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robert way at 14:15 PM on 27 April 2010Has Arctic sea ice returned to normal?
I actually commented over at Watts Blog about how it was disingenuous for him to insinuate that volume was increasing at the end of his blog post and I got a couple snippy comments back but no refutation. -
brjohn9 at 14:08 PM on 27 April 2010A visual depiction of how much ice Greenland is losing
JRuss, it's misleading to talk about a "decline in Global temperature from 2004 to 2009," not least because NASA puts 2005 as the warmest year on record. It puts 2009 as tied for second warmest. The real point is that fractions of a degree off the all-time record do not constitute a meaningful "decline" in temperatures. Even if that statement was true, Arctic sea ice has increased marginally in surface area since its all-time low in 2007, but it remains far belows its average extent in decades previous. Moreover, while the surface area has recovered somewhat, there is strong evidence that much of the new ice is so-called rotten ice that will melt again easily, rather than the multi-year ice that is resistant to melting. Also, the Arctic sea ice minimum is driven by factors much more complex than the global average temperature. Finally, why are you repeating crazy "rumors" you "heard" about active volcanoes melting Arctic sea ice? Let's stick to actual science, shall we? -
JRuss at 13:34 PM on 27 April 2010A visual depiction of how much ice Greenland is losing
My handbook of Chemistry & Physics [1962]says the density of ice is 0.917. Taken to the minus one-third power, that would be 1.0293 km on a side for Gt cube. [Yes, that assumes the ice is pure H2O and is without voids.] I heard the other night that Antarctica ended its 2010 'Summer' at minus 100 degrees Fahrenheit. So perhaps the Antarctic can now gain back some ice. Because of the decline in Global Temperature from 2004 to 2009, the arctic ice has grown in area. The rumors I have heard is that there are three active volcanoes in the arctic ocean that are adding tremendous heat to the arctic ocean and that prevents a gain in the thickness of the thin ice covering the arctic ocean. -
nofreewind at 12:41 PM on 27 April 2010A visual depiction of how much ice Greenland is losing
Ok, Greenland has been warming and loosing ice for well over 150 years and surely that guy above has some pretty cool photography. I was able to catch his show on cable and the pictures were beautiful on my TV. Call me a skeptic, but I don't completely "trust" that this ice loss necessarily correlates with the big TV that I watched the James Balog show on. We know man has pumped tons of CO2 into the atmosphere and the amount has risen exponentially since the mid 1850's. But why were many of the worlds glaciers retreating at a good pace in 1900 when we emitted only 1/8th of the CO2 that we are now? Why were the glaciers in Greenland retreating throughout much of this century when the Greenland temperatures were stable? The same thing was evidenced by the paper written by the glacierologist from India. If man has been only responsible for temperature rise from 1975 onward, why were glaciers melting since 1850? Why are glaciers retreating if the world precipitation is supposed to be increasing because of the super computer climate models, just like the heavy snowfall this winter in the NH was all expected and "modeled" apparently, (but i'm not so sure about that, because there were many IPCC references of less snowfall, but I guess the theories seemed to just change this year in light of the new data. I did the same things as this did here in Montana at Glacier NP and came up with the same results using the raw data from NOAA. Temperatures didn't seem to rise but glaciers did melt. Call me a skeptic, but I am not so sure we have anything to worry about. Surely world sea levels are rising, but isn't this about the same rate as it was when man was just getting started to discover the wonders and wealth of burning fossil fuels over 150 years ago? Last point(sorry for being bandwith hog on this post), but this is my favorite glacier picture, scroll to page 3. Is all of the above "unprecedented" just like the CO3 above 300 and just like the dramatic rise in temperatures pointed out this century? On page 3 the guy is standing on tree stumps created from a glacier that formed 3,000 yrs ago, this may seem like a long time, but is just a blink of the eye in geologic time. -
HumanityRules at 12:22 PM on 27 April 2010A visual depiction of how much ice Greenland is losing
I don't suppose you could add a depiction of the full size of the Greenland icesheet as well to put this in perpective? -
kdkd at 11:32 AM on 27 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
It might be an idea to put the source code for SS up in a version control repository somewhere. That way you can get your code autited, and members of the community might want to add features. Good work on the site by the way.Response: Being a novice at the whole open source community, my initial question to this is wouldn't it also be an opportunity for hackers to peruse the code looking for vulnerabilities? -
ubrew12 at 11:15 AM on 27 April 2010A visual depiction of how much ice Greenland is losing
Apologies if I got this link from this website (I forget sometimes), but this James Balog talk about time-lapse video of melting glaciers is quite stunning. The visual pyrotechnices start at minute 9. At around minute 14:30, he starts showing video from Greenland, and its truly amazing.Response: Thanks for the link. Here's the video embedded: -
Berényi Péter at 09:07 AM on 27 April 2010Has Arctic sea ice returned to normal?
There is a sharp conceptual difference between things measured vs. assumed based on a computational model like PIOMAS (Pan-Arctic Ice-Ocean Modeling and Assimilation System). In this sense sea ice extent is measured, volume is not measured, not even calculated. These values are based on a computational model, heavily interlinked with other models. It is extremely difficult to verify such a thing. However, they have a Seasonal Ensemble Forecasts of Arctic Sea Ice from April 2 to September 26, 2010 in three days steps made at the end of March (for scientific research and education only). I have made a backup, just in case. In five months we can check if sea ice extent prediction is correct or not.
That is, the model is falsifiable. We can put more faith into ice volume reconstructions provided the ice extent prediction in fact will not be falsified. The September 2010 arctic sea ice extent is predicted to be 5.3 million square kilometers. We'll see.
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nofreewind at 08:59 AM on 27 April 2010Has Arctic sea ice returned to normal?
>are the folks at WUWT being disingenuous to make any claims about sea ice extent in March when winter sea ice extent is going to have very little negative feedback GOSH NO!!! Because This NASA page from October of 2007, after the record summer low, explains how the lower "perennial" ice during the previous two winters combined with unusual wind patterns is what led to the record low. Also, NASS specifically states in their article that the March 2007 ice was the lowest ever for that month, so, in turn, NASA knows that the March Ice extent, which leads to perennial ice, is very important. What is going on is that many, including NASA - see YouTube, made predictions that the Arctic Ice was on a one way downhill slide because of feedbacks caused by open water, but just like the stock market and other things in nature (think Hurricanes after Katrina) nature has a way of fooling us all. We ALL just have to wait and see what happens. Things have a habit of reversing themselves and it is VERY IMPORTANT that artctic ice recovered in 2008 from the 2007 low and even recovered more in 2009 and is showing signs of continuing that recovery, it is what it is. -
Flowers blooming earlier now than any time in last 250 years
In my previous comment, it should state that "the hours of daylight for particular days of the year are NOT changing". -
Flowers blooming earlier now than any time in last 250 years
johnd, you state that warmth is primarily driven by lengthening hours of daylight. I hate to state what seems like a tautology to me, but isn't warmth also driven by, well, temperature? If the temperature for a particular day of the year is increasing due to AGW, that will change the date of blooming. Yes, length of day is a factor, yes, soil water content is a factor; but so indeed is temperature. In my area (Pennsylvania, Wash. DC) we have hardiness zone creep; the DC Cherry Blossom festival is occurring earlier and earlier over the years, and the mix of fastest growing/best adapted plants is shifting to warmer varieties. Note that the hours of daylight are NOT changing. -
Rob Honeycutt at 07:28 AM on 27 April 2010Has Arctic sea ice returned to normal?
The discussions here are always very high quality and often well beyond my own level of knowledge on climate change (I come here mostly to learn), but I have a question for everyone. Please pardon me if this is obvious. If I understand this right the issue with sea ice extent is in regards the lower albedo of open sea during the summer months, right? Winter sea ice extent has little effect on albedo because the arctic is mostly in darkness. My question is, are the folks at WUWT being disingenuous to make any claims about sea ice extent in March when winter sea ice extent is going to have very little negative feedback? -
Ed Davies at 05:19 AM on 27 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
Ah, right, err, sorry. Maybe that should have been "any professional programmer who writes a feed generator like that needs a bloody good talking to". Still, generation of markup, whether it be HTML or XML, needs a bit of care with this sort of thing - there wouldn't be so many cross-site scripting loopholes if everybody got it right. -
hu? at 02:50 AM on 27 April 2010Trenberth can't account for the lack of warming
"There is a TOA imbalance of 6.4 W m−2 from CERES data " I'm not sure what this means...but it does not say CERES data indicates an imbalance at all. Where is this 6.4 W m-2 figure coming from? -
sleepership at 22:21 PM on 26 April 2010Flowers blooming earlier now than any time in last 250 years
Here in southern New England we have had the earliest spring bloom in my lifetime (56 years)- We had the warmest March in record- 16 degrees above normal- and thus far April will be at least 10 degrees or more above normal- with the earliest 90 degree weather (April 7th) setting another record. The Hardwoods- Mapple & Oak see a leaf progression today-April 26th- about 10-12 days too early. My garden already has summer perennials robust. I have a windmill palm- trachycarpus fortunei- that suffered little cold damage with minimal winter protection growing well- the palm has been in the ground here- for several years- we are now a zone 6-7- with 'zone creep' the zone 7 line creeping north from the Connecticut coast- should see us become a zone 7 in 10-15 years. With the Co2 level PPM now at 391- it seems the climate models prediction of a rapid rise in temperature at 400 ppm most likely being accurate. Also models have predicted that after 2010- the rise in temperatures would accelerate- are now entering the zone of severe weather/climate change? -
HumanityRules at 21:50 PM on 26 April 2010Has Arctic sea ice returned to normal?
Polar Ice Center have alot of supporting data for thier ice volume model here http://psc.apl.washington.edu/zhang/IDAO/index.html It includes forecasts for the Bering Sea and the whole Arctic. It looks like the model is at least underestimating the ice extent as of today. It'll be interesting to see how this works out. -
CBDunkerson at 21:20 PM on 26 April 2010Has Arctic sea ice returned to normal?
HumanityRules is correct that the 'Polar Ice Center' graph in the article shows modeled results... we don't have sufficient data to accurately calculate Arctic ice volume for the entire timeframe. Thus, what they have done is taken measurements in an attempt to determine a general relationship between ice extent, concentration and volume... which they then project with the model based on observed extent and concentration data. However, from 2003-2007 ICESat gathered data on Arctic sea ice which provided sufficient detail to compute volume... and those results match the model quite well;
There are certainly uncertainties around the model values. Ice extent has been the de facto standard for decades simply because it was the only data available. For ice volume we've only got five years of reliable data (and even that has some uncertainties) which cuts off since ICESat broke down. The recently launched CryoSat II and forthcoming ICESat II should give us much more precise data for a longer period going forward.
All that said, the claim that Arctic sea ice is recovering or has recovered based on just two years of extent data is plainly absurd. Both because it ignores basic statistics and because extent is only one of three variables needed to compute volume (the others being concentration and thickness)... which makes it a poor proxy for determining total ice amount.
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Riccardo at 21:20 PM on 26 April 2010Has Arctic sea ice returned to normal?
Any single short term (i.e. weather) event is, by itself, not that significant. It is significant only when summed up to a previous trend. For Arctic sea ice it's definitely downward and one or two years of presumed "recovery" are not going to change this. Personally, I'm not interested in any climate "icon" if considered outside the global changes, we always need to put things in the proper context. So I'm happy to leave these icons to the media. But I have to admit that climate changes are more evident in some variable or process than in others; the Arctic sea ice shrinking is one of these. -
uh1h at 17:41 PM on 26 April 2010Hockey stick is broken
when 18,000 year old glaciers like the Chacaltaya melt away entirely after haveing obviously survived the MWP its a no brainer that it is warmer now at least in Bolivia. -
embb at 16:28 PM on 26 April 2010Are we too stupid?
Jacob:I claimed a tax and trade restrictions is not like a trade war. And major euoropean econimists claim it is, they actually warned France against it. I go with their opinion. Jacob:States, individuals - no matter. Tit-for-tat beats all-defection. No organization. No judge. No God. Just maths. This is completely false. Once again: for individuals there is a higher authority, namely the state, that can punish defection and reward cooperstion, ON THE SHORT TERM. Taxes would not work if tghe state collected taxes only to avoid an uncertain catastrophe in 100 years, this is even in YOUR article, for heavens sake. So, what is the punishment and what is the reward in the case of the carbon taxes? Surely not the good feeling that the state avoided the global warming??? And what is the higher authority in your view? Can you give a clear answer to that? If not, your statement that it does not matter whether we talk about states or individuals is clearly untenable. Jacob:I have never postulated that. It is the point of the post to analyse how to avoid defection. You must have missed that. You are right, I missed that. So, how can defection be avoided? Can you give a concrete answer? I mean if you just name reciprocity, I would be interested to know how reciprocity would work in the case of carbon taxes and how would the punishment of defection look like? Jacob:What are your solutions to mitigate climate change? You must have something considering your clear stance. What I have are doubts. I am in this discussion to clear them, as yet not with much success :) -
johnd at 16:17 PM on 26 April 2010Has Arctic sea ice returned to normal?
chriscanaris at 13:52 PM, your last two paragraphs make valid points. Both ice caps make it difficult to determine when things are in balance simply because of basic logistics. Energy takes the long road in and the short road out. Anything that forces a change on one side of the ledger may not be balanced by an equal and opposite force on the other side, at least within the region. It may well not tell us much about the global climate because the balance desired is to be found elsewhere in a different form. -
4 billion at 15:17 PM on 26 April 2010Has Arctic sea ice returned to normal?
Incredible that volume is the same now as during the 2007 summer. -
chris1204 at 13:52 PM on 26 April 2010Has 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. -
gallopingcamel at 11:27 AM on 26 April 2010Has 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". -
Alexandre at 08:34 AM on 26 April 2010Has 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. -
johnd at 08:25 AM on 26 April 2010Has 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. -
Ed Davies at 08:07 AM on 26 April 2010Skeptical 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. -
Riccardo at 08:04 AM on 26 April 2010Trenberth 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. -
hu? at 07:47 AM on 26 April 2010Trenberth 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.' -
hu? at 07:44 AM on 26 April 2010Trenberth 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. -
michael sweet at 07:26 AM on 26 April 2010Has 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. -
Robert Murphy at 05:21 AM on 26 April 2010Has 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. -
Karl_from_Wylie at 05:01 AM on 26 April 2010Has 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. -
From Peru at 04:06 AM on 26 April 2010Has 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? -
sailrick at 03:59 AM on 26 April 2010Has 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. -
Jeff Freymueller at 03:54 AM on 26 April 2010Has 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. -
Riccardo at 03:32 AM on 26 April 2010Trenberth 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. -
iskepticaluser at 02:53 AM on 26 April 2010Has 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.” -
hu? at 02:49 AM on 26 April 2010Trenberth 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? -
Andrew Mclaren at 02:21 AM on 26 April 2010Has 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! -
Marcel Bökstedt at 01:12 AM on 26 April 2010Has 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. -
michael sweet at 00:32 AM on 26 April 2010Has 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. -
mspelto at 00:27 AM on 26 April 2010Has 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 -
witsendnj at 23:39 PM on 25 April 2010Tree-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 -
Alexandre at 22:50 PM on 25 April 2010Has 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) -
Alexandre at 22:21 PM on 25 April 2010Has 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... -
bit_pattern at 21:01 PM on 25 April 2010Increasing 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. -
Marcel Bökstedt at 20:45 PM on 25 April 2010Has 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? -
chris1204 at 19:16 PM on 25 April 2010Has 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.' -
Riccardo at 18:10 PM on 25 April 2010Has Arctic sea ice returned to normal?
"Figure 2 is MODELLED data based on ice concentration." and much more ...
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