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2015 SkS Weekly News Roundup #11A

Posted on 11 March 2015 by John Hartz

Arctic sea ice dwindling toward record Winter low

While balmy hints of spring melt piles of snow in the eastern U.S., the impending end of winter marks peak season for Arctic sea ice. But this year, that winter maximum area is currently on track to hit a record low since satellite records began in 1979.

What that low-ice mark means for the spring and summer melting seasons is unclear, but the milestone would still be notable in the global warming-fueled cycle of Arctic sea ice decline.

“The fact that we're starting the melt season with low — maybe record low — winter extents cannot be good,” Jennifer Francis, a Rutgers University Arctic researcher, said in an email.

Arctic Sea Ice Dwindling Toward Record Winter Low by Andrea Thompson, Climate Central, Mar 11, 2015

Climate deniers and other pimped-out professional skeptics: The paranoid legacy of Nietzsche’s “problem of science”

Looking back years later at his first major work, “The Birth of Tragedy,” the philosopher Friedrich Nietzsche gave himself credit for being the first modern thinker to tackle “theproblem of science itself,” for presenting “science for the first time as problematic and questionable.” Dude! If the perverse German genius could only have known how far “the problem of science” would extend in our age, or to what ends his critique of Socratic reason would be twisted. He might be delighted or horrified in equal measure – one thing you can say for Nietzsche is that his attitudes are never predictable – to see how much we now live in a world he made, or at least made possible.

It may seem like a ridiculous leap to connect a scholarly work about ancient Greek culture published in 1872 with the contemporary rise of climate denialism and other forms of pimped-out skepticism, in which every aspect of science is treated by the media and the public as a matter of ideological debate and subjective interpretation. I’m not suggesting that the leading climate skeptics, corporate shills and other professional mind-clouders seen in Robert Kenner’s new documentary “Merchants of Doubt” have read Nietzsche and based their P.R. playbook on what he would have termed an appeal to the Dionysian impulse, the primitive, violent and ecstatic forces that lie below the surface of civilization. (You can see two prime specimens at the top of the page: James Taylor of the libertarian-oriented Heartland Institute and longtime oil lobbyist William O’Keefe, who now heads the George C. Marshall Institute, a climate-obsessed right-wing think tank.) They didn’t have to. That impulse is baked into human culture at this point, and it can be exploited without entirely being recognized or understood.

Climate deniers and other pimped-out professional skeptics: The paranoid legacy of Nietzsche’s “problem of science” by Andrew O'Hehir, Salon, Mar 7, 2015

Earth entering new era of rapid temperature change, study warns

The rate of climate change we're experiencing now is faster than at any time in the last millennium, a new study shows.

Researchers compared how temperature varied over 40-year periods in the past, present and future, and concluded that the Earth is entering a new "regime" of rapid temperature change.

We're already locked into fast-paced changes in the near future because of past emissions, the researchers say.

That means we'll need to adapt to minimise the impacts of climate change, even if greenhouse gas emissions are cut substantially.

Earth entering new era of rapid temperature change, study warns by Robert McSweeney, The Carbon Brief, Mar 9, 2015

Explainer: how countries could come to a global climate deal in 2015

At the end of this year, 196 countries from around the world will meet in Paris for the first attempt to reach a global deal on climate action since the much-hyped climate talks in Copenhagen in 2009. Hope is building that Paris will see an agreement to reduce greenhouse gas emissions beyond 2020, and ultimately keep global warming to below 2C.

In the lead-up to the meeting, countries will submit intended contributions to a global climate deal, known as INDCs, or Intended Nationally Determined Contributions. These may be targets and baselines (for instance, greenhouse gas emissions 40% below 1990 levels by 2030), but may also take other forms.

Essentially, an INDC is a public pledge from a country on how it plans to play its part in post-2020 collective action on climate change.

It is hoped that all countries that intend to publish an INDC will do so well in advance of the upcoming climate conference in Paris in December 2015. The secretariat to the UN’s climate change body is to produce a report on the total effect of INDCs submitted by 1 October 2015.

To date, Switzerland and the European Union have submitted INDCs and the majority of country submissions are expected before September.

But how will these INDCs fit into a global climate deal?

Explainer: how countries could come to a global climate deal in 2015 by Anita Talberg and Malte Meinshausen, The Conversation US Pilot, MAr 11, 2015

Fla. scientist told to remove words ‘climate change’ from study on climate change

By late January of this year, Elizabeth Radke figured she was pretty much done with Florida. She had already graduated from the University of Florida, where she had gotten her PhD in epidemiology. She had moved from the Sunshine State to the Washington area, where she took a job at Arlington County’s public health department. And a paper from her time there, which looked at how climate change in Florida had affected ciguatera — a commonly reported marine food-borne illness — was getting closer to publication.

But then, on Jan. 27, a message popped into her inbox. Subject: “Paper Review.” And Radke realized she wasn’t through with Florida yet. In fact, she was about to get dragged into what has now become a national scandal over an alleged “unwritten policy” among some Florida state environmental offices that forbids the use of terms such as “climate change” and “global warming” in official correspondence.

Fla. scientist told to remove words ‘climate change’ from study on climate change by Terrence McCoy, Washington Post, Mar 10, 2015

Friction means Antarctic glaciers more sensitive to climate change than we thought

One of the biggest unknowns in understanding the effects of climate change today is the melting rate of glacial ice in Antarctica. Scientists agree rising atmospheric and ocean temperatures could destabilize these ice sheets, but there is uncertainty about how fast they will lose ice.

The West Antarctic Ice Sheet is of particular concern to scientists because it contains enough ice to raise global sea level by up to 16 feet, and its physical configuration makes it susceptible to melting by warm ocean water. Recent studies have suggested that the collapse of certain parts of the ice sheet is inevitable. But will that process take several decades or centuries?

Friction Means Antarctic Glaciers More Sensitive to Climate Change Than We Thought, Caltech, Mar 10, 2015

Greenland reels: climate disrupting feedbacks have begun

Greenland is warmer than it has been in more than 100,000 years and climate disrupting feedback loops have begun. Since 2000, ice loss has increased over 600 percent, and liquid water now exists inside the ice sheet year-round, no longer refreezing during winter.

Melt and ice loss dynamics from Greenland are far more complicated than we understood just a few years ago. New discoveries have been made that add large uncertainties as to exactly how fast ice melt and iceberg discharge will increase in the future. Over the last decade, continued research into the rate of ice loss in Greenland has downplayed any rapid acceleration of current melt rates. New discoveries could be changing our understanding of this last decade's work.

Greenland Reels: Climate Disrupting Feedbacks Have Begun by Bruce Melton, Truthout, Mar 5, 2015

How ambitious is the EU's offer to the Paris climate change talks?

The EU has set out its contribution to a new international climate change agreement, in advance of talks in Paris this December.

The EU pledge, known as an Intended Nationally Determined Contribution (INDC), was submitted to the UN Framework Convention on Climate Change (UNFCCC) on Friday and is the second official submission, following first-placed Switzerland.

Carbon Brief runs through the key points from the EU's offer and summarises reactions to the announcement.

How ambitious is the EU's offer to the Paris climate change talks? by Simon Evans, The Carbon Brief, Mar 10, 2015

Merchants of doubt about global warming hope to strike back

Before the release this Friday of the documentary "Merchants of Doubt," S. Fred Singer sought the advice of nearly 30 climate skeptics about their chances of halting the movie and whether he should sue Naomi Oreskes, who co-authored the book on which it's based.

"Has she finally gone too far?" asked Singer.

The discussion is outlined in a chain of emails initiated last fall by the 90-year-old physicist, who is featured in the film for his work questioning the amount of influence people have on rising temperatures. His request reached a mix of academics and others who have been mostly antagonistic toward mainstream climate findings. ClimateWire obtained the emails from a source who received them as a forwarded message.

Merchants of Doubt about Global Warming Hope to Strike Back by Evan Lehmann and ClimateWire/Scientific American, Mar 9, 2015

People's climate march In London draws huge crowd, including Russell Brand 

More than 15,000 protesters gathered in London on Saturday for a climate change march, which is to end with a rally outside Parliament. Activist Russell Brand is scheduled to deliver speeches near Westminster. The event is one of around 2,500 around the world calling for tougher action on climate change.

Caroline Lucas, Green Party MP for Brighton Pavilion, said: "Climate change is here, visible, and we know it's time to act. "It's time to stand up against those determined to burn the last drops of oil and gas and be confident in our power to build a better future. In coming together we help build the climate movement and inspire others to join us."

She added: "Young people, parents, grandparents, those new to the movement and veteran campaigners, we can all play our part, demanding our government legislate for the common good and not short-term vested interests. We're raising our voices for a year of climate action the UK and the world has never seen before."

People's Climate March In London Draws Huge Crowd, Including Russell Brand by Paul Vale, The Huffington Post, Mar 7, 2015

Sao Paulo’s reservoirs feel pinch of failed wet season

Sao Paulo, in the wake of another dry summer in southeast Brazil, continues to struggle with a multi-year drought. The city has implemented water rationing, but reservoir levels still hover at perilously low levels and will likely remain there or drop even further as the usual rainy season ends.

What is traditionally the rainy season runs from September through April and brings the most rain from December through February. Yet for the second year in a row, rains have failed to fully materialize. The 2013-14 wet season saw rainfall deficits of nearly 16 inches and this year, though not quite as bad as last, is running up to 8 inches below normal according to data available from the International Research Institute for Climate and Society.

Sao Paulo’s Reservoirs Feel Pinch of Failed Wet Season by Brian Kahn, Climate Central, Mar 10, 2015

The UN’s climate change body looks inward to move ahead

When there’s a report in the news about the latest science on climate change, the source is very often the United Nations Intergovernmental Panel on Climate Change.

This body plays a very important role in global climate change policy around the world. Its reports, five of which have been published since 1990, enjoy a degree of credibility that renders them influential for public opinion. And more impoClimate Central, MAr rtant, the reports are accepted as the definitive source by international negotiators working under the United Nations Framework Convention on Climate Change (UNFCCC).

Now, though, the IPCC is at a crossroads. Its Fifth Assessment Report (AR5) – the latest of its comprehensive studies published every five to seven years – is complete and largely successful. But, like many large institutions, the IPCC has experienced severe growing pains. Its size has increased to the point that it has become cumbersome. It sometimes fails to address the most important issues.

And most striking of all, it is now at risk of losing the involvement of the world’s best scientists due to the massive burdens that participation entails.

The IPCC is contemplating organizational changes aimed at engaging more scientists and boosting representation from different countries. Because it has so much influence, these changes matter to more than just climate scientists.

The UN’s climate change body looks inward to move ahead by Robert Stavins, The Conversation US Pilot. Mar 9, 2015

Unlike temperatures, climate change deniers are falling fast

The first big item is that solar physicist Wei-Hock “Willie” Soon appears to be firmly in the pocket of fossil fuel interests. He is not a climate scientist, but he’s published papers linking changes in the Sun’s output to Earth’s temperature, claiming that it’s the Sun heating us up, not human-generated carbon dioxide.

His claims about the science have been pretty thoroughly torn apart by climate scientists dating back as far as 2003 and have also been refuted on the Skeptical Science site as well. Despite the claims, the Sun’s output has marginally decreased in recent years, while temperatures on Earth go up.

Greenpeace obtained FOIA documents showing Soon received more than $1 million of funding from Big Oil over the past few years. A funding source isn’t necessarily damning, except for two things. One is that Soon neglected to mention his funding in nearly a dozen papers he’s published, and that is a huge, huge, no-no in science. If you have a potential conflict of interest, you report it.

Unlike Temperatures, Climate Change Deniers Are Falling Fast by Phil Plait, Bad Astronomy, Slate, Mar 11, 2015

Utilities wage campaign against rooftop solar

Three years ago, the nation’s top utility executives gathered at a Colorado resort to hear warnings about a grave new threat to operators of America’s electric grid: not superstorms or cyberattacks, but rooftop solar panels.

If demand for residential solar continued to soar, traditional utilities could soon face serious problems, from “declining retail sales” and a “loss of customers” to “potential obsolescence,” according to a presentation prepared for the group. “Industry must prepare an action plan to address the challenges,” it said.

The warning, delivered to a private meeting of the utility industry’s main trade association, became a call to arms for electricity providers in nearly every corner of the nation. Three years later, the industry and its fossil-fuel supporters are waging a determined campaign to stop a home-solar insurgency that is rattling the boardrooms of the country’s government-regulated electric monopolies.

Utilities wage campaign against rooftop solar by Joby Warrick, Washington Post, MAr 7, 2015

Why fresh water shortages will cause the next great global crisis

Last week drought in São Paulo was so bad, residents tried drilling through basement floors for groundwater. As reservoirs dry up across the world, a billion people have no access to safe drinking water. Rationing and a battle to control supplies will follow 

Why fresh water shortages will cause the next great global crisis by Robin McKie, The Guardian, Mar 7, 2015

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Comments 1 to 33:

  1. Thanks again for these, especially "Friction means Antarctic glaciers more sensitive to climate change than we thought "

    So is anyone putting this together with other recent findings of faster-than-expected movement of various icesheets to come up with new estimates for the range of possible levels of slr we may expect by the end of the century and beyond? It would seem to me that such a project would be most important for policy makers (and for anyone living anywhere near the ocean).

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  2. Here are a few clarifying points regarding the first arcticle "Arctic sea ice dwindling toward record Winter low".

    The image in the article from NSIDC does indeed show the ice extents well below the average maximum and below the +- 2% standard deviation shaded area. However, the maximum ice extent of 14.522 sq km appears to have occurred on Feb 26. Perhaps the article is referring to the extent on March 12 when the average line is at its maximum.

    However, the NSIDC webpage the image can be found on also includes a Chartic Interactive Sea Ice Graph that allows the user to see graphs of all of the previous years. And many previous years reached their maximum extents well after March 12. And some years there were early rapid declines in Arctic extents that were followed by expansion to that later maximum.

    A more important point is that the extent reported by NSIDC is for at least 15% sea ice coverage. Temporary currents or wind conditions could pack brocken up ice into a smaller areas that could expand when current or wind conditions change.

    So, the current Artcic Sea Ice extent is indeed well below any previous values in the NSIDC set of reported years. However, a lot can change in a short time. And the most recent extents are not continuing the rapid decline.

    Time will tell what the resulting summer minimum will be. It may even be that the winter maximum extent of 15% or greater sea ice will exceed the 14.522 sq km that was measured on Feb 26.

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  3. Just a question-no agenda.  I hear various things.  Is Antarctic ice increasing, decreasing, or staying the same.  The article seems to be definitive that Arctic sea ice is decreasing.

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  4. Carbon sinks weaking

    This seems like a pretty important development.

    curiouspa, the north and south poles are polar opposites in more than one way--the Arctic is an ice-covered ocean (mostly) surrounded by continents; the Antarctic is an icesheet-covered continent surrounded by ocean.

    You tell _me_ what you think the result of heating each of these up a bit would likely be. No agenda...just a question.


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  5. Here's the link to a pdf of the original study on failing carbon sinks.

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  6. OPOF @2 - There are a range of Arctic sea ice metrics, which peak at different values on different dates. I've been covering a range of them today, to coincide with The Economist's Arctic Summit:

    The "15% extent" ones are currently at their lowest level for the date by a considerable margin. Cryosphere Today area is also at a record low today, but only just.

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  7. curiouspa - You might want to look (and continue any discussion) on this thread. Short answer - Antarctia is losing ice but there is a statistically significant increase in the sea ice around it. Just dont fall for idea that this somehow offsets arctic ice loss (it is small by comparison and has little climate impact since it occurs in winter). In particular, you need to look at why these things are happening. The skeptic argument is that its getting warmer in arctic but cold in Antarctic so cant be CO2/anything to worry about. Not true. 

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  8. For wili,

    I think if both poles were heated about the same amount, both would lose a similar amount of ice.  The Arctic would lose sea ice and the Antarctic would lose an equal amount of land and sea ice.  

    I'm not excluding that there can be variations with net overall global loss.  I just want to know the facts-simply stated- is Antarctica gaining or losing ice?  It may be there is overall loss of ice but increase in sea ice only.  The only satellite data I can find is sea ice since 1979.  Thanks.

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    Moderator Response:

    [JH] If you enter "Antarctica" into the SkS search box, you will find a wealth of information about what's going on there.

  9. curiouspa - please see the link I provided on Antarctica sea ice for why Antarctica sea ice is expanding - it is paradoxical on first glance because sea temps are rising. However for overall Antarctic ice loss see here. Measurement is done with GRACE satellite or from height of ice sheet. As to assymetry between poles consider:

    South pole is on land at around 2000m altitude - North pole in sea as is most of Arctic ice with exception of Greenland.

    Antarctica is isolated to some extent from rest of planet by circumpolar current and winds. Arctic weather is influenced by air masses from lower latitudes.

    Ozone depletion also plays a part in Antarctic radiative balance.

    Sea ice in Arctic is year round phenomena. Because sea ice is at lower latitudes in Antarctica, (higher latitudes are covered by land)  most of it is completely melted out in summer.

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  10. curiouspa @8, the gain in Antarctic sea ice is less than the loss in Antarctic land ice in terms of volume.  The loss in Arctic land plus sea ice is greater than the loss in Antarctic land plus sea ice, a fact partly due to the fact that the Arctic has warmed more than the Antarctic (for well known reasons the explanation of which is partly explaineded by scaddenp @9).  The Southern Ocean has been warming so that the Antarctic sea ice has grown even though the water on which it floats has been warming.  That is due to the fact that:

    1)  increased rainfall due to the warming has resulted in fresher surface water, that freezes at a higher temperature; and

    2)  increased windspeed due to warming results in ice being pushed further north before it melts, with the open water created by the export of ice refreezing because it is further south.

    Your intuition that "... if both poles were heated about the same amount, both would lose a similar amount of ice" is, therefore, incorrect (quite aside from the fact that the Arctic has been heated more).

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  11. scaddenp-thanks.

    I looked over links provided.  Consensus seems to be that overall Antarctic ice on land is decreasing based on loss of thickness.  Sea ice is increasing a little, and uncertain at this point why.

    One statement I saw "when land ice melts and flows into the oceans global sea levels rise on average; when sea ice melts sea levels do not change measurably"

    Does that imply that expected sea level rise is mainly from land ice loss, such as Greenland ice loss in the Arctic?  Is the loss of Arctic sea ice a direct contibutor to sea level rise, or only secondarily thru loss of albedo and resultant ocean warming? 

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  12. Jim Hunt@6,

    Thanks for the link to the extra information.

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  13. "uncertain at this point why." which should be understood as multiple factors at play with uncertainty over which ones are the most important, as opposed to "havent a clue what's going on".

    Actual sources of sealevel rise are land ice loss, thermal expansion and land water storage change. ( see here for article on this). I dont think it is totally accurate to say sea ice change makes no difference but it is miniscule compared to the others.

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  14. @ scaddenp

    As you well know, there is also the matter of isostacy to consider - especially at the local level. It is a standard (great white?) con trick to talk about there being a drop in measured MSL at such-and-such a place, and present this as a supposed counter argument to concerns over sea level rise. 

    In many areas that, until the geologically recent past, were covered by the Fenno-Scandian or Laurentide Ice Sheets, the crust is still physically rebounding following the loss of giga tonnes (terra tonnes?) of ice since the days of the last glacial maximum.

    What I don't know* is whether or not isostacy has any overall meaningful impact on global sea level. Any ideas? (*That sentence should really have commenced... "Amongst the unimaginably vast number of things I don't know, is whether...)


    @ curiouspa #

    " ... Is the loss of Arctic sea ice a direct contibutor to sea level rise? ..."

    I you look up "Archimede's Principle", especially the corollary regarding a body that is floating on a fluid, you should be easily able to work the answer out for yourself.


    cheers  bill f

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  15. billthefrog @14, melting of sea ice does raise sea level.  The reason is that the ice, being fresh, is less dense than the salt water on which it floats.  As a result, it floats higher than it would if floating in fresh water.  The difference in the amount of ice above water between the ice floating and salt water and equivalent ice floating on fresh water is excess volume that contributes to sea level rise.  The total melting of all sea ice including floating ice shelves would raise sea level by about 4 cm.  (Paper)

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  16. What should we make of the FOUR cyclones now swirling around the Western Pacivic and over Australia? Pam just hit cat 5 status.


    "Angola floods kill at least 35 children and 27 adults".

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  17. In terms of global ice changes I think looking at the rough percentages helps;

    • Antarctic land ice: 90%, decreasing
    • Greenland land ice: 9%, decreasing
    • All other ice: 1%, decreasing

    So yes, it is possible to find examples where ice is increasing (e.g. Antarctic sea ice & individual glaciers), but those are a subset of 1% of the planet's total ice... and even that 1% is overall in decline.

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  18. @ Tom Curtis #15

    Hi Tom,

    Yep, I realise there is a slight density difference between sea water and fresh water, with sea water being in the order of 2.5% - 3% more dense.

    One needs to look closely at the figure of ~4 cms additional SLR that Prof Peter Noerdlinger is talking about. This, however, is not based solely on a total melt out of sea ice (i.e. ice that has formed at sea).

    Instead, he has also included the contribution from ice shelves (ie ice that has formed on land and has subsequently flowed out onto the sea surface).

    From figures available on Cryosphere Today, the annual average area of global sea ice (NH + SH) is 19 million sq kms. If one takes an average thickness at a reasonably generous 2 metres, and somehow smears this over the approx 360 million sq kms of ocean surface, that would give us an ice coating of just over 10.5 cms.

    As the density of ice is around 92% of fresh water, this would in turn equate to a fresh water "film" of some 9.71 cms in depth floating on top of the denser sea water below. Comparing densities of fresh and salt water, the same mass of salt water would have been about 9.47 cms deep.

    Obviously, the difference between these is only in the order of 2.5mm, and that's why I ignored this second (third?) order effect in my earlier response to curiouspa.

    Ice shelves are a different matter all together, and I am somewhat surprised by the fact that they have been lumped together in this fashion. Massive chunks of ice coming down from the Jacobshavn Isbrae, from Petermann, Pine Island or Thwaites, or, more spectacularly from things like the Larssen B Shelf most assuredly do contribute to overall SLR.

    cheers     bill f

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  19. curiouspa, besides following JH's advise, consider that seasons still exist. Then think somemore. In particular, consider what happens to the saltiness of the surface water around Antartcica after a bunch of that landbased ice sheet melts during the summer, and what are the likely, predictable consequences of that for ice extent during the next winter.

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  20. Bill - on time scales of one to two hundred years, isostacy doesnt figure much in the calculation.

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  21. @ scaddenp #20

    Yep, that's what my gut-feel says - it's just that I've never seen anything formal, and certainly don't expect to be right about anything just on gut-feel.

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  22. Tom @ 10 … “increased rainfall”. More likely fresh water run-off from increased  ice sheet mass loss?

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  23. Riduna @22, I have no doubt that fresh water runoff from ice sheets contributes.  Never-the-less, the theory as explained in the literature was (from memory) increased surface fresh water from precipitation.

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  24. February GIS L-OTI is out: 0.79C.  That's the second warmest February (1998) on record and the 7th warmest month overall.  The last 12 months are now the warmest (0.71C) on record, beating Feb 2014 - Jan 2015 (0.68C).  

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  25. Jim Hunt@6

    The Arctic ice extent reported by NSIDC has held fairly steady for the past several days rather than continuing the stead decline that occured from Feb 25 to March 8. And the value for March 13 is a notable increase of the extent. However, it is still well below any of the previous years in the record.  A temporary condition seems to have been producing the reduction of the 15% sea ice extent. Maybe an event was pushing areas of broken up ice into a tighter packing.

    I appreciate that the 15% and 30% sea ice extents are important for navigation. So I understand why the systems are set up to provide that information on a daily basis. And I can see the logic and importance of monitoring the trend of changes in ice extent and trying to develop better ways to predict upcoming ice extents. However, I believe an evaluation of the total ice area, meaning that in areas that are not solid ice only the amount of ice area would be calculated as part of the total ice area would eliminate fluctuations of extents of broken up ice that could occur. Is the Cryosphere Today area calcualted that way? I only quickly reviewed the website and could not see any obvious indication of how he ice area in the chart was determined.

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  26. OPOF @25, sea ice area is also reported, and shows a similar dip to that in sea ice extent:


    It is, however, not at record low values indicating that the ice is more compact than in 2007.

    To be quite honest, however, the minimum variation in extent and area does not occur until mid May.  Until that point, any difference between different years can be washed out by occurrences in mid May - ie, they are almost irrelevant for predicting September minimums.  So while it is interesting that sea ice extent is at record low values, and sea ice area is at near record low values for the time of year, that is still consistent with a September sea ice extent greater than last year, and probably will not result in a new September sea ice minimum.

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  27. Thanks for the additional pointers again Tom,

    What you mention about what happens in May being a more significant indication of what the minimum extent will be than what is happening at this time of year is very easy to see in the NSIDC record of 2012. That year had a large Arctic sea ice extent into May.

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  28. @ OPOF

    Tom C has already provided a link to the Arctic Roos (Regional Ocean Observing System) operated by the Nansen Environmental & Remote Sensing Centre in Bergen, and this shows side-by-side area/extent graphs. (There is a need to exercise a little care, as Arctic Roos posts 2 pairs of charts. One pair shows each year from 2008 onward, but the other pair has 2008 replaced by 2007.)

    If you want to play about with some numbers yourself, I would look at the NSIDC monthly records. As will be obvious from the link, there is an individual file for each month. The monthly average extent and area numbers for every year from 1979 onwards are contained therein.

    You correctly observed that need for measurement of sea ice extent is rooted in history. Basically it would give ship captains an idea of where to avoid. The NSIDC FAQ gives a good description of the difference between area and extent, and also describes (in outline) the calculations involved.  

    cheers   bill f

    P.S. I have just noticed the shocking apostrophe typo in the final paragraph of my post #14. Am now on the way to turn myself in to* the punctuation police, who will, I feel sure, cut off my privileges. (*As opposed to "turning myself into the punctuation police".)

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  29. billthefrog, the Arctic Roos graphs to which I linked not only use different years on the upper panels compared to the lower panels, but also use a different measure of sea ice extent on the right hand upper and right hand lower panels.  The do use the same measure of sea ice area on the left hand upper as on the left hand lower panels, however. 

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  30. Hi Tom,

    I'm afraid I don't know what you mean when you say the Arctic Roos Extent Graphs use different measures.

    The top RHS graph shows extent for each year from 2008 onwards.

    The lower RHS graph shows extent for 2007, 2009-15 and the 1979-2006 average (+/- 1 stnd dev)

    I've pasted these into Powerpoint in order to run a blink comparator, and that's the only difference I'm seeing.

    Could you be a bit more specific please? (NB At this point, my wife would take great pleasure in pointing out that I once failed to find a pair of tracksuit bottoms in my kit bag. As the bag was otherwise empty, this speaks volumes regarding my powers of observation.)


    cheers bill f

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  31. billthefrog @30, sorry, my error.  It appears my powers of observation are no better than yours ;)

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  32. OPOF @25 - The assorted area measures are based on a grid of sea ice concentration numbers. If a particular grid "square" has 75% concentration then 0.75 x the area of the grid "square" are added to the total. Sum over the entire Arctic.

    "Wipneus" at the Arctic Sea Ice Forum calculates the area/extent metrics for a wide variety of satellites and algorithms. For an overview see:

    Volume is of course the best measure of the "amount" of sea ice left, but it is notoriously difficult to measure!

    Bill @30 - Different folks use different satellites, different "algorithms" and different "masks" when doing their sums.  On top of which the Scandinavians include the Great Lakes and other obscure places in their "Arctic" calculations!

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  33. Climate change is not a technical problem..  We all know what needs to be done.  It is a political problem...  PPCT....  who Pays the Piper Calls the Tune.  As long as rich vested interests are allowed to buy our politicians, they will tell them what to do.

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    Moderator Response:

    [JH] Please do not use the SkS comment threads to promote your own blog post. Doing so is akin to advertising.

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