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Comments 120351 to 120400:

120351. chris1204 at 13:52 PM on 26 April 2010
        Has Arctic sea ice returned to normal?
        Jeff Freymueller @ 37 'Simple physics says that everywhere there is open water and air at -20C or -25C will mean there is significant heat loss from the water and this will favor sea ice formation...' I'm relieved that my question wasn't totally naive :). The other variables such as wind and waves are obviously important. However, heat lost from water has to go somewhere - presumably into the troposphere and detectable as a rise in winter temperature. Thus, so long as winter temperatures within the Arctic do not transgress critical boundaries, ice will form regardless even if the overall temperature in the Arctic is recorded as increased. Hence, consideration of summer temperatures may be more relevant. The complicating factor as far as I can tell is precipitation, which is predominantly snow. This is very difficult to measure (see the Wikipedia article on ‘Climate of the Arctic’). Increased temperatures, as we know, lead to increased winter precipitation (snowfall), which would predispose to better preservation of winter ice in summer months due to increased albedo. Does anyone know whether there was increased Arctic precipitation over the last winter? It may be that arguments over ice cover in the Arctic may be a red herring in that increases or decreases may tell us little about world climate at least in the short term. From my very limited understanding, one could plausibly argue for warming even in the presence of increases in Arctic ice cover. The converse - global cooling despite decreased ice cover - may therefore also apply though clearly we have a significant raft of evidence from other sources that the world is not cooling. I suspect that the iconic status of the Arctic and Antarctic ice caps may distract us from less glamorous but more robust climate signals. However, the world at large gets excited by headlines - hence, the need to address the complexities.
120352. gallopingcamel at 11:27 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        As we have had accurate measures of "Ice Extent" for less than 40 years it is a little premature to suggest that we know what "Normal" is. Ditto only more so for "Ice Volume".
120353. Alexandre at 08:34 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        From Peru #39 There's lots of data in the nsidc.org website, like this for instance. I requires some work to dig out the information you need, though.
120354. johnd at 08:25 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        "Normal" is very hard to determine, especially when dealing with anything that changes or evolves over time, the climate and all living things for example. This may be off topic slightly, but perhaps if we are to find a basis for establishing "normal" conditions on our planet, and that includes Arctic ice, we need to establish a bench mark of some relevant indicator that all else can be measured against. As humans we should know what a normal diet is, too little food and we waste away, too much and we become obese, a "normal" diet should be one that allows our bodies to grow and perform close to their full potential. In the natural world plants also have their diet that allows them to grow and perform close to their full potential, and part of that diet is that basic building block of all life, carbon. It is known that many plants need nearly 3 times the present concentration of CO2 in order to reach their optimum growth, and this knowledge is widely used by enriching the immediate atmosphere of the plants with CO2. Therefore should the establishment of a "normal" bench mark for all things related to climate be based on what conditions would be, including Arctic ice, with an atmosphere containing 3 times the present levels of CO2? It seems rather absurd to look for "normal" in time frames so ridiculously short as what are being used.
120355. Ed Davies at 08:07 AM on 26 April 2010
        Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
        Sorry, but I'm afraid a bit more housekeeping is needed. The ampersand character in this post's title is not being escaped properly in the RSS feed: feedvalidator.org which breaks it for my feed reader (RSSOwl). Sorry also if this is a duplicate of a recent similar report here. I know I've seen a problem very like this recently but can't remember where. Whatever, the programmer who wrote the feed generator needs a bloody good talking to - XML's been around long enough that this sort of basic mistake should not be being made any more.
        Response: "the programmer who wrote the feed generator needs a bloody good talking to"
        
        That would be me :-) Every little bit of Skeptical Science was built from the ground up - no pre-packaged blog scripts at all - so inevitably it's a little unpolished. With only so many hours in the day, I tend to take a 'bare minimum policy' - do whatever programming is required to get the job done. As Doug Bostrom said when he helped me improve the website's security, my code is 'idiosyncratic'.
        
        I'll look further into escaping non-XML compliant characters.
        
120356. Riccardo at 08:04 AM on 26 April 2010
        Trenberth can't account for the lack of warming
        "There is a TOA imbalance of 6.4 W m−2 from CERES data and this is outside of the realm of current estimates of global imbalances (Willis et al. 2004; Hansen et al. 2005; Huang 2006) that are expected from observed increases in carbon dioxide and other greenhouse gases in the atmosphere." This means that the imbalance is there but it's absolute value is inaccurate. "The TOA energy imbalance can probably be most accurately determined from climate models and is estimated to be 0.85 ± 0.15 W m−2 by Hansen et al. (2005) and is supported by estimated recent changes in ocean heat content (Willis et al. 2004; Hansen et al. 2005). A comprehensive error analysis of the CERES mean budget (Wielicki et al. 2006) is used in Fasullo and Trenberth (2008a) to guide adjustments of the CERES TOA fluxes so as to match the estimated global imbalance." So they choose to take the value from Hansen et al. 2005 and adjust the CERES TOA fluxes to match this value.
120357. hu? at 07:47 AM on 26 April 2010
        Trenberth can't account for the lack of warming
        'A comprehensive error analysis of the CERES mean budget(Wielicki et al. 2006) is used in Fasullo and Trenberth (2008a)to guide adjustments of the CERES TOA fluxes so as to match the estimated global imbalance.'
120358. hu? at 07:44 AM on 26 April 2010
        Trenberth can't account for the lack of warming
        But Trenberth says repeatedly the data is 'adjusted' to show an estimated imbalance...not that the imbalance is shown by the data.
120359. michael sweet at 07:26 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        The amount of ice that forms in winter is related to the temperature and also to ocean currents. The central arctic entirely freezes over. In the Atlantic Ocean and Bearing sea, currents and winds interact to form ice. This year unusual winds in March and April have caused a lot of ice to form. We will have to see how if affects the summer melt.
120360. Robert Murphy at 05:21 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        Karl (#40), The Arctic ice *is* melting though, and it has been declining for decades. Polar bear habitat *is* threatened. The situation has not reversed at all. It gets tedious as well that every denier thinks that attacking Al Gore is the same as attacking climate science. He's irrelevant to the science.
120361. Karl_from_Wylie at 05:01 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        #38 sailrick If climate alarmists would denounce Al Gore's "proof" being melting ice caps (poor lonely polar bears) and freezing cold winters, then skeptics wouldn't use his own examples against the climate alarmists when those examples reverse.
120362. From Peru at 04:06 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        In the Polar Science Center, how I can get the month-by-month Arctic Sea Ice Volume Anomaly and Total Volume data, so that I can plot it in EXCEL?
120363. sailrick at 03:59 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        HumanityRules #18 And the upshot of what Alexandre explains in #19 is that amateur skeptics, Republican politicians and right wing media take what people like Watts say, and turn it into another global warming skeptic/denier meme, which then becomes more proof to them that AGW is hogwash. It then is a new "proof" in their littany of arguments, which get repeated endlessly in the skeptic echo chamber. An example of this are the claims in Febuary that global warming is over because a big part of the U.S. got a lot of snow. Actually one of the snowstorms that hit Washington DC happened on the warmest Febuary 6th on record, globally that is. But this nonsense was repeated in every right wing media outlet, the blogosphere and by Republican polticians. Donald Trump even said Al Gore's Nobel Prize should be taken away because this was proof against AGW. It was a record warm winter. Another example is the fallacious claim that IPCC scientist Phil Jones said there has been no warming since 1995. He never said that. But it is now another proof for skeptics,- another phony argument in their littany. And Watts feeds and encourages this nonsense. And so it goes.
120364. Jeff Freymueller at 03:54 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        #28 chriscanaris: "Even if much of the Arctic has temperatures below 0 degrees, I would expect the overall area below 0 degrees to be smaller and for 0 degree conditions to persist for shorter periods hence leading to less by way of new ice formation. This is what I consider counterintuitive - hence, my wondering (naively perhaps) just how direct is the dependence of sea ice on temperature." The average winter temperature in the Arctic Ocean is not just below 0C, it is far below 0C. In Barrow, Alaska (Arctic coast), the winter average temp is around -25C (Dec through March), that's the daily mean not the low. I don't know how much this varies across the entire Arctic Ocean basin, but the bottom line is that air temps are far below freezing and this will favor the production of sea ice everywhere in the Arctic Ocean all winter. I would bet that the answer is known to your question about how direct is the dependence on temperature -- but I don't know it. I don't think the question is naive. Simple physics says that everywhere there is open water and air at -20C or -25C will mean there is significant heat loss from the water and this will favor sea ice formation, but the water doesn't just sit there in place so wind and waves causing water to mix will also have an impact, and the formation of some ice will also change the rate of heat flow out of the water+ice to the air.
120365. Riccardo at 03:32 AM on 26 April 2010
        Trenberth can't account for the lack of warming
        hu? "referring to data is not claiming it indicates an imbalance." What's wrong with referring to data that shows imbalance? In the section "dataset" they elaborate on this and on the necessary adjustment of the absolute value of the imbalance.
120366. iskepticaluser at 02:53 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        Steve #6 points out the importance of sea-ice extent relative to a positive ice-albedo feedback. This is underlined by a recent report from the Pew Environment Group concerning the “climate services” provided by arctic snow and ice and the potential economic costs of their disappearance. From a summary of the study: “The report calculates that this year alone, Arctic melting [of sea-ice, snow-cover, and permafrost] may warm the Earth an amount equivalent to pumping three billion metric tons of CO2 into the atmosphere. 'That’s equal to forty percent of all U.S. industrial emissions this year or bringing on line more than 500 large coal-burning power plants,' said Dr. Eugenie Euskirchen, co-author of the report and a scientist from the University of Alaska at Fairbanks’ Institute of Arctic Biology.”
120367. hu? at 02:49 AM on 26 April 2010
        Trenberth can't account for the lack of warming
        Riccardo, Thanks for your reply, but referring to data is not claiming it indicates an imbalance. In fact Ternberth says quite clearly that the CERES data is 'adjusted'. Seriously, what am I missing here?
120368. Andrew Mclaren at 02:21 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        This fake argument about a bit of Seasonal (and Weather-related) ice formation being the "return to normal" was in Canada's Globe and Mail a couple of weeks back and generated plenty of the usual arguments. Interestingly, the article itself was MOSTLY about Mark Serreze (NSIDC)'s frustration that his research was being misappropriated by the usual suspects among the climate skeps/deniers. What really impressed upon me was that most of the ice in question was in the Bering Sea, not noted as a site for Perennial Ice! This really does illustrate the confusion that persists in many people's opinions between long-term and weather-related trends. It has been a spectacularly aberrant Winter this past year, according to many regional expectations for normal weather. It is important to argue and defend a more circumspect perspective e.g. in this case that cold air masses get pushed around by the warmer, especially in a Season characterized by El Nino and a strong NAO, and that persistent cold temperatures WILL yield more Seasonal Ice. In contrast to the dearth of Ice Pack in Eastern Arctic/Canada of course. Anyway I'm new posting here, mostly here to be better informed given that I am not a Climate Scientist, so my contributions to the discussion are pretty much rhetorical. I do want to help combat the ignorant, pasted blogtrotting that goes on in commentary in Mass Media however. So I'll be checking in more or less irregularly!
120369. Marcel Bökstedt at 01:12 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        Also, I don't understand why a high value of AO would lead to less ice, while a high value of the corresponding index in the South hemisphere is supposed to lead to stronger winds, more polynyas and more ice. This is probably related to the overall geography around the poles, but not so intuitive. Alexandre> I find the paper by Francis et al. confusing. It is mostly about statistical correlations, and it is not so easy to figure out what is cause and what is effect. As you say, they don't believe that winds are important - the polynyas don't matter. But they must be there, after all that word is Russian. michael sweet> That's good to know. But it still does not explain why the maps from this year look different from the maps from previous years.
120370. michael sweet at 00:32 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        The ice maps at Cryosphere Today frequently change in color from day to day. Their sensors have difficulty telling open water from melt pools on top of the ice. That means that if it is warm for a few days and pools form on top of thick ice, they show it as broken ice or open water. When it gets cold again the pools freeze and it shows as ice again. It is better to wait for a month to see what melts, rather than speculate how thick the ice is from some small changes in color. The NSIDC uses monthly averages to remove much of this type of error.
120371. mspelto at 00:27 AM on 26 April 2010
        Has Arctic sea ice returned to normal?
        An important current research aim is to improve forecasting sea ice abilities. The 2010 forecast model is available at Polar Science Center They show a slow start to the season, and a greater development of the Northwest Passage than Northeast Passage. The key will be the fine tuning of the model for future years based on its experiences this year. Forecasting a season ahead is tricky of course, what will summer conditions be? It is important just as it is to forecast glacier mass balance before the summer is underway. 2010 Mass balance forecast
120372. witsendnj at 23:39 PM on 25 April 2010
        Tree-rings diverge from temperature after 1960
        Here are links to every article I've been able to find so far about ozone, CO2 and vegetation: http://witsendnj.blogspot.com/p/basic-premise.html
120373. Alexandre at 22:50 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        Marcel Böksted I've just done a quick research myself. This Francis 2005 looks like something I meant before. They basically say direct longwave radiation (ie GHE) accounts for the largest part of sea ice loss (40%). Solar variation in the region is negative. Positive feedback due to albedo variation is also important, and there's some discussion (a bit outside the scope of the paper) about other factors, such as increased precipitable water. About winds: "Anomalies in meridional winds also explain significant variance in most areas except for the Barents and Beaufort Seas, but the influence is much weaker than expected." (I did not read it all, just a quick look at the abstract and conclusions)
120374. Alexandre at 22:21 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        HumanityRules #25 - As far as a whole picture of the trend goes, I don't think you can get much wholer then Figure 1. It shows the full series, as opposed to the snapshots. Marcel Böksted #29 - It is very reasonable to assume that the AO index has some influence in arctic sea ice. On the other hand, there is also some debate whether this oscillation is in some way influenced by the anthropogenic sea temperature rise. The math (ie the models) predicted Arctic Sea Ice would melt under AGW. It is actually melting faster than that. I still want to find that paper about sea ice loss cause attribution. I was hoping some other commenter could help us here...
120375. bit_pattern at 21:01 PM on 25 April 2010
        Increasing CO2 has little to no effect
        Sorry, I meant Chen (2007) Here is the working link [Source]
        Moderator Response: Thanks for pointing that out - I've updated the link.
        [RH] Hotlinked paper in order to fix broken page formatting.
120376. Marcel Bökstedt at 20:45 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        I looked at some links from Peter Hogarth's excellent post. It seems that there is a lot of evidence that the Arctic ice has been getting thinner. The quality of the data can be questioned, but they do pile up. First, there are the submarines. They did measure ice thickness from below, using sonar. Kwok and Rothrock report that there were two periods of submarine voyages under the ice. The first one was 58-76, the second 93-97. The reported difference in thickness is 1-2 meters, which is a lot. The problem with those data is that there were not that many voyages, it seems to have been about 10 in all in either period. Then there are early direct observations 1955-2002, and buoys. Rigor and Wallace report on those. They show a decline in ice thickness. R&W state that this happend very fast in 1989-1990, and blame it on the Arctic Oscillation which was in an extreme "positive" state at this point. A positive AO index means low pressure at the pole. This would be compatible with the submarine observations. They predict (in 2004) that the trend will soon reverse, and the ice thickness will build up again. This prediction has not come true, but on the other hand, the AO index has stayed on the positive side. There are additional data from satellites and observations from locals, that all point to a decrease in ice thickness since about 1955. The conclusion seems to be that we have had a decrease in both extent and thickness, giving an even bigger decrease in ice volume. Humanity Rules> Yes, I noticed that darkening of the purple too, but I don't know what it means. Maybe we should mail the guys at cryosphere today and ask if it is real or an artifact?
120377. chris1204 at 19:16 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        Jeff Freymueller @ 24: warmer than average weather in the Arctic is still plenty cold enough to result in the formation of more sea ice, because the surface air temp is well below 0C. Fair point. However, most of the Arctic was warmer last winter - not just Hudson Bay. As I recall, the argument on this site relating to Northern Hemisphere snowstorms suggested they arose in the context of increased precipitation due to warmer weather. Indeed, we have just had the warmest March since 1979 as per the satellite record. Even if much of the Arctic has temperatures below 0 degrees, I would expect the overall area below 0 degrees to be smaller and for 0 degree conditions to persist for shorter periods hence leading to less by way of new ice formation. This is what I consider counterintuitive - hence, my wondering (naively perhaps) just how direct is the dependence of sea ice on temperature. Given all this, Humanity Rules @ 25 sums it up well saying, 'There is something a little bit extraordinary about this years Arctic ice.'
120378. Riccardo at 18:10 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        "Figure 2 is MODELLED data based on ice concentration." and much more ...
120379. Riccardo at 18:00 PM on 25 April 2010
        Trenberth can't account for the lack of warming
        hu? the TOA imbalance come from satellite data. Trenberth has referred to these data several times, for example here.
120380. hu? at 17:42 PM on 25 April 2010
        Trenberth can't account for the lack of warming
        Anyone?....Anyone?...Bueller?
120381. HumanityRules at 17:08 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        23.Jeff Freymueller I agree. Therefore the quality of the ice volume data has to be highlighted because this is the drawback of that particular metric. I don't see any of this in the article and given we're after the full story then maybe it should. For example from what I can tell Figure 2 is MODELLED data based on ice concentration.
120382. James Wight at 17:06 PM on 25 April 2010
        Every skeptic argument ever used
        I have a few more suggestions about the argument list (nothing too major – it’s mostly nitpicky stuff, so don’t worry too much about it): • One argument recently added is “Global warming does not cause volcanoes”. This is grammatically incorrect – something can’t “cause” an object. Perhaps it could be reworded to something along the lines of “Global warming does not cause volcanic eruptions”. • A while ago I added the arguments “Proponents don’t attempt to falsify AGW” and “It’s not 100% certain”. On second thoughts, I think both belong under “The science isn’t settled”, as both arguments have to do with the nature of science. • “It’s the gulf stream” should probably be in the “It’s the ocean” category. • Doesn’t “CO2 measurements are suspect” belong under “CO2 is not increasing”? • I would also suggest that “It’s ozone” be categorised under “It’s CFCs”, because they caused the ozone depletion. There are some other proofreading-related things which I’ve noticed: • Strangely, the main arguments in the categories “It’s not happening”, “It’s not us”, and “It’s too late” are bold, but not those in “It’s not bad” and “It’s too hard” – why is this? • There’s a full stop after “CRU lost temperature data”, whereas none of the other arguments have a full stop. • In the links for “Climategate was whitewashed”, a article called “Climate-Gate Gets A Whitewash” was counted as pro-AGW, but it seems to be actually a skeptic link. (BTW, is there a possibility of making each resources page show all the links for that argument, rather than just the latest 25?) • Oddly enough, once or twice when I’ve submitted a new skeptic argument, I’ve noticed the list of arguments to check includes “I would really like to see the EPA-OBD II Annual Vehicle Emissions Inspection Law closely examined and changed.As it stands right now, it is entirely possible for any Gasoline powered Vehicle from 1996 to the present to fail it's Emissions Inspection”. Why is this? • Is there any order to the contradictions page? It seems disordered.
        Response: Once again, many thanks for the very specific feedback. The regular contributions you've made have provoked me to add you to the list of people I thank for making contributions to Skeptical Science (look for the bullet point list of thanks at the end of the post). I've made the following changes:

        • Changed "Global warming does not cause volcanoes" to "Global warming does not cause volcanic eruptions". I first encountered this argument on Wattsupwiththat and didn't take much notice of it. Then I saw a peer-reviewed paper from 1992 saying the melting glaciers on Iceland would lead to more volcanic eruptions which piqued my interest. I created the argument just so I could file away that peer-reviewed paper for future reference.
          
        • Recategorised "Proponents don’t attempt to falsify AGW" and "It’s not 100% certain" under "The science isn’t settled".
        • Recategorised "gulf stream" under "it's the ocean".
        • Recategorised "CO2 measurements are suspect" under "Co2 is not increasing".
        • Re ozone, aren't there various factors that might cause ozone depletion such as cosmic radiation? I'll leave as is for now.
        • Fixed those unbolded arguments under "it's not bad" and "it's not too hard" (in a bit of a hack solution, I've hard coded this rather than make it database driven).
        • Removed full stop after "CRU lost temp data" (you have the pedantic eye that any good proofreader worth their salt possesses).
        • Recategorised the "Climategate gets a whitewash" article as skeptic.
        • Re the "I would really like to see the EPA-OBD II Annual Vehicle Emissions Inspection Law..." argument appearing when you submit a new argument, this was because my code was accidentally showing deleted arguments as well as approved ones. I've tightened the code to only show approved arguments. I'd noticed this also but hadn't bothered to fix it - it took your comment to supply sufficient motivation for me to fix the loophole :-)
          

        One of these days, I'll reprogram the resource pages to paginate the links - that way, you'll be able to scroll through all possible links.
        
        Re the contradiction page, I've added a field to the database "Contradiction strength". I did this because once contradictions started getting submitted, I noticed some were more "contradictory" than others. Eg - more blatant contradictions whereas some were arguable. So I've been going through the contradictions (albeit slowly), placing each contradiction along the pecking order depending on how strong the contradiction. It's a bit of an ad hoc process.
        
        However, ultimately the ordering is not that important. My ultimate goal with this page is not to show all the contradictions in a muddled mess like this - I eventually hope to show two top-ten lists: one of the most common contradictions and one of the websites with the most contradictions (eg - the number of different blog posts which contradict each other).
120383. HumanityRules at 16:58 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        There is something a little bit extraordinay about this years Arctic ice. The following show ice concentration, i.e. the % of sea covered by ice. Almost all the Arctic Ocean is covered by 100% ice (dark purple). Shown here are 1st Jan, 1st Feb, 1st Mar and 1st Apr 2010. Compare this with the earliest winter on record, 1980. You can see much more pale purple regions, suggesting areas with as little as 80% coverage. 2007 didn't look great but then neither did 1986, most years seem to look like 1980. The images are generated using a tool on the Cryosphere Today website where you can check as much of the intervening years as you wish. 2010 looks so good you can't help thinking it's a data error. Since we're after the full picture I thought it was worth throwing this into the mix.
120384. Jeff Freymueller at 16:54 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        #20 chriscanaris, warmer than average weather in the Arctic is still plenty cold enough to result in the formation of more sea ice, because the surface air temp is well below 0C. In any case, during the cold spell in North America, the area that was much warmer than average was more like the Hudson's Bay area -- well south of the Arctic Ocean and not really "Arctic". So I'm not sure why it seems "perhaps counterintuitive" that when a cold air mass moves south, it is replaced by other air that in this case was warmer (as opposed to leaving a vacuum in the north?), and in any case the "warm" temperatures in that area were still below freezing, and not in the Arctic Ocean. I don't remember the situation north of Europe -- that may have been more relevant for Arctic sea ice formation, but I just don't recall.
120385. hu? at 16:49 PM on 25 April 2010
        Trenberth can't account for the lack of warming
        Where in Ternberth 09 does it state that satellites indicate an energy gap?
120386. Jeff Freymueller at 16:45 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        #18 HumanityRules: "In fact you could actually accuse SkepticalScience of cherry picking by changing from ice extent, which no longer shows what it would like to report, to ice volume which is more convinient." I'm sorry, HR, but this is a really silly statement. If you want to talk about the AMOUNT of sea ice, you really should be talking about the VOLUME of sea ice (or the MASS, if you like). Extent is useful, but it is not volume. The point is that volume has always been more important than extent, but the continuous time series of extent estimates goes back a lot longer. So there is value in measurements of both extent and volume, but they need to be interpreted based on what they are.
120387. RSVP at 16:24 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        Sorry about my post 21. Very ambiguously written sentence. I meant that ice in general keeps things cooler, so thin ice is not going to help. The thicker the better, obviously.
120388. RSVP at 16:17 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        The increase albedo that Steve L refers to should actually help cooling (looking forward in time). On the other hand, thinner ice is more than a proxy (referring to Gestur's use of the word), as it actually influences climate acting as buffer (energy storage sink) to maintain a cooler planet.
120389. chris1204 at 12:27 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        I would hardly expect sea ice to 'normalise' so rapidly as to be back to normal within a year. The problem here is that both sides of the debate love cherries :-). I do recall recent arguments on this site suggesting that the recent extreme cold weather in Europe and Northern hemisphere generally was effectively a result of warmer weather in the Arctic - perhaps counterintuitive if we have evidence of new ice formation. Moreover, any recovery in ice cover can only begin with newer ice - you can't expect old ice to appear save with the passage of time. Marcus @ 1 points out that new ice is more vulnerable to melting - well, of course. But we don't know how much will melt and how much will eventually form part of old ice until we see the impact of the coming summers and the following winters. Steve L @ 6 notes the possible relevance of albedo with increased ice extent. Steve seems to believe this will ultimately be cold comfort (dreadful pun, I know) to the sceptical camp. John D @ 15 speaks of the contribution of wind forcings. The reality is that we're dealing with highly complex systems. Marcel Bökstedt @ 5 highlights this well. Extrapolations from one winter's data mean little irrespective of where you stand in the warmist - sceptical spectrum.
120390. Alexandre at 12:12 PM on 25 April 2010
        Has Arctic sea ice returned to normal?
        HumanityRules #18 I'm not sure that you understand what cherry picking is. It's to select carefully just the fraction of data that supports what you want to be true. Like picking Germany and Austria in Europe and say "my sampling shows that virtually all Europe speaks German". Watts does not "cherry picks sea ice extent" (as a parameter). He just picks a moment of near-average sea ice extent and shouts "it's back to normal!", as if the problem, if once existed, would be gone now. He does not analyse the whole dataset - he cherry-picks the convenient moments. If he did analyse the whole thing, he would find this near-average blip is as insignificant as the Jan 2008 cool spell as far as the trend is concerned.
120391. HumanityRules at 10:02 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        11.Jeff Freymueller and others Honestly the way you talk you would think Watts invented sea ice extent. All the international and national bodies that concern themselves with Arctic sea ice generally use ice extent as their primary measure. For example NSIDCto make their monthly assessement and daily measurements in terms of ice extent, and I'm not cherry picking NSIDC to make a point either. It's just a ridiculous claim to say Watts cherry picks ice extent. I checked his blog he's been reporting this metric back to 2007 when it was showing the all time low. In fact you could actually accuse SkepticalScience of cherry picking by changing from ice extent, which no longer shows what it would like to report, to ice volume which is more convinient. I actually don't believe this I understand John's wish to show the full story but I equally think you can't really blame Watts for using the 'standard' metric. I still wonder why all the international and national bodies don't use ice volume as their standard metric?
        Response: NSIDC and other organisations use sea ice extent but none of them use sea ice extent to say "Arctic sea ice has returned to normal". It's entirely appropriate to refer to sea ice extent and citing sea ice extent is not the issue here.
        
        The issue is the conclusions you draw from the sea ice extent data. It's inappropriate and misleading to say sea ice has returned to normal based on extent data because this is decidedly not the case - the total amount of sea ice is at record low levels.
        
        So the major point here is that citing sea ice extent data needs to be interpreted in proper context, being aware that the thicker ice below the surface is thinning and that total sea ice is at record low levels at the moment.
        
120392. mdenison at 09:46 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        It appears to me that the skeptics confuse average with normality. They suggest that an average extent recorded for March from 30 years of data represents normality. It does not. Normal sea ice extent is probably better taken as the extent in 1970 or earlier where the records show a long period of steady not declining cover. After that the extent declines so any average of recent data is below the starting point and not useful as a definition of normality. Sometimes average can be used to mean normality and arguments are made where the two terms are interchangeable. This is not the case here. The skeptics deliberately make a false argument by exploiting the fact that these different concepts may be treated as equivalent by the unwary reader.
120393. kdkd at 09:37 AM on 25 April 2010
        Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
        Would it be possible to do an RSS feed of comments for the site?
        Response: It's already available - look for the RSS icon in the left margin with 'Comments' below:
        
        http://www.skepticalscience.com/comments.xml
120394. Gestur at 08:48 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        Another issue with sea ice extent that seems to me to be of importance for its use as a proxy for more relevant metrics like volume as well as for its policy uses derives directly from its low cut-point definition (at least 15% ice covered). Just in terms of coverage itself, two years with equal over-all total sea ice extent, say X million square km, could represent very different amounts of equivalent amount of surface area covered 100% with ice (i.e. what might be called ‘full-ice equivalent’ sea ice extent): say, 0.80 × X million square km in one case and in another, say, 0.40 × X million square km. This would obviously have very different implications for the albedo effect, among other policy-relevant considerations. Indeed, this ‘full-ice equivalent’ sea ice extent metric may well be declining even as the over-all total sea ice extent is gaining, depending on conditions, etc.
120395. johnd at 08:46 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        This report may be of some relevance. Apologies if it has been posted before. http://www.jamstec.go.jp/frsgc/research/d2/masayo.ogi/2009GL042356-pip.pdf Abstract Based on a statistical analysis incorporating 925-hPa wind fields from the NCEP/NCAR Reanalyses, it is shown that the combined effect of winter and summer wind forcing accounts for 50% of the variance of the change in September Arctic sea ice extent from one year to the next ( Δ SIE) and it also explains roughly 1/3 of the downward linear trend of SIE over the past 31 years. In both seasons meridional wind anomalies to the north and east of Greenland are correlated with September SIE, presumably because they modulate the export of ice through Fram Strait. Anticyclonic wind anomalies over the Beaufort Sea during summer favor low September SIE and have contributed to the record-low values in recent summers, perhaps by enhancing the flux of ice toward Fram Strait in the trans-polar drift.
120396. michael sweet at 06:54 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        One reason the NSIDC uses the extent is because it is easy to defend. It is a simple measurement and they have 30 years of data. To obtain the ice area you need to massage the data. Cryosphere Today displays the ice area because they think it is a better measure. Good scientists can disagree on small points. WUWT criticizes the NSIDC for using the SSM/I sensor instead of using the similar AMSR-E sensor. The NSIDC website states that the SSM/I sensor is more precise (the year to year variation is less) but the AMSR-E sensor is more accurate (the measured value is closer to the true value). The difference between the two sensors is small, but WUWT still complains about not using the more accurate value (WUWT does not seem to understand precision versus accuracy). NSIDC values the long term precision for their records. The volume data require even more processing (including a model!) so WUWT would have a fit if a change to that measure was made. In the end the long term trend will win out. If the ice volume is really that much lower the next summer that has conditions favoring melt will really melt. If the volcano in Iceland goes on for a long time it might affect sea ice this summer. We will have to wait until September to see what happens this summer. WUWT will always spout off when there is a small shift toward recovery, even if it is just noise in the data. They will quiet down when the cycle goes back to the long term trend.
120397. actually thoughtful at 05:34 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        Every year in March the skeptics claim everything is fine. Every year, in September the pro-AGW sides claims things are not going well. I think it argues against looking at any year or short span of years. While volume does seem the superior measure, the 5 years of consistent data available are insufficient to make a solid claim (although even at 5 years the data is a notable counter to "ice extent is recovering").
120398. Marcel Bökstedt at 04:54 AM on 25 April 2010
        Tracking the energy from global warming
        Berenyi Peter> Interesting post! (1) How can we be sure that there is no CO2 deep mixing? I agree, if we do know that, it makes it harder to invent a mechanism for sending the energy down to Davy Jones. (2) I believe that the measured OHC has been increasing lately. The rate of increase has fallen though. If I understand your realignment of the OHC and the TOA measurements correctly, the model accepts the recent value of OHC. So why do you say that we have been loosing energy lately? But maybe this is not so important, it seems to me that the main point you are making is that - as you stated earlier - this is not a disagreement between two datasets, its a disagreement between data and theory. I agree, something has to give, either the data or the theory. It will be interesting to see who will win. We should remember that all of this is a higher order question. The first theoretical question to ask about AGW is "how would a given amount of CO2 affect climate". This is essentially a question of finding an equilibrium (yeah, I know I'm simplifying here). The second, more difficult one, is "how will we pass from the present climate to the one forced by the CO2". This is to ask for the path through which a system reaches the equilibrium. That was all theory, but if we can answer those questions, we can compare the result with observations. Well, we can't compare the answer to the first question with observations, but if we can figure out the more difficult second part of the theory, we can compare that. And at present this comparison with observations has difficulties.
120399. Riccardo at 03:48 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        During winter sea ice extent (or area) is largely determined by the weather at the margin of the ice sheet, i.e. at relatively "low" latitudes. Last winter has been cold at these low latitudes but the arctic at higher latitudes was warmer. This is an example of the interannual varibility that says nothing about the trend. And this is why it makes no sense to say that from 2007 arctic sea ice has recovered. Unless one means that the this year number is higher, which no one doubts, a recovery or reversal of the trend cannot be assessed nor we have (at the moment, at the very least) reasons to believe it's going to happen.
120400. Jeff Freymueller at 02:18 AM on 25 April 2010
        Has Arctic sea ice returned to normal?
        #3 HumanityRules, measuring sea ice extent is a fairly simple mapping problem given satellite imagery. I would expect that the extent measurement is largely or totally an automatic process given the input images. Measuring volume requires you to measure the thickness of the ice as well, and until the last several years that required making thickness measurements by direct sampling, submarine, or some other method. Even now, I think it takes more work than measuring extent. In the past, it would have taken a lot of work to make that estimate. So there is nothing wrong with reporting extent or discussing it. You just have to keep in mind what extent is, and what it is not. It is sea ice cover, and not sea ice volume. If you have ever watched the ice break up on a frozen lake, you will know that cover and volume can have very little to do with each other. If Watts is trumpeting a claim that sea ice has returned to normal because extent has returned to normal, while at the same time volume data show the lowest volume yet recorded, then cherry-picking is about the kindest assessment you can make of that.

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