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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Is Antarctica losing or gaining ice?

What the science says...

Select a level... Basic Intermediate

Antarctic sea ice is gaining sea ice but Antarctica is 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)

Arguments that we needn't worry about loss of ice in the Antarctic because sea ice is growing or even that sea ice in the Antarctic disproves that global warming is a real concern hinge on confusion about differences between sea and land ice, and what our best information about Antarctic ice tells us. 

As well, the trend in Antarctic sea ice is not a permanent feature, as we'll see. But let's look at the main issues first.

  • Sea ice doesn't play a role in sea level rise or fall. 
  • Melting land ice contributes to sea level rise. 
  • The net, total behavior of all ice in the Antarctic is causing a significant  and accelerating rise in sea level. 

Antarctic sea ice is ice which forms in salt water mostly during  winter months. When sea ice melts, sea level does not change.

Antarctic land ice is the ice which has accumulated over thousands of years in Antarctica by snowfall. This land ice is stored ocean water that once fell as precipitation. When this ice melts, the resulting water returns to the ocean, raising sea level.

What's up with Antarctic sea ice?

At both poles, sea ice grows and shrinks on an annual basis. While the maximum amount of cover varies from year to year, there is no effect on sea level due to this cyclic process. 



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

Trends in Antarctic sea ice are easily deceptive. For many years, Antarctic sea was increasing overall, but that shows signs of changing as ice extent has sharply declined more recently. Meanwhile, what's the relationship of sea ice to our activities? Ironically, plausible reasons for change may be of our own making:

  • 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, Bintanja 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.

Against those factors, we continue to search for final answers to why certain areas of Antarctic sea ice grew over the past few decades (Turner et al, 2015). 

More lately, sea ice in southern latitudes has shown a precipitous year-on-year decline (Parkinson, 2019). While there's a remaining net increase in annual high point sea ice, the total increase has been sharply reduced and continues to decline. 

How is Antarctic land ice doing?

We've seen that Antarctic sea ice is irrelevant to the main problem we're facing with overall loss of ice in the Antarctic: rising sea level. That leaves land ice to consider. 

Shepherd et al. 2017

Figure 2: Total Antarctic land ice changes and approximate sea level contributions using a combination of different measurement techniques (IMBIE, 2017). Shaded areas represent measurement uncertainty.

Estimates of recent changes in Antarctic land ice (Figure 2) show an increasing contribution to sea level. Between 1992 and 2017, the Antarctic Ice Sheets overall lost 2,720 giga-tonnes (Gt) or 2,720,000,000,000 tonnes into the oceans, at an average rate of 108 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 0.3 mm/yr.

There is variation between regions within Antarctica as can be seen in Figure 2.  The West Antarctic Ice Sheet and the Antarctic Peninsula Ice Sheet are losing  a lot of ice mass, at an overall increasing rate. The East Antarctic Ice Sheet has grown slightly over the period shown.  The net result is a massive loss of ice.

Takeaway

Independent data from multiple measurement techniques (explained here) show the same thing: Antarctica is losing land ice as a whole and these losses are accelerating. Meanwhile, Antarctic sea ice is irrelevant to what's important about Antarctic ice in general. 

Basic rebuttal written by mattking


Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

 

Last updated on 31 January 2020 by BaerbelW . View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

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

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Comments 126 to 150 out of 509:

  1. The WUWT report is about recent ICESat data that apparently show mass gain in the Antarctic ice sheet from 2003 - 2008, citing a paper (and linking a video) by lead author Jay Zwally. The NASA page on it is here.
  2. Apparently an internal document, not a peer-reviewed study. Maybe they have submitted/plan to submit.
  3. Yah, barry - sounds like accelerated loss in addition to accelerated gain - perfectly consistent with global warming, as the authors note: "A slow increase in snowfall with climate warming, consistent with model predictions, may be offsetting increased dynamic losses." Watt's the big deal? Ha ha ha, but more seriously, how long would you expect the mass gain to last, if indeed it is happening?
  4. I would be cautious about reading too much into these results. This is also just a conference abstract. Then again, Zwally does good work. It also keep in mind that they conclude that: "A slow increase in snowfall with climate wanning, consistent with model predictions, may be offsetting increased dynamic losses." If true, one has to wonder for how much longer that might hold?
  5. I would expect Zwally to have the numbers right. The interesting science question is reconciling the ICESAT data with the GRACE data. This abstract was done in July. The point for Watts is provide some reassurance to readers wondering about the arctic meltdown. All his readership cares about is having an excuse to do nothing. I suspect for the average US citizen, the effects of climate change are so far small, in the future, and happening elsewhere, whereas any sort of mitigation is perceived as less spending power by one means or another.
  6. Those responses seem a bit cynical. Yes, (AR4) climate models projected increasing mass balance of the Antarctic ice sheet over the 21st century. Observational analyses since then have tended to discern a mass loss, which was a surprise result - although I can't remember anyone ever mentioning that recent results were in opposition to the models (and perhaps I'm being a bit cynical here myself). The "big deal", to my mind, is that if the ICESat analysis is robust, there are implications for sea level projections, which of late have been much higher than AR4. I need to go back and read some of those papers, but IIRC the recent hike in sea level projections is strongly rooted in the perceived loss (acceleration?) of Antarctic ice sheet mass balance. AR4 projected a negative sea level contribution from the Antarctic ice sheet. I don't think SkS should wave these results away, but present them as an update with the appropriate caveats. If Zwally was up for it, a post by him here would be terrific for all sorts of reasons.
  7. Barry, please do look up those projections. I suspect you'll find them weighted more to the Northern Hemispheric contributions and to the thermal expansion component.
  8. GRACE, Icesat and models all agree on that interior of Antarctica accumulates ices while there is iceloss on the margins. However, size matters and the mass loss or gain depends of the relative magnitudes. Any GCM model-based estimate of sealevel rise would be based on Antarctica accumulating ice. As far as I know, these have only very primitive icesheet dynamics (if any) so sea level results from such an approach are so uncertain that the AR4 statement excluded them entirely. Vermeer and Rahmsdorf instead a semi-empirical approach. This also doesnt incorporate any icesheet dynamics so I dont think this result has any bearing on the estimate at all.
  9. Daniel, first thing I've done is to check the papers referenced in the intermediate version of the top post. Velicogna 2009 [PDF] discerns comparable mass loss for Greenland and Antarcica, with comparable contributions for sea level rise. Chen et al 2009 [PDF] conclude with a mass loss for the whole of Antarcica of 190 +/-77 Gt/yr, comparable to higher Greenland mass loss estimates of ~220 Gt/yr. Chen posits that "Using a simple linear projection for the period 2006 - 2009, Antarctic ice loss rate can be as large as -220 +/-89 Gt yr." Sea level contribution is, again, comparable to Greenland. Inferences on sea level rise from Antarctic mass loss mentioned here (upper bound 1.4 meters by 2100 from Antarctic ice loss). I'll have a better look for papers specifically about sea level/Antarctic ice loss. A quick search of SkS articles on Antarctic ice mass balance yields a range of estimates from -26Gt/yr to -300 Gt/yr, and acknowledgement that new data showing Antarctic ice loss (as wel as Greenland etc) contributes to higher sea level projections. The main SkS article on Antarctic ice mass balance (and mentioning sea level) is probably this one. Watts cites it in his article, and for once I find myself agreeing with him (on SkS updating), particularly in light of the final comment on that page.
    .... but multiple different types of measurement techniques (explained here) all show the same thing, Antarctica is losing land ice as a whole, and these losses are accelerating quickly.
  10. Hello Barry @131, "Those responses seem a bit cynical." I hope that you did not interpret my response that way. I'm just advocating caution, especially given the potential significance of this result. This is probably the first step towards Zwally et al. submitting a paper for publication and things can, and do, sometimes change a lot in the intervening steps. These types of data are incredibly finicky and all sorts of corrections need to be made especially for a long-term space-based monitoring platform. It would be nice to have Dr. Zwally post here, maybe once he has had his paper accepted for publication? If these preliminary findings hold true, this would be the first good news on the global warming front in quite some time.
  11. No worries, Albatross. Maybe the bee in my bonnet is buzzing a little loudly. Anyway, I was scoping google scholar for recent assessments, and found one I'd read a few months ago that probably informed my comments here (as well as remembered SkS posts).
    "Notably, the acceleration in ice sheet loss over the last 18 years was 21.9 ± 1 Gt/yr2 for Greenland and 14.5 ± 2 Gt/yr2 for Antarctica, for a combined total of 36.3 ± 2 Gt/yr2. This acceleration is 3 times larger than for mountain glaciers and ice caps (12 ± 6 Gt/yr2). If this trend continues, ice sheets will be the dominant contributor to sea level rise in the 21st century."
    Rignot, Velicogna et al 2011 [PDF]
  12. Barry, we have two different measurement systems, ICESAT and GRACE. If Zwally's results are correct, then there is a problem with the methodology, calibration or assumptions of one of them. For the moment, the published results say Antarctica is losing ice, and GRACE result indicate that it is accelerating. If it becomes clear that the ICESAT result is better, then obviously (and fortuitously), the conclusions will change.
  13. If published, with the same conclusion, it will be interesting to find out how Zwally's results compare to recent assessments using GRACE gravity satellites: 1. Antarctic ice-mass balance 2002 to 2011: regional re-analysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment -Sasgen (2012). 2. Variability of mass changes at basin scale for Greenland and Antarctica - Barletta (2012). And a forthcoming paper using satellite altimetry from (now defunct?) ENVISAT: Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry - Flament & Rémy (2012). The first two find mass losses are smaller than previous publications suggested, and Barletta (2012) finds a near-neutral mass balance trend in Antarctica between 2002-2007. It has since undergone rapid ice loss since then.
  14. scaddenp, Rob, those posts are fine briefs for an article here. Envisat went offline in April. Lasted 10 years, twice as long as its planned operational life. Various groups are still reprocessing the data.
  15. Tamino has another look at Antarctic sea ice based on 2012 data: http://tamino.wordpress.com/2012/09/20/poles-apart/
  16. NEWS ALERT: What’s happening to the Antarctic ice sheet doesn’t bode well for the future according to the latest research described in: Warming Oceans Will Start Massive Changes In Antarctic Ice Sheet , by Nathan, PlanetSave, Sep 20, 2012 It will be interesting to see how the results of this new research is spun in Deniersville.
  17. John Hartz - Watts (at the hometown of denial) has already commented on this paper, dismissing it with "Oh wait, it's modeling, never mind." Golledge et al 2012 actually looks to be a very interesting paper - considering how fast moving peripheral glaciers in Antarctica may respond to warming oceans, with the potential to drawdown ice over very large areas. Essentially, at how speeding up these fast glaciers may "unplug" the ice stores over significant portions of Antarctica, allowing it to drain into the oceans.
  18. @KR #142: Proving once again that Watts hs spent wat too much tiome rattling around in the Climate Denial Spin Machine. He can no longer distinguish between up and down, right and left, forward and backward, etc. What is even sadder is that his minions automtically lap up every pile of poppycock that he deposits.
  19. Here’s yet another article hot off the press about the topic du jour. Does the expanding Antarctic sea ice disprove global warming? by Eric Berger, SciGuy Blog, Houston Chronicle, Sep 21, 2012 Berger’s opening sentence: “Ice is a hot topic in the climate science community right now so let’s talk about it.” Berger’s concluding statement: “The bottom line is that scientists generally have predicted that the Antarctic sea ice will not begin substantially melting until the second half of this century.” Berger’s blog post was created in response to the recent pious pontifications about polar ice by non-scientists James Taylor and Steve Goddard.
  20. Not sure if this is helpful, but argument by analogy might be worth trying with those of a non-scientific background. The problem of arguing against global warming by using the record ice extent of the Antarctic is the basic one that there is no logical framework that says that a record Antarctic ice extent in winter cannot mean a record Arctic ice low in summer, or that this makes global warming impossible, or that this means that the planet is not going to suffer any consequences. It is simple falacious reaoning. No science is actually required to demolish this non-sequitur. Consider: I am a GP (and I am). A patient, a climate change contrarian, shows up in my surgery. He has a painful left leg. After some necessary investigations, he returns for the results. "I have some bad news", I say, "your investigations show a nasty malignant sarcoma of your left tibia. You will need an amputation to save your life" "Nonsense" says the contrarian, "I don't believe you, there's nothing wrong with me, look, my right leg is fine, in fact it's better than it's ever been" as he jumps up and down on his one good leg to demonstrate the unimpeachability of his logic. The issue is that both the Arctic and the Antarctic belong to the same natural entity, indeed if you subscribe to James Lovelock's thesis, the same organism. A healthy planet depends on the healthy functioning of all its parts. That the Antarctic ocean has so far escaped obvious global warming effects (though the Antarctic Peninsula is warming quickly) then this is neither suprising, nor does it prove anything else.
  21. I don't understand why you acknowledge that the Antarctic Sea Ice is increasing, since it seems to me that any supposed increase is statistically insignificant. Decadal averages (the linked plot is to Cryosphere Today Sea Ice Areas, which I averaged) indicate that there is no significant trend in Antarctic Sea Ice areas. The averages for the '80s, '90s, and 2000's are virtually identical. The clear and accelerating melting trend for the arctic (CT data again) is something else entirely. I'm puzzled as to why you've given the deniers even an inch on this.
  22. TimH - Because science is about looking at the full body of evidence. While 'skeptic' denial is often about looking at cherry-picked data, only the data that appears to support their points. It's quite important to not cherry-pick. You're quite correct, Antarctic sea ice increase is barely significant, while Arctic ice decrease is extremely significant to the point of being appalling (something the 'skeptics' appear to be hiding from, sticking fingers in ears and singing "lalalala!"). Interestingly enough, this effect of some increase in Antarctic ice is consistent with warming due to anthropogenic greenhouse gases. Manabe 1991 Part 1 and Part 2 (a H/T to Rabett Run for the pointer) found when modeling Antarctic effects that increased precipitation from GHG warming led to fresher surface waters, suppressing convection from warmer lower waters through a steeper halocline, and thus slightly decreasing sea surface temperatures and increasing sea ice. Manabe's ideas weren't (at that time) widely held, as far as I can see, but he appears to have correctly predicted current observations by taking into account additional factors like halocline changes. Really (IMO) an interesting result. Note that this means warmer sub-surface water is not cooling as much, retaining more energy, and thus the reduced convection is a positive feedback to warming - effectively insulating, keeping the energy in the oceans. And those warmer sub-surface waters continue to melt Antarctica from beneath at the edges. Something I suspect 'skeptics' will not be pointing out. So - an unexpected observation leading to a better understanding? That's what science is about...
  23. FYI, a more-or-less positive press article on this: http://www.thestar.com/news/world/article/1275441--antarctic-sea-ice-is-increasing-is-global-warming-over (which might be a step forward for The Star, until recently the were still in the habit of including a random denialist quote).
  24. While not directly related to this article, it is always worth keeping in mind that the loss of Arctic sea ice is far bigger than the gain of Antarctic sea ice.
  25. Please read our latest article on the polar ice mass loss problem, it appeared today in Science: http://www.sciencemag.org/content/338/6111/1183.abstract

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