The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice appeared to reach its maximum extent for the year on March 7, marking the beginning of the melt season. This year’s maximum tied with 2006 for the lowest 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. 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.

A recent post discussed new research showing Greenland and Antarctic ice loss is accelerating. Early Warning has now posted an illuminating graphic comparing the latest results with IPCC estimates.

The blue line is the new estimates from Rignot et al, which only includes contributions from ice sheet dynamics in Greenland and Antarctica – a factor almost entirely excluded from the IPCC estimates. The yellow band is under A1F1, which is an all-out fossil fuel intensive scenario. The green is B1, which is still an economic growth scenario but assumes some fossil fuel consumption is replaced by conservation and renewables. The vertical colored bars at the very right hand show the sea level estimates from the IPCC AR4 report for 2100.

Stuart Staniford sums up the current state of knowledge – and warns there’s plenty we still don’t know:

It looks like we are heading for ballpark a foot of sea level rise by mid century (pretty much regardless of what we do) and 3-5 ft by the end of the century (depending on emissions and uncertainties in the climate sensitivity). . .

The one big caveat is this: the climate system is non-linear and keeps surprising the climate scientists. There may be more surprises ahead.

Bad news for low-lying places and coastal locations. Today’s tsunami caused devastation in Japan and substantial damage along the U.S. west coast, despite arriving at the lowest tide point of the day. Imagine if sea levels were five feet higher.

The National Snow and Ice Data Center reports Arctic sea ice extent for February 2011 tied with February 2005 as the lowest recorded in the satellite record.

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.

This year has already seen the lowest January sea ice extent in the satellite record. The persistence of low sea ice likely contributes to the cold and severe weather events experienced this winter in the U.S. and Europe.

A new study published in the journal Science concludes ocean currents entering the Arctic Ocean are the warmest in more than 2,000 years – well outside the natural bounds. The warm waters will likely lead to ice-free seas around the North Pole in summers.

[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.

Dr. Jeff Masters at Wonderblog reports record warm ocean temperatures across much of Earth’s tropical oceans during the summer of 2010 created the second worst year globally for coral-killing bleaching episodes.

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.