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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

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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 76 to 100 out of 432:

  1. No that isn't the entire basis of the argument DSL, far from it. The point is the article attempts to draw climatic trends from periods of under 10 years. Do you think this is an adequate length of time DSL? If we take the claims of the article as truth and extrapolate back over the past century of warming do we obtain a result which is backed up by real world observation for that period? ("mostly steady", the anomaly today sits where it started 12 years ago, yes mostly steady)
  2. RyanStarr, it should be self-evident that ice trends would only follow temperature trends between the time that the temperature was sufficient to cause ice melt and when it was sufficient to have melted ALL the ice. Thus, your insistence that the 'failure' of the Antarctic ice trend to follow the temperature trend over the past 100 years is significant would only be logical if Antarctic ice were melting that entire time... which it wasn't. As to: "the anomaly today sits where it started 12 years ago, yes mostly steady" By that reasoning we would be forced to conclude from a 55 degree day in February and a 55 degree day in May that the temperature had been "mostly steady" over the intervening three months. Any rational person should know better.
  3. CBD I'm not exactly sure what you're getting at in the first paragraph. Are you eluding to the fact that ice melts or doesn't melt and for all temperatures below 0 the ice will be frozen? That's true but we're not dealing with a smooth climate, seasonally the ice expanse at the poles swings wildy. In winter ocean ice is a multiple 5-10 times what it is in summer, as a ball park range. So there is and always has been very much melting at the poles and our concern is the mean figures over time.
  4. RyanS#78: "seasonally the ice expanse at the poles swings wildy. In winter ocean ice is a multiple 5-10 times what it is in summer, ... there is and always has been very much melting at the poles" If by 'poles,' you're including the Arctic, then you are: a). off topic b). making an unsubstantiated claim c). incorrect. Arctic ice extent did not always swing wildly; there are a number of Arctic ice threads with plenty of actual data to examine. If it's credibility you seek, point to some numbers.
  5. We were also talking about LAND ice in Antarctica... not sea ice. Or, at least, that's the only thing I can think of which '10 year trend' might have been referring to. Since surface temperatures on most of the continent (peninsula excepted) seldom get above zero, land ice wasn't expected to start declining for decades. Yet it already has because rising ocean temperatures have cleared out sea ice and ice shelves while also undermining coastal land ice... all of which leads to faster ice export and the recently observed continent wide trend of declining ice.
  6. @ 80 "...rising ocean temperatures have cleared out sea ice.." Cleared out sea ice in Antartica? You need to read the article above, it attempts to explain why the observed rising sea ice in Antartica can occur in a warming climate.
  7. Muoncounter, we've always had and always will have seasons, climate change isn't changing that. Look at photo above showing March and September extents for both the Arctic and Antarctic. Point me to some evidence which shows arctic ice extent used to be a more static quantity than it is now. I recall a picture from the 50s showing a submarine poking through slush at the north pole.
  8. Wow - trotting out the old submarine photo. It's in a polynya! For evidence of part arctic sea-ice, see arctic sea ice threads. You can find pointers to the relevant papers on past sea-ice seasonal limits there.
  9. Ryan, try taking arctic comments to arctic sea ice melt is a natural cycle
  10. RyanStarr wrote : "I recall a picture from the 50s showing a submarine poking through slush at the north pole." Could you post further details on the thread suggested by scaddenp.
  11. Ryan, the "rising" trend in Antarctic sea ice extent is extremely small and in no way contradicts what I was saying. Indeed, breakup of sea ice, collapse of ice shelves, and increased export of land ice into the ocean all cause increased sea ice extent.
  12. Because of errors in Grace data extrapolation, it has been determined that the ice mass on Antarcica is neither shrinking nor growing. So, no net change there.
    Response:

    [DB] Umm, you seem to be confused.  Please read the OP and the comments, with particular attention to Ned's comment at 30 above.  If still unsure, try the Intermediate version of this post.  The totality of Antarctica (the Antarctic Peninsula, the WAIS and the EAIS) are all losing mass, beyond that of the error bars.  And the rate of mass-loss is itself increasing.

  13. Given that ice requires 334 joules per gram to melt where do you propose that energy is coming from over the land of antarctica ?? Do you propose that it coming from the 390 ppm CO2 with its specific heat of less than 1 joule per gram ? I havent done the maths on this because it seems unbelievable that it has the capacity to cause warming on the scale it is credited with.
  14. Rosco, see the Intermediate version of this post. The land ice on Antarctica does not 'melt' by direct heating from air or insolation so much as it loses the balance it formerly had between gains and losses. The losses are (mainly) attributable to the heat now in the oceans, accumulated over the last couple of centuries. The ocean is taking more from the edges than the icecap and glaciers can accumulate at their centre/top.
  15. Rosco, sorry I hit the button too soon. Melting. The issue is that much of the ice does not melt in situ. It thins, weakens and breaks off and the ocean transports it away in the form of icebergs. These may not melt for quite a long time after they've subtracted their bulk from their source glacier.
  16. The ice is not melted by conductive energy transfer so specific heat is irrelevant. Melting is from radiative energy transfer - ie the energy is the from sun and more of it is trapped because of the CO2. Perhaps you should do the math. What does an extra 1.5W/m2 (global annual average all forcing) give you? Also warmer water onlapping Antarctica increases calving which I believe remains the main source of ice loss in the Antarctic.
  17. Following up on posts by Camburn here, the most recent paper on Antarctic Ice Mass Balance I can find is Rignot et al 2011, published in March of this year. It finds:
    "In 2006, the Greenland and Antarctic ice sheets experienced a combined mass loss of 475 ± 158 Gt/yr, equivalent to 1.3 ± 0.4 mm/yr sea level rise. 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."
    It does not distinguish between ice lost from West or East Antarctica. The most recent article I found that does distinguish between them is a review article by Cazenave and Llovel (2010) which finds the majority of the ice loss on the West Antarctic Ice Sheet, with East Antarctica being found to be "in near balance". The most recent GRACE data I can find is from Chen et al (2009) which finds:
    "In agreement with an independent earlier assessment, we estimate a total loss of 190 +/-77 Gt yr^1, with 132 +/-26 Gt yr^1 coming from West Antarctica. However, in contrast with previous GRACE estimates, our data suggest that East Antarctica is losing mass, mostly in coastal regions, at a rate of 57 +/-52 Gt yr^1, apparently caused by increased ice loss since the year 2006."
    This evidence clearly supports the view that ice loss from West Antarctica significantly excedes that from East Antarctica, but is ambiguous about whether East Antarctica is loosing ice. On balance, it is probably loosing ice, but the GRACE experiment may well be overestimating the rate of loss.
  18. There's a nice article over at weather underground explaining the Zhang paper in more comprehensible terms. With pictures. It's here: http://www.wunderground.com/blog/RickyRood/comment.html?entrynum=194
  19. http://www.agu.org/pubs/crossref/2011/2011GL047553.shtml doi:10.1029/2011GL047553 Sudden increase in Antarctic sea ice: Fact or artifact? Three highly-cited data sets depict a sudden large increase in Antarctic sea ice This step-change is fake and is related to a switch in source data Recent sea ice trends are significantly exagerated becuase of this data problem (typos in the original) http://www.agu.org/pubs/crossref/2011/2011GL047553.shtml
    Response: [Dikran Marsupial] Links activated
  20. While I'm very wary of drawing any conclusion from a single paper (an error which this article suffers from particularly, in my opinion), the following paper adds another piece to the puzzle. (Whether it is in the right place is another question.) http://www.aoml.noaa.gov/phod/docs/Shu_etal_2011.pdf (via Ari at AGW observer)
  21. While I'm very wary of drawing any conclusion from a single paper (an error which this article suffers from particularly, in my opinion), the following paper adds another piece to the puzzle. (Whether it is in the right place is another question. Given that they claim an increasing sea ice trend, when the trend itself is barely significant, I have reservations about the statistics.) http://www.aoml.noaa.gov/phod/docs/Shu_etal_2011.pdf (via Ari at AGW observer)
  22. News yesterday: NASA finishes the first Antarctic ice flow speed map.
  23. I was recently quoted Ian Joughin and Slawek Tulaczyk 2002 as proof that WAIS is gaining ice. In the article I read that the sheet is marine based, but grounded, so does that count as land ice? Also, the the third to the last paragraph the article indicates that it is only about the Ross ice streams: “This analysis covers only the Ross Sea sector of the ice sheet, and negative imbalances are observed in other areas of West Antarctica such as Pine Island and Thwaites Glaciers.” Is that why there isn't any conflict between that article's gaining ice conclusion and the GRACE 2002-2009 data showing land ice loss?
    Response:

    [DB] The WAIS is in negative mass-balance.  While the interior of the EAIS is gaining mass, its edges are losing mass sufficient to put the EAIS overall into negative mass-balance.  Now that negative could be as little as 5 Gt/yr or as much as 67 Gt/yr (IIRC).

    Antarctic sea ice is gaining some in the metrics of area and extent, but this is an expected response to increased precipitation to the warming of its circumpolar current.

    The PIG and Thwaites are the linch-pin to the WAIS; without their stabilizing presence, ice flow rates will accelerate greatly.

  24. I understand that both WAIS and EAIS are in negative balance. I am trying to reconcile that knowledge with the paper linked above. The abstract states "We have used ice-flow velocity measurements from synthetic aperture radar to reassess the mass balance of the Ross Ice Streams, West Antarctica. We find strong evidence for ice-sheet growth (+26.8 gigatons per year), in contrast to earlier estimates indicating a mass deficit (−20.9 gigatons per year). Average thickening is equal to ∼25% of the accumulation rate, with most of this growth occurring on Ice Stream C. Whillans Ice Stream, which was thought to have a significantly negative mass balance, is close to balance, reflecting its continuing slowdown. The overall positive mass balance may signal an end to the Holocene retreat of these ice streams." Does the +26.8 Gt apply to only the Ross Ice Streams and not to WAIS as a whole?
    Response:

    [DB] It's good that you question the 2002 study (as that is the skeptical thing to do).  Joughlin does absolutely splendid work and is highly regarded in the field.  From Ian Joughin and Slawek Tulaczyk 2002 (3rd to last paragraph in the paper):

    This analysis covers only the Ross Sea sector of the ice sheet, and negative imbalances are observed in other areas of West Antarctica such as Pine Island and Thwaites Glaciers.

    Emphasis added, obviously.

    Anyone who tries to extrapolate this result, especially in lieu of later, continental scale findings like detailed in the OP above or the Intermediate version of this post, is a serious Cherry-Picker.

    I would also encourage you to review Rignot's latest work, discussed here.  Absolutely fascinating stuff.

    Note:  Science allows individuals to register for free downloads of the older material, such as the study Joughlin study referenced in this comment.  The cherry-pickers and dissemblers of the world count on people not fact-checking their claims. 

    Don't let them win.

  25. SocialBlunder, Have you looked at the intermediate tab? From that article, the 2002 paper might not be in error (since the data was probably obtained sometime before 2002). The 2nd figure (from Velicogna 2009) shows a curve that indicates that somewhere around 2001 or 2002 the ice mass was stable. Now the ice mass is negative and the loss is increasing by ~26 Gt/year. So if that acceleration is constant and if the ice sheet was in balance in ~2002, then in ~2001 the ice sheet would have been gaining 26 Gt/year. A lot of ifs there, but I see no reason to disbelieve the 2002 paper and don't see it contradicting this article - it's just that the 2002 uses outdated information (not their fault - it was current when they printed it). But take that with a grain of salt. IANACS (I am not a climate scientist), just an aerospace engineer living as a computer scientist :).

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