Arctic sea ice minimum 2012…

By popular demand, a thread devoted to the continuing decline of Arctic sea ice, and a potential new record minimum this year. As before, the figures are hot-linked and will update day-by-day.

JAXA Sea ice extent:

Cryosphere Today sea ice concentration (interactive chart):

Estimated sea ice volume from UW PIOMAS (updated every month):

Other links: Tamino, the very informative and detailed Neven’s sea ice blog , and some interesting predictions from Gareth Renowden.

195 comments on this post.
  1. prokaryotes:

    Sea Ice Decimated, Huge Storm May Have Broken Arctic Ocean Stratification

    Rate of Arctic summer sea ice loss is 50% higher than predicted

    New satellite images show polar ice coverage dwindling in extent and thickness

  2. Unsettled Scientist:

    derek, I’m not sure which specific plot you are referring to but I think I can answer your question anyways. The time scale needed to separate the signal from the noise is a dependent upon the dataset, mathematically speaking it’s a property of the dataset and not a property of the climate. Certain metrics, such as global mean temperature, will have a different timescale on which the signal overcomes the noise than other metrics, like Greenland ice mass. It just so happens that for global mean temperature you need about 15 years on either side of a point to identify the trend.

    For a much better explanation check out Tamino’s blog post: Fifteen

  3. Thomas:

    derek: I’m going to give a different answer than unsettled.
    There are two sorts of questions that could be answered. One is if you have only a single
    time series how long must it be accumulate significant enough statistics to establish a trend. That was what Unsettled answered. A second question is: starting at some arbitrary sea ice state, you impose a now constant climate, you would expect the ice state to asymptotically approach an equilibrium state. What is the time scale of that adjustment? I remember that having been discussed at RC at couple of months back, and the claimed timescale was roughly three years. That is of course a different experiment from that of trying to establish a trend in a presumably changing climate. Maybe one of the contributors to that discussion can chime in?

  4. prokaryotes:


    Compilation of recent findings and the science.

  5. dingibily:

    All — There are excellent Arctic ice graphics, animations, and interactive viz tools on the iPad/iPhone App “Climate Mobile,” free at the App store. (Best used on an iPad.) Click on the Interactive Sea Ice Tracker for lots of options, including derived “thickness” from PIOMAS volume and NSIDC area. Very interesting pattern there. One thing that stands out is that PIOMAS volume trend is not consistent with other data sets. Just how thin can the ice get before it disappears?

  6. john byatt:

    #24 “AlaskaHound@8 wrote : “Should reach the same level seen in 1884 by August 23rd:)”

    A bit cryptic that, but where would one actually find the data from 1884 to compare ? I’m dubious, to say the least…”

    I think you will find that Alaska hound was referring to a Goddard post with a newspaper clipping as his evidence,

    will not link that garbage site.

  7. observer:

    @46 Kevin Stanley:

    “I’m not sure what the different colors indicate, but my best guess is that the darkest blue/green is open ocean, white is solid ice, and intermediate colors indicate some concentration of ice, but not solid.”

    The white color means “unexplored”. The map is from 1898 and you can find a version with a better resolution here.

    So, if people like AlaskaHound try to say that the ice concentration in 1884 was nearly the same as today, this would be rather silly, as most of the Arctic wasn’t even explored back then.
    The light blue color in the map indicates the southern limit of drift ice. So nobody back then knew the real extent of the Arctic Sea Ice at a given time. We can only try to derive estimates by putting together various observations. But those estimates would have huge error bars and when people do create such estimates, it indicates a much more bigger Arctic Sea Ice Extent than today.

  8. NeilT:

    I recall reading about the NW passage, let alone the rest of the Arctic, a few years back. Yes, prior to 1906 the passage had been made a few times. The ships which attempted it were destroyed or icelocked and the journeys were completed by dog sled…..

    I say 1906 because the 1903 Amundsen expedition took 3 years of jumping through leads in the summer breakup before it could get through.

    Idiots will believe anything and Goddard and Watts spread just about anything for them to believe.

    Yes, AlaskaHound I think that comment was idiotic. Or at best trollish.

  9. Chris Reynolds:

    Derek, Unsettled Scientist, Thomas,

    In terms of a cooling:

    The timescale of response of Arctic sea ice area/extent is a mere matter of years. This is because the winter growth of new ice is a very fast process. Over the winter the limiting factor for thickening of new ice is not really time, it’s the thermal conductivity of the ice. The thicker the ice gets the better it insulates atmospher from ocean. And thickening of first year ice across much of the Arctic is a matter of sea water freezing onto the base due to heat being conducted away from the ice ocean intefacte driven by the intense cold above the ice.

    The timescale of response of older multiyear ice is a slower process. Multiyear ice is mainly thickened by compression from the sides causing ridging. There is a mecahnical system involved in this. The transpolar drift draws ice from Siberia (creating open water which freezes in the winter making new ice) and crushes it against the north of the Canadian Arctic Archipelago and Greenland. This crushed ice is aged both by remaining off Greenland and the CAA, and by being cycled in the Beaufort Gyre ‘flywheel’ after which it gets drawn back into the transpolar drift. So because of the years involved, multiyear ice grows far more slowly than first year.

    In terms of a warming:

    The response of the ice is rapid, but the dynamics of the ice pack play a moderating role. Since satellite observations started in 1979 the ice pack has transitioned from a mainly multi-year mass, to mainly first year. This process is slow because it takes time to remove the multi-year ice and thin it down. Open water formation efficiency plays a role in this. Say in a given area the ice loses 1m thickness between March maximum and September minimum – with a starting ice pack of 3m thick (i.e. in the 1980s) there is no way that open water will be exposed, back in winter and the 1m lost can regrow. But with a continual +ve forcing the ice thins until in the area under consideration it’s under 1m thick. If that ice still loses 1m thickness during the season it will be able to expose dark ocean, which will then be warmed by the sun (ice albedo feedback). So using only an areal metric (area/extent) over most of the time the forcing applies it might seem like little is changing, but once the ice gets thin enough changes in area are rapid.

    It might seem that this guarantees a rapid transition to a seasonally sea ice free state. But the fast growth of first year ice over the winter acts to limit the area/extent loss – energy must still be expended in melting that ice, and the open water exposed by increased open water efficiency vents a lot of heat into the atmosphere after the sun sets in the Autumn. This doesn’t however guarantee there won’t be a rapid transition.

  10. Jim Larsen:

    58 NielT said, “Yes, AlaskaHound I think that comment was idiotic. Or at best trollish.”

    So you find genetic truths less “good” than deliberate garbage? (I don’t believe that, but wanted to correct the issue)

  11. wayne davidson:

    The current summer is giving a solid glimpse of what the future will look like as far as weather and climate.
    Without sea ice the polar weather zone will become temperate, temperate weather zones will become tropical, without sea breezes for those inside the continents along with a jet stream at about 50 degrees latitude Northwards, the summers will be great for heat lovers in Canada, kind of horrendous in the US with droughts a plenty. For North Africa and Euro-Asia much of the same. It is simple, yet I have watched many TV meteorologists fumble the correct version, they tend to say the “jet stream is up North” without explaining why. The jet stream is roughly at the boundary of atmospheric zones, wipe out sea ice and the summers will be minus the coldest zone with the tropics extending North. The implications need be modeled further but we got a lesson from nature, as Ray wrote, oblivious to our needs.

  12. MARodger:

    prokaryotes @54
    That capitalised sub-headline you copy from the site you link to – that sub-headline is a bit misleading, me thinks.
    It refers to the Cryosat-2 data described in a Guardian article (on Sunday, so actually printed in The Observer) which procaryotes also links to @51 and which describes measuring a 900 cu km annual ice loss between 2004 (measured by ICESat) and 2012. This level of annual loss is also what PIOMAS is suggesting See graph (Usually 2 clicks to ‘download your attachment’).
    There was a bit of confusion caused by a BBC Radio interview with Prof Laxon on Monday linked by Arctico @18 which referred to the same data but suggested it came from 2011 not 2012. Neven managed to contact Dr Laxon and get to the bottom if it. The data (‘summer figures’ 7,000 cu km) was for October/November 2011.
    What is important about this 7,000 figure is that it is the same ice measure that PIOMAS models & so as well as the average 900 drop per year, the 7,000 also allows a confirmation of the absolute PIOMAS values.

    The confusion by the Guardian probably arose because there is a winter figure as well (February/March) and that is for early 2012. As the Feb/Mar ice extends beyond the Arctic Ocean, this figure will not equate to PIOMAS.
    (And if simple arithmatic had been applied, 13,000 (2004) minus 7,000 (2011) yields the ~900 cu km annual drop when 2012 would not.)

  13. prokaryotes:

    MARodger, can you clarify/ suggest what the current ice loss rate is? After all, it must be higher than predicted by most “conservative” estimates…

  14. Dan H.:


    Does that also mean that Britain will be looking at cooler summers from now on? Will South Africa start to see snow regularly now? Will droughts be a thing of the past in Australia? Be careful when substituting current weather conditions for climate. There have always been heat waves (at least since the current interglacial started), and global warming may make them worse, but there is no indication that they will become more plentiful.

    [Response: Not so. The Hansen paper indicates that heat waves (defined by a threshold with respect to a fixed climatology) do become more frequent, and they become worse too. Your point about focusing too much on current weather is however sound. – gavin]

  15. derek:

    Thanks all for explaining to me the time scale issues with the ice pack’s response to climate change. Is it fair to say that this response is consistent with global warming, but not sufficient to prove it, because there have been other natural variations in the ice extent in the past? I guess I am thinking that when the Vikings were in Greenland the ice pack was probably smaller.

  16. MARodger:

    Hi prokaryotes @63
    I know no more than the PIOMAS figures & the data gleaned from ICESat & Cryosat-2. It is dropping at some 900 cu Km or so pa. From POIOMAS, the annual minimums (daily data) from 2005 on are 9200, 9000, 6800, 7000. 6400. 4400, 4000 suggesting an average annual drop of 870 cu km over the period. Unlike Area & Extent, volume is dropping similar amounts winter and summer.
    PIOMAS being a model, it must give a lot of soul-searching for those involved so it is encouraging that their hard work is vindicated by the Cryosat-2 data. Well done, PIOMAS!!
    Now when you say “conservative” estimates, PIOMAS say their output (PIOMAS v2 IC-SST) is “a conservative estimate of the actual trend” but this is a comparison with PIOMAS v1 which gave the trend since 1979 as 25% higher.

  17. Unsettled Scientist:

    Derek, the rapidity with which the ice is currently disappearing is caused by global warming which has already been sufficiently proven previously. Why would you assume that there was less ice for the Vikings, or that it would have relevancy to today’s unprecedented melting. Is there some specific evidence about the time of the Vikings on Greenland? What about the direct ancestors of the Innu who came later? What about the North Americans that preceded the Vikings on Greenland? Is that remark simply based on an assumption that if people were there it must have been warmer with less ice?

  18. prokaryotes:

    Thank you MARodger for helping to improve my article, i’ve updated my post now accordingly.

  19. hinschelwood:

    #64 Derek –

    The ice pack was smaller than what? Than it is now? Very unlikely.

    The Vikings sailed as far as they could and got as far as Newfoundland, but no further. Not through the North West Passage, which is open now. It’s fair to speculate about provisions and why they didn’t go further, but an ice sheet is the most likely obstacle.

    It’s important to remember that Greenland was a very marginal proposition for existence when the Vikings found it. A small change in climate wiped them out. The temperatures at present are higher and far more accomodating for agricultural purposes in Greenland than at any time in human history.

  20. dingibily:

    I’d very much like to hear opinions on the believability of the PIOMAS volume trend, something that was discussed in a previous thread. Projections of that trend are far more dire than of any area/extent trends and I have to question their accuracy. A naive projection of PIOMAS has Sep ice gone in 6 yrs. It was argued here earlier that that is not plausible on statistical grounds — natural variations will bump it back up — yet the trend continues. It doesn’t appear to be a succession of chance events. The 33-year pattern is very systematic. Others suggested that maybe “PIOMAS is crap.” The vast weight of expert opinion by modelers holds that we will not see an ice-free Arctic for 20-50 years. So what’s the deal here? My guess is that there will still be Sep ice in 20 years. At some point PIOMAS will have to bottom out. No?

  21. owl905:

    Pretty much every night for a decade, the arctic conditions gets a quick check. The Jaxa site referenced in the article is the baseline, but since AMSR-E went offline last October it has a problem of possible recalibration issues. The comparative site is:

    It uses a 30% concentration threshold, so there’s an inference on both extent and pattern; draw it with a comparison to the Jarxa site. This became pretty valuable when the 2007 shrivel was diss’d off: a freak weather anomaly that caused a massive arctic exit through a clear southern channel.

    In the Daily Kos article, there’s a picture of a decline graph that uses the same 15% concentration threshold as Jarxa – and the interactive ability is worth the price of admission:

    While both extent and thickness are scientifically important, it’s extent that dominates the albedo issue and the stabilizing effect of ice mass of any kind.

    Another comment asked about the track record of the pro-pollutionists. In at least one watts-up-doc case, it trumpeted the ‘Arctic Recovery’ after the 2007 anomaly … and before 2011.

    Last but not least, if seeing is believing, Washington U has been the banner carrier – placing a pair of Arctic cameras on the flo’s each spring.

  22. Kevin McKinney:

    “At some point PIOMAS will have to bottom out. No?”


    Unfortunately, that point is zero.

    IMO, the statement that PIOMAS is inconsistent with other measures is not true. Because the relationship of ice thickness to extent or area is not fixed a priori in any way that we know, it’s quite conceivable that the thickness (and thus, volume) can decrease much faster than the other parameters mentioned. (Perhaps there are even physical reasons to expect thickness to decrease most rapidly.)

    AFAIK, PIOMAS is consistent with in situ measurements of ice thickness–indeed, they use such measurements to constrain the model. So, no reason to think PIOMAS is terribly far off the reality.


  23. dingibily:

    To illustrate my point above, here are some 33-year [ Ice Plots] for Area, Extent (both interpolated NSIDC monthly means), Volume (PIOMAS), and “Thickness” derived from PIOMAS volume divided by NSIDC area. If all of these are correct we would have to conclude that thickness has not yet fallen to the critical level that would result in a wholesale collapse of area/extent in a short time; and that if the Sep volume trend were to continue at the present rate, within a few years we would see such a collapse in order for all of them to reach zero at the same time.

    Possibly. Alternatively, if the ice were to persist for another 20+ years the volume trend will have to change. Either it’s wrong to begin with or whatever is driving the current decline will have to lose its force. I tend to suspect that if the volume data were truly accurate the area would be declining more rapidly already — though maybe this year heralds a new trend. I guess we’ll find out soon enough.

  24. Chris Reynolds:


    Anyone who dismisses PIOMAS in the terms you state is talking ‘carp’. PIOMAS uncertainties are discussed in Schweiger et al 2011, “Uncertainty in Modeled Arctic Sea Ice Volume.”

    This paper includes intercomparison with available measured thickness. The recent Cryosat results indicate that the recent strong decline in volume shown by PIOMAS is real, and that the good agreement with observation in the past is maintained, i.e. the recent crash in volume is not an artefact of the model.

    It is reasonable to expect that the current acceleration of trend may not continue. I think that being able to add this season to 2007 and 2011 will help answer that question. 2007 and 2011 were joint record lows, and both showed a reduction in loss during and after the last week in August. If this year follows suit then it will be reasonable to expect that volume loss may pause while the ice loss advances in the season. I think the reduction of loss in 2007 and 2011 in late season is probably because the melt edge had extended well into the 80degN area and reduced insolation by late August meant the area began net heat loss rather than gain. So the melt stalled.

    Furthermore the massive loss of volume between 2009 and 2010 was due to the virtually complete annihilation of grid boxes reporting thick ice. This process cannot repeat, and the behaviour of the ice pack since then may be epiphenomenal of thin ice, rather than part of a process of rapid transition. Then again it may lead to a rapid transition. At present I’m not convinced anyone knows either way.

  25. john byatt:

    #69 “.” The vast weight of expert opinion by modelers holds that we will not see an ice-free Arctic for 20-50 years. So what’s the deal here?”

    are we confusing an iconic one sept ice free day?
    My understanding is that the models are projecting a seasonal ice free Arctic not a single day event.

  26. MARodger:

    dingibily @69
    If it was just PIOMAS that was predicting an early ice-free summer, then it would be hard to justify it. But you hit on something broader than just PIOMAS when you say “The vast weight of expert opinion by modelers holds that we will not see an ice-free Arctic for 20-50 years.
    The climate models that suggest 20-50 years (or more correctly 30-60 years) also seriously underestimate present Sea Ice Extent & Area which is something we can measure with confidence. The question is then, why are the models not modelling the ice? For some time, the answer given was “natural variation” but the variance has continued to grow for many years and is now far too big to be explained away as “natural variation.” Even the latest AR5 models are not capturing the decline in the ice! (I have seen a graph of this but cannot place it to link to. Here is an AR4 version.)

    So why are the models off target? I think it’s because general climate models of increasing sophistication take longer and longer to build and to run. Ice data relies on the short satellite record. And it is only 10 years ago that predictions of 2030 first started appearing & 5 years ago for sub-2020 predictions.

    Conversely, the thickness data PIOMAS produces has been checked against the thickness measurements that are available and it has not been found wanting. The latest Cryosat-2 data will allow yet more checking. Prelimenary data suggests again PIOMAS is an accurate reflection of the ice. So PIOMAS is being questioned but the answers are not good for Arctic summer ice.

  27. Dan H.:

    The size of the ice pack during the reign of the vikings is highly speculative, and neither your claims nor Derek’s can be substantiated. Given the pospect of more fertile land to the South and West, why would the Vikings even venture through the Northwest passage? Your last statement about Greenland temperatures is contradicted by ice core data.

  28. SecularAnimist:

    dingibily wrote: “The vast weight of expert opinion by modelers holds that we will not see an ice-free Arctic for 20-50 years.”

    If by “ice-free Arctic” you mean an ice-free Arctic ocean in summer, I’m not sure that’s what the “vast weight of expert opinion” holds any more.

    It appears to me that “expert opinion” at the moment is stunned by the unexpected rapidity of Arctic sea ice decline.

  29. wili:

    We just dipped below the 3 million k^2 mark.

    Here are some observations by Jim Pettit at Neven’s blog on the event:

    * That’s only the third time in the record area has been below 3 million km2 (2007 and 2011 were the others, of course).

    * It only took 138 days this year for area to fall below 3 million from this year’s maximum. 2011 accomplished that feat in 169 days–one month longer–while 2007 needed 178 days, nearly six weeks more. Perhaps more astonishing, that 138 days is less time than it took most years that fell below 5 million km2 to reach that point from their individual maximums.

    * 2012 SIA fell below 3 million km2 nine days ahead of 2007, and ten days ahead of 2011. 2012 area is currently 405k km2 ahead of 2011 on the same day, and 356k km2 ahead of 2007.

    * As others have noted, an area record is just 81,585 km2 away. Even if area were to see an additional decrease this year equivalent to only the lowest post-6191 drop on record–1997’s 194k–2012 would still end up with just 2.793 million km2. At the other end of the scale, 1984’s post-6191 drop of 1.113 million km2 would render a very far-fetched 1.874 million km2.

    * 2012 SIA has now been in first place for the past 47 consecutive days–since June 30–and 63 out of the last 68.

    * 2012’s SIA anomaly has been below -2 million km2 for 14 consecutive days. That’s 20% of the 70 days on record with an anomaly greater than -2 million. (The greatest anomaly so far this year ranked #20 on that list of 70; the 19 largest negative anomalies were all in October of 2007.)

  30. NeilT:



    by stating it was idiotic I was being nice…. Trollish has nothing to do with genetics and everything to do with attitude.

    Interesting though

    I make that about 2m sqkm of pack ice and lots of floating chunks to keep your drinks cool. Even Trolls can’t argue with 0. Although they can start talking about November to March and how it’s “recovering”….

    That’s what Internet trolls do. They tell lies for effect.

  31. Perk Earl:

    ‘Greenland Melting Breaks Record Four Weeks Before Season’s End’

    Similar articles on Greenland’s 2012 melt have been circulating these past few days. In particular, what struck me as dramatic is this part:

    This year, Greenland experienced extreme melting in nearly every region — the west, northwest and northeast of the continent — but especially at high elevations. In most years, the ice and snow at high elevations in southern Greenland melt for a few days at most. This year it has already gone on for two months.

    If that last sentence is the beginning of a new level of melt that continues into subsequent years, then the Greenland melt has entered a new, much greater era of Summer melt, but along with the dramatic melt of arctic ice in 2007 and subsequent much lower yearly ice extents and volume, suggests the situation is accelerating. The question is; Is the acceleration exponential? And if not, what is the best way to describe the acceleration curve?

  32. Perk Earl:

    Reply to #69: I’m not sure how there can be a strong argument against piomass, because regardless of the accuracy of the volume measurements, there is at minimum a comparison of different years and the trend is clear in the direction of approaching zero in some future melt season.

  33. Unsettled Scientist:

    Dan H, what does the Younger Dryas have to do with the Vikings? I think you are confused about history. The Vikings were in Greenland in the 10th Century AD and the Younger Dryas was about 10,000 years before that. Looking at the PDF you linked which does include a temperature graph for the period of the Vikings it shows a strong decline in temperature around the time of the Vikings settling Greenland down to -32.5 C (Figure 1) which is lower than today’s temps. Yes the paper shows there have been warmer temps in the past (at the Summit region of Greenland), but not at the time of the Vikings. This paper actually supports the idea that it was very cold indeed for the Vikings in Greenland.

    As that Kobashi et al paper you linked notes it’s conclusions are different than others for a couple reason, one main reason being they aren’t using summer temp but an a mean-annual temp. When placing the current temps in context with the past 4000 years that paper actually uses decadal-mean temp, so an average of 2001-2010, over which we’ve seen accelerating increases of ice mass loss. They even point to Kaufmann et. al as an indication that for summer temps, this is the warmest it has been since humans have been to Greenland.

    So depending on how you measure it, mean-annual temp or summer temp when the melting occurs, this is the warmest it has been since humans have set foot on Greenland. Regardless of how you measure it, it was colder for the Vikings.

    Lastly, one quote I’d like to pull from the conlusions of the Kobashi paper you linked. When discussing why their conclusions differ somewhat from other recent reconstructions they write “our site is not necessarily representative of the the Arctic as a whole, and may respond in opposite ways to annular mode fluctuations.”

  34. Jim Larsen:

    ” why are the models not modelling the ice? For some time, the answer given was “natural variation” but the variance has continued to grow for many years and is now far too big to be explained away as “natural variation.” Even the latest AR5 models are not capturing the decline in the ice! ”

    I wonder at the seeming mule-headedness of ice scientists. I asked at the beginning of this thread if a SINGLE run of a SINGLE model has produced results approximating reality. Nary a peep in response. Truly amazing. “There is SUPPOSED to be more ice!!!!” while stamping their feet….

  35. AMay:

    re: Vikings, Greenland, and sea ice.
    My recollection (which may be faulty) is that even during this “warm period”, south Greenland was only seasonally accessible by boat, and in later years visits were not possible every year. That is to say, unlike today, no part of Greenland was ice-free year round. By contrast, today Sisimiut is Greenland’s northernmost year-round port.

  36. Jeffrey Davis:

    There’s an interesting problem with the idea of heatwaves becoming more frequent: there’s a fixed number of days in a year. If every day were above average for the year, there would be 1 single heat wave that year.

    The problem is, of course, that “heat wave” is a vague term, and as the climate warms, the significance of individual weather events might blur. Like this year: was July several heat waves or one monster one?

  37. derek:

    Thanks again for the comments everyone. I wasn’t trying to suggest that climate change isn’t causing the drop in ice coverage; mainly I was just trying to get at whether there would be longer term (say 100-year) variations in ice coverage. I am curious whether, if you ignore everything else, one could use the Arctic Sea Ice Volume Anomaly plot to show that climate change is occurring, or if that is consistent with, but insufficient to prove, a general increase in the heat budget of the Earth.

    I picked the Viking example out of the air, and phrased it poorly. I meant to suggest that maybe there was less ice in the 1200s relative to surrounding centuries.

  38. wayne davidson:

    Dan H. #77 “Does that also mean that Britain will be looking at cooler summers from now on?”

    You confuse cool summers with a wet climate because the temperate to tropic boundary is just at or South of Britain. That statement is typical of name games trying to be clever, however intelligence is elsewhere, I foresaw it in my long range projections. The wetter weather in the UK was due to a great deal of heat and moisture combined with the presence of cooler upper air.

    “Will South Africa start to see snow regularly now?”

    It is winter there , so what is your point? The long Antarctic night will be cold for a long time to come.

    ” Will droughts be a thing of the past in Australia?”

    Don’t bet on it you might be poorer from doing so. ENSO is a strange cycle, I understand it better, but much more is needed to figure it out.

    “Be careful when substituting current weather conditions for climate.”

    The new world climate order will be an extended tropical zone well into the Northwards for the NH. The weather it gives depends on location. Be careful when making not so bright statements about weather, makes you sound like a TV meteorologist.

  39. Dominik Lenné:

    I put PIOMAS absolute volume data online years ago:
    Don’t need no math and statistics to see what’s going on.

  40. Dominik Lenné:

    I don’t know wether my post went into nirvana or not, so I give it a 2nd try, just in case:

    PIOMAS arctic sea ice volume data – not anomaly, can be found here:

    Need no math and statistics to get the message.

  41. Unsettled Scientist:

    derek > I am curious whether, if you ignore everything else, one could use the Arctic Sea Ice Volume Anomaly plot to show that climate change is occurring

    But why? We don’t need to do that. The amount of evidence that climate change is occuring is overwhelming, why do you want to ignore it? I guess I’m not sure what the point of your exercise is.

  42. tamino:

    Re: #87 (derek)

    There may have been more ice in the 1200s than in surrounding centuries. At least that’s the result of a 1400-year reconstruction of Arctic sea ice:

    It has been suggested that part of the reason for warmer medieval temperatures in part of the northern hemisphere is that heat was diverted from the Arctic to other regions.

  43. owl905:

    ‘The Viking settlements in Greenland are a proxy for climate drivers that disprove the hockey stick and, by extension, global warming … ‘

    Stop it … just, stop it.

  44. Craig Nazor:


    Once again, your links don’t really support what you claim they do. The first link is only concerned with decadal temperature averages, which is not going to tell you much about year to year ice variations, particularly in comparison to the most recent years. Your second link is to a paper discussing temperatures in “central greenland.”

    It appaears to me that you are scrambling to generate evidence that does not exist.
    There is evidence that Viking technology spread into the plains north of the treeline and west of Hudson Bay in central Canada in pre-Columbian times, but that it came overland from the east, and not down from the north. The better question is why WOULDN’T the Vikings have taken avantage of a clear northwest passage, if it had existed.

  45. Andy Lee Robinson:

    I made a divx video visualization today from the same source gz data using perl and povray:

    piomas-arctic-1979-2012-07-pov-anim.avi 180 frames 6.8 MB

  46. prokaryotes:

    Arctic sea ice loss has created negative NAO-like conditions to atmospheric circulation.

    We also find some evidence of a late winter (March-April) polar stratospheric cooling response to sea ice loss, which may have important implications for polar stratospheric ozone concentrations.

  47. Dan H.:

    The Younger Dryas has nothing to do with the Vikings. It was a period shortly after the planet started emerging from the last glacial maximum when temperatures plunged suddenly. It was 11,000 years before the Vikings ever built their first ship. Also, I think you may be confusing the Little Ice Age with the Viking colonization of Greenland, when temperatures plunged to -32.5C. That period was several centuries later, from about the 16th to 19th centuries. The Viking era was associated with the Medieval Warm Period, which was centered around the year 1000.

    While summers may be warmer (this paper does mention the 2000-yr cooling trend, but shows higher temperatures prior to its onset), the paper clearly states that the current surface temperature (-29.9C) was similar (-29.7C) in the Medieval Warm Period. Also, 72 decades were warmer than the present, some by 1-1.5C, during which time Greenland was inhabited by several other groups of humans, before the Vikings arrived. The present decade is not outside the envelope of variability. So unless you which to redefine “human,” your statement still contradicts the data.

    Getting back to Derek’s original question, it cannot be answered, as historical extent of the floating sea ice cannot be determined by proxies. Some studies present the sea ice extent off Greenland and Iceland during the past millenia, or so.

    We can get an indication of what the sea ice extent may have been like, by using temperature proxies for nearby sites. The local sea ice, which is indicative of the maximum sea ice extent in the North Atlantic, correlates with temperatures, which would indicate that the greater Arctic sea ice would likely follow. Since the mean decadal Greenland temperature has varied by 4C over the past four millennia, it is reasonable to conclude that large variations in sea ice also occurred. During the past two centuries, temperatures have risen ~2.5C, and there has been a significant decrease in Arctic sea ice.

  48. Dan H.:


    Did you read Gavin’s response about weather vs. climate? You claim in your post superior intelligence, but your response suggests a lack of comprehension. My previous post, which was bathed in sarcasm, cautioned against using recent weather patterns to claim climate shifts. Repeated weather patterns would be a better indication. By the way, snow is a rarity in South Africa. It has not snowed in Pretoria in decades, and this was the first recorded snowfall in all nine South African districts simultaneously.

    Not sure what Antarctica night has to do with South Africa. Being just south of the Tropic of Capricorn, the minimum winter sunlight is still ten hours.

  49. Lawrence Coleman:

    Looking at the arctic seaice graphs for area, extent and volume using decadel averages since 1980-89 etc till today. All three demonstrate that the ice loss is accelerating rapidly every single year. However the sea ice volume graphs sends shivers up my spine. Here you can extrapolte that the summer sea-ice will be long gone within 10 years. The decadel volume graph since 1980 is practically exponential. Send these graphs to your policy makers urgently and there is absolutely no mistaking their significance!.

  50. MARodger:

    Although most of the record minimums of the Arctic Cryosphere are looking shaky as the melt season forges ahead, as of today none have fallen yet – except that is for Land Snow Cover. (There is an issue with pre-satellite Greenland measures of snow cover but that can be dodged by excluding Greenland.) I reckon it stands as the first scalp of the 2012 melt season, the 24 year record tumbling during the second half of July.

    Northern Hemesphere
    Minimum Land Snow Cover
    (excluding Greenland)
    (Data – Rutgers Uni Snow Lab weekly)
    Pos.. Year….. Min (Sq Km)
    1….. 2012….. 159,325 to date.
    2….. 1988….. 202,563
    3….. 2011….. 204,226
    4….. 1990….. 204,658
    5….. 2009….. 281,217
    6….. 1992….. 282,868
    7….. 2008….. 286,271
    8….. 1968….. 286,507
    9….. 2010….. 286,788
    10….. 2004….. 288,068