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An update on the Arctic sea-ice

Filed under: — rasmus @ 26 August 2012

We noted earlier that the Artic sea-ice is approaching a record minimum. The record is now broken, almost a month before the annual sea-ice minima usually is observed, and there is probably more melting in store before it reaches the minimum for 2012 – before the autumn sea-ice starts to form.

The figure shows annual variations in the area of sea-ice extent, and the x-axis marks the time of the year, starting on January 1st and ending on December 31st (for the individual years). The grey curves show the Arctic sea-ice extent in all previous years, and the red curve shows the sea-ice area for 2012.

(The figure is plotted with an R-script that takes the data directly from NSIDC; the R-environment is available from CRAN)

UPDATE on the update The National Snow and Ice Data Center announced today (August 27th, 2012) that the 2007 record has now been broken by their more conservative 5-day running average criterion. They also note that “The six lowest ice extents in the satellite record have occurred in the last six years (2007 to 2012).”

343 Responses to “An update on the Arctic sea-ice”

  1. 101
    Lawrence Coleman says:

    82: Jaime Frontero: Ok! I apologise for the rather insensitive comment earlier. To a non american (I live in australia), it does appear as though the machinery in your country to downplay important issues and climate change would have to be the biggest, to belittle the whole issue seems to be in hyperdrive. What I am essentially saying is that the top climate scientists should have collabarated with policy makers and the media a long time ago to get them on side before the spreading ‘cancer’ of the denialist lobby could have so effectively strangled the truth which you the climate scientists are continually reporting. Ok! I generalised a little too much but that’s the perception I believe that the outside world has. Take the canadians, they luckily seem have been forgotton by ‘big oil’ and ‘big vested interest’ and their education system has been teaching their future leaders and voting public the uncensored version of AGW and lo and behold their populaces understanding of climate change is one of the world’s best with an corresponding overwhelming majority saying they realise that Climate change is one of the most serious issues facing mankind but more important they realise that humans are behind it.
    And for the record my lifelong heroes you could say have been, Carl Sagan, Jim Hansen and Albert Einstein( well he became american).

  2. 102
    Jack Mist says:

    Re #75 – Comment by Steve Fish — 27 Aug 2012 @ 9:19 PM:

    “News be entertainment.”

    And that’s the problem. We’re not entertaining enough. Entertainment involves drama and conflict. They can get the conflict by putting a real scientist up against the likes of Monckton. Unfortunately, there’s no drama in the scientist dropping his jaw, lost for words apart from “But… but… but…”

    The whole thing needs to be framed as conflict/conspiracy. Pick & mix from:

    1. It’s the Russians. Climate change is warming the tundra while drying out the US grain heartlands.

    2. It’s the Canadians – see (1).

    3. It’s the Muslims. We know they aren’t worried about spending their own people to destabilise the West – extreme flooding in Pakistan, Bangladesh sinking beneath the waves will lead to a tidal wave of refugees.

    4. It’s the Europeans. Those pinkos have been jealous of our freedoms for centuries – they’re trying to hurt our society by wrecking the weather.

    5. It’s the rulers of the New World Order. To reduce overpopulation, they’re setting the planet up for widespread famine.

    Add a catchy title: Weather Wars.

    Job done.

  3. 103
    Dan says:

    The National Ice Center arctic ice extent product says that 2012 is not a record minimum. Can someone explain the difference to the NSIDC product? Thanks!

    [Response: This is an operational product for people who need to be aware of where any ice might be. It uses whatever data is available and is put together manually. There is no consistency over time in data sources, nor corrections for biases or inhomogenities. Thus it is not very useful for trends – for that you are much better looking at products that use a consistent methodology over time (such as the passive microwave products seen in JAXA, NSIDC and Bremen plots). – gavin]

  4. 104
    Chris Dudley says:

    In the six days of record breaking on ice extent. 0.75 million square km have been lost, a rate 2.3 times faster that the average rate in the prior ten years for the same period.

    Jaw drops….

  5. 105
    Chris Dudley says:

    Oops, should be 0.475 million square km have been lost in six days of records. Typo….

  6. 106

    #101–Yes, Canadians are in general better-informed on the GW issue, according to polls. However, that didn’t prevent them from electing a majority Conservative government which IMO is busily enacting a plethora anti-science/anti-environmental measures that the Tea Party can (for the moment at least) only dream about.

    I think that some ‘voter’s remorse’ may be starting to kick in, but Harper & Co. have 4 years left in their mandate, so a there’s a lot more damage ‘in the pipeline.’

    (Full disclosure: I’m a Canadian citizen, living in the US.)

  7. 107
    flxible says:

    Lawrence Coleman@101: “Take the canadians, they luckily seem have been forgotton by ‘big oil’ and ‘big vested interest’ and their education system has been teaching their future leaders and voting public ….”
    Your mis-perception of Canada ignores the majority governments aggressive support of the biggest of ‘big oil’ -the tar sands- and the focus of the PM on ‘Northern Development’ made possible [and necessary] by rapid Arctic ice loss. While the media here do a slightly better job of reporting on climate than the US, we also have some of the worst denialators among our academics.

    [Response: Not to get into the politics at all, but an interesting geo-political-economic reality I’ve come to appreciate only recently is that the race to the Arctic is not really being driven by climate change, nor even “made possible” by it. Certainly, some things are easier and less expensive when there is less sea ice, but economists and industry people I’ve talked to have said that the cost of oil would have driven things in this direction, regardless of climate change. I find that interesting. We who focus on climate tend to assume that everything gets determined by it, but in the case of the Arctic, the changes we’re observed their have apparently more influenced HOW we exploit Arctic resources, rather than determining WHEN we exploit those resources. –eric]

  8. 108
    Killian says:

    Eric, yes and no. To those of us calling for a well-rounded discussion of climate, energy, governance and solutions, what is surprising about your comments is that you seem surprised. This is a whole-system issue. It is literally impossible to understand climate change outside of economic and energy issues. The sources of the rising GHG’s are, after all, anthropogenic. To the extent these issues are treated as separate by various blogging sites, let alone thinkers, progress will remain limited.

    Your contention that it is mostly the “how” that is affected is generally incorrect. Just as the tar sands were not really viable on the scale they are today even five or ten years ago was economic: they are very expensive to produce. Though there has been some innovation in the last ten years, the technology applied to the vast majority of tar sands has been around a long time.

    The price of oil, driven by demand and scarcity of high quality supply, has risen well over 300% from ten years ago. That does drive the need to explore in the Arctic, however, without the melt, it would still be a pipe dream. Don’t let anyone fool you on the tech side: the vast majority of what the public believes to be “new” technology, like fracking, is anything but, and without that melt, Arctic Ocean energy extraction would not be a serious effort right now because it is simply too expensive to build drills and rigs strong enough to withstand the ice, and to also keep personnel safe.

    Climate is driving the how *and* the when.

    I don’t want to derail the general topic here, so for those interested in the energy side of this, there is no better site than The Oil Drum. There is also some climate crossover there with this site often mentioned.

  9. 109
    Hank Roberts says:

    >> National Ice Data Center …?
    > [Response: This is an operational product for people who
    > need to be aware of where any ice might be….

    Ships are at risk “where any ice might be” — from chunks of ice in otherwise open water. You know that thing the Titanic hit? It was that sort.

    “… A bergy bit is classified as a medium to large fragment of ice. Its height is generally greater than 1 meter but less than 5 meters above sea-level and its area is normally about 100-300 square meters. Growlers are smaller fragments of ice and are roughly the size of a truck or grand piano….”

    This is explained in detail in their FAQ:

  10. 110

    To Killian, I’ve got a couple of comments, based on interviews I’ve done with Coast Guard officers, oil industry executives, and academics who study arctic policy.

    Regarding the decline in sea ice and the rise in oil drilling, Shell and others drilled many dozens of wells in the Chukchi and Beaufort Seas in the 1980s and 1990s and it seems clear that they stopped because the price of oil dropped, not because ice inhibited them. Prospecting for oil from the those seas 10 years from now will be easier than it would have been 10 years ago, but the engineering required for production is basically the same: Hugely massive oil platforms or artificial islands, and deeply buried pipes to link the oil to the facilities in Prudhoe Bay. The retreat of summer sea ice seems to be a relatively small factor: No matter what, you still need to build the infrastructure to withstand midwinter conditions and multiyear ice.

    Overall, the process is probably harder now because there’s more regulation and more opposition to drilling than there was a generation ago.

    Shipping is clearly a different story. Quite a few freighters have now traveled through the Northern Sea Route in Russian waters, including some carrying fossil fuels. The Northwest Passage has been slower to open up, but you do see cruise ships and some others passing through there. Traffic through the Bering Strait has climbed very steeply in recent years, a fact that worries the Coast Guard, local residents, and biologists, among others.

  11. 111
    Edward Greisch says:

    Do we have a graph of sea ice extent or volume or area extending back a century or 2? We may need to refute the idea that there was less ice way back when. It seems preposterous, given that wooden ships had so little success looking for a Northwest Passage.

  12. 112
    Jim Larsen says:

    110 Jerry says, “No matter what, you still need to build the infrastructure to withstand midwinter conditions and multiyear ice.”

    pshawh. as if multiyear ice even touches the equation for fossil extraction in the arctic….
    Ice is seasonal and exists for over a year only as a scientific curiosity…

    SO last century…..

  13. 113
    Deep Climate says:

    2012 Arctic sea ice minimum, part 2: September 2012 projected at 3.6 million sq km, 700K below previous low in 2007

    In my previous discussion of the extraordinary 2012 melt, I noted the eclipse of the old daily record on August 24, three weeks ahead of the 2007 pace. But I also gave a series of short-term projections for the September extent average, which is the metric typically used to track the decline in Arctic sea ice. The 2012 September projection now stands at 3.56 (+/- .0.13) million sq km, slightly down from my previous projection of 3.67 million sq km. That’s more than 700,000 sq km less than the previous 2007 record of 4.30 million sq km.

  14. 114
    Edward Greisch says:

    Here is the one
    ” Adrian O
    State College, PA


Speaking of not knowing, the most mysterious thing for me is that the Arctic melt cycle, recorded around 1820, then 1920-1940 and now 2007-ongoing, has a period of 90-100 years which seems to be completely unrelated to the multidecadal oscillation at a period of about 60 years.

In particular the 1920-1940 melt was in the middle of the warming 1910-1940 while 2005-on melt s in the middle of the cooling 1998-on.
    Aug. 28, 2012 at 2:49 p.m.

    Adrian Ocneanu is supposedly a math professor at Penn State.

  15. 115

    #111 ” Do we have a graph of sea ice extent or volume or area extending back a century or 2?”

    yesss make that 1100 years in this case:

    Note the maps, the Dorset culture was maritime based, a coastal people.
    Note where they lived, Always where the ice clears during summer, Now look at the NW Arctic Archipelago, Its a no human zone, despite lands pretty much glacier free.
    If there was a warmer climate like today, there would have been ruins all over the archipelago. There aren’t any. I have further evidence, more detailed with bowhead catches, 17th to 20 th century, the whalers, including American whalers, never went much past Lancaster Sound. Hundreds of hunts by the toughest guys in the world, yet they couldn’t make it due to ice.

    About this subject contrarians have nothing but conjecture to offer, I rather believe in Harry Potter magic than anything they say!!!

  16. 116

    #107 Eric . Correct, there was a time during the 70’s when oil exploration in the Arctic was driven up by the arab boycott of Israel, they drilled during the most brutal conditions known. There was intense exploration everywhere, in fact there are many capped wells from that time. Ready for export even. The reason why they don’t extract these resources now are market driven.
    Perhaps they wait for the right price,you must ask an economist.

  17. 117

    @114. Yes, Edward, last time I looked he was indeed at PSU. He’s a pretty hard core denialist; I wouldn’t be surprised to find him on one of those lists of “scientists” who dispute the role of CO2 in climate.

  18. 118

    If the use all current knowledge of paleoclimate data – this week milestone may even be first time since Home sapiens start walking on this planet:

  19. 119
    David B. Benson says:

    Edward Greisch @114 — Could we please avoid copying any of Adrian O’s stuff here? It is quite clear that he is clueless with regard to climatology.

  20. 120
    David B. Benson says:

    Kjell Arne Rekaa @118 — Last time might have been as long ago as the Eemian interglacial (which is, according to some, when Homo spaiens first left Africa).

  21. 121
    Perk Earl says:

    Has runaway GW already begun? Exhibit A, B & C:

    Per those animations, it’s easy to see (for those not simply standing their ground, holding a position of denial for political, religious or personal reasons irrespective of data to the contrary) that ice volume is dropping fast?

    Exhibit D:

    Per that comparison we can see methane emissions from the Arctic are rising fast.

    Exhibit E: ‘Large Release of Methane Could Cause Abrupt and Catastrophic Climate Change as Happened 635 Million Years Ago, UCR-led Study Warns’

    From the article: The researchers posit that the methane was released gradually at first and then in abundance from clathrates — methane ice that forms and stabilizes beneath ice sheets under specific temperatures and pressures. When the ice sheets became unstable, they collapsed, releasing pressure on the clathrates which began to degas.

    Nothing new there, as much has been discussed about methane releasing, as well as positive feedbacks. However, we now need to ask if the thinning ice, (which in spite of less than favorable weather conditions to 07’s melt season is this year exceeding that year’s minimum), acting as a positive feedback. As more ice melts – more methane degasses – with the methane itself acting as the major heat source for accelerated melting.

    Have the scales tipped? Are we now in the throes of runaway GW? Keep in mind people tend to think in very short time periods, so many expect runaway GW to be super fast, but it’s probably more like a train gaining momentum over several Summer melt periods. Once the positive feedbacks reach a certain threshold, the process accelerates much faster, which would account for the loss of Arctic ice exceeding even the most dire projections including this year’s record setting minimum (to be determined later in Sept.).

  22. 122
    Kozo Nagase says:

    The date when the lowest reaches this year may be later than September 24 recoreded in 2007. Why? The ice extent itself is a cooling syastem. Now that the cooling system has become much smaller, the date can be more likely to the end of next month or even to the beggining of October….

  23. 123
    Hank Roberts says:

    > Per that comparison we can see
    Do you know the altitude that data set refers to?
    You need to convert millibars to elevation above sea level.
    The same thing has been posted over and over, many places, always with assertions, never with any further support.
    Maybe something will be published — but that isn’t it.

  24. 124
    Lawrence Coleman says:

    121: Perk Earl,
    By what I am seeing on the graphs and trend lines I would saw the data is highly consistant with a stable system quicky going into +f/b oscillation. I studied electronics engineering for a number of years and it is always remarkable how relatively little forcing is required to create oscillation. From rest to full amplitude oscillation the decibel graphs follows an exponential curve so starts off at an almost impercepible rate eg. before 1950 and then slowly gains momentum 1990 and now in 2012 it’s getting really obvious and building up a good head of steam. The time to have begun to act on CC was probably in the 1950-60s. In 2012 is looks as though pandora’s box is well and truly open. 1700Gt of CO2 and NO and CH4 in the tundra permafrost and an additional 1400Gt of methane clathrates under the arctic ocean. The powder keg seems set to explode!

  25. 125
    Lawrence Coleman says:

    121: Perk Earl, I forgot to mention that the speed on onset of the forcing componant determines the energy of the +f/b. Eg. if the rate of CO2 was slowly going up over the last few thousand years in a more or less linear fashion then nature usually has a way of buffering the effect, but this time the incredible rapidity and extent of anthropogenic CO2 onset is unprecedented!. 250ppm, to almost 400ppm now, 100-200 years is unheard of in geological time, that’s like a bullet hitting a pane of glass. You get the picture.

  26. 126
    Paul donahue says:

    I hope the foregoing comment isn’t too big a digression, but the US media’s non-coverage of the record polar ice melt and fires in Spain has been a recurring sub-topic in this discussion. One commenter stated that it is as if the major press is “following” orders, another stated that such a remark was too “tin foil hat” for him. One mentioned the problem is that the media is only interested in news that is entertaining, and the science is too un-entertaining. Another stated that scientists needed to have developed good relations with the media before the “denialists” got to them.

    All these assertions fall short, because they are based on the wrong assumptions about the privately-owned, advertiser-supported media that dominates the US and other industrial nations. So, a few clarifications and facts about the modern media are on order:

    1. The reading/listening/viewing public is not the privately owned media’s customer.

    2. News, information and entertainment is not the product they are selling.

    3. The media’s actual customers are its paying advertisers. For major outlets, these are mostly large corporations – in many cases, subsidiaries of the same corporations that own the media outlets

    4. The media’s actual product is the readers, viewers and listeners. Specifically, their product is people who will be suitably influenced as to be compliant to the advertiser’s business interests, both the narrow interest of buying the advertiser’s product and the broader interests of the industry the business is part of, extending all the way out to include US foreign policy. The reader or viewer must not be made to feel guilty buying cars and burn fossil fuels, nor to oppose business-friendly aspects of US foreign policy, among other things.

    5. Any “firewall” that existed between a media outlet’s business department and its news and editorial rooms has largely broken down over the past few decades. There is a quiet unwritten code among most mainstream journalists that one does not write news stories or analyses that hurt the business interests of the corporate advertisers and owners if one want to advance in their career. I have yet to meet a reporter who will acknowledge such a code exists, but media scholars such as Robert McChesney, Edward Herman, Noam Chomsky, and organizations such as Fairnes and Accuracy in Reporting (FAIR) can find no other consistent and logical explanation for the patterns of news coverage and non-coverage.

    So, no “tin-foil hat” is needed – only an understanding of the things that govern any private business in a competitive environment with powerful customers who can threaten to take their money elsewhere.

    I will leave it to others to find a way for climate scientists to find a way to break-through the corporate media system. But I must warn you that activists in other issues – labor policy, US foreign policy and other environmental issues have had very little luck.

    I refer the reader to the works or Robert McChezney, the public relations and “consent manufacturing” theories (his term) of Edward Bernays, the famous critical work “Manufacturing Consent – The Political Economy of the Mass Media” by Herman and Chomsky.

    Paul D.

  27. 127
    Dan H. says:


    This paper may help with your inquiry into Arctic sea ice during the past several centuries:

    This other oldie, but goodie, describes the mechanism of the multidecadal Arctic oscillation during the latter 20th century.

    For research going back several millenia, the following has some good analyses.

  28. 128
    Perk Earl says:

    Reply to #126: Great explanation of the media situation. “No tin foil hat is needed”, is right.

  29. 129
    Perk Earl says:

    Post 124: By what I am seeing on the graphs and trend lines I would saw the data is highly consistant with a stable system quicky going into +f/b oscillation.

    Post 125: …the incredible rapidity and extent of anthropogenic CO2 onset is unprecedented!. 250ppm, to almost 400ppm now, 100-200 years is unheard of in geological time, that’s like a bullet hitting a pane of glass. You get the picture.

    LC, very interesting view from an electrical engineering standpoint. Also agree the time to have done something was long ago. What a lot of people do not understand, but I am sure you probably are aware of is the lag time from emissions to its influence on the weather, called thermal inertia. The 30-40 year lag between increased energy in the atmosphere and that energy’s penetration into the biggest holder of thermal energy, the oceans (which drives the world’s weather). To think of the situation in the Arctic in the context of that long a lag time really puts the direness of the situation front and center. The illusion I think many have is, if we decide to really do something about this we can just stop emissions (which is a pipe dream because the economy would falter) in an instant and the problem would go away. Oh wrong, there’s baked in increases for at minimum 30-40 more years. There is no light switch to turn off. I like your bullet hitting the pane analogy – it drives home the idea that once fired it cannot be stopped.

  30. 130
    One Step Beyond says:

    Serious question, is it true the antartic sea ice has increased by about 1% a year since satellites have tracked it, if so why the difference with the artic?

  31. 131
    Lennart van der Linde says:

    Paul #126: I fully agree that the ‘propaganda-model’ of the media by Herman and Chomsky is by far the best explanation of the modern ‘media-logic’. Few journalists recognize or acknowledge this, and neither does most of the public. Once we wake up, maybe we’ll be able to democratize the media so they can paint the full picture on global warming and many other vital topics.

  32. 132
    Bryson Brown says:

    @130 OSB: Others here are far more expert, but I’ve heard two relevant points about this– one was that increased melt has led to fresher surface waters which freeze more easily, and the other was that the circumpolar winds which isolate the Antarctic from weather further north have strengthened, slowing warming in the region.

  33. 133
    flxible says:

    OneStep – No, it’s not true, the rate has been 1% per decade, and the differences from the Arctic are myriad.

  34. 134
    Hank Roberts says:

    for “One Step Beyond” — the Antarctic sea ice increase is as predicted:
    WUWT trumpets result supporting climate modelling
    <a href="; NSIDC Reports That Antarctica is Cooling and Sea Ice is Increasing

  35. 135
    Dan H. says:

    One Step Beyond,

    First, the research shows that the increase was 1% per decade, not annually.

    Here are a couple explanations by profs. Liu and Trenberth as to why Antarctic sea ice may have grown while Arctic sea ice declined.

  36. 136
    tamino says:

    Re: #127 (Dan H.)

    It’s misleading to characterize Arctic sea ice by two papers focusing only on very limited regions — one on east Greenland, the other on north Greenland.

    Instead one can find a 1450-year reconstruction for the whole Arctic in Kinnard et al. (2011). It looks like this:

    An even longer-term view can be found in Polyak et al. (2010).

    And if one wants graphs of the last century and more, download the Walsh & Chapman data set. It gives plots like this:

    [edited for images]

  37. 137
    M Tucker says:

    This discussion makes it sound like ALL Antarctic ice is increasing. The Antarctic Peninsula is warming and the Larsen ice shelves are disappearing. Due to warm water currents other ice shelves are melting at various locations in other parts of that vast continent. I would not be at all surprised that some ice in some locations is growing and I for one prefer to get my information from actual experts on the Antarctic ice shelves and Antarctic glaciologists who make repeated visits in order to make sense of an obviously complicated system.

  38. 138
    Chris Dudley says:

    Kozo (#122)

    Using the JAXA data, we can find the time during the last nine years when the ice extent loss rate was as large as during this last week of daily records. On average that was 17 days earlier than now. From the last period at the current rate of loss in those earlier years to the minimum of each year was on average 33 days, though it can happen in as short as ten days. Sigma, estimated from the sample variance is 12 days. So, just based on phenomenology, there seems to be a fairly good chance that this year’s minimum will happen in October. And, we have not really started the 33 day turn around clock either.

  39. 139
    SecularAnimist says:

    From The Carbon Brief:

    Two new research papers published today improve our understanding of the planet’s methane emissions, and might raise worries about the role of the gas in warming the planet. The first suggests that there may be extensive methane deposits under the Antarctic ice sheets. Meanwhile, the second concludes that emissions of the gas from Arctic permafrost have been underestimated.

  40. 140
    cowichan says:

    Interesting that everyone is going gaga over the ice cube/km2 count while PIOMAS indicates that the show was over 2 months ago.

  41. 141
    Hank Roberts says:

    Cowichan, you misread the PIOMAS _anomaly_ chart. See the earlier posts explaining that to me, among others. Early on in the past few years more ice goes away than did historically. The difference is the ‘anomaly’ — bigger earlier. By this time of year the _anomaly_ is not as big.

  42. 142
    MARodger says:

    cowichan @140
    The 2012 PIOMAS volume has yet to reach its minimum as the year-on-year graph of PIOMAS volumes [I edited this because it looked like a dubious site — please clarify]> here (usually 2 clicks to ‘download your attachment’) which is data generated up to this August 25th (or there abouts).

  43. 143
    sidd says:


    verified by ICESAT,Cryosat
    sets August record

    graphs from Wipneus at Neven’s site

    fat lady sings in 2015 +3/-2


    [Response: Hmm.. What justifies using an exponential fit? –eric]

  44. 144
    sidd says:

    Re: PIOMASS, exponential fit

    i have no justification for a mechanism where the ice loss goes as the exponential trend fitted. A straight line thru the last decade gives similar result. A hyperbolic tangent would probably do the same. I claim the graph argues for the min volume drop to effectively zero _within the noise range_ of +/-2e3Km^3 around 2015. And from the physical standpoint, I see no mechanism that can stay ice loss from the heat load from the ocean, or the albedo flip, the graph is telling us how fast it is going, how fast these processes can work.


  45. 145
    Norman says:

    I am wondering why is all the ice melting? When you look at the historical summer temps in the Arctic region, 2012 does not stand out as a well above normal warm one.

    From looking through the different years, Arctic summer air temperatures do not seem unusually warm. Why do years like 2007 and 2012 have such large ice melts even though the temperatures in the area is not above the long term normal?

  46. 146

    #145 Norman, excellent proof of a cloudy summer, exactly cloudy, with IR reflected back up and down from sea ice to clouds. SST’s are for the larger part much warmer, another good reason to melt the ice.

  47. 147
    tamino says:

    Re: #145 (Norman)

    First: the DMI temperature data you linked to is not what it appears to be. It’s not measurements, it’s the output of computer models. More important, it’s the output of different computer models for different years, and those models have an inherent bias between them which makes them not really comparable. That’s the main reason that those who deny the reality of global warming like to reference it so often.

    Second: if you want a decent perspective on how Arctic temperature has changed, look at this.

    Third: a great deal of melting happens from below (due to warmer ocean temperatures) rather than above (due to warmer air temperatures).

    Bottom line: 2012 is “well above normal warm,” the Arctic has warmed. A lot.

  48. 148
    Norman says:

    Tamino at 147,

    Thanks for the link to the Arctic temp graph. The problem with this graph is it is for yearly temps. Unless broken down to summer melt months it could just indicate much warmer winters, which would still be several degrees below freezing. It may not be evidence that the summer temps really are much warmer than before.

    Here is an older article that you have probably seen:

    This one explains the reason the North Atlantic has warmed so much in the last few decades. This warmer north atlantic water does move into the Arctic ocean via ocean currents and could explain the rapid melt of summer ice since the 1990’s. The article may be correct as other ocean basins are not heating as rapidly.

  49. 149

    #145 additional, DMI might be off for the summer but closer to reality during winter. It was a very warm Arctic winter, thus ice thickness not building up so much,

  50. 150
    Edward Greisch says:

    Several people: Thanks for your help.