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Is Antarctica losing or gaining ice?

What the science says...

Select a level... Basic Intermediate

Antarctic sea ice extent has expanded at times but is currently (2023) low. In contrast, Antarctica is losing land ice at an accelerating rate and that has serious 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)

At a glance

Who discovered the great, South Pole-straddling continent of Antarctica? According to the National Geographic, Captain Cook came within an estimated 80 miles of it in the late 1700s, but the three first 'official' discoveries all took place in 1820 by Russian, British and American teams of seafarers respectively.

Since that initial discovery, Antarctica has attracted and inspired researchers and explorers alike. It's a challenging place, fringed by sea-ice that, unlike the Arctic, has not steadily declined but whose extent fluctuates on a seasonal basis: it's currently (February 2023) at a very low coverage, but it can and does recover from such dips. Antarctic sea-ice is no great problem, with the exception of albedo-loss in low extent years: if it all melted, it would have no effect on global sea-levels. It's the stuff on land we need to focus upon.

The land of Antarctica is a continent in two parts, divided by the 2,000 m high Transantarctic Mountains. The two parts differ in so many respects that they need to be considered separately. East Antarctica, that includes the South Pole, has the far greater landmass out of the two, some 4,000 by 2,500 kilometres in size. Although its massive ice-sheet, mostly grounded above sea level, would cause 52 metres of sea level rise if it completely melted, so far it has remained relatively stable. Snow accumulation seems to be keeping in step with any peripheral melting.

In contrast, in the absence of ice, West Antarctica would consist of islands of various sizes plus the West Antarctic Peninsula, a long mountainous arm pointing northwards towards the tip of South America. The ice sheet overlying this mixed topography is therefore grounded below sea level in many places and that's what makes it far more prone to melting as the oceans warm up. Currently, the ice-sheet is buttressed by the huge ice-shelves that surround it, extending out to sea. These slow down the glaciers that drain the ice-sheet seawards.

The risk in West Antarctica is that these shelves will break up and then there will be nothing to hold back those glaciers. This has already happened along the West Antarctic Peninsula: in 1998-2002 much of the Larsen B ice-shelf collapsed. On Western Antarctica's west coast, the ice-sheet buttressing the Thwaites Glacier – a huge body of ice with a similar surface area to the UK - is a major cause for concern. The glacier, grounded 1,000 metres below sea level, is retreating quickly. If it all melted, that would raise global sea levels by 65 centimetres.

Such processes are happening right now and may not be stoppable - they certainly will not be if our CO2 emissions continue apace. But there’s another number to consider: 615 ppm. That is the CO2 level beneath which East Antarctica’s main ice sheet behaves in a mostly stable fashion. Go above that figure and the opposite occurs - major instability. And through our emissions, we’ve gone more than a third of the way there (320 to 420 ppm) since 1965. If we don’t curb those emissions, we’ll cross that line in well under a century.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

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. However, under a high-emissions scenario, ice-loss from the East Antarctic ice-sheet is expected to be a much greater in the decades after 2100, as reported recently by Stokes et al. (2022). That’s a scenario we must avoid at all costs.


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.

Last updated on 14 February 2023 by John Mason. View Archives

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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.

Denial101x video

Related lecture-video from Denial101x - Making Sense of Climate Science Denial

Additional videos from the MOOC

Interviews with  various experts

Expert interview with Jonathan Bamber

Expert interview with Isabella Velicogna



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.

Fact brief

Click the thumbnail for the concise fact brief version created in collaboration with Gigafact:

fact brief


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Comments 326 to 350 out of 567:

  1. Ref #321: "Ah, I see. You don't like your peers scrutinizing your work. Good to know." - Do you not realise that when you write something like that, anyone else with the wit can quickly see that you do not (have much wit)? As I have already stated, my work has already been scrutinized by my peers, and no substantive errors have been found. These include, shall we say, fairly senior people (e.g. the person who is nominally the top astronomer in the realm of HM Queen Elizabeth, if you have the wit to get my meaning). 

    By publishing things on the web I make them available for scrutiny by anyone and everyone, not just those who have access to journals (which can be expensive to obtain). 

  2. Ref #319: Yes, you are a slow reader. I previously pointed out here (#305) that one might seize on the distinction between the surface area and the cross-sectional area of the Earth as a complaint. 

    None of this is important. As I made clear in my 'essay', my reason for comparing the natural changing insolation values (in W/m2) against the IPCC net AGW figures (the AGW 'forcing') is simply this: is the insolation change significant, or is it a value only one part in a million of the IPC AGW value? The answer is: it (natural changing insolation value) is of the same order as the AGW value, and therefore it is significant and cannot be ignored. Hitherto it does not appear in the IPCC reports, and so it has been ignored, or neglected. (It is also true that all papers I have examined which consider the changing insolation due to apsidal precession have been wrong - so much for peer-review - because they have made erroneous calculations based on Berger's correct insolation values.) The IPCC reports document the plausible intrinsic solar output increase of perhaps 0.12 W/m2 since 1750 as being the only significant natural agency in terms of climate change: if my calculations of the natural changing insolation values are correct, then the IPCC is demonstrated to have erred in that respect. 

    Those who like to call me "arrogant" might care to note that I preface essentially all statements regarding my own work with a qualifying term such as "unless I have made an error" or "if I am correct". It behoves anyone and everyone to have some humility in the face of complex matters. Note also that I have appealed to all to inform me of any publications, anywhere, in which the same sorts of insolation change calculations as I have performed are described; that is, I am admitting ignorance of any such work having been done, and asking for help. As of yet no-one has pointed me towards any such publications. 

    In any case you, like all others here it seems, are still misunderstanding the crux of the CSI hypothesis. It's not the magnitude of the changing insolation that is important: it's when and where it occurs! The small changes in insolation will cause earlier and more extensive spring melting of Arctic ice, and indeed less ice formation over winter because northern winters are now shorter and milder than they were in 1750, due to apsidal precession. If you have a square metre of snow (albedo circa 0.9) receiving insolation of 500 W/m2, the absorption rate is 50 W; once that snow is gone, exposing (say) wet soil beneath (albedo circa 0.1) the absorption rate goes up to 450 W on that square metre, nine times that previously. Thus, to assess the actual magitude of the CSI effect will require a large amount of work and debate and discussion, far more than I can possibly do myself. My intent is solely to flag the issue, and let others take over. 

    To develop an understanding of how the CSI affects the climate will require the development of new models (evolved from the present GCM efforts) incorporating gradual changes in insolation and ice and snow coverage and following the various influences on the climate over many annual cycles. So climate scientists are not going to be put out of work. 

  3. Ref #322:

    "What he does not do, and should have done is plotted the change in the effect over time against some emperical measure of either temperature or surface heat content"

    It is not for you or anyone else to tell me what I should have done. 

    Equally well it is not for me to tell you how you should spell various words (such as empiricalpropaganda, and several others). 

    What you are describing is what you would like to see done, so as to elucidate matters. I agree. All I have done - and it has taken me two years of work, it now being 16 years* since I realised what was going on - is to flag to anyone interested a physical effect which I believe will be causing climate change to some extent. Others can pick up the ball and run with it, including yourself, if they so desire. 

    *I first indicated the significance of this effect in pp.358-362 in my book Marking Time (Wiley, NY, 2000), which I completed writing late in 1998. 

  4. It is time for me to take my leave from this website. Sorry to have disturbed your arguments. 

    I have been bemused by various things I have seen here. For example, Mr Curtis (in #299) sits in judgement and states with regard to my work that it is: "an example of pseudo-science, not science." Within 48 hours he is writing (#309): "It is the editor and peer reviewers of a suitable journal who will be far more able to pick up any errors in your assumptions or calculations than I. " That is, he feels able to make unwarranted and unjustified criticisms at one stage, but when challenged pleads a lack of competence to have made such criticisms in the first place. 

    As the saying goes, democracy is a wonderful thing apart from that bit about any old yokel getting a vote. The same applies to the internet. Anyone reading this website is mostly reading garbage. It is clear that the motivation of many participants is simply arguing and chest-beating, not any search for scientific truth. 

    Time for a moment of honesty. Who amongst the readers out there can honestly say that they knew how apsidal precession is causing the lengths and the natures of the seasons to change? Here is the plot that appeared in my 'essay':

     So, who knew that winter is getting shorter? And also it is getting milder, because during winter the Earth is closer to the Sun now than it was 250 years ago? And who knew that the same applies to spring, because throughout the first half of the year our planet is closer to the Sun than it was 100 or 250 years ago? And where does this information appear in any IPCC report? It is obvious that such an astronomical effect must be causing some climate change, so why is it missing from the IPCC reports? 

    If you look at any of the posts about the missing Malaysian airliner on my website, you will find that generally I am a person who favours cock-up theories over conspiracy theories. This is a cock-up: climate scientists have made a grievous error in their analysis of how the insolation reaching different latitudes at different times of year is varying across the decades and centuries, and so have missed the effect I term CSI. 

    In leaving you, here are my own views at present: 

    -Yes, the global mean temperature has increased over the past century or so. 

    -Yes, there appear to be various changes in the climate occurring. 

    -Yes, the increase in so-called 'greenhouse gases' since 1750 is responsible in part (of course!). 

    -No, AGW is not the only agency causing the changes: there appears to be a natural effect (CSI) which has been ignored or neglected or not recognised previously. 

    That set of views I hold now in the light of such information and facts as are available. As the available information and understandings alter, I may well change my views. What do you do, when new information becomes available to you? From what I have seen on this site so far, mostly you shout, scream, and hurl abuse.  

    Yesterday evening I was walking down the street when some delirious drunk yelled at me the opinion that I was a "black bastard." Now, I am neither of those things, although I would not regard either term as being an attack on my basic character, which is far more important than my skin colour or parentage. However, I chose not to engage him in any debate on the matter, for obvious reasons. 

    The reason I am leaving this webpage/blog after a brief foray is similar. 

    The method employed I would gladly explain,
    While I have it so clear in my head,
    If I had but the time and you had but the brain—
    But much yet remains to be said.

    Lewis Carroll, The Hunting of the Snark

  5. duncansteel @305 Cont.

    TC: "Berger (1978), from whom he draws his algorithms"

    DS: "False statement. I did not draw my algorithms from Berger's wonderful papers. I derived the algorithms from first principles. It was only after the fact, when I saw what my results must imply, that I turned to Berger's FORTRAN program to do check calculations, as I have described in some detail. It is noteworthy that, as I discuss in my essay, essentially the only parameters needed in order to derive a good-enough calculation of the insolation changes are the lengths of the mean tropical year and the anomalistic year. The difference between those indicates the circa 58 years it takes perihelion to shift by one day closer to the vernal equinox. The use of the changing orbital eccentricity and obliquity of the ecliptic is nice, for completeness, but over only a century or two those slowly-altering values have little effect. Just the comparative values of the two year lengths are all that is required, to first-order."

    (My emphasis)

    First, sorry for my mistaken impression of your reliance on Berger.  

    Second, I wish I had twigged to the significance of the section on anomalistic and tropical years in your blog post a little earlier.  While I had read it, I had not noted its significance.  However, yesterday, I realized the possibility and set up the calculations in a spread sheet.  On that basis I accept that there has been a drift of the equinox relative to the perihelion of approximately 4.3 days over the last 250 years, and 17.3 days over the last 1000 years.  That drift has been to a very close approximation, linear with time.  Further, the change in average spring insolation has also been linear over time to a close approximation:

      The change in Autumn insolation has been also very nearly linear, and opposite in sign, while those of summer and winter have a detectable curve, but are opposite in sign and neglibible relative to the changes in spring and autumn.

    Based on this, I withdraw any suggestion that you may have made an error in your calculations of the orbital effects.  I do not accept that climate scientists have made the mistake you attribute to them.  Climate models do not in general, simply look up Berger's table of values, but independently calculate insolation based on orbital mechanics.  To show that they have made an error, you would need to show the error in the code.

    Returning to the linear change shown, here are temperature reconstructions for the Northern Hemisphere over the last two thousand years:


    And for the entire Earth:

    Here are sea levels for the last 3000 years:

    Ninety percent of the total increase in heat content at the Earth's surface goes into the oceans, so that any significant increase in that heat content should be reflected in rising sea levels due to thermal expansion in addition to ice melt.

    And speaking of ice melt:

    "Change in average length of all glaciers around the world
    Credit: Figure adapted from Oerlemans, 2005"

    No measure of historical temperatures or proxies of heat content show the linear increase over the last thousand, or the last 250 years that is required by your theory.  So, even allowing my error in criticizing you on the orbital mechanics, your theory stands refuted by empirical evidence.  (As I said before, this is the crux of the issue.)

  6. Duncan Steel, how does your proposed mechanism account for stratospheric cooling, please?

  7. Dr. Steel is correct, there is an effect but it is well known. A recent paper that pointed out the importance of orbitally driven change in NHemis. spring insolation coupled with albedo flip from ice melt driving deglaciation over the last 4 stades was by Hansen, but I do not immediately recall the reference.


  8. One paper from 2007 that mentions the effect is Hansen(2007) in Phil. Trans. Roy. Soc doi:10.1098/rsta.2007.2052 (specifically Fig 3, discussion thereof.)


  9. Humbly, I have to admit error.
    @319, when I wrote that I had identified a problem within DuncanSteel's account of his CSI hypothesis, I failed to identify the nature of that problem. That problem in my opinion is evidently DuncanSteel.

    His reply @327 to my comment @319 correctly points out that he did mention within his lengthy comment @305 the difference between projected and global measures of forcing but he never manages to say that he had at one point within his CSI 'essay' underestimated the strength of today's AGW by 83%.
    He did manage @327 to say (of his critics in this thread) “It behoves anyone and everyone to have some humility in the face of complex matters.” I think he fails to grasp that “anyone and everyone” includes himself.
    I am thus not minded to spend any more time reading the ravings of such a one. However, I have probably read enough to allow a useful assessment of this CSI theory & its presentation by DuncanSteel.

    Ignoring the many petty errors made, the analysis may well identify an error, that is an omission within insolation calculations used in climatology. If his thesis is correct, an omission exists in the NOAA tables plotting insolation in 1,000 year steps over the last 10 million years. The omission may exist more widely.

    However DuncanSteel fails to enumerate the size of this potential error. Strangely, the 'essay' appears to dodge such a step. The account moves too quickly beyond CSI as an omission within insolation calculations, to instead dwell at great length on the climatological impact of CSI. This climatological impact work is pure nonsense. The unqualified author naively attempts to out-IPCC the IPCC, all on his lonesome.

    As for enumerating the size of the potential CSI, the 'essay' provides two graphical results. (Apologies here, but the 'essay' has no way of referencing its various parts. The first graphic result is a plot of 'Difference in Ecliptic Longitudes AD950-AD1950' and the second is two series of thumbnail monthly charts of 'Change in Insolation AD1000 to AD2000 ' one with and one without CSI.) Neither of these graphical results allows a direct reading of the strength of CSI.
    Be CSI an omission or not, examination of those graphics suggests the size of the CSI effect AD1000 to AD2000 amounts to +2Wm^-2 insolation (+0.002Wm^-2/year) over high northern latitudes during the merry months of April & May and -2Wm^-2 insolation (-0.002Wm^-2/year) over higher northern latitudes during the jolly months of July & August.

    To compare this with AGW, AR5 Table AII.2 yields an annual average year-round and global forcing increase averaged over the last 30 years of +0.026Wm^-2/year, many times higher than the part-year, part-globe CSI which is also a small part of the insolation changes over the last 1,000 years, an effect which is adjudged, with or without any omission, to be insignificant in comparison to AGW.

    I thus concur with the many critics of DuncanSteel here. CSI, if it has been overlooked, is very small compared with AGW. Thus DuncanSteel would be in grave error to continue to state:-

    “the CSI model should be adopted as the central working hypothesis for contemporary climate change, although as I alluded earlier it would not be reasonable to think that AGW is not also contributing to the observed changes.”

    However, the evidence demonstrating a small CSI will likely not stop him.

  10. The arrogance exhibited by DuncanSteel on this comment thread does not square with how he describes himself on the About Me & Contact Information page of his website. Steel states:

    I am a friendly and affable sort of a guy, but somewhat of an introvert in person.

  11. duncansteel...  "By publishing things on the web I make them available for scrutiny by anyone and everyone,..."

    And yet you seem to find the act of people here scrutinizing your work "bemuzing."

    Duncan, look, you're making claims here relative to AGW that contradict (or minimizes) the position of nearly everyone who actively researches this issue, as with your statement, "No, AGW is not the only agency causing the changes: there appears to be a natural effect (CSI) which has been ignored or neglected or not recognised previously."

    No one rejects that you might have something worthwhile to contribute to the body of research, but posting a blog essay and using that as your primary reference... let's say, that just falls well short of what is expected of a significant finding.

    If you believe your ideas are valid, do what every other researcher does. Submit to peer review. As I said in my first comment, you're clearly capable of producing publishable research. So, just do it. 

    From my experience watching the climate science issue advance over the years, what I continually see is people, like yourself who have clear expertise in a specific area, believing that they understand the entire breadth of the climate change issue when, in actuality, they understand very little of the other broader elements of the global climate system that come into play. And worse, in these situations, people such as yourself seem to lack the self awareness to understand what they don't yet understand relative to other areas of research.

  12. duncansteel wrote... "Those who like to call me "arrogant" might care to note that I preface essentially all statements regarding my own work with a qualifying term such as "unless I have made an error" or "if I am correct"."

    Okay, you say "unless I have made an error" but you don't seem capable of accepting that you could have made an error. That is the arrogance that people are pointing out.

  13. An addendum to my post @330, casual readers may wonder why I am so completely dismissive of the possibility that the heat gain postulated by Duncan Steel should be absorbed by the melting of ice alone, so that it has no temperature response.  That is a key suppositon of DS's, designed to evade empirical tests in that we have a reasonably good idea as to what has happened to temperatures over the last 1000 years, and better yet over the last 250 years.  Over the last 1000 years, global temperatures have declined slightly until about the last 150 years, since when they have risen sharply.  In contrast, DS's theory predicts a linear increase in temperature since prior to 1000 AD.

    In his blogpost, he writes:

    "I can now conduct the desired experiment, which has an aim of calculating the total solar energy that would have been absorbed back in 1750 if the absorptivity were slightly lower in that region of interest. When I do this computation, the result is that the total absorbed solar energy is 3.652 x 10^24 joules, and the average terrestrial albedo 0.332. In the previous calculation the figures were 3.674 x 10^24 joules, and an albedo of 0.328."

    That calculation is made based a simply false assumption about albedo that DS chose as "a free parameter", or which more in a later post.  For now, however, we can accept that as his estimate of the warming effect, which according to his theory goes into ice melt rather than temperature rises.  Some simple calculations shows that that amount of energy going into icemelt would melt 71,850 km^3 of ice annualy.  That in turn is enough ice to raise sea levels by 0.2 meters per year.

    Further, because the primary effect is linear, we can calculate a rough approximation of the effect over 250 years, which would be to melt 8,980,000 km^3 of ice, raising sea levels by 24.9 meters.

    I think we would have noticed.

    Note that these calculations do not refute DS's basic theory.  They do refute his evasion of the expectation that his basic theory should predict a linear rise in global temperatures (if he is correct about the impacts).  Of course, the later expectation together with the global temperature record refutes the idea that the orbital changes he identifies has had any significant impact on global temperatures.

  14. Further to the issue of peer reviewed publication, it turns out that DS has published in an open access, online Journal of Cosmology (article 6 of issue 22).  The Journal of Cosmology purports to be peer reviewed, and does have some members of its editorial board who are noteworthy, and do publish in the Journal.  Nevertheless, it does appear as #249 on Jeffrey Beall's 2014 list of "Questionable stand alone jounals"

    The article differs in that, unlike the blogpost, it contains no estimate of the magnitude of the effect.  Rather, it restricts itself to suggesting  that the effect may be a factor in the reduction in Arctic sea ice extent and concurrent extension of Antarctic sea ice extent (which may be true).  It also gives a more detailed account of climatologist's errors, actually naming names and citing articles.  I have not gone through the list to see if Steel is correct, but none of the articles mentioned deal with recent climate change or climate models.  So no evidence that DS presents that I have seen shows that climate models (and hence IPCC accounts of recent climate change) fail to correctly calculate changes in monthly insolation by latitude.

    On a side not, DS has been busy promoting his theory, with two articles for the GWPF.  He also has a 2002 article for the Guardian telling us that "Climate Change is good for us", apparently because it ensure we won't stumble into an ice age.  That is inconsistent with his current account, based on which natural warming due precession of the perihelion relative to the equinox should guaranttee that for quite some time.

  15. I looked over Duncan Steel's paper that Tom linked.  DS  claims:

    The changing insolation theory (CIT) mooted herein is capable of explaining various observed phenomena which the AGW hypothesis has not yet been able to accommodate. Specifically, what has been observed and is pertinent here are the following:

    1. A gradual rise in mean global temperature over the past two centuries;

    2. Accelerating spring and summer melting of Arctic sea ice reaching an extent not previously witnessed;

    3. No substantial loss of Antarctic sea ice, and actually a small growth in its extent (Shepherd et al. 2010; Parkinson and Cavalieri 2012);

    4. The greatest rises in regional temperatures (and temperature variability) being at high northern latitudes (Liu et al. 2007; Wu et al. 2011).

    Perhaps if DS read Arhennius paper from 1896 (see link in article) he would not make such an absurd claim.  Arhennius predicted that the Arctic would be affected before the Antarctic.  In addition Arhennius predicted that the night would warm faster than the day (not predicted or explained by DS), the winter faster than summer (the opposite is wrongly predicted by DS) and the land would warm faster than over the ocean (not predicted by DS).  DS provides no data on snow and ice cover to support his claims.  If these are the reasons to adopt DS proposal it will be easy to make the decision.

  16. I have read this thread with sheer astonishment, as it seems to contain mostly complaints that Dr Steel didn’t do what they would have done. Since none of the posters admit to any scientific training whatsoever (Mr Curtis is apparently a ‘philosopher’), or have stated their qualifications, I am inclined to agree with Dr Steel’s conclusions that “Anyone reading this website is mostly reading garbage. It is clear that the motivation of many participants is simply arguing and chest-beating”. An interesting example of how science is not done.



    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  17. This is my last planned comment on Daniel Steel's theory.

    The most fundamental problem with his theory is that, averaged over the year, the difference in insolation between 1750 AD (or 1000 AD) and now due to the milankovitch cycles is neglibible.  Consequently he needs some method whereby the near linear increase in NH spring insolation over that period can become significant.  His answer to that problem is found in changes in seasonal albedo due to the increased seasonal insolation.  It is unsurprising that he should appeal to this, as a similar mechanism is thought to be involved in the milankovitch forcing of the glacial cycles.

    To compute the effect of the interaction of changing seasonal insolation and albedo, he uses albedo data from NASA's Terra satelite, finding a total of 3.674 x 10^24 Joules of solar energy absorbed over the Gaussian year (equivalent to 228.25 W/m^2 averaged over the globe.  He then faces a problem determining the albedo data for 1750.  He writes:

    "I continue with a rhetorical question for which we do not, and cannot, have a definitive answer. Unfortunately governments in 1750 were not far-sighted enough to start a satellite observation program similar to those currently being carried out."

    and then continues three paragraphs later:

    "With that in mind I can argue that the albedo back in 1750 is what scientists often call a free parameter[9]. I can choose any values that I want in order to conduct the experiment that I want to do. I should be sensible, though, and make a justifiable choice."

    I would not be so hasty to jump to an arbitrary choice in generating a theory.  The issue is, however, what is his choice, and is it any good.  He continues:

    "What I will do is to pick up the absorptivities in a region of interest (latitudes northwards of 30 degrees north, March through June), and replace them with the absorptivities from 30 days earlier (February through May), so as to simulate the effect of the putative delayed melting of the snow and ice back in 1750 compared to the present. We certainly know that the amount of Arctic ice coverage now is rather less than in the past, with record lows of sea ice being recorded in the north, justifying in principle my choice of free parameter."

    Now, it is very far from evident that this is a reasonable choice, from basic principles.  The recession of the perihelion relative to the NH vernal equinox only results in a drift of 4.33 days.  That is not the only effect driving the theory, but it is by far the most important.  That 4.33 day drift in the perihelion is, however, being asked to justify a 30 day drift in albedo.  That is a very large ask.

    Nor is Steel's justification valid.  Regardless of the merits of his case, AGW has caused considerable warming over the last century (something Steel acknowledges).  Therefore at least some of any early ice and snow melt in the NH must be due to AGW, yet in justifying his theory he wants to count it all as a consequence of seasonal drift in insolation.  That is, he is counting the ice albedo feedback to global warming as an intrinsic effect of the seasonal drift in insolation, which is certainly invalid.

    Further, his approach not only requires that ice melt earlier in the spring, but also that water freeze later in the autumn.  If it does not, because the insolation change is near zero averaged over the year, there will be near zero effect.  That, however, is not what we see.  Rather, we have both earlier melting and later freezing:

    You will notice the changes for Autumn and Spring are closely matched.  Those for Summer and Winter are not, but the seasonal change in insolation for those times of year is small.  (You will also notice the lack of an obvious trend in retreating ice in the early twentieth century, contrary to Steel's hypothesis.)

    That, of course, is just one measure.  Other measures of times of freezing, or thawing are available, of which one of the most convenient is the freezing and thawing dates for Lake Mendota, Wisconsin:


    As it happens, the lake is freezing later by 8.3 days per century, and thawing earlier by 8.5 days per century, so the change in albedo for Autumn is nearly that for Spring.  That is not projectable back to 1750, however, as other evidence strongly suggests an ongoing cooling at that time (again contrary to Steel's theory).

    So, not only is Steel's hypothesis about ice and snow albedo unjustified, its most crucial point (the opposite trends in spring and autumn) is directly contrary to available evidence.  This key point to his theory also stands as empirically refuted.

    As a final note, using his faulty albedo assumptions, Steel calculates a difference in energy recieved over the gaussian year of 0.022 x10^24 Joules (ie, a "forcing" of 1.37 W/m^2).  He calculates that as a difference of 0.6% in absorbed solar radiation, which he compares to the 0.17% of TOA insolation found by the IPCC.  Experienced AGW-myth busters will immediately recognize the misleading comparison made by the switch of units.  In fact, the "forcing" from seasonal drift in insolation is 0.1% of top of atmosphere insolation.  Put another way, as calculated it is just 60% of the anthropogenic radiative forcing.  Even that, however, is misleading for a substantial part of the "forcing" from seasonal drift in insolation is part of the ice albedo feedback.  The correct way to caclulate the actual forcing from a given albedo model would be to take the difference between the model with unchanged insolation and that with changed insolation, rather than treating it all as being a consequence of the drift in seasonal insolation.

    This point, however is inconsequential, for (as previously noted), Steel's assumptions about albedo are simply false, and if corrected will radically reduce the calculated effect.

  18. karly @341, regardless of his qualifications, Steel derived a massively flawed theory which he has not tested in any appreciable way against empirical evidence.  When he recognized it faced criticism that he needed to respond to to retain any credibility for his theory, he squidded.  That is, he disappeared in a puff of (electronic) ink, scattering ad hominens in abundance.

    You may not be able to follow the nuances, but you should be able to follow these simple points:

    1)  His findings on orbital movements are sound, but have no implications about climate without an albedo model to change the minor seasonal variations into a significant global variation;

    2)  His albedo model requires both an earlier melting of ice, and and earlier freezing of the ice;

    3)  He claims is model is shown to be reasonable by what has been occuring with with Arctic sea ice;

    4)  Ergo, he claims that this data justifies a belief that the ice is both melting and freezing earlier:


    That claim is transparently bollocks.

  19. Rob Honeycutt asked:

    "You're clearly capable of publishing research. So, if you're so confident of your "essay" why is it not published in a respected peer reviewed journal?"

    Steel answered:

    The answer is because I make my living generally in other ways than gathering funds from government grants, and therefore do not need to publish in journals (in order to gather yet more grants); and also choose not to spend the considerable time required putting things into the necessary format for journal publication. On my own website I can publish what I like, and what I believe to be correct, without being forced by referees with vested interests to alter what I want to say.


    Karly... Regardless of the actual flaws in Mr Steel's argument, and his failure to show that his CSI considerations can produce anything like a hockey-stick shaped temperature profile, this statement alone makes it impossible for me to take Mr Steel seriously. He expects us to believe that he has a world-changing theory that, if confirmed, would make him a household name and earn him a fortune as the poster-boy for the fossil-fuel industry, and he has been working on this theory for 16 years while the rest of the world has been barking up the wrong scientific tree... but no, he could not be bothered spending the few hours needed to format his work for submission to a reputable journal.

    After a brief round of criticism here, he refuses to continue the discussion towards any sort of conclusion, takes parting shots at his critics' spelling, of all things, and disappears.

    It doesn't pass the sniff test. Doesn't come close.

  20. One more little comment ;)

    Duncan Steel's biggest claim that his theory is empirically born out is the fact that it explains the falling Arctic Sea Ice Extent, and the rising Antarctic Sea Ice Extent over the twentieth century:

  21. Tom Curtis @338.

    Oh dear. You shouldn't have cut & pasted that quote from duncansteel's 'essay'. You forced me to go and finish reading duncansteel's ravings (something I was resolved not to do) because, as an inveterate number-checker, I noted 3.652/3.674 was not equal to (1-0.332)/(1-0.328).

    As I pretty-much expected, within the duncansteel 'essay' there is no explanation for the difference which amounts to +0.048Wm^-2 (AD1750-2000). It is presumably the forcing he asserts is causing all the change in albedo but it seems very high for a net annual average for duncansteel's silly CSI theory (which in his thumbnail graphical presentation appears to only peak at 10x this value seasonally and regionally, peaks then balanced by negative peaks). So I wonder if this 0.048Wm^-2 figure (AD1750-2000) is the net annual change in insolation due to orbit (of which duncansteel CSI is but a small part).

    Duncansteel's Journal of Cosmology paper reported by Tom Curtis @339 adds an interesting extra dimension to all this nonsense. Why is duncansteel silent about it? Why post his 'essay' on his website in Spetember with an "Invitation to review and identify errors" when a version of it has already published six months before?

    Okay within the published paper he is discussing the well-understood total change due to insolation (CIT) and not the very minor effect of taking months to equal a twelfth part of the orbit (CSI). But all that climate work done on the subject that already accounts for duncansteel's CIT doesn't prevent duncansteel boldly writing:-

    "The role of rising levels of anthropogenic greenhouse gases since the Industrial Revolution in causing some elevation in global temperatures is not denied herein. Rather, the measured temperature rise coupled with other observed phenomena (melting Arctic ice, growing Antarctic sea ice) are suggested to be due to the combination of AGW and CIT but with the latter being dominant."

    This is different from his 'essay' where he puts (or appears to put) CSI as the great relvelation and the climate effect unaccounted for by AGW, rather than CIT.

    The Journal of Cosmology paper does do a little bit better at presenting (rather than hidding) the CIT/CSI case. I note that when duncansteel does a check on his calculations, using the autumn rather than spring equinox as a start-of-year, so precise (ha) are his calculations that he loses 30% of the CIT at the vital 60ºN. But duncansteel fails again to assist the reader. You have to scale two graphs to obtain this 30% value. This inability to present his findings fairly and his inability to maintain a focused account of his work is symptomatic of the man.

    So it would have been simplicity itself to plot the differences between his Figures 6a & 6b and show the size of this CSI. But as with his 'essay' the reader is left to eyeball the two graphs.

    But cut&paste the figures into a graphics package and, with a more delicate bit of scaling, the size of CSI for that vital 60ºN can be calculated. It is very small. An average increase in insolation due to CSI amounts (ha) to a whopping 0.02Wm^-2 over the period mid-March to mid-July with the bulk of it occuring before mid-May. And this is the AD950-1950 figure, So safe to assume CSI is a very tiddly effect and the accusation that it is absent from AGW calculations is not yet demonstrated and not a major error if it is absent. I could continue to calculate the full annual effect for 60ºN or examine the thumbnail graphics in his 'essay' to see if they a similar or conflicting result, but I don't think it's worth the bother.

  22. Karley,

    As a new perhaps you should read more and insult other commenters less.  Several of the posters responding to DS have pHd's and long lists of papers published on the topic of climate change.  DS has less experience than they do.  If we are to bow to authority, DS does not have the strong hand.  The fact that you are ignorant of others contributions does not mean that those contributions do not exist.  The rest of us are up to date.

    I have a Masters Degree in Organic Chemistry and have published around 10 peer reviewed papers.  I doubt that anyone here cares about that since many of the other posters have pHd's.  At this site we care about the qualtiy of the arguments preseted and the data that support them. 

    I note that DS has not produced a single data point about snow and ice extent and/or albeido.  This is the critical point of his hypothesis and only Tom has presented data.  That data directly contradicts DS proposal. 

    As I noted above, DS proposal is that precession causes a warmer spring and day with the rest of warming following.  This is in direct contradiction to what is observed: a warmer winter and night with the other seasons and daytime following.

    Can you provide any data or an argument to suggest why we should further entertain DS proposal when it is in contradiction to the observed data?

  23. MA Rodger @346:

    1)  The ratio's are not the same, but (a) the difference is sufficiently small that it could be due to rounding era, and (b) there should be some slight change in annual insolation between the two periods in any event (although I suspect it is too small to show up with either rounding).

    2) I don't think there is any difference between the theories (other than the name).  The only substantive difference is that, so far as I can tell, the Journal of Cosmology paper assumes a spherical Earth for simplicity, whereas the blog post includes effects due to the actual shape of the Earth.  (I have, of course, not repeated the calculations so cannot be certain of this.)

    3)  The differences between Figure 1 (calculated from NH Spring equinox) and 4 (calculated from NH Autumnal equinox) appear to balance out to zero over the year, and are mostly confined to polar latitudes.  They are probably a consequence of the fact that the time from spring to autumnal equinox is approximately eight days less than the time from autumnal to spring equinoxes.  

    4)  Most importantly, Fig 6b is just Fig 6a reproduced with an inaccurate notional day of year scale for the x-axis.  The true comparison should be between Fig 6b (which the climate scientists are purported to use) and 6d (Steel's own calculation), or between 6c (The correct calculation for a scaling by day of year from Berger) and 6d.

  24. At firsdt glance, this wholetheory does not appear come close to approach the quantitative sensible test. It's like someone trying to demonstrate by using lots of numbers that they got skin cancer from taking too many selfies with the flash on.

  25. karly... "I am inclined to agree with Dr Steel’s conclusions..."

    I'm curious why you would think it is so outrageous to question his work or suggest that he publish it in a reputable science journal?

    "Skeptics" seem to have no problems with people questioning research that is published in respected journals. Why should you or or duncansteel feel so put upon by those here question material that is published in an unreviewed essay published on a website?

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