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Is Antarctica losing or gaining ice?

What the science says...

Select a level... Basic Intermediate

Satellites measure Antarctica is gaining sea ice but losing land ice at an accelerating rate which has implications for sea level rise.

Climate Myth...

Antarctica is gaining ice
"[Ice] is expanding in much of Antarctica, contrary to the widespread public belief that global warming is melting the continental ice cap." (Greg Roberts, The Australian)

Skeptic arguments that Antarctica is gaining ice frequently hinge on an error of omission, namely ignoring the difference between land ice and sea ice.

In glaciology and particularly with respect to Antarctic ice, not all things are created equal. Let us consider the following differences. Antarctic land ice is the ice which has accumulated over thousands of years on the Antarctica landmass itself through snowfall. This land ice therefore is actually stored ocean water that once fell as precipitation. Sea ice in Antarctica is quite different as it is ice which forms in salt water primarily during the winter months. When land ice melts and flows into the oceans global sea levels rise on average; when sea ice melts sea levels do not change measurably.

In Antarctica, sea ice grows quite extensively during winter but nearly completely melts away during the summer (Figure 1). That is where the important difference between Antarctic and Arctic sea ice exists as much of the Arctic's sea ice lasts all the year round. During the winter months it increases and before decreasing during the summer months, but an ice cover does in fact remain in the North which includes quite a bit of ice from previous years (Figure 1). Essentially Arctic sea ice is more important for the earth's energy balance because when it increasingly melts, more sunlight is absorbed by the oceans whereas Antarctic sea ice normally melts each summer leaving the earth's energy balance largely unchanged.

Figure 1: Coverage of sea ice in both the Arctic (Top) and Antarctica (Bottom) for both summer minimums and winter maximums
Source: National Snow and Ice Data Center

One must also be careful how you interpret trends in Antarctic sea ice. Currently this ice is increasing overall and has been for years but is this the smoking gun against climate change? Not quite. Antarctic sea ice is gaining because of many different reasons but the most accepted recent explanations are listed below:

i) Ozone levels over Antarctica have dropped causing stratospheric cooling and increasing winds which lead to more areas of open water that can be frozen (Gillet 2003, Thompson 2002, Turner 2009).

and

ii) The Southern Ocean is freshening because of increased rain and snowfall as well as an increase in meltwater coming from the edges of Antarctica's land ice (Zhang 2007, Bintanga et al. 2013). Together, these change the composition of the different layers in the ocean there causing less mixing between warm and cold layers and thus less melted sea and coastal land ice.

All the sea ice talk aside, it is quite clear that really when it comes to Antarctic ice and sea levels, sea ice is not the most important thing to measure. In Antarctica, the largest and most important ice mass is the land ice of the West Antarctic and East Antarctic ice sheets.

Therefore, how is Antarctic land ice doing?

Shepherd et al. 2012
Figure 2: Estimates of total Antarctic land ice changes and approximate sea level contributions using a combination of different measurement techniques (Shepherd, 2012). Shaded areas represent the estimate uncertainty (1-sigma).

Estimates of recent changes in Antarctic land ice (Figure 2, bottom panel) show an increasing contribution to sea level with time, although not as fast a rate or acceleration as Greenland. Between 1992 and 2011, the Antarctic Ice Sheets overall lost 1350 giga-tonnes (Gt) or 1,350,000,000,000 tonnes into the oceans, at an average rate of 70 Gt per year (Gt/yr). Because a reduction in mass of 360 Gt/year represents an annual global-average sea level rise of 1 mm, these estimates equate to an increase in global-average sea levels by 0.19 mm/yr.

There is variation between regions within Antarctica (Figure 2, top panel), with the West Antarctic Ice Sheet and the Antarctic Peninsula Ice Sheet losing ice mass, and with an increasing rate. The East Antarctic Ice Sheet is growing slightly over this period but not enough to offset the other losses.  There are of course uncertainties in the estimation methods but independent data from multiple measurement techniques (explained here) all show the same thing, Antarctica is losing land ice as a whole, and these losses are accelerating quickly.

Last updated on 10 July 2013 by mattking. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Further reading

Tamino compares and analyses the long term trends in sea ice data from the Northern and Southern Hemisphere in Sea Ice, North and South, Then and Now.

Update

On 20 Jan 2012, we revised this article upon learning it referenced an incorrect quote. We apologize to Dr. Michaels and to our readers for the error.

Comments

Prev  1  2  3  4  

Comments 151 to 158 out of 158:

  1. ejo60: Congrats on the publication, even if it isn't exactly good news (Greenland ice mass loss in particular is alarming).
  2. @ejo60 #150:

    Does the information on the Greenland ice melt presented in in your Science paper take into account the findings of the also just-published PNAS paper, Mapping Greenland's mass loss in space and time?
  3. Can you adjust this page to take into account the most recent science on this topic?
    Mass Balance of the Antarctic Ice Sheet 1992-2008 from ERS and ICESat: Gains exceed losses – Presented by Jay Zwally, NASA Goddard

    I came to this site to learn more (I'm a mildly informed skeptic, hoping to be better informed, but I'm skeptical of most things), but after 10 minutes of research on this "myth", I am having trouble with your explanations.
    If the most recent research is showing ice mass gains, wouldn't ignoring that be denial?
    If the research is flawed, I want to know about the flaws.
    If it is too new to analyze, then mention that there is ongoing research that raises questions.
    If the researcher is known to be biased, show that.
    Or, if the research represents the best science on the subject, change your page to reflect it. (Maybe the skeptics aren't 100% wrong?)
    But to have a 2 year old page with information that seems out-of-date does not help me learn.
  4. Zwally paper is a conference presentation highlighting an issue. A full reconciliation of the data sources has now very recently been published here which still finds net ice loss. You can find more discussion from one of the authors here. The important bit in the paper is understanding the uncertainties and errors in the various estimation methods and how to reconcile them. Funnily enough, it is nothing about author bias. (You might like to ask Jay Zwally his opinions on climate change (he is not a skeptic) and whether he thinks King's paper is invalid).

    I do think the page should be updated with the King numbers. Of some relief to modellers, the new numbers more closely reflect what the models predicted would happen in Antarctica.
  5. Jack O'Fall, before commenting on a thread, it is wise to examine a page or 2 preceeding your intended comment.

    On the previous page, you could have found references to Sasgen(2012), Barletta(2012) and Flament&Remy (2012). You could also have found a comment from a member of the team that reconciliated the data in a paper published in Science, a team that includes both Barletta and Zwally.

    http://www.sciencemag.org/content/338/6111/1183.abstract

    So, as it turns out, not only some recent info is available in this very thread, but SkS is regarded highly enough by researchers at the forefront of the field that they kindly help to stay on top of the current research.
  6. scaddenp-
    Thank you for the links. I could only read the Nature abstract as it was behind a paywall.
    It looks like both the Nature article and the discussion at realclimate are updates to the GRACE methodology, not the ICEsat results. Did I miss that part?
    Philippe-
    Like most people reading a website for knowledge, I rely on the actual website for the knowledge, not the 150+ comments to fill holes left in the website. I will peruse the comments, but don't treat them with the same level of respect that I do to the actual webpage on the topic.
    I'd like to stay on top of the current research, that's why I'm reading this. If I can find things that are more recent, seem reputable, and disagree with SkS in just a few minutes of research, shouldn't I point them out so SkS can include them or rebutt them accordingly?
    I'm not taking sides, I'm here for enlightenment.
  7. Jack, I'm not sure what your concept is of what kind of website this is and what is expected from commenters. It is a site that is mainly about the published science on a variety of topics that are related. Commenters have countless opportunities to familiarize themselves with the topic of a post by using the site's search engine, looking at recent posts on the thread they consider, or better, looking up the referenced articles on Google Scholar and following the citation trail that will lead to more recent work.


    The "thing" that you provided was not a peer-reviewed science article. The author of that very same piece has since been involved in a published paper that is way more comprehensive, and is referenced earlier on this thread. Since the piece caught your attention in the 1st place, following the very easy internet trail leading to the paper with Zwally as a co-author should have been part of your normal process of discovery, a process indispensable to one willing to avoid taking sides.

    I understand that you would want to point out "things" to SkS. However, these things deserve more attention when they are actual peer-reviewed articles. Furthermore, it doesn't hurt to do some basic verification that the "thing" has not already been discussed. All SkS threads from the beginning are accessible. It is less realistic to expect every single OP to be updated with the latest information than it is to expect that a reader will read about 10-20 posts back.

    For the latest articles in general, refer to Ari Jokimaki's posts, he does a tremendous job.
  8. Jack, the Realclimate article and the science article are about reconciling the various measurements including ICESat (that is the satellite altimetry referred to). King goes further and from the constraints establishes better estimate for GIA (principle uncertainty in GRACE) to get better mass measurement of this. Since Zwally is a coauthor of the science paper, I would guess that he is happy with the reconciled estimates.
  9. Alternate interpretations of the mass changes driven by accumulation variations are given using results from atmospheric-model re-analysis and a parameterization based on 5% change in accumulation per degree of observed surface temperature change. A slow increase in snowfall with climate warming, consistent with model predictions, may be offsetting increased dynamic losses.

    The above was tail end of the conclusion of Zwally's presentation (I believe it was his presentation and not his paper), but anyway, my question is this; Is he correct in his statement that models predicted this increase in ice?  I believe "Barry" even suggested that AR4 had similar predictions.

    I'm not asking if his paper or his observations are correct, just the above statement.  If it is correct, does this debunking need to be re-done?

  10. "Is he correct in his statement that models predicted this increase in ice?" What he says is that models predict an increase in snowfall, and yes they do (going back to TAR I think). Warming in the southern ocean inevitably means more humid air moving into the interior of the Antarctica where it will fall as snow. The prediction was that this would increase the ice thickness in the interior (GRACE shows this happening). However, ice loss from the margins is so far outpacing that gain. These predictions were not about sea ice.

  11. scaddenp,


    So you are saying that antartica has a net loss of land ice.  But you just said that back as far as TAR 1 that models were predicting a net gain in snow fall, but did they predict a loss of coastal ice?  So which is it?  That is the point of my last post.  There seems to be some ambiguity here. 


    This whole thread is about how models and reality predict a loss in land ice, and that skeptics are confusing the gain in sea ice as proof of the failure of AGW.


    So, again, do the models predict a gain or loss of land ice?

    Response:

    [JH] Please lose the tone. BTW, there is nothing precluding you from doing your own research on the issues you have raised. 

  12. Kevin,

    Why does an increase in snowfall need to lead to an increase in land ice?  And why would any increase in land ice need to remain as a constant, unchanging effect?  A the same time, why do the models have to perfectly predict every reaction in a complex event never before seen by man?  If the models got a single thing wrong, at some point in time, then that means all of climate change theory is wrong and we can just ignore it all?

    I think you need to be more specific about what your questions (or criticisms) are.  As it stands, your comment seems to demonstrate nothing but confusion about some pretty simple issues.

  13. Kevin:

    As far as I can see there is no ambiguity. The behaviour of Antarctic land ice along the coast is not the same as the behaviour of sea ice.

  14. Composer99,

    Here is the ambiguity.

    Support for the idea that higher temperatuics will lead to

    significantly largei accumulation also comes horn observations

    on the Antarctic Peninsula Over the past "?() yeais

    temperature has gone up here by almost 2°C, wheieas

    accumulation increased by as much as 2 W in paiallel with

    this (Peel and Mulvaney, 1988) Although this cannot be

    taken as proof of a causal relationship it is in line with the

    sensitivity estimates listed in Table 9 7 which span a lactoi

    ol two

    In summary, all quoted studies show an inciease in

    accumulation with warming and thus a decrease in sea

    level An ablation zone does not effectively exist in

    Antarctica, and a laige wanning would be icquired in older

    for ablation to influence mass balance

    That is a quote from the first assessment.  It clearly predicts that there should be an increase in Land ice in Antartica.  The SkS thread here says that there should be a decrease in Land ice.  One of these predictions is obviously in error.

     

  15. Kevin...  Can you provide an actual link to that passage.  The strange formatting and spelling make me question the source.

  16. On first pass, other than the weirdness, it sounds like the passage is discussing snow accumulation rather than ice. But without a reference it's hard to know. Increased snow accumulation at higher altitudes has long been predicted and known.

  17. The link is;


    IPCC FAR link


    It is the First assessment.  Chapter 9, page 273.



    Increased snow accumulation at higher altitudes has long been predicted and known.



    This is not about high altitudes, this is about the antartic (which has a lot of land at high altitudes but..).  The assessment is saying that there will be ice build up (snow build up - same thing as snow that gets piled on becomes ice) in the interior, with a net result of, a positive build up of ice through out antartica, not a loss.


    The SkS thread clearly states that there will be a net loss, so again, clearly something is amiss.

    Response:

    [RH] Fixed link that was breaking page formatting.

  18. Rob,


    Here's the link to the chapter from the First Assessment Report, published in 1990.  The reason for the typos is that the PDF online is a scan (image), not text, so it had to be transcribed.  See section 9.4.5, and as usually, read the entire thing, not just the cherry-picked section chosen by a denier for a quote... particularly things like the opening line ("The question of the balance of the Antarctic ice sheet proves to be a very difficult one from a physical point of view...") and later ("It must be stressed that the inference of ice mass discharge from a limited number of surface velocity measurements involves many uncertainties.").  The quote in question is on page 273.


    So Kevin's complaint appears to be that in 1990 (23 years ago) scientists did not perfectly understand and predict exactly what would happen a quarter of a century later as a result of climate change.  And we should "update" the current rebuttal to properly reflect what scientists didn't perfectly understand 23 years ago.


    [You just can't make this stuff up.]

  19. Rob Honeycutt - That passage apears to be from the 1990 IPCC FAR report, chapter 9, page 27. 

    Kevin - Two notes. First, list your references.

    Second, do you honestly think that the science wouldn't be updated in the last 23 years? Sea level contributions and cryosphere mass balance are still under investigation, and cryosphere contributions to sea level are still at a somewhat lower certainly in the 2007 AR4 report. Not to mention that the last 23 years of warming will have changed the situation somewhat. 

    Current measures (including GRACE mass measures) indicate a net loss of Antarctic land ice. Mass balance includes both accumulation (increased snowfall due to higher absolute humidities) and loss (increased melting at the coasts due to warmer sea water). Snowfall can increase and Antarctica still lose mass, because there are two terms to that balance. 

  20. Yup.  Just reading through it.  It's all relative to sea level changes.  What's particularly interesting to me (and encouraging) is that the report isn't overstating their confidence levels.  They're using very careful wording to accurately convey what they knew at that time.  If you read on, they're also talking about the instability of the WAIS.  Clearly, you can be adding ice (snow) in the interior but also be losing ice through ablation.  And that is what I've always read in the literature.  I'm not seeing the FAR chap 9 disagreeing with this at all.

  21.  

    I could not find an actual prediction regarding antartic ice sheet levels in the fourth assessment (they do discuss the peninsula).  They do, however, in the openning comments address the projections of the TAR as indicated below.

    Key regional projections highlighted in the TAR

    Increased melting of Arctic glaciers and the Greenland ice sheet, but thickening of the Antarctic ice sheet due to increased precipitation, were projected.

    It is interesting that this is not sea ice they are talking about, but land ice.

     

    So Sphaerica, has the science advanced enough for the fourth (actually third) assessment?  If not, then I guess they have no business commenting on anything.  The Third assessment was saying that snow gains more than covers coastal losses.

     

  22. I would also add that the passage cited by Kevin is not a prediction (contrary to his assertion), but a description of observed contemporary ice sheet behaviour, of Antarctica as a whole, up until the publication of FAR, while the discussion in the OP has to do with observed (not predicted) behaviour in the last decade (as per the publication dates of papers cited), so there is little surprise that the OP mentions more ice mass loss than FAR.

    Finally, scaddenp mentioned the Third Assessment Report, in 2001, whose descriptions of observed behaviour in Antarctica would differ from the observed behaviour described in the 1990 FAR and also from the behaviour discussed in the present day.

    Kevin, was it your intent to suggest that:

    1. There is something illegitimate about having a superior understanding of ice sheet behaviours after 20+ years of further study, such that predictions are more refined and observations more robust and less uncertain?
    2. There is something illegitimate about conditions changing such that what was the case up until 1990 (net balance or even land ice mass gain) has changed by the present day (net land ice mass loss)?
  23. (Clarification to my post #172: it does not include any comments posted by Kevin in #171.)

  24.  

     

    From the Scenarios of future change, 16.1.4 of the Third assessment report...

    Models predict that land areas in the Arctic will receive substantially increased snowfall in winter and that the climate will be markedly warmer. Summer could be much warmer and wetter than present. The climate over the Arctic Ocean does not change as dramatically, but it will become warmer and wetter by 2080. For the Antarctic continent, the models tend to predict more snow in winter and summer. Although temperatures are forecast to increase by 0.5°C, there will be little impact on melt because they will remain well below freezing, except in limited coastal localities. The Southern Ocean warms least, especially in summer. Precipitation increases by as much as 20%, so there will be more freshwater input to the ocean surface. This chapter also refers to other climate models. Some are equilibrium models for the atmosphere only; others are transient, coupled atmosphere-ocean models. Some deal with aerosols and other do not. In polar regions there can be large differences in predictions, depending on the model chosen, although most predict large changes in climate over the next 100 years. Assessments of impacts will vary, depending on the climate model chosen. This should be kept in mind in assessing the impacts described in this chapter.

    And yes, there is extensive uncertainty in this prediction, as some processes are not understood entirely.

     

    Bottom line though, the latest prediction by the IPCC has Antartica Land Ice gaining as temps increase.

  25. Kevin,

    The bottom line is that you don't understand what it is that you are reading, and you are projecting that ignorance onto everyone else.

    The Antarctic Ice Sheet is a complex environment, consisting of an interaction between rising temperatures, increasing precipitation, ice at extreme altitude (hence always below freezing), ice just above sea level (affected by air temperature), ice below sea level (affected by the warming water beneath), and gravity (which threatens to flow ice gains in the interior quickly down into the ocean, where it will melt).  This now is recognized to be further complicated by the freshening of the surrounding ocean water due to the melt, changes in currents, etc.

    And out of all of this, your takeaway is that the IPCC reports have some comments that you can cherry-pick to raise false doubt.

    This is why the term "denier" is used at all.

    Bottom line:   You don't understand what you are reading, and you are going out of your way to create an illusion of doubt and incompetence, because you can't come to terms with the idea that your actions (and lack of action) are going to affect future generations, and you maybe will need to demonstrate more responsibility (and yes, maybe a little sacrifice) when you don't want to.

    I am always appalled at the way my generation lauds The Greatest Generation for the great sacrifices they were repeatedly able to make... and yet they won't surrender their multi-ton SUVs until you pry them from their baked, dead hands.

    Response:

    [JH] Please tone down the judgemental rhetoric. We simply do not know whether Kevin posts to cause mischief, or is honestly trying to understand a very complex subject matter. Kevin has also been advised to tone down his posts. 

  26. Kevin@174

    Why is it that you stop reading/processing information as soon as you see something that you think supports your predtermined conclusons?

    The passage you quote talks about snowfall and melt. It does not talk about ice flow. Mass balance of a marine-terminating glacier depends on more than just snowfall and melt. Thre is not enough information in that quoted passage to support your conclusion that Antarctic Land Ice will increase.

    Until you do a complete mass balance calculation, you will continue to arrive and unspported (and/or unsupportable) conclusions.

  27.  


    Sphaerica,


    How do you read the quote from the AR4?



    Key regional projections highlighted in the TAR


    Increased melting of Arctic glaciers and the Greenland ice sheet, but thickening of the Antarctic ice sheet due to increased precipitation, were projected.



    This is not cherry picked.  This is AR4's summary of the TAR's prediction.  It is not my interpretation.  I copied the words directly.


     


    How about the actual prediction from the TAR?  Models predict....  Not Kevin interprets these models to predict.  It says the models predict.


     


    Explain how I am not understanding these predictions. 

    Response:

    [JH] You seem to be more interested in playing "Gotcha" games with other commentors than engaging in a civil discussion of the science. As far as I am concerned, playing Gotcha is sloganeering which is banned by the SkS Comments Policy. Please cease and desist. If you do not, your posts will be summarily deleted.

  28. Bob Loblaw,


    How about the AR4's summary?  The ice sheet is predicted to thicken!


    I have shown IPCC's prediction that the ice sheet will thicken.  Does someone have an IPCC prediction that the ice sheet will lessen?

    Response:

    [JH] You seem to be more interested in playing "Gotcha" games with other commentors than engaging in a civil discussion of the science. As far as I am concerned, playing Gotcha is sloganeering which is banned by the SkS Comments Policy. Please cease and desist. If you do not, your posts will be summarily deleted.

  29. Kevin, the bottom line is that you're quoting FAR or TAR as a representative position.  It's not.  AR4 summarizes FAR but does not say, "And we still draw those conclusions."  Discussing F/TAR might be interesting, but it's not relevant.  AR4 is already being set aside.  The science upon which AR5 rests is already in publication.  Refer to it, as AR5 will.  We now know more about the Antarctic.  Get back into your time machine and return to the present.

    Or don't, but don't be surprised if people ignore you, because F/TAR is just not that interesting.  

  30. DSL,

    As I stated earlier, the latest prediction that the IPCC has made, predicts that Antartica will gain ice as temp increases.

    The whole gist of this particular thread is that the ice will go down as temp increases, and that "Deniers" were incorrect in their belief that the increase in ice was contrary to predictions because it was only sea ice that increased, not Land ice.

    I noted that there is a discrepancy in that the IPCC predicted an increase in Land ice, not a decrease.  It very well could be that you are correct in that this thread was created after new research indicated that Land ice should decrease and not increase.

    The AR4 did in fact come out prior to 2008, having come out in 2007 (with research obviously prior to that).  

     

  31. AR4 Ch 4.6.3.1 (2007): "Long-term data are very sparse, precluding confident identification of continent-wide trends."

    Shepherd et al. (2013)

    "We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth’s polar ice sheets. We find that there is good agreement between different satellite methods—especially in Greenland and West Antarctica—and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by –142 ± 49, +14 ± 43, –65 ± 26, and –20 ± 14 gigatonnes year−1, respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year−1 to the rate of global sea-level rise."

    Antarctica, like Greenland, can show mass increase in the interior while still showing an overall net loss.  That may be the source of some confusion.  

  32. Kevin - "...the latest prediction that the IPCC has made, predicts that Antartica will gain ice as temp increases."

    That would be completely incorrect. From IPCC AR4, Chapter 4.6.2.2:

    Taking the Rignot and Thomas (2002), Zwally et al. (2006) and Rignot et al. (2005) results as providing the most complete antarctic coverage suggests ice sheet thinning of about 60 Gt yr–1... [ ] 

    Assessment of the data and techniques suggests overall Antarctic Ice Sheet mass balance ranging from growth of 50 Gt yr–1 to shrinkage of 200 Gt yr–1 from 1993 to 2003. [ ] 

    Acceleration of mass loss is likely to have occurred, but not so dramatically as in Greenland.

    From the same document, FAQ 4.1:

    Taken together, the ice sheets of Greenland and Antarctica are very likely shrinking, with Greenland contributing about 0.2 ± 0.1 mm yr–1 and Antarctica contributing 0.2 ± 0.35 mm yr–1 to sea level rise over the period 1993 to 2003. There is evidence of accelerated loss through 2005. Thickening of high-altitude, cold regions of Greenland and East Antarctica, perhaps from increased snowfall, has been more than offset by thinning in coastal regions of Greenland and West Antarctica in response to increased ice outflow and increased Greenland surface melting. [ ] 

    The geographically widespread nature of these snow and ice changes suggests that widespread warming is the cause of the Earth’s overall loss of ice.

    [Emphasis in both quotes added]

    ---

    You have been quote-mining old reports, not reading or incorporating the current science or observations, and clearly only looking at one side of the mass-balance equation while ignoring increased melting. I dislike saying this, but your last few posts have been nonsensical. 

  33. Everyone:


    Please resist the temptation to "dogpile" on Kevin. Let his current conversation with DSL play out without interjecting comments. 

    Response:

    KR excepted. 

  34. DSL,


    I stated earlier that AR4 did not make a prediction, the prediction came from the TAR.


    So, assume that AR4 is correct, and no trend is there.  How does SkS come up with this thread then?  Losing or gaining ice, sea or land, has no bearing, right?


     

    Response:

    [JH] You are now skating on the thin ice of sloganeering. Please cese and desist or face the consequences. 

  35. Kevin, where do the main articles rely on AR4?  SkS is not a defense of AR4, nor would it matter in this case (see KR's response). 

  36. Kevin...  "The ice sheet is predicted to thicken" ≠  Total ice mass balance will increase.

    You're cherry picking and vastly oversimplifying.

  37. DSL & Rob Honeycutt:


    Kevin fell through the thin ice of slogannering and his most recent comment was deleted. 

  38. We know that Kevin has recused himself from participation, but lets take a quick review of insane denial, and clear things up along the way.

    Kevin first quoted the 1990 IPCC First Accessment Report as claiming that Antarctica would experience increased snowfall.  Kevin (1) quoted a 23 year old report and (2) proceeded to conflate increased snow fall with increased land ice.  He also ignored the balance of the actual report, which very clearly lays out the details, as understood at that time, of Antarctic ice gain and loss.  The tone of that report is nothing like Kevin's quote suggests.

    When called on this, Kevin next quoted the 2007 IPPC Fourth Assessment Report -- but he chose to quote the FAR's review of the TAR —the Third Assessment Report, from 2001, 12 years ago.  That section was a mere review of the previous report, in preparation for the more recent update.  What's the point?

    Somehow he skipped over the actual content of the FAR, which even more clearly than the first two reports discusses the ice gain and loss in Antarctica, including this:

    Zwally et al. (2006) obtained SRALT coverage for about 80% of the ice sheet, including some portions of the Antarctic Peninsula, and interpolated to the rest of the ice sheet. The resulting balance included West Antarctic loss of 47 ± 4 Gt yr–1, East Antarctic gain of 17 ± 11 Gt yr–1 and overall loss of 30 ± 12 Gt yr–1.

    Anyone can follow the link provided by KR to the actual page.  People can judge for themselves what the IPCC has actually said about the subject, and how their understanding has progressed over time.

    It is very, very important when faux-skepticism raises its ugly head to follow the quotes and the denial to the source, read everything with an open mind, and to understand what is truly there — not merely what some denier chooses to misrepresent.

  39. Readers - There is actually a useful lesson in the last exchange(s) with Kevin. What he did was to selectively quote-mine old analyses (ignoring the last quarter-century of work), cherry-pick the data (East Antarctic while ignoring Antarctica as a whole), and misrepresent implications (wrongly equating increased snowfall with mass balance, ignoring greatly increased melt and calving). And concluding with a Bizzaro-world interpretation exactly opposite that of the IPCC. 

    This is in fact a fairly common denier tactic - select tiny bits of the science out of context and miscast them in contradiction to the whole. I strongly suggest reading the original sources (which isn't difficult if you start with abstracts and work your way up as you can or as desired), and check the quotes and sources

    IMO denial is broadcast with selective reading and presentation, some of which (see anything from Lord Monckton) is simply false. Armor yourself by checking the assertions from all participants. 

  40. I think it's a very good lesson in how "fake skepticism" works.  You start with your preferred conclusion, find exceptions in the research that support than conclusion, then avoid attempting to understand the issue as a whole.

    I have to admit, I see the attraction to doing this!  It takes far less work to operate this way.  Antarctica, in particular, is incredibly complicated (as if any aspect of climate change is simple).  It's not easy to go through all the information and fully grasp what's going on.  And it's especially hard when you clearly do not want to accept what scientists are saying.

  41. How much time and energy does it take to quote mine, particularly when the targeted conclusion is going to be easily dismissed by readily available research?  What a complete waste for Kevin, but what a nice, short example of the James Taylor School of Journalism for SkS.  

  42. Speaking of the complexity of Antarctica's climate...

    Two different areas of Antarctica tell two very different stories about how climate change might be affecting ice melt. The data appear to confirm that climate change impacts can be very local.

    Source: Antarctic ice tells conflicting story about climate change's role in big melt by Pete Spotts, The Christian Science Monitor, Apr  16, 2013

  43. John Hartz - While not an SkS moderator, I might suggest that presenting 3-4 repeats of the same claims while disregarding other comments to be 'troll-like' behavior, and should probably be rewarded with the staged moderation warnings seen in other contexts here. 

    Response:

    [DB] All parties:  please return the discussion to the topic of this thread, Antarctica is gaining ice.

  44. John, I have to question the logic of that Steig study reported in CSM. Basically, they looked at ice cores from the peninsula and high on the WAIS. The cores from the peninsula showed recent melting at a rate 10 times greater than the highest previous values while the cores from the WAIS showed melting at rates comparable to the highest previous values. From this they concluded that the peninsula is melting due to global warming and the WAIS due to natural variability.

    The problem, as I see it, is that the majority of the WAIS ice loss is not occuring at the far inland locations where they gathered the ice cores. The WAIS (and the EAIS for that matter) are losing ice from the edges of the continent. Ice loss far inland may indeed be largely due to natural variability... but that is a tiny percentage of total ice loss. Much more is being lost at the edges of the ice sheet as warmer water (from global warming) causes ice shelves to break up and land ice calves into the oceans at a faster rate.

    Essentially, the Steig study seems to be the equivalent of attempting to measure global warming by looking only at mid-day temperatures along the equator... the data which should show the least greenhouse warming signature. They failed to find a global warming signature in the WAIS ice loss because they only looked at the ice which is least likely to be impacted by global warming. If they had looked at ice loss around the edges of the ice sheet, where the vast majority of it is actually occurring, they should have gotten very different results.

  45. Ok, so I am a noob here. but if I am reading this right there is increased loss of Land Ice in Antarctica and this fresh water freezes easier causing the sea ice to be greater? And even with the rise in temperature it is too small to cause the sea ice to melt.  Is this basically the short version of the article?

  46. Not sure if this has been mentioned, but 2012 study points to changing wind patterns responsible for increasing sea ice in the Antarctic:
     
    The ultimate cause of the wind and ice changes lies in the large-scale climate variability of the Southern Hemisphere. Antarctic sea ice can contain 35-year cyclic anomalies that might be partly aliased into our calculations, but our trends cover several such cycles and are consistent with longer-term studies. Aspects of the wind trends (and therefore ice-motion trends) can be attributed to large-scale modes such as the Southern Annular Mode and El Nino/Southern Oscillation. Modern trends in these modes could arise through natural variability, but some evidence suggests that they are forced by the Southern Hemisphere ozone hole and increased greenhouse gases. Our conclusions that ice-motion trends are dominated by winds, and that winds contribute significantly to ice concentration trends through both dynamic and thermodynamic effects, reinforce the need for a better understanding of both the wind changes and the anthropogenic forcing of relevant climate modes.
     
    http://xa.yimg.com/kq/groups/18383638/1671623978/name/Antarctic+sea+ice.pdf
  47. I don't believe the ozone hole is the reason the south pole is getting colder. By saying this, we are basically saying that ozone is a more important greenhouse gas than CO2. If ozone is decreasing, in the presence of increasing CO2, the south pole should be getting warmer unless CO2 is less important than ozone as a greenhouse gas. But since the ozone is not currently decreasing, (it's been flat for years), this means we need to stop making this false claim. My null hypothesis is that ozone is NOT the reason the south pole is getting colder, for the reasons I gave. Disprove my null hypothesis, please. 

  48. What I mean is, since CO2 is much more important than ozone as a greenhouse gas, and CO2 is increasing, there is nothing O3 can do to make the south pole get colder. O3 can decrease, increase, stay the same, or drop to zero (it's close to zero anyway and has been for 30 years), there is no logical way we can deduct that O3 can make the south pole get colder. It is not logically possible, when CO2 is increasing. Impossible.

  49. Morgan Wright @197 & 198, you appear to be missing several crucial facts in your discussion.

    First, Antarctica is getting warmer, not colder.  This has been shown in several recent studies, including by Steig et al (2009) and O'Donell et al (2010)

    The rate of warming is low relative to much of the rest of the planet, an in particular the Arctic, but it is still warming.  That has little bearing on the formation of sea ice, however, as during the Antarctic winter when sea ice forms, temperatures plummet so that it remains cold enough for sea ice to form even with the slight warming.

    Second, it is not postulated above that ozone depletion encourages the formation of sea ice by cooling Antarctica, but rather by causing stronger winds, which push sea ice apart, exposing additional surface area in which sea ice can form.  Reduced ozone does in fact cause cooling, but in the stratosphere, where the reduced ozone results in less UV radiation being absorbed, and hence less warming of the stratosphere.  As it happens, increased CO2 reinforces this effect by radiating that heat which is captured away more effeciently.  Therefore, at the relevant level of the atmosphere (the lower stratosphere) both reduced ozone and increased CO2 reinforce the same effect, ie, cooling the lower stratosphere.

    The result of this colder air is that warmer air from the further north is drawn towards the low pressure system formed by the cooling of the air.  This is particularly the case in the Southern Hemisphere summer, when the air north of Antarctica is particularly warm due to the Sun being more directly overhead.  However, as the air is drawn towards Antarctica, it moves from a position of high rotational velocity to one of lower rotational velocity.  Because angular momentum is conserved, this diverts the winds westward, forming a circumpolar vortex.  The colder the Antarctic stratosphere, the further south the warm winds from further North penetrate, and hence the greater their angular velocity relative to the surface, ie, the faster the circumpolar vortex.

    These faster winds then tend to break up the ice as explained above.

    Third, the greenhouse effect over Antarctica is very weak, and sometimes negative.  This may seem counterintuitive, but the greenhouse effect is a consequence of the difference in temperature between the source of IR radiation emitted at the ground, which is then absorbed by the atmosphere, and the temperature of the layer of the atmosphere which emits most IR radiation to space.  In Antarctica, the surface is very cold.  More importantly, most of the heat in Antarctica is brought by warm air from the north rather than from the direct radiation from the Sun.  As a result, the air above Antarctica is very warm relative to the surface compared to, for example, the tropics.  As a result, the greenhouse effect is very weak in Antarctica.  Indeed, sometimes, and particularly in winter, the air above Antarctica will be warmer than the surface, resulting in a reverse greenhouse effect - ie, a cooling tendency from the greenhouse effect rather than a warming tendency.  This can be seen in the figure below, showing IR radiation to space at various locations.  You will notice in Antarctica there are humps at the same locations where in other areas their are dips.  The humps indicate the atmosphere was warmer than the surface, and that at that time there was a reverse greenhouse effect.

    Finally, a strengthened circumpolar vortex does in fact reduce the rate at which heat is transported into Antarctica.  This does not cool Antarctica, for the strengthened vortex was created by an increased initial heatflow southwards.  But it does significantly reduce the rate at which heat penetrates to the interior of Antarctica.  This is plain in the heat map of Antarctica by O'Donell et al (2010) (above), where (I believe) the warming on the Antarctic Peninsula is much stronger than that in the rest of Antarctica.  That is because it sticks out under the vortex (at least some of the time), and into the circumpolar currents driven by the vortex.

  50. First, I did not say Antarctica is getting colder. I said the South Pole is. The chart you presented, of O'Donnell et al, clearly shows a large patch of blue over the south pole. Most other studies show the same thing. I understand the peninsula is warming and the pole is cooling. I am concerned about, and dispute, claims that the O3 hole is the reason for south polar cooling.

    Second, you mention a low pressure system caused by the cooling of this air. This is never found. Cooling of air causes a high pressure system, always. 

    Third, you say CO2 increases cooling by radiating heat into the stratoshpere, and describe a reverse greenhouse effect over the pole. I appreciate that and find it interesting. I'm sure what you say is true because I've noticed the same thing flying over the arctic, where stratospheric temps outside the cabin were -40 F and the ground temp over northern Canada and Alaska were -60 or lower. Very interesting and probably more true of the antarctic. I see the hump in illustration (c) and vaguely remember that from college. Thank you.

    Fourth, you say air north of Antarctica moves southward and the rotational velocity slows down because it conserves angular momentum. This is the opposite of how a vortex works. Air moving towards the center of a vortex always increases rotational speed as its radius from the center of the vortex decreases. Oh wait, at the end of the same paragraph you say the speed increases. Never mind. Maybe it was an error. However, a true vortex is caused by a low pressure zone and adjacent air moving into the low and rotating as it moves in due to conservation of angular momentum. In this case, the center of the vortex is a high pressure zone, the air is not moving in but moving west, and the rotation is caused by the rotation of the earth. It's not really a vortex at all. Compare this to how a hurricane works. Not even similar.

    This conversation has been fun but says nothing about my original ozone skepticism.

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