Arctic sea ice is disappearing much faster and more dramatically than expected, according to new research by the Norwegian Polar Institute (NPI). Consequently, the Arctic Sea could be free of ice in the summer in ten years, rather than the 50 to 100 years previously estimated.

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.

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.

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.

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.

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.

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 key findings of the International Earth system expert workshop on ocean stresses and impacts Summary Report should be enough to shake any cognizant being out of their lethargy:

• Human actions have resulted in warming and acidification of the oceans and are now causing increased hypoxia – symptoms that indicate disturbances of the carbon cycle associated with each of the previous five mass extinctions on Earth.
• The speeds of many negative changes to the ocean are near to or are tracking the worst-case scenarios from IPCC and other predictions. Consequences matching those predicted under the “worst case scenario” include decrease in Arctic Sea Ice, melting of the Greenland and Antarctic ice sheets, sea level rise, and release of trapped methane from the seabed.
• The magnitude of the cumulative impacts on the ocean is greater than previously understood, as interactions between different impacts can be negatively synergistic.
• Timelines for action are shrinking. Delays will mean increased environmental damage with greater socioeconomic impacts.
• Resilience of the ocean to climate change impacts is severely compromised by the other stressors from human activities, including fisheries, pollution and habitat destruction.
• Ecosystem collapse is occurring as a result of both current and emerging stressors including chemical pollutants, agriculture run-­off, sediment loads and over-­extraction of many components of food webs.
• The extinction threat to marine species is rapidly increasing due to overexploitation, habitat loss, and, increasingly, climate change.

But don’t count on any response from our political or economic elites, other than wanton disregard. They have proved to not be cognizant beings.

A press release quotes Dr. Alex Rogers, Scientific Director of the International Programme on the State of the Ocean (IPSO), which convened the workshop:

The findings are shocking. As we considered the cumulative effect of what humankind does to the ocean the implications became far worse than we had individually realized. This is a very serious situation demanding unequivocal action at every level. We are looking at consequences for humankind that will impact in our lifetime, and worse, our children’s, and generations beyond that.

Co-author Dan Laffoley issued a call for action:

The world’s leading experts on oceans are surprised by the rate and magnitude of changes we are seeing. The challenges for the future of the ocean are vast, but unlike previous generations we know what now needs to happen. The time to protect the blue heart of our planet is now, today and urgent.

The chances of any significant action being taken are precisely zero. The sad reality is the ocean and its ecosystems are doomed to succumb to a constantly bombardment of multiple attacks.

Dan Allen at Energy Bulletin scathingly observes that humans have proved to be less than rational:

[A]ny sane society . . . when faced with such an overwhelming abundance of scientific evidence, would be gnashing its collective teeth and running for the powerdown-exits en masse at this point. No sane society would ignore the screaming warnings of every single Earth system. No sane society would knowingly doom their children and grandchildren to misery and starvation. No sane society would stand by and do NOTHING — NOT ONE DAMN THING!! — while their very life-support systems eroded away before their eyes.

But we are surely not sane.

Political solutions have failed us, are failing us, and will certainly continue to fail us. The only option we have – to slam on the brakes and to stop burning coal, tout de suite – won’t be undertaken voluntarily; to think otherwise is delusional. Climate catastrophe is where we are. As Allen says, that’s the bed we’ve made:

So, sadly, at this late hour, we just flat-out NEED the dark angel of economic collapse to swoop down onto the stage, ‘Deus ex Machina’ style, and save the day.

God help us.

Pray for the collapse of the global industrial economy. And do what you can to begin fashioning a replacement.

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 amount of older, thicker ice has increased slightly over last year. Older ice that has survived several summer melt seasons tends to be thicker, while newer ice is thinner and more vulnerable to melt in summer. The trend of spring ice cover becoming increasingly dominated by younger and generally thinner ice (because of strong summer melting reducing the amount of ice surviving into winter) remains striking.

There is still almost none of the oldest ice, older than four years old, that used to dominate much of the Arctic Ocean.

Scientists have found that the freshwater content of the upper Arctic Ocean has increased by about 20% since the 1990s. This corresponds to a rise of approximately 8,400 cubic kilometers and has the same magnitude as the volume of freshwater annually exported on average from this marine region in liquid or frozen form.

Around 10% of the global mainland runoff flows into the Arctic via the enormous Siberian and North American rivers in addition to relatively low-salt water from the Pacific. This freshwater lies as a light layer on top of the deeper salty and warm ocean layers and thus extensively cuts off heat flow to the ice and atmosphere. Changes in this layer are therefore major control parameters for the sensitive heat balance of the Arctic. The scientists expect that the additional amount of freshwater in the near-surface layer of the Arctic Ocean will flow out into the North Atlantic in the coming years. The amount of freshwater flowing out of the Arctic influences the formation of deep water in the Greenland Sea and Labrador Sea and thus has impacts on global ocean circulation.

The study, by researchers of the Alfred Wegener Institute for Polar and Marine Research Bremerhaven, Germany, is published in the journal Deep-Sea Research.

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. Sea ice extent in February and March tends to be quite variable, because ice near the edge is thin and often quite dispersed. The thin ice is highly sensitive to weather, moving or melting quickly in response to changing winds and temperatures, and it often oscillates near the maximum extent for several days or weeks.

The graph above shows daily Arctic sea ice extent as of March 22, 2011, along with daily ice extents for 2006, which had the previous lowest maximum extent, and 2007, the year with the lowest minimum extent in September.

This winter, the Arctic has seen the lowest December, January, and February (tied with 2005) sea ice extent in the satellite record.

Even more importantly, Arctic ice volume is also continuing its long-term decline.

Shaded areas show one and two standard deviations from the trend.

Monthly average Arctic ice volume for September 2010 was 78% below the 1979 maximum and 70% below its mean for the 1979-2009 period.

Arctic ice continues in its downward death spiral.

Sea ice extent was particularly low in the Labrador Sea and Gulf of St. Lawrence.

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

[E]arly–21st-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.

The scientists say that waters at the Fram Strait – at the northern end of the Gulf Stream, between Greenland and the Norwegian archipelago of Svalbard – averaged 6 degrees Celsius (42.8°F) in recent summers.

The study showed that water from the Fram Strait 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 CE to 1300 CE and affected the climate in Northern Europe, Greenland, and northern North America. Air temperatures in Greenland have risen roughly 7 degrees F in the past several decades.

Joseph Romm at Climate Progress has posted a key graph from the study:

Due to positive feedbacks between the ice, the Arctic Ocean and the atmosphere, the rate of Arctic sea ice decline has been accelerating – as seen is this graph from the University of Washington’s Polar Science Center:

As Arctic temperatures rise, summer ice cover declines, more solar heat is absorbed by the ocean, and additional ice melts. Warmer water delays 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.

Lead author Robert Spielhagen of the Academy of Sciences, Humanities and Literature in Mainz, Germany says the decline of Arctic sea ice is due in part to the warmer waters reaching the Arctic:

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.

Arctic sea ice is in a death spiral.

The summer 2010 bleaching episodes were worst in Southeast Asia, where El Niño warming of the tropical ocean waters during the first half of the year was significant. In Indonesia’s Aceh province, 80% of the bleached corals died, and Malaysia closed several popular dive sites after nearly all the coral were damaged by bleaching. In the Caribbean’s Virgin Islands, coral bleaching was not as severe as experienced in 2005. But in other portions of the Caribbean, such as Venezuela and Panama, coral bleaching was worse than that experienced in 2005.

Masters says the outlook for Earth’s coral reefs is grim:

The large amount of carbon dioxide humans have put into the air in recent decades has done more than just raise Earth’s global temperature–it has also increased the acidity of the oceans, since carbon dioxide dissolves in sea water to form carbonic acid. Corals have trouble growing in acidic sea water, and the combined effects of increasing ocean temperatures, increasing acidity, pollution, and overfishing have reduced coral reefs globally by 19 percent since 1950. Another 35 percent could disappear in the next 40 years, even without the impact of climate change, according to a report released in October 2010 by the World Meteorological Organization and the Convention on Biological Diversity. Coral loss has been the most severe in Earth’s hottest ocean, the Indian Ocean. Up to 90% of coral cover has been lost in the Maldives, Sri Lanka, Kenya and Tanzania and in the Seychelles. Global warming has heated up most of the tropical ocean surface waters by about 0.5°C (0.9°F) over the past 50 years, and the remarkable bleaching episodes of 1998 and 2010 both occurred when strong (natural) El Niño episodes heated up Pacific tropical waters to record levels. If the Earth continues to heat up this century as expected, coral bleaching episodes will grow more frequent and intense, particularly during strong El Niño episodes. The twin stresses of ocean acidification and increasing ocean temperatures will probably mean that by 2050, it will be difficult for any coral reefs to recover when subject to additional stresses posed by pollution or major storms, according to a talk presented by Stanford climate scientist Ken Caldeira at last month’s American Geophysical Union (AGU) meeting.

Corals cover just 0.2% of the world’s oceans, but contain about 25% of all marine species. What’s more, coral reefs are the linchpin of the Ocean’s ecosystems: if coral reefs fail, other ocean ecosystems will topple as well. And the greatest of them all, Australia’s Great Barrier Reef, is at risk. With the southern hemisphere now in mid-summer, Ocean temperatures along the reef are currently up to 1°C above average, due, in part, to the current moderate to strong La Niña event. NOAA’s Coral Reef Watch has issued its highest level of coral bleaching alert for the northern 2/3 of the Great Barrier Reef.

Forecast stress on coral due to warm ocean temperatures for Australia, Jan - Apr 2011. The northern 2/3 of the Great Barrier Reef are under the highest alert level for coral bleaching. Waters are cooler along the southern portion of the reef, due, in part, to the storms that have brought record flooding to portions of Queensland, Australia. Image credit: NOAA Coral Reef Watch.

A new study finds that the world’s fishing industry is depleting older fishing grounds through unsustainable harvesting practices – and that there’s no place left to look for new ones.

The study, titled The Spatial Expansion and Ecological Footprint of Fisheries (1950 to Present), was conducted by researchers at Vancouver’s University of British Columbia in conjunction with the National Geographic magazine.

The study says that 90 million tons of fish were landed in the late 1980s, up from 19 million in the 1950s. The researchers tracked the expansion of fishing activity, examining both the total number of fish caught and the impact that catching different types of fish has had on the ocean’s productivity. By the late 1990s, the world’s fishing fleets had largely run out of new fishing grounds to exploit.

Co-author Enric Sala says we can’t afford to do nothing.

The sooner we come to grips with it, the sooner we can stop the downward spiral by creating stricter fishing regulations and more marine reserves.

The researchers said that in 1950 most heavy fishing was done in the North Atlantic and the Western Pacific, but by the mid 1990s, a third of the world’s oceans and two-thirds of the continental shelves were exploited. That expansion has left only unproductive fishing areas on the high seas and the ice-covered waters of the Arctic and Antarctic for boats to move into.

Here’s the abstract.

Using estimates of the primary production required (PPR) to support fisheries catches (a measure of the footprint of fishing), we analyzed the geographical expansion of the global marine fisheries from 1950 to 2005. We used multiple threshold levels of PPR as percentage of local primary production to define ‘fisheries exploitation’ and applied them to the global dataset of spatially-explicit marine fisheries catches. This approach enabled us to assign exploitation status across a 0.5° latitude/longitude ocean grid system and trace the change in their status over the 56-year time period. This result highlights the global scale expansion in marine fisheries, from the coastal waters off North Atlantic and West Pacific to the waters in the Southern Hemisphere and into the high seas. The southward expansion of fisheries occurred at a rate of almost one degree latitude per year, with the greatest period of expansion occurring in the 1980s and early 1990s. By the mid 1990s, a third of the world’s ocean, and two-thirds of continental shelves, were exploited at a level where PPR of fisheries exceed 10% of PP, leaving only unproductive waters of high seas, and relatively inaccessible waters in the Arctic and Antarctic as the last remaining ‘frontiers.’ The growth in marine fisheries catches for more than half a century was only made possible through exploitation of new fishing grounds. Their rapidly diminishing number indicates a global limit to growth and highlights the urgent need for a transition to sustainable fishing through reduction of PPR.

The Sunday New York Times has an article warning that accelerating sea level rise means we’d better start thinking of abandoning some of our coastal areas – even some large cities.

“We can’t afford to protect everything. We will have to abandon some areas.”

The latest science shows we should be planning for a sea level rise of at least 3 feet over this century.

Scientists long believed that the collapse of the gigantic ice sheets in Greenland and Antarctica would take thousands of years, with sea level possibly rising as little as seven inches in this century, about the same amount as in the 20th century.

But researchers have recently been startled to see big changes unfold in both Greenland and Antarctica.

As a result of recent calculations that take the changes into account, many scientists now say that sea level is likely to rise perhaps three feet by 2100 — an increase that, should it come to pass, would pose a threat to coastal regions the world over.

And the calculations suggest that the rise could conceivably exceed six feet, which would put thousands of square miles of the American coastline under water and would probably displace tens of millions of people in Asia.

The scientists say that a rise of even three feet would inundate low-lying lands in many countries, rendering some areas uninhabitable. It would cause coastal flooding of the sort that now happens once or twice a century to occur every few years. It would cause much faster erosion of beaches, barrier islands and marshes. It would contaminate fresh water supplies with salt.

Joseph Romm at Climate Progress has posted a graph showing sea level rise in three scenarios.  Of course we’re on track for the worse-case scenario which would result from our “do nothing” policies, where the midpoint of the range of sea level rise is nearly five feet.

The Times article says Orrin H. Pilkey of Duke University, one of the deans of American coastal studies, is advising coastal communities to plan for a rise of at least five feet by 2100. Romm points out that Pilkey in fact is advising to plan on a rise of at least seven feet.

Oregon Shores Conservation Coalition recently proposed a new Goal 20, which would require Oregon communities to begin planning for sea level rise. Oregon Shores’ draft goal assumed a modest 2-foot rise by 2100, about half the sea level rise considered likely in the 2009 report  The Impacts of Sea-Level Rise on the California Coast prepared for California’s Interagency Climate Action Team by the Pacific Institute. Oregon Shores’ proposal, inadequate as it was, was dismissed by the Land Conservation and Development Commission.

Especially after the most recent election results, planning for anything other than a continuation of business as usual is a non-starter, in the U.S. as well as here in Oregon. We will continue to do nothing until we are literally swamped by events.

The National Snow and Ice Data Center (NSIDC) has updated its call of the end of the Arctic ice melt season, reporting that ice extent reached its lowest value for the season on September 19, 2010.

Daily Arctic sea ice extent as of September 26, 2010, along with daily ice extents for years with the previous four lowest minimum extents.

The 2010 minimum ice extent was the third-lowest recorded since 1979, 37,000 square kilometers (14,000 square miles) above 2008; 470,000 square kilometers (181,000 square miles) above the record minimum in 2007; and 500,000 square kilometers (193,000 square miles) below 2009. The 2010 minimum ice extent was 2.11 million square kilometers (815,000 square miles) below the 1979 to 2000 average and 1.74 million square kilometers (672,000 square miles) below the 1979 to 2009 average.

The revised minimum ice extent on September 19 occurred ten days later than the average date of the minimum ice extent for the period 1979 to 2000, and 8 days later than the 1979 to 2009 average. With the additional days of ice loss, 2010 is no longer the shortest period of summer ice loss since 1979.

Professor Orrin Pilkey, one of America’s most outspoken coastal geologists, warns we’re set to experience one of the first major impacts of global warming:  sea levels will rise by 2 meters by 2100.

Two meters far exceeds the projections of the International Panel on Climate Change (IPCC) in its 4th Assessment Report, which range from a low of .18 meters to a high of  .59 meters. However, the IPCC report contains this disclaimer:

This report does not assess the likelihood, nor provide a best estimate or an upper bound for sea level rise.

The IPCC projections explicitly exclude future rapid dynamical changes in ice flow from the Greenland and Antarctic ice sheets. The IPCC range assumes a near-zero net contribution of the Greenland and Antarctic ice sheets to future sea level rise, on the theory that Antarctica’s ice sheets will gain mass from an increase in snowfall.

The two-meter rise that Pilkey warns is possible is consistent with recent research based on semi-empirical models.

Estimates for twenty-first century sea level rise from semi-empirical models as compared to the IPCC Fourth Assessment Report

Semi-empirical models have the merit that they reproduce past sea level rise very well, unlike the physical models used thus far. But they too have a serious limitation: there is no way to ensure that the historic relationship between sea level rise and temperature will continue to hold in future.  The semi-empirical approach does not account for non-linear changes. When it comes to ice sheets, the relationship between temperature and sea level rise may not be linear, and the ranges shown in the chart above could underestimate future sea level rise.

Pilkey says more needs to be done to prepare coastal communities from climate change threats – including planning for an orderly retreat.

If you’re going to have development and its close to the beach, make sure the buildings movable. It means you recognise there’s rising sea levels and you move things back as required, or you demolish the buildings.

As sea levels rise over the next 50 to 100 years,  we can try to fortify and protect existing development, and repair it when damaged. But in many cases, retreat will eventually be the only option. Whole communities may have to be relocated. Where will the money come from, and who will pick up the tab?  These questions are certain to be at the center of future political and legal battles.

Johnny Cash said his song Five Feet High and Rising wasn’t just a lamentation about destruction. The flood waters left a blessing in their wake.

My mama always taught me that good things come
from adversity if we put our faith in the Lord.
We couldn’t see much good in the flood waters
when they were causing us to have to leave home,
but when the water went down, we found
that it had washed a load of rich black bottom dirt across our land.
The following year we had the best cotton crop we’d ever had.

But this time, the water’s not coming down – at least not anytime soon. Or maybe we just need to take a longer view of things.

Orrin Pilkey is Professor Emeritus of Earth Sciences, and Founder and Director Emeritus of the Program for the Study of Developed Shorelines (PSDS) within the Nicholas School of the Environment at Duke University.

Arctic summer sea ice cover is in a death spiral. It’s not going to recover.

This foreboding statement is from Mark Serreze, director of the National Snow and Ice Data Center.

More than 2.5 million additional square kilometers of Arctic Ocean waters have been opened up to the heat of the 24-hour summer sun, absorbing tremendous amounts of extra heat.  A warmer Arctic Ocean not only takes much longer to re-freeze, it emits huge volumes of additional heat energy into the atmosphere, disrupting the weather patterns of the northern hemisphere.

Especially worrisome to Serreze is warming in the coastal regions of the Arctic, where average temperatures are now three to five degrees C warmer than they were 30 years ago:

I hate to say it but I think we are committed to a four- to six-degree warmer Arctic.

If the Arctic warms by six degrees, half of the world’s permafrost is likely to thaw, releasing carbon and methane accumulated over thousands of years. And methane is much more potent as a greenhouse gas than carbon dioxide.

Serreze said Arctic sea ice has reached its four lowest summer extents in the last four years – and ice volume likely reached the lowest ever level this month. On September 15, NSIDC called the end of the 2010 ice melt season, with sea ice extent at its third lowest ever. On September 21, NSIDC withdrew its call. What looked to be an unusually early end to the melt season is turning out to be an unusually late end.

This summer’s Arctic ice melt was notable for another reason besides near-record low ice extent and probable record low ice volume: the Norwegian-crewed Northern Passage, a 31-foot fiberglass sailing boat equipped only with a 10 horsepower outboard motor for emergencies, circumnavigated the Arctic Ocean, traversing both the Northwest and Northern Passages.

Tags: Arctic ice

On September 15 the National Snow and Ice Data Center reported Arctic ice extent had started increasing again, calling September 10 the end of the 2010 Arctic melt season and pegging 2010 as the third-lowest ever recorded, behind 2007 and 2008.

But not so fast! Their daily image update shows sea ice extent declining again. Sea ice extent has now fallen below that recorded on September 10.

The late-season dip shows up even better in this chart at the Japan Aerospace Exploration Agency website.

The IJIS website explains why their data may differ slightly from NSIDC’s:

In general, sea-ice extent is defined as a temporal average of several days (e.g., five days) in order to eliminate calculation errors due to a lack of data (e.g., for traditional microwave sensors such as SMMR and SSM/I). However, we adopt the average of two days to achieve rapid data release. The wider spatial coverage of AMSR-E enables reducing the data-production period.

Sea ice extent is defined as the areal sum of sea ice covering the ocean (sea ice + open ocean).

NSIDC reported sea ice extent on September 10, 2010 at 4.76 million km². According to IJIS, the minimum as of September 17 was 4.83 million km² – 120,000 km² below the September 10 extent of 4.95 million km² and just 130,000 km² above the minimum extent of 470,7813 km² reached on September 9, 2008.

Note that IJIS data on sea ice extent differs slightly from NSIDC data. The IJIS web site explains that they average the most recent two days of data rather than the more widespread methodology of averaging five days of data to “achieve rapid data release.” But this wouldn’t seem to explain why their numbers are higher than NSIDC’s.

Ice extent has been falling more than 50,000 km² a day for the past four days.  If that decline keeps up for just a couple more days, the 2010 minimum extent would dip below the 2008 mark and become the second lowest ever recorded.