Neven at Arctic Sea Ice Blog reports that the 12 month rolling average for Arctic sea ice extent set a new record in October 2011 at 10.66 million km². The previous record of 10.67 million km² had been set in October 2007.

The record for Arctic sea ice area has also been broken. The October 2007 was again the previous record, standing at 8.39 million km². Annual average Sea Ice Area dropped to 8.34 million km² for the 12-month period ending in October 2011.

Sea ice volumes have been decreasing far more quickly. The previous record value from PIOMAS was 15,075 km³, set in the 12-month period ending in January 2008, a record that held for just 29 months. The 12-month period ending in September 2011 set a new record, averaging 13,140 km³.

Global sea ice area (Arctic and Antarctic combined, as calculated at Cryosphere Today) has also reached its lowest maximum on record, as seen in this graph posted here.

It’s hard to see the new record in the graph above, but Neven posts this chart showing the numbers.

Earth’s cryosphere continues to wither under the assault from global warming.

Here’s the abstract from “Thinning of Arctic sea ice 1990-2010 as observed by upward looking sonars – or why the Arctic Ocean could be ice free in summer in less than ten years“:

Time series of sea ice thickness observed in Fram Strait by moored sonars show a 35 percent reduction in multiyear (MY) modal ice thickness since 2005. The MY mode reflects the thickness of level ice which has survived at least one melt season, and is hence a reflection of the thermodynamic equilibrium. During the 1990s the late winter MY modal thickness was 3.4+-0.4 m. Following excessive export of MY ice during the winter of 2005, late winter MY modal ice thickness dropped to 2.2 +-0.1 m, which persisted until the end of our record in 2010. The reduced MY modal ice thickness is a result of the Arctic sea ice cover entering a new state, where dynamic and thermodynamic effects appear to have combined to shift the equilibrium towards thinner ice.

This new state includes a dramatic reduction in the fraction of ridged sea ice, compared to the 1990s. The vast fields of ridged ice thicker than 5 m, constituting 28 percent of the winter Arctic sea ice cover during the 1990s, is nearly gone. At the end of winter in 2010, ice thicker than 5 m constituted only 6 percent of the total ice mass observed. The combined effect on late winter mean ice thickness is a reduction from 4.3+-0.4 m during the 1990s to a record low value of 2.0 m in late winter 2010. We speculate that increased ocean heat flux plays an important role in the thinning of the thick ice. With the thickest ice nearly gone and the MY level ice thicknesses close to thicknesses typical for first year sea ice, we are approaching a state where favorable conditions could melt most of the Arctic sea ice cover during one summer. 

This graphic provided by the U.S. Navy shows how little older, thicker ice is left – just a thin band along the northern edge of the Arctic Archipelago and the north coast of Greenland.

The graphic here is animated – you can watch the older ice flowing out of the Arctic Sea through the Fram Strait.

Alerting message from the Arctic: The extent the Arctic sea ice has reached on Sep. 8 with 4.240 million km2 a new historic minimum (Figure 1). Physicists of the University of Bremen now confirm the apprehension existing since July 2011 that the ice melt in the Arctic could further proceed and even exceed the previous historic minimum of 2007. It seems to be clear that this is a further consequence of the man-made global warming with global consequences. Directly, the livehood of small animals, algae, fishes and mammals like polar bears and seals is more and more reduced.

The University of Bremen’s ice map shows the Northwest and Northeast passages are simultaneously ice free
This happened for the first time in 2008 – it did not happen in 2007, the year that saw the record minimum ice extent.

The daily sea ice maps of the University of Bremen are based on observations of the Japanese microwave sensor AMSR-E, in orbit on board the NASA spacecraft Aqua since 2002. The institute receives the data from two servers in the US and Japan and produces the maps based on the ASI (ARTIST Sea Ice) algorithm using the 89 GHz channels of AMSR-E. Other retrieval algorithms like NASA Team or Bootstrap may find slightly different sea ice extent values.

To wit: the National Snow and Ice Data Center has just called the yearly minimum Arctic sea ice extent, finding it the second lowest in the satellite record.

Arctic sea ice appears to have reached its lowest extent for the year. The minimum ice extent was the second lowest in the satellite record, after 2007, and continues the decadal trend of rapidly decreasing summer sea ice.

Please note that this is a preliminary announcement. Changing winds could still push ice flows together, reducing ice extent further. NSIDC scientists will release a full analysis of the melt season in early October, once monthly data are available for September.

* * *

The last five years (2007 to 2011) have been the five lowest extents in the continuous satellite record, which extends back to 1979. While the record low year of 2007 was marked by a combination of weather conditions that favored ice loss (including clearer skies, favorable wind patterns, and warm temperatures), this year has shown more typical weather patterns but continued warmth over the Arctic. This supports the idea that the Arctic sea ice cover is continuing to thin. Models and remote sensing data also indicate this is the case. A large area of low concentration ice in the East Siberian Sea, visible in NASA Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, suggests that the ice cover this year is particularly thin and dispersed this year.

The Japan Aerospace Exploration Agency (JAXA) also pegs 2011 as the second lowest year for Arctic sea ice extent.

If September 9 holds up as the date of minimum ice extent, that’s the earliest date of minimum extent in years – and earlier than the average date (September 10) over the period of satellite records, which began in 1979.

While the absolute sea ice extent values might vary slightly from one method to the other – and even the day of the absolute minimum might vary slightly – all methods find consistently that all minima since 2007 have been lower than all minima before, i.e. the last four minima (2007-2011) are the four lowest on record.

And there’s little doubt that 2011 saw new record for Arctic sea ice volume . . .

. . . and area.

Global warming and climate change have already come to the Arctic. The full consequences of this new reality have yet to be seen.

]]> http://casafoodshed.org/archives/2011/09/15/nsidc-calls-minimum-arctic-sea-ice-extent-sea-ice-extent-area-volume-set-new-records/feed/ 0 http://casafoodshed.org/archives/2011/09/07/arctic-sea-ice-challenging-record-lows-for-extent-area-setting-new-record-low-for-volume/ http://casafoodshed.org/archives/2011/09/07/arctic-sea-ice-challenging-record-lows-for-extent-area-setting-new-record-low-for-volume/#comments Wed, 07 Sep 2011 23:12:38 +0000 jim http://casafoodshed.org/?p=6797 The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice extent averaged for August 2011 reached the second lowest level for the month in the satellite record, tracking near the record lows of 2007.

Arctic sea ice extent will likely reach its minimum extent for the year sometime in the next two weeks. If ice stopped declining in extent today, it would be the second-lowest minimum extent in the satellite record.

Both the Northwest Passage and the Northern Sea route appear to be open – for the fourth consecutive year.

Sea ice is now almost completely gone from the channels of the Northwest Passage, with the exception of a small strip of ice across a stretch of the Parry Channel. The southern route (Amunden’s Route) is ice free. According to the Canadian Ice Service, sea ice extent in the western Parry Channel is now the lowest at this time of year since record keeping began in 1966 and very little multi-year ice remains.

The fabled Northwest Passage opened for the first time in 2007. Now, it’s become routine. In 2008 the Northwest Passage and the Northern Sea Route were open simultaneously for the first time. This, too, seems now to be the new normal.

This chart from the Japan Aerospace Exploration Agency (JAXA) shows sea ice area approaching the record low set in 2007.

The area of sea-ice cover can be defined in two ways, sea ice “extent” and sea ice “area.” Sea ice “extent” is defined as the areal sum of sea ice covering the ocean (sea ice + open ocean), whereas sea ice “area”  counts only sea ice covering a fraction of the ocean (sea ice only). Thus, the sea ice extent is always larger than the sea ice area.

A new study confirms the minimum summertime volume of Arctic sea ice fell to a record low last year (2010) – but this year has already broken that record, as seen in this PIOMASS graph from the University of Washington’s Polar Science Center.

The decline in volume is even more apparent from this graph posted at Neven’s Arctic Sea Ice blog.

Sea ice volume in 2011 is already below last year’s record low. 2011 has already seen a new record minimum volume – and the melt season is not yet over.

2011 is the fourth consecutive year – and the fourth time in recorded history – that both Arctic shipping routes have become open to navigation.

Arctic ice extent is declining at a brisk pace, but melt is slightly behind the pace set in 2007, the record low year – as seen in this image at the IJIS Web site provided by the Japan Aerospace Exploration Agency (JAXA).

The National Snow and Ice Data Center (NSIDC) reports weather conditions in late July spread the ice out, but that conditions are now again such that sea ice extent may decline rapidly:

During early summer, a high-pressure cell persisted over the northern Beaufort Sea, promoting ice loss. This weather pattern broke down toward the end of July, slowing ice loss but spreading out the ice pack, making it thinner on average. The weather has now changed again, bringing another high-pressure pattern. Winds associated with this pressure pattern generally bring warm temperatures, and tend to push the ice together and reduce overall extent. In the Kara Sea, the combination of a high-pressure cell with low pressure to the west has resulted in strong northward ice movement, pushing the ice pack away from the coast and reducing ice extent. The same weather pattern is also increasing the movement of ice out of Fram Strait, between Greenland and Spitsbergen.

Right now, there is a record divergence between area and extent, as Neven reports at Arctic Sea Ice Blog. The difference is often substantial, as can be seen by comparing the graph of sea ice extent, above, with that of sea ice area, below, posted by Joseph Romm at Climate Progress.

The ratio of sea ice area to sea ice extent is now at a record low, as seen in the graph below.

NSIDC also reports that Arctic sea ice volume is now showing record lows. Through July 20 this year, the ice surface was melting faster than the underside of the ice. As the Arctic days grow shorter surface melt will slow – but ocean waters warmed during the summer will continue to melt the ice from below, reducing ice thickness and extent into September.

The University of Washington’s Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) model projects that this year’s minimum volume in September will very likely finish below 2007, reaching a new record low volume.

Ice loss slowed substantially over the latter half of the month as the weather changed. A high-pressure cell centered over the northern Beaufort Sea broke down and a series of low-pressure systems moved over the central Arctic Ocean, bringing cooler conditions and likely pushing the ice apart into a thinner but more extensive ice cover.

Daily Arctic sea ice extent as of August 2, 2011, along with daily ice extents for previous low-ice-extent years. Light blue indicates 2011, dashed green shows 2007, dark blue shows 2010, purple shows 2008, and dark gray shows the 1979 to 2000 average. The gray area around the average line shows the two standard deviation range of the data.

In the first week of August, with a month or more to go in the melt season, Arctic sea ice area has already dropped below not just the year-to-date values, but the annual low points of any satellite-era year before 2007.

Shipping routes in the Arctic have less ice than usual for this time of year, and more of the Arctic’s oldest ice has disappeared.

Sea ice concentration (left) and ice age (right) over the Arctic Ocean. In the Beaufort Sea off the coast of Alaska, ice has melted back to the edge of a tongue of older, thicker ice. In the "Ice Age" image, red shows ice 5 years old and older, green shows 4-year-old ice, light blue shows 3-year old ice, dark blue shows second-year ice, and purple shows first-year ice.

Over the past few weeks, the sea ice edge has retreated from the shores of Siberia and Eurasia, opening up much of the Northern Sea Route – the shipping lane that runs along the Eurasian Arctic coast from Murmansk on the Barents Sea, along Siberia, and through the Bering Strait. Some ice remains, particularly in the East Siberian Sea, but the reduced ice cover in the region has already made the route feasible this year. Taking advantage of the early retreat of sea ice in the Kara and Barents seas, the tanker Perseverance set sail on June 29, 2011 from Murmansk, Russia, aided by two icebreakers; and completed the passage on July 14. The company plans to send six to seven more ships through the Northern Sea Route this summer.

On the other side of the Arctic, the Northwest Passage is still choked with ice. However, ice loss in the Northwest Passage is well ahead of average, nearly matching last year when sea ice in the Parry Channel (the northern part of the Northwest Passage) reached the lowest levels in records dating back to 1968.

Arctic sea ice extent declined at a rapid pace through the first half of July, and is now tracking below the year 2007, which saw the record minimum September extent. The rapid decline in the past few weeks is related to persistent above-average temperatures and an early start to melt. Snow cover over Northern Eurasia was especially low in May and June, continuing the pattern seen in April.

To date in July, air temperatures over the North Pole (at the 925 millibar level, or roughly 1,000 meters or 3,000 feet above the surface) were 6 to 8 degrees Celsius (11 to 14 degrees Fahrenheit) higher than normal.

NSIDC explains why the early ice melt is significant:

When sea ice starts to melt in spring, small ponds known as melt ponds form on its surface. The small pools create a darker surface (a lower albedo) that fosters further melt. How early sea ice melt starts is one indicator of how much the ice will melt in a given year. New research by Don Perovich and colleagues shows that an early start to sea ice melt increases the total amount of sunlight absorbed through the melt season.

Arctic sea ice volume continues to plunge to record lows, too . . .

. . . as older, multi-year ice is replaced by younger, thinner ice more susceptible to melting in the summer.

The Arctic’s death spiral continues.

]]> http://casafoodshed.org/archives/2011/07/20/the-arctic%e2%80%99s-death-spiral-continues/feed/ 0 http://casafoodshed.org/archives/2011/07/08/arctic-ice-continues-in-death-spiral/ http://casafoodshed.org/archives/2011/07/08/arctic-ice-continues-in-death-spiral/#comments Fri, 08 Jul 2011 21:23:27 +0000 jim http://casafoodshed.org/?p=6637 The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice extent for June 2011 was the second lowest in the satellite data record. Average ice extent fell below that for June 2007, which had the lowest minimum ice extent at the end of summer, but was greater than in June last year.

The Japan Aerospace Exploration Agency posts this colorful graph showing the last ten years of Arctic ice cover.

Weather over the next few weeks will determine whether the Arctic sea ice cover will again approach record lows. Regardless, the long-term trend is clear.

The University of Washington’s Polar Science Center reports Arctic sea ice volume  for June 2011 averaged 15,700 km³ – 37% lower than the mean over the 1979 -2010 period, 47% lower than in 1979, and 2.5 standard deviations below the trend.

Total Arctic sea ice volume from PIOMAS showing the volume of the mean annual cycle, the current year, and 2007 (the year of minimum sea ice extent in September). Shaded areas indicate one and two standard deviations from the mean.

While in the graph above 2007 is shown as the year of minimum sea ice volume in September, in a recently published reanalysis of their data the scientists conclude 2010 saw a new record low:

The 2010 September ice volume anomaly did in fact exceed the previous 2007 minimum by a large enough margin to establish a statistically significant new record.

Neven at Arctic Sea Ice Blog has posted this graph by Wipneus showing all the trends in the period 2002-2011:

Arctic ice continues in its death spiral.

The chart below shows the lowest year for May was 2004, followed by 2006. The long-term rate of decline for May now stands at -2.4% per decade.

During the month of May, sea ice declined at a near average rate, while air temperatures in the Arctic remained generally above average.

Although ice extent is low for this time of year, ice extent at the end of summer largely depends on Arctic weather over the next few months. Years with dramatic ice loss, such as 2007, have been associated with comparatively warm, calm, and clear conditions in summer that have encouraged ice melt. Summers with slow melt rates are opposite and tend to be stormier than average. The number of storms influences how warm, windy and cloudy the Arctic summer is.

The chart below compares this year to 2007, which saw dramatic, record-breaking ice loss in the Arctic.

NSIDC explains why

The last four summers have been dominated by an atmospheric pattern known as the Arctic dipole anomaly, which has been associated with low sea ice extent at the end of summer. This pattern features unusually high pressure over the Beaufort Sea and unusually low pressure over the Kara and Laptev Seas, which promote warm southerly winds along the Siberian coast, helping to melt ice and push it away from the coasts and out of the Arctic Basin through Fram Strait.

While the atmospheric pattern for May 2011 bears some resemblance to the Arctic dipole anomaly pattern, the centers of the pressure anomalies are in different locations this year, and it is not yet clear whether the pattern will persist through the summer and contribute to low ice extent.

Arctic sea ice volume continues to drop, too. In this chart published at the Polar Science Center, shaded areas represent one and two standard deviations of the anomaly from the trend.

Sea ice volume is an important climate indicator, as it depends on both ice thickness and extent and is therefore more directly tied to climate forcing than extent alone.

The assessment finds that the past six years (2005–2010) have been the warmest period ever recorded in the Arctic. The higher surface air temperature are driving changes in the cryosphere. Two components of the Arctic cryosphere – snow and sea ice – are interacting with the climate system to accelerate warming in a feedback loop. Loss of ice and snow in the Arctic enhances climate warming by increasing absorption of the sun’s energy at the surface of the planet. Temperatures in the permafrost have risen by up to 2 °C and the southern limit of permafrost has moved northward in Russia and Canada- a trend which could result in dramatically increased emissions of carbon dioxide and methane. Melting ice could change large-scale ocean currents. Melting glaciers and ice sheets worldwide have become the biggest contributor to global sea level rise. Arctic glaciers, ice caps, and the Greenland Ice Sheet are contributing much more to global sea level rise than previously measured. High uncertainty surrounds estimates of future global sea level, with latest models predicting a rise of 0.9 to 1.6 m above the 1990 level by 2100. But, the assessment cautions, the combined outcome of these effects is not yet known. Interactions (‘feedbacks’) between elements of the cryosphere and climate system are particularly uncertain.

The assessment was done by the Arctic Monitoring and Assessment Programme (AMAP), an international organization headquartered in Norway. Member nations include the eight Arctic rim countries: Canada, Denmark/Greenland, Finland, Iceland, Norway, Russia, Sweden, and the United States. Other nations and organizations participate as well.

The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice extent declined through April more slowly than usual, as cool conditions helped retain ice in Baffin Bay, between Canada and Greenland. Still, April 2011 continued the overall downward trend of the past thirty years, ranking fifth lowest in the satellite record. The two lowest years for April were 2007 and 2006.

University of Washington’s Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) model of sea ice volume shows continued very low ice mass in the Arctic compared to previous decades.

Joseph Romm at Climate Progress reports on a study showing the Greenland ice sheet has been losing mass over the last decade.

Greenland ice mass anomaly – deviation from the average ice mass over the 2002 to 2010 period.

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