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Climate Hustle

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)

Update Nov. 7 2015

A study published by Jay Zwally and his team on Oct. 30 (Zwally et al. 2015) has suggested that until 2008 there might have been a bigger increase in ice on East Antarctica than there is a decrease in the west, meaning that total Antarctic land ice is increasing. While their results for the Antarctic Peninsula and much of West Antarctica agree with other research, the study disagrees with many other techniques. We will update this discussion once more studies address this issue. Until then here are links to some recently published takes on the study:

A controversial NASA study says Antarctica is gaining ice. Here’s why you should be skeptical - Chris Mooney (Nov. 5)

NASA Scientist Warned Deniers Would Distort His Antarctic Ice Study — That's Exactly What They Did - Media Matters (Nov.4)

More on Antarctic Ice Melt - ClimateCrocks (Nov. 3)

Is Antarctica Gaining or Losing Ice? Hint: Losing. - Phil Plait (Nov. 3)

Q&A: Is Antarctica gaining or losing ice? - Carbon Brief (Nov. 3)

Just Because Antarctica Might Be Gaining Ice Doesn't Mean Climate Change Isn't Happening - Vice (Nov. 2)

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.

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 8 November 2015 by BaerbelW . 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

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Comments 201 to 250 out of 463:

  1. OK on second read where you say the air moves from a position of high rotational velocity to low velocity, you were talking about the velocity of the rotating earth, not the rotational velocity of the air. OK never mind. As long as we are on the same page.

    Now, what about the ozone? Or lack thereof.

  2. Morgan Wright @200 & 202:

    1)  The South Pole itself is not in the blue patch shown on the O'Donell et al map, but rather on the border.  The temperature trend at the South Pole as measured by instruments on the surface is scarcely distinguishable from zero (0.007 C per decade), but is not falling.  But, does that really matter.  Does any part of your argument actually hinge on the South Pole cooling while Antarctica in general warms?

    2)  I'm so glad your vast fount of knowledge has put the American Meteorological Society in its place:

    "cold low

    (Or cold cyclone;
    also called cold-core low, cold-core cyclone.) At a given level in the atmosphere, any low that is generally characterized by colder air near its center than around its periphery; the opposite of a warm low.

    A significant case of a cold low is that of a cut-off low, characterized by a completely isolated pool of cold air within its vortex. The cyclonic intensity of a cold low increases with height in accordance with the thermal wind equation."

    Or possibly you just don't know everything about meteorology, and you got that one wrong.

    3)  I say that increased CO2 cools the stratosphere by radiating from the stratosphere, not into it.

    4)  I say that when air moves from a location with high rotational velocity (m/s following a circumference) to a location with a low angular velocity, the air will conserve angular momentum and hence be diverted at right angles to the the initial impetus, resulting (at the poles) in a vortex around the pole.  The greater the reduction in rotational velocity of the surface on over which the air is located, the greater the relative velocity of the air to the surface as a result of conserving angular momentum.  I think, however, you had figured this out by your post 201.

    5)  I am not much concerned about your original ozone skepticism.  The OP does not claim that decreased ozone cools the surface.  Rather it claims that decreased ozone increases the velocity of the circumpolar vortex, thus breaking up pack ice and allowing more ice to form at the surface, thereby contributing to greater sea ice extent.  The mechanism for doing this involves cooling of the stratosphere, not the surface.  Reduced ozone cools the stratosphere by the very simple mechanism that less ozone results in less UV radiation being absorbed, and hence energy in the stratosphere.

    You are welcome to be as skeptical as you like about your straw man.  It just has no relevance to the topic discussed on this thread.

  3. http://i.imwx.com/web/multimedia/images/blog/antarctica_wind_pattern.jpg

    South polar high, as I said. Winds go towards the sea, rotation of the earth to the east causes the wind to turn west to make polar easterlies.

  4. Most papers on the subject state that the south pole, and much of Antarctica, are cooling. Study the following chart from NASA:

    http://www.hyzercreek.com/nasa2005.jpg

    The original explanation of how ozone is causing the south pole to cool is wrong, since the ozone level is not changing, (it is already at zero), and yet the south pole is cooling. Your attempt to tweak the ozone hole explanation with a new twist also does not work...you say the ozone fails to absorb UV in the stratosphere, causing more sea ice to form in the winter. This is impossible, because there is no sunlight at the south pole in the winter, and therefore no UV. 

    http://i.imwx.com/web/multimedia/images/blog/antarctica_wind_pattern.jpg

    Listen to me closely. Look at the above link and notice that the vortex has its center over the south pole and is blowing outward, not inward. Polar cooling of the air in winter causes high pressure which sends frigid air north along the surface. At the pole the air has almost no angular momentum, so as it moves north it will not spin as in a vortex. Rather, as the air moves north, the west-to-east rotation of the earth underneath it becomes increasingly fast, making the air blow to the west relative to the earth even though the air itself has little motion. These are referred to in the literature as polar easterlies. They are not really a cyclone because they are caused by the rotation of the earth, not conservation of angular momentum. 200 miles from the pole the earth is rotating  around 50 MPH but 1000 miles from the pole the earth is rotation 250 miles per hour. You can see the winds can become frighteningly fast fairly quickly.

    The colder the pole, the stronger the high, and the faster the northward motion of the air, and the sooner it can get north before picking up angular momentum from the friction against earth's surface. Therefore, the colder the pole, the stronger the polar easterlies will be. The increase in the polar easterlies is caused by increasing cold. Therefore, the increase in sea ice is caused by increasing cold at the pole. Therefore, we need to know why the pole is getting colder. It's not a straw man to mention the O3 hole, since we need to know whether it's cooling due to the ozone hole, or whether it's cooling because AGW is a false hypothesis.

    This web site is for skeptics of skeptics. All the skeptics are saying the antarctic sea ice is increasing because it's getting colder down there, and there is no AGW. Skeptics of skeptics are saying.....Some are saying, ok the south pole is getting colder but it's from the ozone hole. Some (this OP) are saying it's not even getting colder, the sea ice is from the wind, and part of that explanation is to pretend the wind is coming from the wrong direction and saying the south pole is a low pressure vortex. We need to iron this out.

  5. Morgan Wright @204:

    1)  Of recent papers on Antarctic temperatures all that I have checked show warming.  These include not only Steig et al, and O'Donnell et al, but also:

    Muto et al (2011), which shows warming of 1 - 1.5 C in East Antarctica, most of which has been in the last two decades.

    Bromwich et al (2013), which shows "Central West Antarctica [to be] among the most rapidly warming regions on Earth".

    Screen and Simmonds (2012), which shows mid tropospheric warming and stratospheric cooling over all of Antarctica, with the stratospheric cooling being concentrated in Spring and Summer.

    Schneider et al (2010), which shows a 0.1 C per decade trend averaged over all of Antarctica, with warming strongest in the pensinsular, and second strongest in the West Anarctic spring.

    And finally, because your initial comments regarded the South Pole, we have Lazzara et al (2012), who show a cooling trend at the South Pole till about 2000, and a rapid warming trend thereafter:

    It should be noted that when the data is extended to include 2012, the trend of the full data sets becomes positive (as previously noted).

    So, there is little doubt from recent literature that Antarctica is warming, with most of the warming being in the last two decades, and in West Antarctica.  If you have a paper published in the last 5 years that disputes that, I would be interested to see it - but I see no reason to reject recent studies in prefference to older studies, particularly given that the older studies are now obsolete due to the recent rapid warming trend.

    2)  You are simply wrong about ozone.  Ozone has never fallen noticably below 100 Dobson Units in the period of observations:

     

    Your repeated errors on simple matters of fact are very damaging to your case.

    You are also wrong to claim the effect cannot occur because it happens in winter when the sun does not reach the pole.  That is first, because the effect occurs in the Autumn when sea ice is growing, but when the sun can still reach the pole.  It is also because the ozone hole often extends beyond the Antarctic Circle, which together with its high altitude ensures sunlight reaches regions of depleted ozone long after the pole falls into shadow at the surface.

    I will respond to your other points later.

  6. Thanks for the graph showing that ozone has not lowered since around 1988, backing up my argument, that it cant be the cause of south pole cooling.

    I also read the Lazarra paper you cited, in which he shows that the south pole winter temperatures are decreasing slightly as the south pole summer temperatures increase slightly, but that neither of which is statistically significant. So let's just say the south pole is staying the same, i.e. not warming. 

    Now, let's iron this whole thing out. South pole, not warming. Rest of earth, warming. The earth is a heat engine where most solar forcing is in the tropics, heated tropical air moving toward the poles, cold air returning toward the tropics to be heated again. So the earth is a heat engine, like a Sterling Engine, and it operates on the difference in forcing at the equator vs the poles. 

    So, the south pole is not changing, the equator is getting warmer, so the heat engine is getting stronger. That's why there is more polar easterly wind around Antarctica. That's why there is more antarctic sea ice. Has nothing to do with ozone which is just a stupid theory. Drop it. Let's never mention the word ozone again. There is no UV in Antarctica in the winter, almost none in the spring or fall. I'll give you the summer, which is when no sea ice forms. So, ozone has nothing to do with it. Time to burn the straw man.

    OK I'm done with this. Case closed. Forget ozone forever, ok?

  7. Morgan,

    This is a scientific board.  You must refer to the scientific literature or no one will bother with your posts.  You have linked to several blog posts, including an unlabeled graph from a frisbie golf site (this one: http://www.hyzercreek.com/nasa2005.jpg).  At the same time Tom has linked to a number of peer reviewed publications.  Please bring your posts up to the standard used here or stop posting.  

    You will not convince anyone here with a frisbie golf graph with 2005 in the link.  No one cares what your interpretation of the data is.  Link to peer reviewed papers that support your view.

  8. Morgan Wright@206: "Now, let's iron this whole thing out. South pole, not warming"

    While I realize that this is not peer reviewed, or even strictly speaking a scientific result, it might bear some counter value to the claim above:

    "The 2013 winter – the months of June, July and August – will already go down as the warmest such season at the South Pole since records began in 1957. That trend continued into September – now the warmest on record – with four new daily maximum record temperatures falling in the middle of the month."

    And while MW does refer to a NASA-produced anomality-picture from 2005 (apparently), there are newer ones, which are showing that the anomality is positive.

    So, old information says cooling. New information says warming.

  9. Morgan Wright @204 (cont), I have been a bit confused about my account of the effect, specifically with regard to the location and altitude of the relevant winds.  In particular, I thought the relevant winds were those bringing warmth into the upper troposphere of Antarctica, whereas they are those related to bringing warmth to the Antarctic Ocean.  To avoid furhter confusion, I think it best that I lay out the observations directly.

    First, the winds involved are those bringing warmth along the surface from about 30o to about 60o South:

     

    These result in westerly winds (clockwise around the pole as viewed from below) just above the edge of Antarctica in the region where the seasonal sea ice forms, ie, the west wind drift:

    These have been strenthening, and it is their increased speed that is one of the postulated causes of increased Antarctic sea ice.

    Gillet and Thompson (2003) show a comparison between the observed increase in westerly strength and that prediced from a model driven only be reductions in ozone set to match observed reductions:

     

    Gillet and Thompson indicate the strongest effect occurs in the spring in the stratosphere, but then propogates downward to summer (summer and autumn according to Turner et al, 2009).

    How could ozone drive this pattern?

    The west wind drift is formed by air coming south and then rising as it encounters colder air from Antarctica.  For it to rise, air above it must disperse, ie, move either north or south.  If it does not disperse, the rising air will cause a build up in pressure that will stop further rises in air.  The air moving south in turn must fall at or near the south pole in order to make room for more air.  That, however, creates a problem.  The air moving south is typically of a similar temperature to the surface in Antarctica, or warmer.  If it falls, it will be warmed by increase pressure, making it warmer than the surface air.  As a result it will not fall any further.  Unless upper troposphere are over Antarctica falls to temperatures approximately 6.5o C per km of altitude above the surface, it cannot fall, with the consequence that pressure will build up at altitude stopping further circulation.  Therefore the air coming south must be cooled, primarilly by radiation to space.  The radiation to space is made less efficient by the existence of a warm stratosphere above the air, generating IR radiation from above, and limiting the net cooling of the upper troposphere.  At this stage, reduced ozone results in a cooler stratosphere and more efficient cooling of air in the upper troposphere.  Reduced ozone, of course, cools the stratosphere by the simple expedient of reduced absorption of UV radiation from the sun.

    It should be evident that increase CO2 should also result in more efficient cooling of the upper troposphere.  When the air below this effect is overwhelmed by increased IR radiation from below.  But over Antarctica, increased CO2 should also accelerate the  circulation of the polar cell, and hence indirectly that of the mid-latitude cell, and with it the west wind drift.  Models do in fact show this effect, but show it to be significantly weaker than the effect of reduced ozone.

  10. I'm wondering about Transantarctic mountains, altitude, humidity, dehumidification, increased cloud cover and the creation of more Antarctic ice through this process. This is the process I'm thinking about and I want to know if it's possible or not. Can someone please tell me where this 'theory' goes right or wrong.

    The warming earth causes the atmosphere to hold more moisture all the way from the North pole to the south pole. When this moisture reaches Antarctica it's forced to altitude by the Transantarctic mountains.

    This rise of moist air across the cold altitudes of the Transantractic mountains causes whatever moisture that remains in the air to create clouds over the TransAntarctic mountains.
    These clouds then spread out and reflect the sun dropping temperatures even further causeing even more cloud cover and increased percipitation in the cold zone.

    In other words, the TransAntractic mountains are acting as a giant dehumidifier thats causing clouds to further cool an Area of Antarctica along with increased ice creating snow.

  11.  

    Found the article of value in terms of understanding.

    The statistic seem obvious, towards,100 Giga tons of Land Ice melt, per annum, will result in 0.2mm in sea level rise, p.a. rough maths and a benchmark.

    The trend line in round numbers, seem supported, by scientific evidence.

    The overal position of Antartic Ice increasing correct, but peridic in nature, the desalination of the area, and lowers water tempratures, will increase freezing, perhaps minor, but will affect tidal range globally, on an annual basis.

    The objective of the article that focuses on land mass ice, being the more significant component, and Sea Ice being an anual effect stated, but not quantified, as the absolute measure being the more important element.

    The overall effect being higher sea levels and a slighly greater tidal range, prediction.

  12. http://www.nytimes.com/2014/05/13/science/earth/collapse-of-parts-of-west-antarctica-ice-sheet-has-begun-scientists-say.html?hp&_r=0

    "Two papers scheduled for publication this week, in the journals Science and Geophysical Research Letters, attempt to make sense of an accelerated flow of glaciers seen in parts of West Antarctica in recent decades."

    "The collapse of large parts of the ice sheet in West Antarctica appears to have begun and is almost certainly unstoppable, with global warming accelerating the pace of the disintegration, two groups of scientists reported Monday."

    "The new finding appears to be the fulfillment of a prediction made in 1978 by an eminent glaciologist, John H. Mercer of the Ohio State University. He outlined the uniquely vulnerable nature of the West Antarctic ice sheet and warned that the rapid human release of greenhouse gases posed “a threat of disaster.” He was assailed at the time, but in recent years scientists have been watching with growing concern as events have unfolded in much the way Dr. Mercer predicted. (He died in 1987.)"

    Response:

    Fixed link

  13. I know that all of these scientists are much smarter than me, but there are millions of years of data no one has.  It is so easy for all of these scientists to get all caught up in the details they have learned and focus on this fact and that fact, but the truth is they don't know much of anything, no one does!!!!  They have a less than miniscule snapshot of what has happened in the last however many years and they are claiming their beliefs in climate change are fact.  The earth has warmed and cooled for millions of years.  No one knows why it has cooled and heated for those millions of years.  As a society we can't even predict the weather with much accuracy, why does anyone believe they can predict what is happening to the earth?   So pretentious....

    Response:

    [JH] If I had seen this comment prior to anyone reponding to it, I would have deleted it for being in violation of the SkS Comments Policy. 

    Geneally speaking, when someone posts a comment that looks like and smells like concern trolling, it would behoove everyone to refrain from responding until a Moderator has had a chance to review the comment and take appropriate action.    

  14. b1rdinski:

    Assuming your comment survives moderation, as it may well be considered sloganeering, your argument from ignorance (that is, lack of knowledge) is not universalizable.

    You may not know what's been going on with paleoclimate. That doesn't mean no one knows.

    So instead of asserting with such certainty that "no one knows why it has cooled and heated for those millions of years" - because you are incorrect - how about you start by asking how scientists know what they know? You might even get a helpful answer.

    Response:

    [JH] If I had seen b1rdinski's comment prior to your reponding to it, I would have deleted it for being in violation of the SkS Comments Policy. 

    Geneally speaking, when someone posts a comment that looks like and smells like concern trolling, it would behoove everyone to refrain from responding until a Moderator has had a chance to review the comment and take appropriate action.  

    Please let the official Moderators moderate the comment threads. 

  15. b1rdinski, this is a thread on Antarctic sea ice.  There are many other threads at SkS more appropriate to your concerns.  

    I'll also point out that the fundamental piece in the theory of anthropogenic global warming is simply the theory of the greenhouse effect (GHE).  That theory (the GHE) is one of the strongest science has to offer.

    FYI: If you want to avoid having your comments deleted--that is, if you want your voice to be heard--you'll need to show that you're capable of 1) understanding/recognizing the responses people give you and 2) providing evidence to support your claims.

    Response:

    [JH] If I had seen b1rdinski's comment prior to your reponding to it, I would have deleted it for being in violation of the SkS Comments Policy. 

    Geneally speaking, when someone posts a comment that looks like and smells like concern trolling, it would behoove everyone to refrain from responding until a Moderator has had a chance to review the comment and take appropriate action.  

    Please let the official Moderators moderate the comment threads. 

  16. ugh - "Antarctic land and sea ice"

  17. The Vice news program on HBO had an interesting story of how the Glacial land ice is melting in Greenland at a rapid rate. If Greenland becomes green, and all the land ice melts, can we really expect the sea level to rise by that much?

  18. Anthony,

    This SkS thread says tht if Geenland melted it would raise sea level 6 meters.  You would expect at least the same amount from Antarctica.  Here in Florida a 12 meter sea level rise would inundate 3/4 of the state, home to about 15 million people.  Bangladesh would be long gone.  That seems like a lot to me. How much is a lot to you?

  19. http://pubs.usgs.gov/fs/fs2-00/

    SLR

  20. Anthony, check out the sea level rise explorers here and here to see what a few meters or a few dozen meters of SLR mean for agricultural and infrastructural destruction, and population displacement. 

  21. I simply ask a factual question as to the basis of the study pointing to 97.1% peer reviwed abstracts. The opening excerpt quantifies the study in the following "...peer-reviewed scientific literature, examining 11 944 climate abstracts from 1991–2011 matching the topics 'global climate change' or 'global warming'. We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming. Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming..." - After doing the math - Including the small percent of those that do not support AGW) doesnt this mean that 97.1% of 4014 (or so) abstracts and not 97.1% of the science "community" or scientists agree ?? And if so, in the interest of truth and fact, dont you seek to clarify this within the media so they can more intelligently inform the public ?? - http://iopscience.iop.org/1748-9326/8/2/024024/pdf/1748-9326_8_2_024024.pdf

  22. edaaaa - Please re-post your comment to a thread where it is on topic.

  23. Without reading all the comments, it seems as if the volcanic activity in the area of Antarctica is being significantly underestimated in IPCC circles.  They admit there is volcanic activity and if you twist arms one can even get an admission that volcanic activity has been steadily increasing in the antarctic as geological studies clearly show that the tectonic plates between the eastern and western antarctic ice sheets have been moving (away from each other causing volcanic emission) at an increasing rate.  The pro-AGW answer seems to be "No it's not", or "It is not important."  Indeed it is not mentioned in the article above and is ignored in most of the abstracts concerning the Antarctic ice loss.  The strongest answer is that warm ocean currents is the much greater contributor.  How does this reconcile with record sea ice sheets?  Wouldn't warm ocean water trends affect sea ice even more effectively than land ice?  I understand that the Antarctic land ice is more important in models, but then why ignore that the region -under the landmass- is warming?  Considering that one major volcano can cool the world for decades, it seems that the pro-AGW group is quite dismissive of their power to affect climate change.

  24. Tuerqas, show me a study — any study — that shows Antarctic volcanic activity increasing over the past fifty years.

  25. Further to DSL - a big volcano close to tropics can cool the world for a few years (not decades) because stratospheric aerosols block the sun. A volcanic eruption in the polar regions, especially Antarctic, doesnt distribute aerosols worldwide. Furthermore, dust would blacken the snow, sharply reducing albedo and leading to more melt but there havent been such eruptions in Antarctica.

    To the paradox of warm ocean but increasing seaice, see the intermediate version of this article.

    To volcanic effects on icesheet losses, note that incoming radiation is measured in watts in summer, (daily mean ~25W/m2 in December) whereas geothermal heat measured in milliwatts. For a calculation on volcanic effect on ice sheet using recently published paper on Thwaites,
     see here and for an update which reduces it further, see here

  26. Tuerqas @223, here is a USGS map of the major fault lines around the world:

    The key thing to note is that there are no fault lines within the Antarctic plate, and hence no fault lines within Antarctica.  Therefore East Antarctica and West Antarctica are not moving away from each other at all, let alone at an increasing rate.  They are not even on different tectonic plates.  That is why there are very few earthquakes in Antarctica (see also),and limited volcanic activity.

    There are some minor faults within the Antarctic plate, but I can find no evidence of rifting or mountain building in Antarctica more recently than 65 to 100 million years ago.  Given that, absent peer reviewed evidence to the contrary, it appears you have simply made up (or swallowed somebodies line) about increased vulcanism in Antarctica.  

  27. One at a time, DSL:  Non-theoretic studies are relatively sparse on many
     topics concerning Antarctica.  What I can do is point out that if you look up a list of volcanoes in Antarctica with eruption history, there were 9 with listed dates or approximate guesses of dates going back to 5550 BC.  Four of the have been in the last 50 years.  That seems like pretty significant evidence to me that there is increased activity.

    scaddenp:  Roger Highfield an AGW proponent wrote an article in Feb 2006 about how Krakatoa is still cooling the earth today.  I said decades. An expert who fully believes in AGW said a century.  What is your evidence for 'a couple of years'?  I agree there have been no eruptions of this type in the Antarctic region, yet there have been at the very least 4 in the last 50 years that have not spewed tons of debris in to the stratosphere.  Is the heat, contained under ice, insignificant?  As DSL obliquely points out, there is little interest in doing studies in Antarctica that minimize AGW, so we don't know.  I do know that geothermal heat activity has kept a place like Iceland free of ice and livable since long before the industrial age.  it shows to me that volcanic heat is capable of affecting glaciers on a significant scale.

    Tom Curtis:  I could find no maps that show the plates from either of the pole sides so you may be 100% correct.  It is evident in your picture above that the Antarctic plate splits nearly in half as it approaches the Scotia plate.  I could not find a map that shows both this plate picture and the placement of the Seal Nunatak volcanic range.  I did read that the range splits the Antarctic plate and that it was on plate fault line, but it was from a skeptic author so I won't bother pushing it.

     <Snip> (removed accusations of fraud and inflammatory political comment)

    Response:

    [PS] Please read the comments policy. Compliance is not optional. Note particularly political rants and accusations of fraud etc. This is a site for discussing the science. There are other places which welcome commentary of this type.

  28. Tuerqas, you wrote @ 227: "I could find no maps that show the plates..."

     So what did you base your contention @ 223 on that: "... geological studies clearly show that the tectonic plates between the eastern and western antarctic ice sheets have been moving (away from each other causing volcanic emission) at an increasing rate."

  29. Roger D, please read more carefully.  I could find no maps with a polar oriented view.  Need I explain to you that a flat map makes the north and south pole areas look bigger than they really are?  The only tectonic plate map I could find was the same one Tom Curtis linked and if it were accurate, the Antarctic plate is larger than the Pacific plate.  Are you maintaining that the map above is accurate in size and that the Antarctic plate is actually larger than the pacific plate?  If you are, I know how seriously to take you.  If you now understand my point and can provide a tectonic plate picture as seen with the south pole at the center so that the Antarctic plate is not vastly distorted, it would be greatly appreciated. 

  30. To the editor, I understand that ad hominem attacks will be deleted and am delighted.  How about blatant misrepresentations, like taking part of a commentary quote out of context for badly scored 'gotcha' attempts?  Are they deleted?

    Response:

    [RH] Roger has asked you to substantiate the fundamental position you've put forth. That's hardly a "gotcha." Everyone who comments at SkS, regardless of their position on AGW, is expected to be able to cite sources for their claims.

    Edit: Just to clarify. When you state something as clear as "geological studies clearly show" that should be accompanied by references to the actual geological studies (plural in this case) that are clearly showing what you are saying. 

  31. Tuerqas:

    "Non-theoretic studies are relatively sparse on many topics concerning Antarctica."

    No kidding?

    "What I can do is point out that if you look up a list of volcanoes in Antarctica with eruption history, there were 9 with listed dates or approximate guesses of dates going back to 5550 BC. Four of the have been in the last 50 years. That seems like pretty significant evidence to me that there is increased activity."

    Does it?  And you say nothing about the increased observation of Antarctica in the last fifty years?  But that's not really what we're talking about here.  We're talking about generally increased volcanic activity that would result in the kind of general net decline in Antarctic land ice.  Am I correct in assuming you've picked up the meme going around concerning Antarctic geothermal flux in the Thwaites region. 

    Can I get an acknowledgment that this part of your original claim is baseless: "one can even get an admission that volcanic activity has been steadily increasing in the antarctic."

  32. Tuerqas @227, in no particular order:

    1)

    "I do know that geothermal heat activity has kept a place like Iceland free of ice and livable since long before the industrial age. it shows to me that volcanic heat is capable of affecting glaciers on a significant scale."

    In fact Iceland is one of the few areas at its latitude to have icecaps, which are largely absent at that latitude in Eurasia, and found futher north in Canada.  Greenland has ice sheets further south, and hence represents the unusual case.  Further, there is no correlation between volcanism in Iceland and the lack of ice caps:

    This does not mean that geothermal activity is not a factor in keeping parts of Iceland ice free.  However, it is not the major factor, even in Iceland.

    2)

    "What I can do is point out that if you look up a list of volcanoes in Antarctica with eruption history, there were 9 with listed dates or approximate guesses of dates going back to 5550 BC. Four of the have been in the last 50 years. That seems like pretty significant evidence to me that there is increased activity. "

    Comparing with Iceland again, since 900 AD there have been more than 205 eruptions in Iceland.  More than, because 13 of the "eruptive events" have been "fires", the most recent of which (Kraffla 1975-84) contained 9 distinct erruptions.  Over that period there has been an "...An apparent stepwise increase in eruption frequency is observed over the last 1100 years...", but that merely "... reflects improved documentation of eruptive events with time".  Given that exploration of Antarctica has been exlusively restricted to the last 150 years, with significant observations restricted to the establishment of Antarctic bases in 1958 and later, an increased observation of erruptions in the 20th century proves no more than an increased frequency of observation in the 20th century.

    3)

    " It is evident in your picture above that the Antarctic plate splits nearly in half as it approaches the Scotia plate."

     That is not obvious to me at all.  What is obvious is that the map only shows some of the coastal regions of Antarctica and so gives no true indication of its width.  This map will give you some indication, with the Scotia Plate lying just north east of the Antarctic Peninsula (60 degrees West):

    4)

    "I could not find a map that shows both this plate picture and the placement of the Seal Nunatak volcanic range. I did read that the range splits the Antarctic plate and that it was on plate fault line, but it was from a skeptic author so I won't bother pushing it."

    The Seal Nunataks are near the Larsen Ice Shelf on the Antarctic Peninsula, and hence most certainly do not split Antarctica.  Indeed, as can be seen from the map above, observed volcanism in Antarctica is largely restricted to a coastal band south of the Pacific Ocean.   

  33. Tuerquas - Yes you are correct about volcanic influence lasting more than decade. You did not provide a link but I assume you refer to an article where Highfield (a science editor) reports on a paper by Gleick et al. While the aerosol influence last less than a decade, the influence on surface temperatures continues because of the slow mixing of cooled waters on the ocean surface.

    However, as to effect in the antarctic, a better representation of volcanic record is from ice core. Ie from this paper. Interesting the major impacts on Antarctic ice have been mostly from tropical volcanoes rather than local ones which does not support your thesis.

  34. Tuerqas @229.
    Are you having a laugh? How many maps with a southern projection do you need?
    And you ask "Are you maintaining that the map above is accurate in size and that the Antarctic plate is actually larger than the pacific plate?" Are you entirely unfamiliar with the Mercator Projection?
    Indeed, do you find Wikipedia difficult to cope with? It is hardily an obscure source and it says of the Antarctic tectonic plate "The Antarctic plate is roughly 60,900,000 square kilometers. It is the fifth biggest plate in the world." and of the Pacific Plate "At 103 million square kilometres, it is the largest tectonic plate."

    <Snip> Inflammatory tone

    Response:

    [PS] Can everyone please cool it and stick to the science.

  35.  Shepherd et al. (2012) estimate the mass balance of the entire Antarctic Ice Sheet to be -81 ± 37 gigatonnes per year. The tolerance band is less than Lake Superior's 2014 ice volume change when 2 feet thick ice formed over the 32 thousand square mile lake. Canada has over 320 thousand square miles of lakes that get ice each winter. Antarctica's 81 GT loss per year may not be much when compared to the millions of GT there.

  36. Are you serious? Let's suppose say that Canada's lakes gain and lose say 1000Gt of ice between summer and winter. Only a change in the surface area of lakes frozen or a change in timing (which would both affect earth albedo) would have any climate significance. On the other hand, 81Gt of  ice loss from Antarctica is going straight into sealevel rise. Furthermore, as rock is exposed albedo is reduced.

  37. jetfuel, setting aside the different effects of ice in different locations outlined by scaddenp... you are also comparing the antarctic annual volume loss rate to (vague generalizations of) the Canadian annual volume maximum. That is obviously illogical.

    That 81 GT average was over the period 1992 - 2011... twenty years. So the total ice loss for that period was ~1,620 GT. Meanwhile, the total annual ice gain in Canadian lakes over the same period was, what? Approximately zero? In Summer they are melted out so we've gone from zero ice volume to zero ice volume. In winter they freeze to varying extents, but setting aside the one anomalous year you cite, the overall trend has likely been decreasing ice volume. In any case, any changes in average volume over the course of the year have been minimal compared to the Antarctic ice loss.

  38. jetfuel is IMO grasping at straws, and has been for some time.

    Although that's really all that needs be said, I should add that jetfuel is trying to compare cumulative year-over-year land ice mass loss in Antarctica with (cyclical) seasonal river/lake ice volume gain in Canada - and ignoring the inevitable melt-away of the latter.

    At best, maybe jetfuel would be on to something if the change in seasonal ice/snow cover in Canada is measurably altering the albedo, as scaddenp notes, but I doubt we'll see jetfuel come up with any evidence showing the existence or magnitude of such an effect.

  39. The twenty year cumulative 1620 GT loss of Antarctic Land Ice, when compared to the 26450000 GT on Antarctica is .00006 or .000003 per year on avg. as a fraction. Since 97% of all water is ocean water, and Antarctica holds 61% of all fresh water, all those 20 years of melt together have dilluted the oceans by .0000010 as a fractional addition of fresh to salt water. What evidence is there that that tiny fractional change alters the temp at which the ocean salt water freezes or makes any discernable change to the behavior of the oceans? How could a large percent of the 81 Gt of net melt per year exposing rock? The ice is 8200 feet thick even on the penninsula. As far as am I serious, I was comparing to the seasonal N.A. lake ice because 81 out of 26.45 million gigatonnes isn't an appreciative amount of loss. If a larger amount of temporary lake ice gain is unimportant, how is that amount (81 GT) of loss important?

    Response:

    [JH] Please document the sources of the data that you have used in the above post.

    You have a history of posting comments like the above without providing any citations. You have been repeatedly asked to provide documentation. For the most part, you have ignored these requests. If you continue this pattern of behavior, you will relinquish your privalege of posting on this website.  

  40. jetfuel: "What evidence is there that that tiny fractional change alters the temp at which the ocean salt water freezes or makes any discernable change to the behavior of the oceans?"

    Are you assuming that Antarctic runoff is instantly dispersed throught the world's ocean volume?

    Jetfuel: "If a larger amount of temporary lake ice gain is unimportant, how is that amount (81 GT) of loss important?"

    This is almost identical to the "temp changes by 15-20C over the course of year in some places; therefore, getting worked up over 0.7C in fifty years is ridiculous" argument.  The thing is, Antarctic land ice loss will continue and accelerate as glacial terminators erode more and more quickly.  Antarctic land ice won't reach equilibrium with global climate for hundreds if not thousands of years. 

  41. DSL .... is global warming and the related CO2 rise causing Antarctica to lose its land ice?

    Response:

    [TD] Donny, you need to read the original post before commenting on this thread, so you don't waste space and everyone's time asking questions that already are answered.  If you then want to ask specific questions about, or object to (with data to back you up), contentions made in the original post, please do go ahead.

  42. And make sure you read the intermediate tab, Donny.  You might also want to look at the literature on the subject.

  43. I have.   Wanted to hear your educated opinion.

  44. The problem I have with the original post (yes intermediate) is what study was used to make the leap that despite sea ice gains the thermal energy of the warming oceans make its way through the ice (which is an insulator) and causing land ice loss.  Land ice loss seems more likely to come from geothermal dynamics.   The authors original post would make more sense if all land ice loss was relegated to the coast. ... not sure from my readings if that is the case.

  45. I also wonder if the antarctic ocean waters cool more in the summer because of a lack of sea ice.  There may be too much thermal mass (as well as other variables) involved to see seasonal trends.

  46. "What evidence is there that that tiny fractional change alters the temp at which the ocean salt water freezes or makes any discernable change to the behavior of the oceans?"

    DSL:"Are you assuming that Antarctic runoff is instantly dispersed throught the world's ocean volume?"

    Remember when the Malaysian airline went down in the Indian Ocean west of Australia? Remember how the surface wreckage was expected to have moved by 150 miles per day? It's called currents. .00006 over 20 years isn't much of a fraction of fresh water addition to water moving many miles per day. Most AGW arguments are based on substantial dispersion of one substance into another. When the dispersion doesn't support your ideas, sorry, you can't make it stop. Unusually high Antarctic sea ice is surrounding most of the continent across thousands of miles of sea ice perimeter. My question remains.

  47. And not to pile on .... but why is the increased atmospheric moisture level going to result in increased perception in the desert of Antarctica?  

  48. Jetfuel. ... it probably freezes before it can disperse. 

  49. DSL: "The thing is, Antarctic land ice loss will continue and accelerate as glacial terminators erode more and more quickly. Antarctic land ice won't reach equilibrium with global climate for hundreds if not thousands of years."

    The quick increase of a miniscule rate is not of any consequence. Eventually people will be educated that 81 GT to 24.5M GT is like a couple droplets to an avg size swimming pool.

     

  50. But wait. ... if most of the melting comes in the summer (which I would assume but don't know for sure) then yes the water would have time to disperse before the ice started to form again. 

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