23, 2011
Annual maximum ice extent reached

On March 7, 2011, Arctic sea ice likely reached its maximum extent for the year, at 14.64 million square kilometers (5.65 million square miles). The maximum extent was 1.2 million square kilometers (463,000 square miles) below the 1979 to 2000 average of 15.86 million square kilometers (6.12 million square miles), and equal (within 0.1%) to 2006 for the lowest maximum extent in the satellite record.

Since the start of the satellite record in 1979, the maximum Arctic sea ice extent has occurred as early as February 18 and as late as March 31, with an average date of March 6.

http://neven1.typepad.com/blog/2011/...affin-bay.html
A guest post by Patrick Lockerby

It looks like the ice floes in Baffin Bay didn't compact too well during the winter. Instead of slabbing and compacting, the floes appear to have merely become congealed together with winter ice. That ice is now first year ice. 'First year' doesn't imply year-old: the ice which surrounds older floes in Baffin Bay is just over 6 months old.

Recent images from the Arctic mosaic show cracks in the newer ice running outside of the older ice. This appears to me to be yet one more positive feedback in the ice-melting saga. Previously the ice in Baffin Bay has built up in thickness by slabbing. It takes much more energy to crack thick multi-year ice than to crack the first year ice that surrounds last year's floes.

My expectation is that this ice will break up, disperse and melt rapidly as the melt season gets fully under way. Baffin Bay ice usually presents a great obstruction to the export of ice from Nares Strait and the Canadian Archipelago. I suggest that it will not continue to do so for long.

http://climateprogress.org/2011/03/2...ellite-record/
Joe Romm has a say

The various estimates of ice extent have different alogorithms and produce slightly different results. The figures are also preliminary and subject to change. The equal record low may not stand, but the picture is still grim.

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http://www.eurekalert.org/pub_releas...-imp033111.php
Icy meltwater pooling in Arctic Ocean: A wild card in climate change scenarios

A massive, growing pool of icy meltwater in the Arctic Ocean is a wild card in future climate scenarios, European researchers said today.

Estimated in 2009 at more than 7,500 cubic km – twice the volume of Africa's Lake Victoria – and growing, the water could flush quickly into the Atlantic with unpredictable effect when prevailing atmospheric patterns shift, as occurred most recently in the 1960s and 1990s.

"In addition, sea ice that is thinner is more mobile and could exit the Arctic faster. In the worst case, these Arctic outflow surges can significantly change the densities of marine surface waters in the extreme North Atlantic. What happens then is hard to predict."

The hypothesis is that additional ice melting throughout the Arctic region would dilute northern saltwater and alter its density, causing the conveyor to slow.

Among other physical ocean changes either underway or foreseen by European researchers:


•Rising seas around Europe will become warmer and more acidic;
•The seasonal mixing of deep and shallow waters, essential to the marine food chain will be disrupted; and
•More powerful and more frequent storms brewed offshore will batter coasts.

Some of the most dramatic findings to date involve acidification of the oceans as they absorb more of the atmosphere's growing load of carbon dioxide.

"Ocean acidification is detectable and underway," says Marion Gehlen, of the Laboratoire des Sciences du Climat et de l'Environnment, near Paris.

Acidification undermines the ability of certain plankton species to grow shells. These tiny creatures support the entire ocean food web and help consume and sink much of the oceans' carbon dioxide content. Harmful plankton species will replace beneficial varieties in some areas.

Let see I remember another case of freshwater lensing
http://www.travelrivieramaya.com/divingcenotes.htm

You must be certified as an Advanced Diver and logged at least 20 dives. A unique feature of this dive is that a layer of hydrogen sulfide separates the fresh water from the salt water below. This mystical cloud is found at about 100 feet (30 m) and stretches down to 110 feet (34 m) We will descend to approx. 130 feet (40 m). An indescribable dive. You have to see it for yourself!

Actually I would rather not see it for myself, especially on a global scale.

Is this the right thread? In a way yes, what happens to the melted ice.
Furthermore our reduced Arctic freeze up each year is now freezing relatively fresh water. When this fresh water flushes out, how badly will the freeze be affected?