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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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Antarctica is gaining ice
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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 26 to 50 out of 353:

  1. protestant, soot and black carbon are not significant factors in Antarctica, due to the continent's isolation. Comparison to the Arctic or to montane glaciers in northern hemisphere regions with heavy soot/BC loadings are not realistic. You're right that there aren't sufficient data to construct a mass balance for Antarctica in the 1930s, or any time before the International Geophysical Year (and estimates from before the launch of GRACE will have much wider confidence intervals). But most of that uncertainty is in the accumulation side, not the ice loss side, where there's a reasonable degree of confidence that ice loss has been accelerating. Thus, for example, a series of ice shelves on the Antarctic peninsula have partially or fully disintegrated over the past two decades, all of which managed to survive the 1930s. And in recent years these effects have been moving progressively further south, an additional confirmation that warming is accelerating in the west Antarctic. Finally, I think you're mistaken about the ARGO data, though it's understandable since the claim "ARGO data show the oceans are cooling" has been very widely publicized among "skeptical" websites over the past few years. This is discussed in great detail elsewhere on this site: Does ocean cooling disprove global warming? In particular, whether or not you accept the more recent analyses of ARGO showing that the perceived 2003-2006 "cooling" was an artifact, we're talking here specifically about warming of the Southern Ocean around Antarctica. This has unequivocally been warming faster than the ocean as a whole -- see, e.g., Roemmich 2009. Note Figure 3.1(a), which shows relatively high warming of surface waters (down to 400 dbar) from 40-60 South latitude.
  2. For a comprehensive analysis of Antarctica sea ice data, including the effect of the ozone hole see http://www.roperld.com/science/AntarcticSeaIce.htm . Dave Roper
  3. A group of scientists ( Eric Rignot, Jonathan L. Bamber, Michiel R. van den Broeke, Curt Davis, Yonghong Li, Willem Jan van de Berg & Erik van Meijgaard) recently assessed the loss in ice mass from 1992 to 2006 in Antarctica using radar interferometry and regional climate modeling and published their findings in Nature Geoscience. In a nutshell their findings identified ice mass loss in East Antarctica to be minimal but in the western part of the continent identified widespread losses along the Bellingshausen & Amundsen seas in the amount of 59% over ten years. In the Peninsula area losses were estimated at 140%. However they identified the losses as being concentrated along narrow channels occupied by outlet glaciers and attributed the cause to ongoing and past glacier acceleration. The concludedthat "changes in glacier flow have a significant, if not dominant impact on ice sheet mass balance." This issue goes back to my previous comment that any interpretations made from aggregated data should be taken with a grain of salt - especially when dealing with gravimetric readings. Contoured maps showing highs and lows and changes to those highs and lows over time are more relevant than a simple time series graph as posted in this article.
  4. Geo Guy, I think that upon reading the text and not just looking at the figures, the two sentences "While the interior of East Antarctica is gaining land ice, overall Antarctica is losing land ice at an accelerating rate. " and "The ice gained in the interior is roughly balanced by the ice loss at the edges." address your point and quite well describe what is going on down there.
  5. Geo Guy writes: In a nutshell their findings identified ice mass loss in East Antarctica to be minimal but in the western part of the continent identified widespread losses along the Bellingshausen & Amundsen seas in the amount of 59% over ten years. In the Peninsula area losses were estimated at 140%. Here's a link to the Rignot 2008 paper. Just to be clear, since readers might be confused how the peninsula could lose 140% of its ice ... From 1996 to 2006, annual loss of ice mass from West Antarctica increased from 83 Gt/yr (+- 59) to 132 Gt/yr (+- 60), which is a 59% increase in the rate of loss. Likewise, annual loss of ice mass in the peninsula increased from 25 Gt/yr (+- 45) to 60 Gt/yr (+- 46), a 140% increase in the rate of ice loss. I think these kinds of regional-scale analyses nicely complement the continent-wide GRACE data. GRACE tells us, with a pretty high degree of confidence, how much mass Antarctica is losing per year. Studies like this one help elucidate the different components of the mass balance budget that should add up to the net change in mass as measured by GRACE.
  6. One thing that seems to have been missed here is that an increase in sea ice will not change the ocean level since that mass is already in the ocean. A decrease in land ice will add to the sea level.
  7. I find it interesting too that as the land ice moves toward the sea, not only will there be less land ice, but it occurs to me that there is likely to be much more sea ice as well. Rather like a migration. Moves from here to there. At some point as that nasty green line becomes vertical, there is going to be a whole grunch of sea ice as no land ice remains to jump in.
  8. ESA CryoSat 2 successfully launched, replacing spacecraft lost in the 2006 launch attempt and neatly slipping into place to take over for ICESat, now (RIP) to be retired by NASA after a final laser failure late last year. Excellent article w/many interesting details here at SpaceFlightNow. ESA mission homepage here Interesting note: this launch was from a old missile silo, the subterranean type. Talk about swords to plowshares, eh?
  9. BTW, CryoSat uses radar sensing as opposed to lasers so it's not really a direct substitute for ICESat, whose replacement is laconically scheduled for 2014. However CryoSat will be able to provide extent measurements which can combined w/NASA'a stopgap coverage to continue gathering data. Another splicing controversy smorgasbord for rejectionistas, doubtless, but unfortunately priorities in the U.S. leading up to ICESat's final failure precluded timely launch of a substitute.
  10. Cryosat-2 does have a better radar altimeter in comparison with previous radar methods (ERS and so on)therefore it hopefully will eliminate some of the resolution issues with previous methods of radar altimetry and can make up for the issues with icesat. (I'm thinking extremely small coverage area by comparison)
  11. Thanks for pointing this out over at CP. There, I made the assumption that "sea ice" meant floating icebergs. My bad.
  12. Might be interesting to keep a watch on Antarctic sea ice extent and the rate of change , it seems to be doing some interesting things down there .
  13. Yah, people, when does Antarctic sea ice extent begin to look a little freaky. I don't expect it to continue to nosedive, but I'd like to hear from any experts as to when the dive might/should stop.
  14. DSL, wow that IS a bit odd. Antarctic sea ice is expected to eventually start declining, but this seems more likely to be some sort of short-term fluctuation. The 'growth' in Antarctic sea ice has been small enough that the current year amount still drops below the long term average semi-regularly. This contrasts with the situation in the Arctic where skeptics got excited earlier this year about the extent coming CLOSE to the long term average for the first time in years. Thus, the current dip is unusual, but not unprecedented. Looks like the Southern melt season started about two weeks early for some reason.
  15. Slimboy, how about redoing the last paragraph of your comment except this time w/sources?
  16. Actually Slimboy it would be better if you sourced your entire comment. You do a back-of-the-envelope calculation, lay out a bunch of speculation and expect to be persuasive? Not up to snuff.
  17. He wasn't able to tell certanly that global warming was the reason but the ice weight loss from Antarctica is being influenced by warm water temperatures, which in turn are caused by climate change and altered ocean currents. The losing of ice is thought to be partly attributable to the processes that take place over thousands of years. “How it reponds to climate takes place over many different time scales,” Professor Bamber said. “There are changes taking place now that are a result of what happened to the climate 12,000 years ago.” Athmosphere thermal rises are caused by climate change are more visible at the poles than in other regions of the world but researchers have an incomplete understanding of the mechanisms controlling ice in Antarctica.
  18. Did you look at the graphs showing increasing loss of land ice? Or not.
  19. I don't see anyone pointing out that Ice core temperature proxy data shows that as Greenland warms, Antarctica cools. As Greenland cools, antarctica warms. They seem to have an inverse temperature relationship http://www.agiweb.org/geotimes/nov06/WebExtra111006.html Chris Shaker
  20. It used to be so. Not anymore apparently, we are seeing warming both in the north and in the south. Something different is going on, guess what?
  21. I would appreciate it if you would provide pointers to data to back up those claims, because so far, all I've seen is data agreeing with the inverse. Chris Shaker
  22. cjshaker - Have you actually read the article at the top of this topic? The one with the seven (7) article references, by my count? You might also want to look at Is Greenland gaining or losing ice. Both Antarctica and Greenland are currently losing ice due to warming.
  23. I assume that you are talking about the article about mass measurements from the Grace satellite? If so, yes, I read the article. Are the ice cores taken from ice on land, or taken from ice on water? I don't know the answer to that, but it would seem to be important if sea ice is growing, but land ice is melting? If the ice cores were taken from ice on water, the inverse temperature relationship should still hold? Chris Shaker
  24. I'm fully aware that the climate appears to still be warming. I'd still like to know how that warming is incompatible with the natural glacial cycle. According to this National Geographic source, we reached temperatures of 4.5 C warmer than today during the previous glacial warming phase http://news.nationalgeographic.com/news/2007/07/070705-antarctica-ice.html Why would we not expect to reach similar temperatures during this warming phase? Thank you, Chris Shaker
  25. cjshaker - I'm referring to this article by John Cook, listing a number of peer-reviewed papers indicating overall mass loss in Antarctica. The increasing sea ice is a bit more complex - it appears to be due to changes in Antarctic winds and ocean circulation, most likely caused by (wait for it) global warming.

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