ONE TOWN SQUARE: at the intersection of peak oil, climate change, and land use

A study published in the September issue of the Journal of the Geological Society found that increasing CO2 levels are causing foram diversity to plummet:

A unique ‘natural laboratory’ in the Mediterranean Sea is revealing the effects of rising carbon dioxide levels on life in the oceans. The results show a bleak future for marine life as ocean acidity rises, and suggest that similar lowering of ocean pH levels may have been responsible for massive extinctions in the past.

Rising carbon dioxide levels acidify the ocean, which has a particularly devastating effect on organisms that have calcium carbonate shells, like Foraminifera. The study, published in the September issue of the Journal of the Geological Society, found that increasing CO2 levels caused foram diversity to fall from 24 species to only 4. The study found a tipping point occurs at mean pH 7.8, the pH level predicted for the end of this century.

Forams record past events in the geological record. The Paleocene-Eocene Thermal Maximum (PETM), 55 million years ago, was a period of massive carbon release and rapid warming, accompanied by extinctions in marine life.

This statement by study co-author Dr. Jason Hall-Spencer in the Geological Society’s press release is not optimistic:

Our natural laboratory provides a glimpse into the future of our oceans.

Joseph Romm at Climate Progress has posted this chart showing trends in ocean CO2 concentrations and pH at one sampling station off Hawaii.

Romm also points out that the disappearance of forams has grave implications for the rest of the food chain.

For an analysis of what that could mean, see 2009 Nature Geoscience study concludes ocean dead zones “devoid of fish and seafood” are poised to expand and “remain for thousands of years.”

Dr. Jeff Masters at WunderBlog reports that both the Northwest Passage and the Northern Sea Route are now open. Data at the University of Illinois site Cryosphere Today shows it is now possible to completely circumnavigate the Arctic Ocean in ice-free waters – and this will probably continue to be the case for at least a month.

This year marks the third consecutive year–and the third time in recorded history–that both the Northwest Passage and Northern Sea Route have melted free, according to the National Snow and Ice Data Center.

The Northeast Passage opened for the first time in recorded history in 2005, and the Northwest Passage in 2007. It now appears that the opening of one or both of these northern passages is the new norm.

Here’s an updated graphic:

As this graphic from Chris Mooney’s article in New Scientist shows, ice volume has been decreasing even more precipitously than ice area.

The average volume of Arctic ice between July and September has fallen from 21,000 cubic kilometres in 1979 to 8000 cubic kilometres in 2009, a 55% decline compared with the 1979 to 2000 average. This is even faster than the decline in ice extent, which is 40% below the long-term average.

Not only has the total volume of Arctic ice continued to decline since 2007 considerably more quickly than predicted by most climate models, the rate of loss is accelerating. The Arctic Ocean may soon be essentially ice-free during the summer months. The dark ocean waters, mostly devoid of ice, would then absorb still more sunlight, further warming the overlying atmosphere during an increasingly lengthy ice-free season, reshaping weather throughout the region and well beyond it.

A good friend recently asked me why I give so much attention to news about Arctic sea ice extent at this blog, saying he just glosses over posts on this subject.

Here’s the reason: the area of sea ice cover is an important, amplifying climate feedback. Loss of sea ice is a cause of concern because as the area of ice decreases, increased absorption of sunlight by the darker ocean causes more sea ice melting. As this graph from Makiko Sato & James Hansen’s new blog shows, Arctic sea ice extent has been declining steadily . . .

. . . as has sea ice volume. What ice remains is getting thinner.

It’s not just sea ice that is melting. Ice sheets are shrinking too, both in Greenland and in Antarctica.

And the ice loss over the last few years has been at a time of minimum solar irradiance. Solar irradiance is now once again on the upswing.

It seems likely that September Arctic sea ice may be all but gone within a few decades – or perhaps even sooner. What does less Arctic sea ice mean for Earth’s weather patterns?

NASA is predicting loss of summer sea ice will mean more severe winter storms in the northern hemisphere – a prediction which is already being borne out.

Following Arctic sea ice extent is fascinating because it shows that global warming is not something to worry about in the future. Global warming is here and now, and is already affecting us in our daily lives. What’s worrisome is that the impacts will only get more severe. By the time the impacts are bad enough to get our attention, it will be too late – the damage will already have been done. Under the best-case scenario it will take Earth a thousand years or more to recover. Under the worst-case scenario, Earth will flip into a different, stable climate regime which won’t be hospitable to human existence.

According to the National Snow and Ice Data Center (NSIDC), neither the Northwest Passage through the Canadian Arctic nor the Northern Sea Route along the coast of Siberia are yet free of ice and open – but it’s looking like they soon will be.

A Russian gas tanker set out from Murmansk on August 14 across the Northern Sea Route, escorted by two nuclear ice breakers, and is expected to deliver its cargo of gas condensate to China by early September.

Ice in the Vilkitsky Strait is the only remaining impediment to shipping across the Northern Sea Route . . .

. . . as seen in this NSIDC graphic of sea ice extent.

While this latest graphic shows the northern route of the Northwest Passage as being open, NSIDC’s Arctic Sea Ice News reports that as of August 17 neither the northern route (Western Parry Channel) nor the southern route (Amundsen’s Passage) through the Northwest Passage were completely clear of ice.  NSIDC says that sea ice area within the northern route is currently well below the 1968 to 2000 average and almost a month ahead of the clearing that was observed in 2007. In the southern route, there is still a substantial amount of ice.

If winds push sea ice away from the entrance to M’Clure Strait, the northern route of the Northwest Passage could open again this year – if it hasn’t already.

M'Clure Strait, Northwest Territories, Canada.

On August 21, 2007, the Northwest Passage became open to ships without the need of an icebreaker.  The Northwest Passage opened again on August 25, 2008. In late August 2008, satellite images showed that the last ice blockage of the Northern Sea Route had melted – which would be the first time since satellite records began that both the Northwest Passage and Northern Sea Route were open simultaneously.

The Northern Sea Route was open in 2005 but closed again by 2007. A Russian nuclear icebreaker escorted a small convoy including two Western commercial vessels westward through the Northern Sea Route in 2009.

Microscopic life crucial to the marine food chain is dying out. The consequences could be catastrophic.

So reads the headline of an article in the U.K. Independent reporting on new research published in the journal Nature. The study, titled Global phytoplankton decline over the past century, finds there has been a 40% decline in the ocean’s phytoplankton over the last 100 years – and global warming is to blame.

The microscopic plants that support all life in the oceans are dying off at a rate of about 1% per year. The decline is related to rising sea surface temperatures.

According to the Independent, the scientists said if the findings are confirmed by further studies, the decline in phytoplankton will represent the single biggest change to the global biosphere in modern times, even bigger than the destruction of the tropical rainforests and coral reefs. Phytoplankton are microscopic marine organisms capable of photosynthesis, just like terrestrial plants. They float in the upper layers of the oceans, provide much of the oxygen we breathe and account for about half of the total organic matter on Earth. Phytoplankton are the basis of life in the oceans and are essential in maintaining the health of the oceans. A 40% decline would represent a massive change to the global biosphere.

The press release explains that in warmer oceans, the water becomes stratified, with warmer water on top of colder deeper water. Nutrients which are normally replenished by upwelling colder water are cut off, and the photosynthesizers living in the surface waters starve to death.

Rising sea surface temperatures were negatively correlated with phytoplankton growth over most of the globe, especially close to the equator. Phytoplankton need both sunlight and nutrients to grow; warm oceans are strongly stratified, which limits the amount of nutrients that are delivered from deeper waters to the surface ocean. Rising temperatures may contribute to making the tropical oceans even more stratified, leading to increasing nutrient limitation and phytoplankton declines.

Dave Cohen points out we’re caught in a nasty downward spiral:

It is clear that we have a disastrous positive feedback loop at work here, in which warmer surface water supports fewer phytoplankton, which then take up less CO₂ from the atmosphere, which causes the surface water to warm some more due to the greenhouse effect, etc.

Here’s the abstract of the Nature article:

In the oceans, ubiquitous microscopic phototrophs (phytoplankton) account for approximately half the production of organic matter on Earth. Analyses of satellite-derived phytoplankton concentration (available since 1979) have suggested decadal-scale fluctuations linked to climate forcing, but the length of this record is insufficient to resolve longer-term trends. Here we combine available ocean transparency measurements and in situ chlorophyll observations to estimate the time dependence of phytoplankton biomass at local, regional and global scales since 1899. We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of ~1% of the global median per year. Our analyses further reveal interannual to decadal phytoplankton fluctuations superimposed on long-term trends. These fluctuations are strongly correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries.

The National Snow and Ice Data Center (NSIDC) reports the rate of ice loss in the Arctic slowed in the first half of July, primarily because of a change in atmospheric circulation as the dipole anomaly, an atmospheric pattern that dominated the Arctic in June, broke down.

The report explains:

Through much of May and June, high pressure dominated the Beaufort Sea with low pressure over Siberia. Winds associated with this pattern, known as the dipole anomaly, helped speed up ice loss by pushing ice away from the coast and promoting melt.

However, the dipole anomaly pattern broke down in early July. In the first half of July, cyclones (low pressure systems) generated over northern Eurasia tracked eastward along the Siberian coast and then into the central Arctic Ocean, where they tend to stall. This cyclone pattern is quite common in summer. The low-pressure cells have brought cooler and cloudier conditions over the Arctic Ocean. They have also promoted a cyclonic (anticlockwise) sea ice motion, which acts to spread the existing ice over a larger area. All of these factors likely contributed to the slower rate of ice loss over the past few weeks.

In the last few days, high pressure has started to build again in the Beaufort Sea, but whether this will continue remains to be seen.

Still, Arctic sea ice extent at this time is the second lowest ever recorded, as seen in this chart from the Japan Aerospace Exploration Agency website, IJIS.

The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice declined at the fastest rate ever recorded in June, and the average ice extent in June was the lowest in the satellite data record (from 1979 to 2010).

The previous record for the fastest rate of June decline was set in 1999. The linear rate of monthly decline for June over the 1979 to 2010 period is now 3.5% per decade.

Whether or not 2010 will see a new record low set for Arctic sea ice extent depends upon weather patterns. NSIDC explains:

The record low ice extent of September 2007 was influenced by a persistent atmospheric pressure pattern called the summer Arctic dipole anomaly (DA). The DA features unusually high pressure centered over the northern Beaufort Sea and unusually low pressure centered over the Kara Sea, along the Eurasian coast. In accord with Buys Ballot’s Law, this pattern causes winds to blow from the south along the Siberian coast, helping to push ice away from the coast and favoring strong melt. The DA pattern also promotes northerly winds in the Fram Strait region, helping to flush ice out of the Arctic Ocean into the North Atlantic. The DA pattern may also favor the import of warm ocean waters from the North Pacific that hastens ice melt.

June 2010 saw the return of the DA, but with the pressure centers shifted slightly compared to summer 2007. As a result, winds along the Siberian coastal sector are blowing more from the east rather than from the south. Whether or not the DA pattern persists through the rest of summer will bear strongly on whether a new record low in ice extent is set in September 2010.

A report in Science magazine brings together dozens of studies that collectively paint the dismal picture that the deterioration of ocean health is rapidly approaching the point where it may be irreversible.

Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland in Australia and a co-author of the report, says:

This is further evidence we are well on our way to the next great extinction event.

Important conclusions in the report, titled The Impact of Climate Change on the World’s Marine Ecosystems, include:

• The average temperature of the upper level of the oceans has increased more than 1 degree Fahrenheit during the past 100 years, and global ocean surface temperatures in January were the second warmest ever recorded for that month.
• Though the increase in acidity is slight, it represents a “major departure” from the geochemical conditions that have existed in the oceans for hundreds of thousands if not millions of years.
• Nutrient-poor “ocean deserts” in the Pacific and Atlantic oceans grew by 15 percent from 1998 to 2006.
• Oxygen concentrations are dropping off the Northwest U.S. coast and the coast of southern Africa, where dead zones appear regularly. There is paleontological evidence that declining oxygen levels in the oceans played a major role in at least four or five mass extinctions.
• Since the early 1980s, the production of phytoplankton, a crucial part of the food chain, has declined 6 percent, with 70 percent of the decline found in the northern parts of the oceans. Scientists also found that phytoplankton are becoming smaller.

Here’s the abstract:

Marine ecosystems are centrally important to the biology of the planet, yet a comprehensive understanding of how anthropogenic climate change is affecting them has been poorly developed. Recent studies indicate that rapidly rising greenhouse gas concentrations are driving ocean systems toward conditions not seen for millions of years, with an associated risk of fundamental and irreversible ecological transformation. The impacts of anthropogenic climate change so far include decreased ocean productivity, altered food web dynamics, reduced abundance of habitat-forming species, shifting species distributions, and a greater incidence of disease. Although there is considerable uncertainty about the spatial and temporal details, climate change is clearly and fundamentally altering ocean ecosystems. Further change will continue to create enormous challenges and costs for societies worldwide, particularly those in developing countries.

A new paper in the journal Nature titled Robust warming of the global upper ocean concludes that the world’s oceans have been warming more than previously thought – and more than even climate models were suggesting.

RealClimate has posted this graph showing the measured warming as compared to previous and model estimates:

Basically, if the total flux of energy entering the Earth’s atmosphere is greater than energy losses, then has to go somewhere – and that somewhere is mainly the ocean. Other reservoirs for this excess energy, like the land surface or melting ice, are much smaller and are for most purposes negligible.

An article about the study by Jason Socrates Bardi quotes Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colorado (Trenberth was not involved with the study):

Ninety percent of the energy [trapped by increased greenhouse gases] goes into the ocean. It’s important to track this in order to properly understand what is happening in the climate system. If you dump heat in the ocean and it gets moved around and reappears somewhere, it has consequences in terms of the weather patterns.

Another new study in the journal Oceanography titled The Volume of Earth’s Ocean finds the Earth’s ocean is smaller  than the most recent published estimates, by a volume equivalent to 500 times the Great Lakes or five times the Gulf of Mexico. The study’s authors used satellite altimetry data to better measure ocean depth and thus to more accurately estimate the ocean’s volume.

This transcript of a talk by Jeremy Jackson talking about how we wrecked the ocean, posted at The Oil Drum,  may be the saddest thing I’ve ever read.

Jackson describes himself as “an ecologist, mostly a coral reef ecologist.” He talks about the degradation of coral reefs and ocean ecosystems that he’s seen in his lifetime. Scientists used to believe that coral reefs and oceans were infinitely resilient – after all, they’ve survived for untold millennia. But they have succumbed to but a few decades of abuse by humans.

And we got it all wrong. And the reason was because of overfishing, and the fact that a last common-grazer, a sea urchin, died. And within a few months after that sea urchin dying, the seaweed started to grow. And that is the same reef. That’s the same reef 15 years ago. That’s the same reef today. The coral reefs of the north coast of Jamaica have a few percent live coral cover and a lot of seaweed and slime. And that’s more or less the story of the coral reefs of the Caribbean, and increasingly, tragically, the coral reefs worldwide.

Now, that’s my little, depressing story. All of us in our 60s and 70s have comparable depressing stories. There are tens of thousands of those stories out there. And it’s really hard to conjure up much of a sense of well-being, because it just keeps getting worse. And the reason it keeps getting worse is that, after a natural catastrophe, like a hurricane, it used to be that there was some kind of successional sequence of recovery, but what’s going on now is that overfishing and pollution and climate change are all interacting in a way that prevents that. And so I’m going to sort of go through and talk about those three kinds of things.

Jackson does go on to talk about those things. About fish disappearing. About habitat destruction, the sea floor being turned into a desert of mud. About biological pollution and seas becoming poisonous. About warming oceans and dying corals. And about the synergies among these tragedies, the positive feedback loops, that are making the whole of the catastrophe vastly greater than the sum of the parts.

Jackson’s prognosis?

So what are the oceans going to be like in 20 or 50 years? Well, there won’t be any fish except for minnows, and the water will be pretty dirty, and all those kinds of things, and full of mercury, etc., etc. And dead-zones will get bigger and bigger, and they’ll start to merge. And we can imagine something like the dead-zonification of the global, coastal ocean. Then you sure won’t want to eat fish that were raised in it, because would be a kind of gastronomic Russian roulette. Sometimes you have a toxic bloom; sometimes you don’t. That doesn’t sell.

The really scary things though are the physical, chemical, oceanographic things that are happening. As the surface of the ocean gets warmer, the water is lighter when it’s warmer, it becomes harder and harder to turn the ocean over. We say, it becomes more strongly stratified. The consequence of that is that all those nutrients that fuel the great anchoveta fisheries, or the sardines of California, or in Peru, or whatever, those slow down, and those fisheries collapse. And, at the same time, water from the surface, which is rich in oxygen, doesn’t make it down, and the ocean turns into a desert.

The shame of being human is sometimes unbearable.

A recent post reported on scientists’ findings that Greenland’s glaciers are melting from the bottom up. Findings from another team of scientists help explain why: subtropical waters from warmer latitudes are reaching Greenland’s glaciers, driving melting and likely triggering an acceleration of ice loss.

Credit: Jack Cook, Woods Hole Oceanographic Institution

The research team, led by Fiamma Straneo, a physical oceanographer at Woods Hole Oceanographic Institution, found that subtropical waters are reaching Greenland’s glaciers, driving melting and likely triggering an acceleration of ice loss. Melting ice also means more fresh water in the ocean, which could flood into the North Atlantic and disrupt a global system of currents, known as the Ocean Conveyor.

Science Daily quotes Straneo:

This is the first time we’ve seen waters this warm in any of the fjords in Greenland. The subtropical waters are flowing through the fjord very quickly, so they can transport heat and drive melting at the end of the glacier.

The Greenland ice sheet’s contribution to sea level rise over the last decade has doubled due to increased melting and especially to the widespread acceleration of outlet glaciers.

The research teamconducted two extensive surveys during July and September of 2008 in Sermilik Fjord, a 100-kilometer long glacial fjord in East Greenland connecting Helheim Glacier with the Irminger Sea. In 2003 alone, Helheim Glacier retreated several kilometers and almost doubled its flow speed.  Deep inside the fjord, researchers found subtropical water as warm as 39 degrees Fahrenheit (4 degrees Celsius). The team also reconstructed seasonal temperatures on the shelf using data collected by 19 hooded seals tagged with satellite-linked temperature depth-recorders. The data revealed that the shelf waters warm from July to December, and that subtropical waters are present on the shelf year round.

The National Marine Fisheries Service (NMFS ) is considering listing corals as endangered species under the Endangered Species Act.  From the Federal Register:

[W]e initiate status reviews of 82 species of corals to determine if listing under the ESA is warranted.

In October 2009 NMFS received a petition from the Center for Biological Diversity to list 83 species of coral as threatened or endangered under the ESA. The petition asserts that synergistic threats of ocean warming, ocean acidification, and other impacts affect these species and that these global habitat threats are exacerbated by local habitat threats posed by ship traffic, dredging, coastal development, pollution, and agricultural and land use practices that increase sedimentation and nutrient loading. The petition states that immediate action is needed to reduce greenhouse gas concentrations to levels that do not jeopardize these species and requests that critical habitat be designated for these corals concurrent with listing under the ESA.

A species or subspecies is ‘‘endangered’’ if it is in danger of extinction throughout all or a significant portion of its range, and ‘‘threatened’’ if it is likely to become endangered within the foreseeable future throughout all or a significant portion of its range.

NMFS will have to “assess conservation measures to determine whether they ameliorate a species’ extinction risk” and, once critical habitat is designated, ensure that Federal agencies do not fund, authorize or carry out any actions that are likely to destroy or adversely modify that habitat.

Any area may be excluded from a critical habitat designation if the benefits of exclusion outweigh the benefits of designation, unless excluding that area “will result” in extinction of the species. So economic and national security considerations could trump the science.

So much for the “immediate action” that is needed to reduce greenhouse gas concentrations.

It’s nothing but Kabuki theater – highly stylized ritual rather than meaningful action or even honest discussion. action.

New NASA-led research shows that the melt season for Arctic sea ice has lengthened by an average of 20 days over the span of 28 years, or 6.4 days per decade.

The research team discovered that the melt season lengthened the most – more than 10 days per decade – in Hudson Bay, the East Greenland Sea, the Laptev and East Siberian Seas, and the Chukchi and Beaufort Seas.

Earlier melt means more heat can be absorbed by the open water, promoting more melting and later freeze-up dates — more than eight days per decade later in some areas.

Thorsten Markus of NASA’s Goddard Space Flight Center in Greenbelt, Md. explains how the feedback loop works:

This feedback process has always been present, yet with more extensive open water this feedback becomes even stronger and further boosts ice loss. Melt is starting earlier, but the trend towards a later freeze-up is even stronger because of this feedback effect.

Scientists have upped their estimates of the waves that a “100 year event” might produce along the coast of the Pacific Northwest. Their finding heighten concerns for flooding, coastal erosion and structural damage.

Waves crawl up against the lower level of a structure in Neskowin, Oregon, during a storm in January, 2008. (Photo by Armand Thibault, Neskowin)

As recently as 1996, the maximum in ocean wave heights was estimated to be 33 feet. In a study just published online in the journal Coastal Engineering, scientists from Oregon State University and the Oregon Department of Geology and Mineral Industries conclude that the highest waves may be as much as 46 feet and the 100-year wave height could actually exceed 55 feet. Impacts of the bigger waves would dwarf impacts expected from sea level rise in coming decades.

Over the last few decades, increasing wave heights have had 2 – 3 times the impact of sea level rise in terms of erosion, flooding and damage. The largest wave height increases have occurred off the Washington and northern Oregon coasts, with less increase in southern Oregon and nothing of significance south of central California.

Possible causes cited are changes in storm tracks, higher winds, more intense winter storms, or other factors probably related to global warming but also possibly related to periodic climate fluctuations such as the Pacific Decadal Oscillation. What is clear is that waves are getting bigger.

The significant rise in sea level expected over future decades and centuries will only add to the damage already being done by higher waves.

Scientists have found evidence confirming predictions of climate models that higher atmospheric CO2 levels will lead to acidification of Earth’s oceans.

Scientists from the University of South Florida College of Marine Science measured CO2 levels in the northeastern Pacific Ocean. By comparing pH readings from 1991 and from 2006, they found the first direct evidence of acidification across an entire ocean basin, leaving no doubt that growing CO2 levels in the atmosphere are exerting major impacts on the world’s oceans.

If greenhouse gas emissions continue unabated, by the end of the century surface water pH would drop approximately 0.4 pH units and the carbonate ion concentration would decrease almost 50%. This surface ocean pH would be lower than it has been for more than 20 million years. Even if substantial reductions in emissions are made, ocean acidification will continue for hundreds of years to come, which means we are already committed to many centuries of ugly consequences.

The study is published in the American Geophysical Union’s journal Geophysical Research Letters.

The rapid loss of summer ice cover over the Arctic Ocean is creating internal waves in the Arctic waters that could dramatically accelerate the sea ice loss.

That’s what Luc Rainville of the University of Washington’s Applied Physics Laboratory in Seattle and his colleague Rebecca Woodgate report in a study just published in the latest issue of Geophysical Research Letters.

Underwater waves in the Pacific and Atlantic, stirred up by surface winds, keep the oceans from becoming stratified in layers. Near Hawaii, for example, such underwater waves have been measured at depths of up to 200 meters, preventing the ocean from becoming a quiet pool with warm waters on top and colder waters below. The ice-topped Arctic Ocean, on the other hand, is just such a stratified, calm place because sea ice muffles all waves “like a big damper,” as Rainville explains. But that is becoming less the case as summer sea ice melt is opening up ever wider expanses of water.

Unlike any other ocean basin, the Arctic has a lot of very fresh, very cold water on top from melted ice – the cold halocline layer. But below about 100 meters the waters become very salty and slightly warmer. If internal waves become powerful enough to mix these waters, then the warmer surface could accelerate the melting of sea ice.

Here’s the abstract:

The Arctic is generally considered a low energy ocean. Using mooring data from the northern Chukchi Sea, we confirm that this is mainly because of sea ice impeding input of wind energy into the ocean. When sea ice is present, even strong storms do not induce significant oceanic response. However, during ice free seasons, local storms drive strong inertial currents (>20 cm/s) that propagate throughout the water column and significantly deepen the surface mixed layer. The large vertical shear associated with summer inertial motions suggests a dominant role for localized and seasonal vertical mixing in Arctic Ocean dynamics. Our results imply that recent extensive summer sea ice retreat will lead to significantly increased internal wave generation especially over the shelves and also possibly over deep waters. This internal wave activity will likely dramatically increase upper layer mixing in large areas of the previously quiescent Arctic, with important ramifications for ecosystems and ocean dynamics.

The National Snow and Ice Data Center reports temperatures over the Arctic this winter have so far been unusually warm. Paradoxically, this could affect the winds that push the ice out of the Arctic to warmer waters, helping to retain some of the second- and third-year ice through the winter and potentially rebuild some of the older, multiyear ice that has been lost over the past few years. However, NSIDC cautions it is not known whether these weather conditions will persist through the winter or what the net effect will be.

As the chart below shows, Arctic sea ice extent has been declining steadily over the past 30 years.

Arctic sea ice is now tracking at or near record lows.

A new report warns that by 2100 the sea level will rise by up to 1.4 meters — far exceeding the 0.59 meter rise predicted only two years ago by the IPCC in its 2007 4th Assessment Report.

SCAR scientists said that the IPCC underestimated grossly how much the melting of the Antarctic and Greenland ice sheets would contribute to total sea-level rises.

The report found that the hole in the ozone layer caused by the release of CFC (chlorofluorocarbon) gases has cooled temperatures and shielded most of Antarctica from global warming. Measures to control CFC gases will begin to “heal” the hole in around 50 to 60 years, leading to additional warming of about 3.0 Celsius (5.4 Fahrenheit) by century’s end. Even with the ozone hole, Antarctic ice sheets are already starting to melt.

The study also report the powerful Antarctic Circumpolar Current – which, by keeping warm ocean waters away from Antarctica enables that continent to maintain its huge ice sheet – has been warming faster than the global ocean as a whole. This is disrupting the region’s ecosystems, including enabling invasive species to compete with and replace native Antarctic inhabitants. That process has already begun on the Antarctic Peninsula. Sea ice loss and ocean acidification are directly affecting wildlife, and could reduce Antarctica’s rich biodiversity. Tiny krill at the bottom of the food chain have declined significantly, and in some areas Adelie penguin populations have dropped due to reduced sea ice and prey.

The report, Antarctic Climate Change and the Environment (warning – 20 MB) was prepared by the more than 100 scientists composing the Scientific Committee on Antarctic Research. The press release is available, as is a summary of the study’s top ten points.

I would argue that, from a practical perspective, we almost have a seasonally ice-free Arctic now, because multiyear sea ice is the barrier to the use and development of the Arctic.

That’s what David Barber, Canada’s Research Chair in Arctic System Science at the University of Manitoba, reported on returning from an expedition that tried and pretty much failed to find a giant multiyear ice pack that was supposed to be in the Beaufort Sea. Instead he found only hundreds of miles of  “rotten ice” – 20-inch thin layers of fresh ice over small chunks of older ice.

An article in RedOrbit quotes Barber:

From a practical perspective, if you want to ship across the pole, you’re concerned about multiyear sea ice. You’re not concerned about this rotten stuff we were doing 13 knots through. It’s easy to navigate through.

The 2009 ice cover was the third-lowest on record, after 2007 and 2008. Joseph Romm has posted this graphic at Climate Progress:

According to Barber, the ice is currently being melted both by rays from the sun as well as from below by the warmer water. Scientists have also been seeing more cyclones, which become stronger as they pick up heat from the warmer water. The cyclones produce waves that break up ice sheets and also dump large amounts of snow, which provides a form of insulation and keeps the ice sheets from thickening.

Many scientists now expect the North Pole to be void of ice during summers by 2030 at the latest.