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North Pole notes (continued)

Filed under: — gavin @ 22 August 2008

This is a continuation of the previous (and now unwieldy) post on the current Arctic situation. We’ll have a proper round up in a few weeks.


638 Responses to “North Pole notes (continued)”

  1. 151
    Chris says:

    #141 Timothy:

    “in most areas it appears that surface melt has been greater than bottom melt **due to warm ocean**, whereas bottom melt dominated last year.”
    [double asterisks my emphasis]

    No, surface melt depends on air temperature, wind and sunshine; bottom melt depends on the ocean temperature under the ice. Colder SSTs (sea surface temperatures) in the open water surrounding the ice imply colder sea temperatures under the ice as well, hence less bottom melt.

    “We could be two degrees cooler and still see pretty much the same given this year’s vs last year’s ice”

    I find this claim extraordinary. Is it really plausible that the salinity over millions of km2 of Arctic sea is so different from a year ago that the thin ice which has melted in the last few weeks will only reform at a temperature an extra 2C lower than when it melted, compared with last year?
    Wayne’s argument (#130) depends on the assumption of “vaster saltier 1st year melt”. But this is weakened by two further points: (1) he also claims that “a huge fresh water melt in 2007 has caused a greater freeze up” i.e the first year ice is fresher than it would normally be; (2) new ice that forms gradually at temperatures not far below zero has surprisingly low salinity in any event (through brine rejection).
    Moreover, you’ve been highlighting the relatively large surface melts this year: the surface ice/snow is the freshest of all!

    The story is different away from the Arctic ocean. Consider the following comparison of 2005 minimum ice with 2007 minimum.
    http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=09&fd=15&fy=2005&sm=09&sd=15&sy=2007
    Notice that there is nothing special about the 2007 melt on the Atlantic side, and consider that the Atlantic side is dominated by the Gulf Stream and powerful depressions over the winter bringing strong winds and waves (i.e. lots of mixing of the water). I find it hard to see how changes in salinity could be such a major influence on late winter sea ice here. If you look at the Pacific side, then the Bering Strait is relatively narrow, and the sea ice in the summer always melts well into the Arctic ocean from here. So again, colder winter SSTs in the North Pacific would seem a much more credible explanation of greater ice extent in winter 07/08 than relatively small average changes in surface salinity channelled through the Bering Strait.

    “it would appear that the melt has been picking up for several days now”

    Please see my post above #133 re: the inaccuracy of equating ice *extent* with “melt”.
    If you look at ice *area*, you will see that by this more accurate measure, “melt” has been only ~100,000km2 *in total* in the last 5 days (3.681 million km2 on Aug 21st down to 3.579 million km2 yesterday.

    As for hurricanes, I might be concerned if tropical SSTs, surface air temperatures and lower troposphere temperatures were at record highs. But this is a very long way indeed from being the case at the moment.

  2. 152
    Chris says:

    #149 Alastair:

    “When the ice is less concentrated it will be thinner”

    Not necessarily – ice often becomes less concentrated following break up/dispersal, in the absence of melt. For example, the following buoy from the edge of the Beaufort Sea (where I understand ice was broken up last winter by storms) still shows ice thickness of >3m, despite southward drift:
    http://www.crrel.usace.army.mil/sid/IMB/2008F.htm
    Yet ice is clearly what you would describe as “less concentrated” where the buoy is located:
    http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/arctic.seaice.some.000.png

    “However, when the ice extent reaches zero so will the ice volume, and there will be an exact correlation.”

    In fact, especially in this scenario, there would be a complete lack of correlation. If the ice extent reaches zero (and we all hope this won’t happen of course) then this will mean that any remaining areas with ice will have coverage of 0)

    Well, for the sake of argument, let’s consider the areas in the Arctic where ice coverage is currently 0. As of yesterday there was ~5.23 million km2 with coverage between 15% and 100%. So let’s say that there is currently ~500,000 km2 (that’s ~500,000,000,000 m2) with coverage between 0 and 15%. And let’s assume that the average ice thickness in these areas is a mere 0.5m. Thus, total ice volume in this large area of *zero ice extent* is very approximately a conservative 250,000,000,000 m3.
    I know this doesn’t prove very much, but I don’t think the quoted statement does either :)

  3. 153
    Chris says:

    For some reason the WordPress system seems to have left out some symbols and words from my previous post, making the second part of it look rather ridiculous!

    I’ll spell out the relevant parts again, all in words, so that hopefully this time it all appears properly.

    “…this will mean that any remaining areas with ice will have coverage of less than fifteen percent and more than zero.

    Well, for the sake of argument, let’s consider the areas in the Arctic where ice coverage is currently less than fifteen percent and more than zero…”

  4. 154

    Me, in comment 80

    Energy programs do not depend on uranium enrichment. Britain’s first foray out of the weapons arena into civilian power didn’t require any isotopic separation at all, and neither does the scheme in the paper I link from my website.

    Nick Gotts, from comment 88

    I went to your website, but can’t find any paper such as you refer to. Maybe the information is buried somewhere in your paper recommending nuclear reactors in large land vehicles (!!!), but a quick scan suggested there’s hardly room to describe a scheme for proliferation-resistant nuclear power generation.

    Supposing his intent not to have been a discouraging display of reading incomprehension, can anyone help him?

    Remember, what I advertised was an enrichment-free nuclear fission power scheme, not a proliferation-resistant one. Advertising the proliferation-resistance of a fission power scheme would be like advertising the bidirectionality of a manual screwdriver. It would be more revelatory to find one that wasn’t.

    [Response: Please don't play games - no has time for that. If you want to point someone to a specific paper, please include the link. - gavin]

  5. 155
    Hank Roberts says:

    Chris: Google search for “less than” +symbol +”Wordpress” will find the answer at codex.wordpress.org/Glossary.

    Ironically, you’ll have to “view source” to actually see what I’ve pasted in below from the codex.wordpress.org/Glossary page. That’s Catch-22:

    Glossary « WordPress Codex
    use < for the less than () symbol ….
    codex.wordpress.org/Glossary

  6. 156
    Timothy Chase says:

    Chris quoted me and then responded in 151:

    #141 Timothy

    “in most areas it appears that surface melt has been greater than bottom melt **due to warm ocean**, whereas bottom melt dominated last year.”
    [double asterisks my emphasis]

    No, surface melt depends on air temperature, wind and sunshine; bottom melt depends on the ocean temperature under the ice. Colder SSTs (sea surface temperatures) in the open water surrounding the ice imply colder sea temperatures under the ice as well, hence less bottom melt.

    The phrase “due to warm ocean” was meant to modify the noun immediately preceding it: bottom melt, not this year’s melt. However, I can see how you might have been confused… sort of. In any case, I think people are more familiar with surface melt — and that at least at the popular level it is overemphasized. As such I didn’t think it required any explanation — but I thought the phrase “bottom melt” could be elaborated upon with just a few words for someone just coming in.

    Chris quoted me and then responded in 151:

    “We could be two degrees cooler and still see pretty much the same given this year’s vs last year’s ice”

    I find this claim extraordinary. Is it really plausible that the salinity over millions of km2 of Arctic sea is so different from a year ago that the thin ice which has melted in the last few weeks will only reform at a temperature an extra 2C lower than when it melted, compared with last year?

    Given the volume of last year’s melt? And you yourself said earlier that this year was only a degree cooler throughout most of the Arctic for June and July:

    You had written in 145:

    At the same time, temperatures overall have been significantly lower than in 2007 (almost 1C less on average north of ~60N for June/July according to the MSU satellite “NoPol” figures) and the seas on average in the Arctic are significantly cooler.

    Sure, there are millions of square kilometers of ocean, but it is the Arctic, and the ice that melted covered pretty much the same. And there is ocean stratification. Due to a difference in buoyancy between salt water and fresh water, if I’m not mistaken.

  7. 157

    Re #153 where Cris says:

    “…this will mean that any remaining areas with ice will have coverage of less than fifteen percent and more than zero.

    Well, for the sake of argument, let’s consider the areas in the Arctic where ice coverage is currently less than fifteen percent and more than zero…”

    But these areas do not exist! Or, if you are going to be pedantic are very small. See Bob Grumbine’s sea ice map. The red areas 16-21% ice concentration only occur as a thin line on the edge of the pack, and in the North Atlantic edge not at all. The ice pack has an edge. The edge is normally sharp and there is very little low concentration ice there.

    Earth science is different from the physical sciences. They have laws which are true until proved false. In earth science, every law has an exception, probably even this one! Therefore it is wrong to become too precise when discussing earth science matters.

    Whether or not this years melt, ice extent, ice area, or ice volume is a new record will not determine whether there is an ice free Arctic in the summer of 2013.

    Cheers, Alastair.

  8. 158
    Chris says:

    Oops, in #152 the guesstimated total ice volume in “zero extent” areas with ice coverage up to the 15% threshold should have been much lower at a mere ~18.75 billion m3 (I forgot the step of multiplying the overall area by 0.075 to get to total ice coverage, before multiplying by average thickness)
    Not that it really matters as it was a somewhat facetious reply to a somewhat facetious point :)
    I’ll try and avoid posting for a little while as I think I’ve done more than my fair share for now!

  9. 159
    not a boffin says:

    Re #90, Jack Mist:
    > “I can’t find anything in the literature, but I have a strong suspicion that ice at 0°C cools air faster than ice at subzero temperatures. At the melt-point it’s primed to absorb a sudden energy hit, using latent heat to become water.

    > “This could explain why the melt goes on, even though the air temperatures seem to be steady or falling. Cause and effect goes the other way – the continuing melt is reducing air temperature. Can anyone tell me when significant areas of ice in the Arctic and Greenland reached melt point? 1998 maybe? If so, this could explain the temperature “plateau” that the denialists get so excited about.”

    Like Jack, I found nothing on the effect he proposes, for or against. Current research is normally subscription-only, I understand that. Basic science is freely available though – and “how ice melts” is about as basic as you can get!

    I had the equipment to hand (and a bit of spare time) for a quick&dirty test of the theory: I took a length of drainpipe, set it horizontal in a freezer, half-filled it with water and froze to -10°C. Tilted it slightly downwards. Fan and air thermometer at one end, air thermometer at the other, plot the air temperatures as the ice warms. There was a slight but definite downward jig in air temperature as the melt point was reached, but there might be another cause – aircon kicking in at the wrong time, for instance. It would need much more precise measurement and better equipment to prove anything.

  10. 160
    Chris says:

    Ok I am just going to post one more, to reply to a couple of other posts that have just come in.

    Firstly, #155 Hank, thanks for the info on WordPress, and the carefully worded presentation which enabled me to access it without the same problem occurring!

    #156 Timothy:
    “The phrase “due to warm ocean” was meant to modify the noun immediately preceding it: bottom melt, not this year’s melt.”

    I can see how my reading of what you said was a poor reflection on your level of knowledge, and for that I’m sorry. But it doesn’t change my point that average Arctic ocean temperatures were, and remain, lower than at the equivalent date last year, and now that surface melt has slowed, the predominance of bottom/side melt means that other things being equal, net re-freeze should be earlier.
    Of course, other things aren’t necessarily equal in particular because of salinity. Then the question has to be addressed of just how different the overall salinity levels are. They would have to be hugely different to make net refreeze commence at SSTs a full degree C lower, let alone 2C lower. And I’m just not convinced of this, for some of the reasons expressed in my earlier post. In other words, I’m perfectly aware of ocean stratification, but it’s the quantitative argument I’m concerned about re: higher salinity vs colder SSTs. (Another thing you need to consider by the way is the choppiness of the open water – it’s not as if the fresh water is always sat calmly on the top with no mixing)
    Meanwhile, the net re-freeze of the last week continues in any event over the main Arctic Basin area of sea ice: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.1.html

  11. 161
    Chris says:

    And just one very final post! (I hope….)

    #157 Alastair: “But these areas do not exist! Or, if you are going to be pedantic are very small.”

    Of course they exist lol!!!! The map you link to doesn’t have any precision below 16% so of course you can’t see them! Check out the following map for the eastern Beaufort and you’ll see that the areas of less than 10 per cent coverage but not ice free are larger than all other areas combined!!!!

    http://ice-glaces.ec.gc.ca/prods/WIS40CT/20080826180000_WIS40CT_0003936564.gif

  12. 162

    #145 Chris, Thanks for the cool links! If the SST data is right the mystery deepens, 2007 sst’s were caused by clear slies. Warm winds? Only from the Beaufort, as far as I know. Its been more cloudy than compared to last year, SST’s are lower, average temperages are colder, yet the melt is virtually the same. Only a volume calculation would disprove my hypothesis. I suspect
    at the very least an equal volume melt, at cooler surface and SST temperatures. That is a mystery
    which deserves a lot of attention. Winds were indeed a factor, they reduced compression by mainly going against the sea current and tides, causing the ice the spread out more, increasing albedo compared to last year. I dont see your wind point at all, if the winds carried warmer air by advection the temperature record would have been much warmer…

  13. 163
    Nick Gotts says:

    G.R.L. Cowan,

    I apologise for writing “proliferation-resistant” instead of “enrichment-free”; few experts seem to share your confidence that most approaches to civil nuclear power are proliferation-resistant. I assume you are referring to “How Fire Can Be Tamed”, at http://www.eagle.ca/~gcowan/235_248.pdf, the main topic of which is fueling cars with metals, and which, in the middle of the text, gives a 2-page informal description of what is, as far as I know, a completely untested proposal for a novel form of nuclear reactor. I’m afraid I am not prepared to take such a description as good evidence it would work. Perhaps you can point me to a source, preferably a peer-reviewed article, where the idea is worked out in more detail?

  14. 164
    Phil. Felton says:

    Re #161

    The blue color on the map you showed stands for ‘open or bergy water’, a few floating bergs are enough to qualify.

  15. 165
    Chris says:

    One final post, honest….?

    #162 Wayne – cheers, glad you like the links.

    I had to reply to your post, because I think the warm winds (combined with the thinned ice following summer 2007) are absolutely critical. I’ve been following the weather maps throughout August, and there’s no doubt in my mind that the persistent southerly winds over a broad swathe of the north Siberian coast for much of the month brought extremely anomalous warmth (certainly compared with the recent decade) and were the key driver of the rapid melt in the Laptev/East Siberian/Chukchi seas (as well as adjoining parts of the central Arctic Basin) since then. As a start, you could check out the temperature records for Tiksi on the Laptev coast which was in the heart of the zone of anomalous warmth
    http://www.weatheronline.co.uk/RussianFeder/Tiksi.htm
    The reason this may not show up in the Arctic temperatures overall is that it was balanced by colder weather elsewhere. For example on the Beaufort Sea – but the trouble was here the ice had already mostly gone, after the hot July centred in N / NW Canada. So all the cold did was to keep the Beaufort Sea colder than it would otherwise have been.

    I would say that broadly, what happens in the Arctic reflects global temperature trends, with a lag, and modified by changes in weather patterns/ocean currents etc.

    So from summer 07 to summer 08 the world got cooler and this was reflected to some extent in Arctic temperatures, but the record melt of 07 had a big knock-on effect, and weather patterns were unfavourable to a major ice recovery. As for summer 09, we’ll have to wait and see……………

  16. 166

    It occurred to me that the issue of salinity might apply more to the first-year ice than to the melt-water. If first-year ice were, say, 30% more saline than multi-year ice, might not that result in a freeze/melt temp several tenths of a degree colder than that of the nearly-freshwater multiyear ice? It seemed alluring; if this idea were correct, then you might expect to see just the sort of difference in the curves for 2007 and 2008 that we observe.

    A little poking about was more than enough to show that my understanding was way too simple to draw conclusions, however. (See this interesting site: http://findarticles.com/p/articles/mi_m1200/is_7_158/ai_65301546) Internal structure of first-year ice sounds pretty complex, and I can’t decipher how this structure would act in terms of–well, let’s call it “apparent freezing point”.

    However, it seems clear that first-year ice is relatively more frangible than multiyear ice, even correcting for its typical thinness. The more finely comminuted the ice, the more surface area for bottom melt action, and the more rapidly the ice can melt.

  17. 167

    I probably should have said “frangible and porous!”

  18. 168

    Re #130 where Wayne wrote:

    I suspect some warmer air than measured at 2 meters a factor in this years melt. The physics of ice and air interactions needs very close scrutiny, if warmer air is responsible, as I think so, we have to find it.

    Wayne,

    I found it hard to imagine warm air creeping in from the Pacific or Atlantic sea surfaces below 2 metres and covering the Arctic. Then I realised that I already knew where it came from – the greenhouse effect!

    It is generally believed that the greenhouse effect works high in the troposphere. See Busy Week for Water Vapor. But as that thread explains, Phillipona et al. [2005] had reported that water vapor was acting near the surface in Europe. You commented that you thought the same was happening in the Arctic.

    In fact the greenhouse effect was first measured by Horace-Benedict de Saussure using a box 1 foot by 9 inches by 9 inches. He obtained temperatures of around 110C (230F.) [de Saussure, Journal de Paris, 108, April 17, 1784]

    What is happening is that the greater concentrations of CO2, operating in the bottom 9″ of air, are now leading to the ice melting. This increases the water vapour density, which through its greenhouse effect drives the melting even faster. I’ll put more details on my blog. Have to read “Busy Week for Water Vapor” again and Philipona’s response.

    Cheers, Alastair.

  19. 169

    Chris,

    If you cherry pick the area and time you map, of course you can show charts with of less than 15% ice. I already wrote that every rule has an exception. The ice has an edge, whether you are willing to believe it or not.

    Cheers, Alastair.

  20. 170

    #165 Chris, Lets look at this a little closer:

    http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2008&month_last=7&sat=4&sst=0&type=anoms&mean_gen=07&y

    It wasn’t that warm over Beaufort in July, Certainly not on the Russian side of the Pole

    North of Seberia was cold in June as well.

    So this is the set up, you have much colder cloudier weather, which affected the Russian side in question,

    If NOAA is accurate, Russian side ice had an average anomaly of +2 C in August… In our days of higher Arctic temperatures, this was quite a mild heat wave. Must wait for a formal August result. Total volume loss is the big number to wait for. If anyone may publish?

    Alastair, Interesting, there such a thing as different air temperatures at ,5, 1, 1,5 meters,
    been there done that, it depends on so many factors, but its possible. 2 meter high measurements over ice in the summer, most likely give a cooler reading than the air just above, But near ice level, a few centimenters above, that is an idea worth investigating at a much grander scale.

    http://www.rap.ucar.edu/weather/upper/cymo.gif

    is the closest upper air measurement to the Arctic available on the net, if someone knows another www link to particular arctic stations, it would be nice to look at more northern profiles. But this one shows a typical inversion.

    At any rate, one fast ship can circumnavigate the world above the arctic circle in no time now:

    http://www.seaice.dk/iwicos/latest/amsr.n.comb.20080826.gif

  21. 171
    CobblyWorlds says:

    The latest Bremen AMSRE shows a substantial area of low concentration heading into the pack from Beaufort Sea along the 120degWest line of longitude.

    This can be seen in the following visible NASA satellite images:
    Terra
    http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?T082400200
    Aqua
    http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?A082401540

  22. 172

    #120 tarmov
    #123 Hank

    Yeah, the thing that is different about this is that the melt curve is slightly convex, not concave. That indicates a different inertia to me.

    I’m not saying we’re going to bust last year but the thermal inertia seems to have a little extra heat in the water and the pattern is funny compared to other years.

    2004 has more in common with the melt rate pattern. If this goes on for two weeks we will be close. If it goes for three, I’d bet we will likely pass 2007.

    I just wish I knew more about the currents to understand it better.

    #124 R. Gates

    I think 2012/13 is a pretty good guess at this point barring new data and when 24 and El nino gear up.

    #127 Alastair McDonald

    I think it’s mostly coming form underwater warm currents. Something did change. If anyone knows the current current dynamics that could explain it, I’m all ears.

    #135 wayne davidson

    This is puzzling if true. I am suspecting that there was a current shift of some sort but have n ow idea if anyone is looking for or found anything that indicates it?

    #145 Chris

    I think the mystery is the odd acceleration while indications are cooler. Maybe, it’s ice thickness vs. temperature since the ice is thinner than a previous year and the melt rate dynamic is taking advantage of the break up capacity?

    A sort of cascade effect once the thickness reaches a certain point combined with the warm water still under the ice.

    The surface melt has pretty much stopped but according to a knowledgeable friend, the ocean side melt can go for anywhere from 1 to 3 weeks from now. It’s still up in the air…, so to speak.

  23. 173

    Hi Wayne,

    That last link is a day out of date. It should now be:
    http://www.seaice.dk/iwicos/latest/amsr.n.comb.20080827.gif

    Cheers, Alastair.

  24. 174

    #172–”I think the mystery is the odd acceleration while indications are cooler. Maybe, it’s ice thickness vs. temperature since the ice is thinner than a previous year and the melt rate dynamic is taking advantage of the break up capacity?”

    Also, porosity and relative fragility due to brine pockets & channels in the first-year (as opposed to multi-year) ice. See the description on the NSIDC site, as well as on the site I linked in my #166.

  25. 175

    Alastair,

    Just an idea…. Does ice absorb significant amounts of IR? I couldn’t find anything
    concrete, but the literature I read indicates so,

    http://prola.aps.org/abstract/PR/v26/i6/p771_1

    I suspect Thermal IR properties of thinner sea ice as somewhat involved in all this. However, it requires a “mirror” zone of air, not so high above, which is equally warmer than 2 meter temperature measurements. Presumably near the ice as yu suggest, or well above, below or at lower dominant cloud levels. Thanks to the links from Chris, we can discount a warmer sea current, because there is no indication of warmer temperatures. THe solution is in the air and ice.

  26. 176
    Lawrence Coleman says:

    Re 147 Levenson.. Geo Thermal great!..if you are lucky enough to live in a geologically active region of the world. Same with tidal wind generators..except if you happen to live in landlocked country or one where the difference between low and high tide isn’t very great. All these techologies are fine but I think you will see the percentage nett energy output of renewables if falling further behind while coal/oil and gas derived energy are still rocketing ahead laregly thanks to the US, China, Japan and India. The wide spread use of photo voltaics or sun reflector systems is the cleanest and greenest and potentially the cheapest to produce, roll-out, deploy etc. Their efficiency is going up almost every year and indeed would be the ‘best’ continual source of power. So why aren’t governments embracing the concept, subsidising the cells so that almost everybody can afford them??
    Would you happen to have a link to show what percentage of electricity is being generated by renewables as opposed to fossil fuels – 10 years ago up to the present?

  27. 177
    Lawrence Coleman says:

    Looking at the uni-breman website just now, I would say the north-west passage is officially open or if not a medium sized icebreaker could do the rest. If you want to go for a dip at lat 90 degree N better dust off your snorkel..I think it’ll happen again this year!

  28. 178
    Chris says:

    I haven’t explained what I think has happened in the last 4 days to cause the average daily extent reduction of ~81,000 km2 (which has caused such a fuss!) compared with the average daily reduction of ~46,000 km2 in the previous 4 days – you can download the daily data from IARC-JAXA here http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

    Up until about a week ago, there had been low pressure stuck for several weeks roughly just north of the north-central tip of Russia, feeding persistent strong southerly winds up over much of the north Siberian coast. The ice had been persistent here until the end of July, so it took a while for melt to get going (and therefore for the SSTs to pick up) But the more open seas were exposed to wind (and sun – anecdotally, it was sunnier than average at Tiksi on the Laptev coast), the more “fetch” the winds had and the more the seas could be warmed, and waves/chop/currents set in motion against the retreating ice edges and individual floes/local ice packs. (Please note this is a one-sentence simple summary, there’s more to it than that.)
    The low which formed at the beginning of August was intense enough to be called a storm (a “summer” storm if you like since it brought strong mild winds, rather than any freezing temperatures) and it resulted in a period of high exent reduction (daily average reduction 105,900 km2 from 3rd-7th August) which caused a similar fuss to the most recent one. Of course, it was followed by a 4-day period of just 48,500 km2 average daily reduction, as the ice packs settled and the southerly pattern temporarily eased.

    About a week ago, the weather pattern finally shifted, with a strong low moving from close to the north pole towards the East Siberian sea, bringing northerly gales, sub-zero temperatures and even snow to large areas that had previously been anomalously warm. This almost certainly dispersed a lot of the sea ice (into warmer waters) which had previously been blown against the main pack, as well as increasing the “slosh” of the warmed seas against the clusters of ice that had become separated/fragmented from the main pack. So paradoxically, a shift in weather pattern bringing a sharp cooling over wide areas also brought (temporarily?) a sharply increased ice extent (coverage greater than 15%) reduction and associated localised increased melt. The weather pattern is remaining relatively cool over large areas, so the question is, what happens now that the outlying clusters of ice are close to being largely melted/dispersed? Is it possible that we can’t read too much into the very recent trend? Is it possible that it doesn’t have the “inertia” that has been claimed earlier on this thread?

    One very interesting perspective comes from considering what happened in the Arctic in summer 2004. Compare the extent reduction of the last 3 weeks then and now:

    08,06,2004,7424063
    08,27,2004,6024844
    = -1,399,219 km2

    08,06,2008,6579844
    08,27,2008,5175313
    = -1,404,531 km2

    The first thing that is clear is that there is nothing “unprecented” about the recent 3-week trend, taken as an overall average.

    So what was happening in 2004: was it a season where there was a lot of very late season melt? Not at all: consider the following article on the “Short Arctic Summer of 2004″ – freeze-up was actually earlier than in previous years.

    So what happened to extent in the next 3 weeks in 2004?

    08,27,2004,6024844
    09,17,2004,5821250
    = -203,594 km2

    Now I’m not optimistic enough to expect that the reduction in the next 3 weeks of this year will be that small – there’s various reasons why I think it may well be significantly larger. But the 2007 minimum was as follows:

    09,24,2007,4254531

    In order to match that, 2008 will still have to lose a further 921,000 km2, and even to finish within 10 per cent of it 2008 will have to lose a further 495,000 km2. So, as has already been said, the outcome is still “up in the air”.

    A further note: there is little discernible difference in SST anomalies between Aug 2004 and Aug 2008
    http://sharaku.eorc.jaxa.jp/cgi-bin/amsr/polar_sst/polar_sst.cgi?lang=e

    08,27,2008,5175313
    09,17,2008,???????

    Hope some of this is useful!

    Chris

  29. 179
    Chris says:

    I forgot to add the link to the article on the “Short Arctic Summer of 2004″:
    http://www.arctic.noaa.gov/essay_untersteiner3.html

  30. 180

    Lawrence Coleman writes:

    Geo Thermal great!..if you are lucky enough to live in a geologically active region of the world.

    Or even if you aren’t. Google “hot dry rock geothermal.”

  31. 181
    Timothy Chase says:

    wayne davidson wrote in 175:

    Thanks to the links from Chris, we can discount a warmer sea current, because there is no indication of warmer temperatures. THe solution is in the air and ice.

    If that is the case then we are currently experiencing surface melt. However the guys at NSDIC say its pretty much all bottom melt at this point. That and higher salinity (with ocean level salinity resulting in a two degree reduction in melting point and the effects of salinity being linear) would seem capable of accounting for a great deal given the fact that this is almost all new, saltier ice after last year’s melt. Particularly since temperatures have been less than a degree cooler from last year. And given the fact that concentration is low and the ice is thin, there is less ice to dampen the waves over broad stretches — so that should delay refreeze somewhat.

    In either case, if you can figure out how an atmospheric effect can result in bottom melt but little or no surface melt please let me know. At the moment I am just going to sit back and watch the ice melt.

  32. 182
    Anne van der Bom says:

    #176

    So why aren’t governments embracing the concept, subsidising the cells so that almost everybody can afford them??

    As far as I know, Germany is the only country that does this. Other countries have limited subsidies.

    Energy from pv is still the most expensive there is. Wind is currently favoured for this reason and another very important one: wind is much more constant than solar.

    In the winter in Europe a pv panel delivers around 1/6th of the power that it delivers in the summer. But the energy demand in the winter is higher than in the summer. Average wind is slightly higher in the winter, so that is a much better match.

    Until there is a viable solution for seasonal energy storage at any significant scale, pv for Europe and many other regions in the world is not attractive at the current price level.

  33. 183

    181–

    This post seems to agree with Wayne D’s on the “ice” part–which, as stated, I suspect may be important in what we are seeing.

    We sure seem to have a growing spectator sport on our hands here!

  34. 184
  35. 185
    Phil. Felton says:

    Re #152

    Not necessarily – ice often becomes less concentrated following break up/dispersal, in the absence of melt. For example, the following buoy from the edge of the Beaufort Sea (where I understand ice was broken up last winter by storms) still shows ice thickness of >3m, despite southward drift:
    http://www.crrel.usace.army.mil/sid/IMB/2008F.htm

    Since last january that has been the case in the Beaufort sea, lots of broken old ice which is in low concentration now, however the individual ice is often ~3m thick however it is melting rather rapidly. Some of the old buoys in that region are indicating near total melt, here for example:
    http://www.crrel.usace.army.mil/sid/IMB/buoy_plots/ice2007E.gif
    The one Chris referred to above is new, less than a month’s data but has melted ~10% in three weeks.

  36. 186
    Andrew says:

    Re: 181 “all pretty much bottom melt at this point”

    No, I don’t think so. The bouys are restricted to non-Russian waters and that’s where the temps are still high and are causing surface melt.

  37. 187

    #181 Timothy, I agree that bottom melt is happening now, and also there should be higher salinity. However I think in terms of every component. If the air was dramatically colder
    the melt would stop quite rapidly, The atmospheric contribution has been huge, even now. I am deeply interested in knowing why a likely equal volume of ice has melted under colder air and water conditions. Lately I came to think about Thermal IR contributions from clouds and thinner ice feedback combo, Is there other factors causing this melt to be so substantial under apparently colder temperatures? The idea floated about that first year ice is less salty than old multy year ice does not pass the tea tasting test.

    #183 Kevin , you might be a spectator, but I don’t believe thinking is a sport!

  38. 188
    Timothy Chase says:

    Kevin McKinney wrote in 183:

    181

    This post seems to agree with Wayne D’s on the “ice” part–which, as stated, I suspect may be important in what we are seeing.

    We sure seem to have a growing spectator sport on our hands here!

    I’m thinking this bottoms out around 4,033,000 km^2 (give or take 20,000 km^2) on about 30 Sept 2008.

    Strictly my amateur guess, though.

  39. 189
    Hank Roberts says:

    Andrew, what’s your basis for those statements?

  40. 190
    Andrew says:

    Photovoltaics (PV) CO2 emissions…

    I realize this sure seems like OT, but since climate change and the melting of sea ice is due to rising atmospheric CO2 levels, we need to accurately understand how to reduce CO2 emissions and not be mislead about PVs potential as a solution.

    $4.68: Cost per peak watt for PV
    20%: Fraction of cost needed to refine silica into silicon
    $0.92: Electric cost per peak watt PV module
    $0.03: Wholesale cost of coal fired electricity in China
    31 KWH: Electric need to produce 1 peak watt PV
    4 hr/day: Typical equivalent sunlight for PV installation in Germany or US
    7700 days: Time needed for PV to produce power consumed in production
    21 years: Time needed for PV to produce power consumed in production.

    Understandably, PV manufacturing executives will tell a far more optimistic story.

    Yes, the numbers can be tweaked up or down, but from what I can tell, the PV industry is trying to sell themselves as something that they are not.

  41. 191
    NeilT says:

    #178 Chris, it all makes a pretty story except for two things.

    1. you are talking about extent all the time. Assuming that the melt is only happening from the Extremities of the Ice. Nothing could be further from the truth today. OK Area is unreliable because of the meltwater issues, but compare these two.

    1.

    2004

    http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2004/aug/asi-n6250-20040828-v5_visual.png

    Today (although the link will update tomorrow)

    http://www.iup.uni-bremen.de:8084/amsr/arctic_AMSRE_visual.png

    The clear and quite extensive melt inside the leading edge of the ice is massively different from 2004. I’d suggest that there is no single point of contact, except the SST figures. More on that in a second.

    2.

    I have noticed the the entire Ice cap has been moving in response to the wind. Stacking up on Svalbard and the islands off Russia then pushing down on the Archipelago and opening up from the islands and Svalbard.

    I’ve never seen that before. Have you?

    Back to the SST. Clearly there is a massive difference between the SST for 2004 and the SST for 2008.

    It’s quite simple really, there is nearly 1 Million sq km “More” warm sea this year than in 2004 where the sea was insulated under the ice. I’d guess that would be a pretty huge energy budget even at the same SST as 2004? I’m no good at Maths and equations but even I can see that raising 1 Million sq km of water by a degree or two “C” is some massive amount of energy. Energy which will power yet more fall and spring warming in the Arctic.

    Or did I get that wrong?

  42. 192
    NeilT says:

    I don’t know if captcha got me or not so I’ll repost

    #178 Chris, it all makes a pretty story except for two things.

    1. you are talking about extent all the time. Assuming that the melt is only happening from the Extremities of the Ice. Nothing could be further from the truth today. OK Area is unreliable because of the meltwater issues, but compare these two.

    1.

    2004

    http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2004/aug/asi-n6250-20040828-v5_visual.png

    Today (although the link will update tomorrow)

    http://www.iup.uni-bremen.de:8084/amsr/arctic_AMSRE_visual.png

    The clear and quite extensive melt inside the leading edge of the ice is massively different from 2004. I’d suggest that there is no single point of contact, except the SST figures. More on that in a second.

    2.

    I have noticed the the entire Ice cap has been moving in response to the wind. Stacking up on Svalbard and the islands off Russia then pushing down on the Archipelago and opening up from the islands and Svalbard.

    I’ve never seen that before. Have you?

    Back to the SST. Clearly there is a massive difference between the SST for 2004 and the SST for 2008.

    It’s quite simple really, there is nearly 1 Million sq km “More” warm sea this year than in 2004 where the sea was insulated under the ice. I’d guess that would be a pretty huge energy budget even at the same SST as 2004? I’m no good at Maths and equations but even I can see that raising 1 Million sq km of water by a degree or two “C” is some massive amount of energy. Energy which will power yet more fall and spring warming in the Arctic.

    Or did I get that wrong?

  43. 193
    Anne van der Bom says:

    #190

    Andrew,

    Interesting numbers. I have a few questions for you.

    In Germany a PV panel produces typically 800 Wh per Wp per year. So with an energy cost of 31 kWh per Wp, that would mean 31.000/800 = 38 years energy payback time, not 21. Can you comment on that?

    How did you get to an energy cost of $0.92 / Wp? Simply 20% of $4.68? Is the cost of refining silica into silicon only electric cost? No machines? No labour? Isn’t the $4.68 price not an end user price including margins for the manufacturer and reseller?

    How did you get to the 31 kWh energy cost per Wp? Divide $0.92 by $0.03? Isn’t the $0.92 / Wp based on the price that the manufacturer pays to the energy company?

    Can you enlighten us a bit on the justification of this calculation? No offence, but to me it seems you just typed a few numbers into your calculator without really understanding what the numbers mean.

  44. 194
    NeilT says:

    #190, Andrew, your figures are well thought out but they fall down on one small fact. You are calculating the number of hours per day with Bright Sunlight. which is what you need to produce the 1 peak watt PV.

    However there will be at least two more hours on average where the cells will produce half your 1pwPV.

    Taking the figure to 5 from 4 reduces your years from 21 to16.

    Using mirrors to focus sunlight could reduce it even more.

    If the manufacturers produce PV cells to generate their own power for manufacturing then the figure drops even more.

    OK the German government are skewing the market by subsidising this, however at the end of the day there will be millions of households who will input power to the grid. Microgeneration in other words. which means their energy security will be much higher than if they had not done it.

    Which is an entirely different equation.

  45. 195
    Chris Dudley says:

    Andrew, (#190)

    You might be interested in a more careful calculation of energy payback time:
    http://www.nrel.gov/pv/thin_film/docs/lce2006.pdf
    Energy payback time in Southern Europe (more comparable to the US) is 1.7 to 2.7 years, much shorter than your calculation. Part of your problem may be that you
    are basing you calculation on a retail price for solar.

    Chris

  46. 196
    Timothy Chase says:

    wayne davidson in 187 wrote:

    The idea floated about that first year ice is less salty than old multy year ice does not pass the tea tasting test.

    First year ice is more salty than old multi-year. The salty bits melt first — before the icier bits, drain out as brine, and then the wind and the waves compactify the ice over the years. But I assume you misspoke. And then of course we have the other factors: thin ice, waves, a lower freezing point / melting point, etc.. Don’t see a need to invoke some mechanism for surface melt where melting is taking place almost entirely at the bottom.

    In any case, I am at work, so I have to keep it short at this point. But what do you think? 220,000 km^2 below last year’s sea ice extent minimum by the 30th of next month?

  47. 197
  48. 198
  49. 199
    A.C. says:

    220,000 km2 is right around the size of utah, right?

  50. 200

    #175 Wayne Davidson

    NSIDC mentioned that it is the undersea current doing this and pretty much all bottom melting. I think the sun is to low on the horizon at this point.

    Did you folks see the NSIDC chart today.

    http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png

    http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm


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