At least, a real debate on climate change (I hope)

Slowly the Western world is facing up to the real possibility that the catastrophe that was supposed to lie in wait for us, as a result of our use of fossil fuels, might have been over-egged, and that climate change may not even be accessible to human action, let alone caused by it. Germany is having trouble with its push to make alternative sources the core of its electricity production. China has stopped subsidizing solar panels. A newly elected provincial government in Ontario is set to wipe out carbon-pricing rules. The UK has seen two weeks of nil power from its offshore wind turbines. And in the USA there has been a public debate between two proponents for each side: Michael Mann of the hockey stick and David Titley, a meteorologist formerly of the US Navy, for the warmists, and Judith Curry, well known to sceptics, and Patrick Moore, former President of Greenpeace Canada, for the pragmatists, realists, sceptics, call them what you want, though not, please, ‘deniers’. Patrick Moore was one of the founders of Greenpeace, but has since declared that the organisation has been taken over by scaremongers and disinformers. The debate, at  local university, was organised by a legal firm in Charleston, Virginia, and you had to pay something to attend.

Judith Curry has published her own contribution to the debate, and you can read it here. It is such a sane and sensible statement that I am devoting this essay to it, but of course you should read the entire statement, which is too long for me to publish. I am writing as the debate is starting, and there will be more to say when it is finished, and we have had several accounts of it. But here is the core of her statement. She starts with what she sees as the main areas of agreement and disagreement, first agreement.

  • Surface temperatures have increased since 1880
  • Humans are adding carbon dioxide to the atmosphere
  • Carbon dioxide and other greenhouse gases have a warming effect on the planet.

However, there is substantial disagreement about the issues of greatest consequence:

  • Whether the recent warming has been dominated by human causes
  • How much the planet will warm in the 21stcentury
  • Whether warming is ‘dangerous’
  • How we should respond to the warming.

I have bolded the two issues that are the focus of this conversation.

Now there is nothing wrong or bad about scientific disagreement.  In fact, the scientific process thrives in the face of disagreement, which motivates research in new directions.

You can express all this in a simple diagram, which she does (an earlier version is here):

If that is isn’t enough, she adds a cartoon, which I like. People tend to look at this or that aspect of the elephant, but not at the elephant as a whole.

The debate matters, she insists. Oh yes, it does. Look at electricity prices. Look at the slow winding down of attempts to replace fossil fuels with alternative energy sources. Look at the avoidance of nuclear power. A third diagram (there are several more in the contribution itself):
She makes the important point that most, a big most, of the research that bears on this issue has been focused on carbon dioxide and its role, rather than on sources of natural variability. And the result is that we really don’t know much about the causes of a change in climate.Why not? The bottom line is that we don’t yet have a unified theory of climate variability and change that integrates all this.

And what do we really know about sea-level rise? I found this part of her contribution to be most important, if only because I have spent a lot of my time on it too. She points out that Michael Mann and James Hansen have both made sweeping claims about the importance of sea-level rise, for which there is no support from scientific evidence. Here is a pointed graph (yes, from a peer-reviewed and much cited journal article):

On that evidence, carbon dioxide emissions simply can’t be responsible for sea-level rise in the last century. Then what is causing the slow rise that we see? The major part seems to be coming from melting of the Greenland ice-cap. Yet there is abundant evidence to show that the Greenland ice-cap melted in similar fashion in the 1930s, indeed, there was rather more melting then than is occurring today. That 1930s melting could not have been caused by carbon dioxide emissions, but looks as though it is related to the AMO, the Atlantic Multi-Decadal Oscillation, a long cyclic change that affects climate. Once again, we don’t know enough about it, and one reason is that it is not fashionable to study it.

The panelists in the debate were asked ‘to what extent are man-made CO2 emissions contributing to climate change?’ Dr Curry’s response is that we don’t know.  The reason is that we don’t know how to disentangle natural internal variability from the effects of CO2–driven warming. Back to square one. Should we be reducing emissions to prevent warming? There is a clear division between the two groups here. Her view is that the best way forward to is to keep economies strong, ensure that energy is available to everyone (which means it needs to be cheap) and focus on resilience. To expand:

What makes most sense to me is Climate Pragmatism, which has been formulated by the Hartwell group.  Climate pragmatism has 3 pillars:

  • Accelerate energy innovation
  • Build resilience to extreme weather
  • No regrets pollution reduction [DA: ‘pollution’ here does NOT mean CO2]

These policies provide near-term socioeconomic & environmental benefits and have justifications independent of climate mitigation & adaptation

These are no regrets policies that do not require agreement about climate science or the risks of uncontrolled greenhouse gases.

And finally, a statement on what she calls ‘the Madhouse effect’.

I would like to make a few comments on the state of the scientific and public debate on climate change. Here is my take on the Madhouse effect.  The madhouse that concerns me is one that has been created by climate scientists.  The madhouse is characterized by

  • Rampant overconfidence in an overly simplistic theory of climate change
  • Enforcement of a politically-motivated, manufactured ‘consensus’
  • Attempts to stifle scientific and policy debates
  • Activism and advocacy for their preferred politics and policy
  • Self-promotion and ‘cashing in’
  • Public attacks on other scientists that do not support the ‘consensus’.

Most of what she says was my position before I ever heard of Dr Curry, but because she is a well-published and sensible scientist I have been reading her website ever since I discovered it, about 2012. It is the case, for these reasons, that I think her contribution to this debate deserves to be read far and wide.


ENDNOTE  One audience member has posted on WUWT to the effect that it wasn’t a real debate, but more a set of positions presented by the four speakers, and questions thereafter. I was in one such event a few years ago in Melbourne. I felt it was unsatisfactory.



Join the discussion 69 Comments

  • Bryan Roberts says:

    When figures are wafted around, it is usually in the context of ‘sea level will rise by X metres by ‘(date to be advised)’. However, whatever you may think of the BOM, it has conducted the Pacific Sea Level Monitoring Project since 1994. The data are available online, and completely fail to show any increase whatsoever, particularly for the ‘imperilled’ nations of Tuvalu and Kiribati. One could be forgiven for believing that this is real evidence against catastrophism. The BOM may manipulate climate data, as alleged by Jennifer Marohasy, but it can hardly manipulate tide gauges. So, it is irrefutable that the feared disappearance of the Pacific Island nations is simply a political stunt. They may have their problems, but they are not due to climate change. When theories conflict with facts, the latter eventually triumph. I repeat, Tuvalu has not sunk, and shows no likelihood of ever doing so.

    • BoyfromTottenham says:

      Bryan, thanks for the link to the BoM PSLM project site. Very interesting – not much SLR to see anywhere since the early 1990’s!
      BTW – Do you happen to know why the Country Reports are only available for years 2007 to 2010? Could it be that the initial SLR trend of 4-5 mm/yr slowed down so much that it was better not to publish them?

  • Ian MacCulloch says:

    Your summary of the ‘debate’ is rather concise and thank you.

    Regrettably, the dilemma facing the climate debate industry is the section of time frames for the debate. The other aspect the great reliance on the paper of one man, Arrhenius. The aspect of the debate is that it also relies on the discussion of one ‘greenhouse’ gas when there upwards of 32 contributing ‘greenhouse’ gases lurking in the atmosphere. So far the analysis industry can report on one of them i.e. CO2.

    The more I look at sea level changes the more I am convinced that the overriding event is that of geodynamics. The mapped ice distributions at critical points by the USGS clearly indicate there is a huge gap in the ice mass balance calculations of onshore ice at peak periods of glaciation versus sea level fluctuations. The terminal moraines in Europe and in North America are great indicators of extent and little else in terms of ice volumes. Claims of 5 km ice sheets are sheer nonsense. Reasonable Isostatic behaviour is about 5 metres on the west coast of the UK and precious little elsewhere.

    6,000 years ago Prof Fairbridge (1960) showed that the recent peak seal level was 2 metres about LWM I have sampled those fossil strandlines in Bremer Bay, WA at exactly that position above the current LWM in 1969. These elevated beach strandlines were heavily mined during the 1950’s along the Gold Coast. Actual sea levels dropped back and rose to their current levels since 6,000 years ago. The current rises in sea levels have a long way to go as evident from the work of Fairbridge.

    For Professor Curry to be able to identify a small amount of movement in sea levels due to the melting of ice is a huge call.

    The bigger picture of the emerging science of geodynamics overrules these minute considerations of the influence of ice melting on sea level.

    Finally one of the most under reported discoveries is the that of the dating at 2.1 million years of blue ice at Allan Hills in Antarctica. At about 1,800 metres elevation it is a huge result that indicates that the overall climate has been stable in Antarctica since that time and that there is a 1 million year time gap between this ice and the ice being intercepted in Dome C and Vostok drill cores. Absolutely fascinating stuff.

  • Neville says:

    The real elephant in the room is the fact that we can’t mitigate their so called CAGW.
    The non OECD countries will be building many hundreds of CF stations for decades into the future and of course S&W are delusional at best.
    This means that co2 emissions will soar into the future, even though OECD countries have mostly refused to build more Coal Stns even though costs have sharply risen for decades.
    But the USA is the exception and cheap gas has taken over from coal and today coal supplies just 17% of their total energy needs. Of course today China generates 66.7% of TOTAL energy from Coal, much higher than any other country. See the EU based IEA data

  • Don Aitkin says:

    The other day a worriedly intoning presenter on SBS news told us that 3 trillion tonnes of ice had been melted from Antarctica. Her tone was of doom coming. I said ‘Rubbish!’ and other parliamentary phrases as this went on, and then thought I had better do some homework. Three trillion tons is about 0.011 per cent of the ice sheet. The rubbish rejoinder came from the notion that the ice in the present Antarctic is capable of melting. The correct explanations, if any are really needed, are that two likely sources for any reduction (and there is no real evidence of any reduction, it is all estimates and re-analysis of existing data) are magma vents under the Antarctic Peninsula (there seem to be about 150 of them) and ablation (evaporation) from wind. The Antarctic ice sheet is frozen solid and can’t ‘melt’ until somewhere the temperature gets to around 1 degree C.

    Anyway, for those who would like to learn more about the original story, try the NY Times:

    For those who would like to see the fun that some had with the story:

    And at much the same time another group of scientists have decided that the Antarctic ice survived the Pliocene, when temperatures were hotter than today…

  • Neville says:

    Don is correct, even the RSS TLT shows little SP warming since 1979 or about 0.03 c decade.

    And no change from UAH V 6 SP TLT over the last 39 years.

    It seems that their co2 has magical qualities, able to warm the NP regions, but not the SP. But earlier 20th warming did the same, well before 1950.
    Of course much more likely to be the NATURAL warm phase of the AMO.

    • Chris Warren says:


      You are the chief cherry picker. Global warming is not represented by the south pole. The north pole and every other part of the globe are exact opposites in that they all are warming at rates almost 5 times the value you have cherry picked.

      You should have noted that global warming over this period is approaching 2C per century.
      You should have noted that NH warming over this period is over 2.4C per century.
      You should have noted that SH warming over this period is approaching 1.5C per century.
      You should have noted that Tropics warming over this period is around 1.5C.
      You should have noted that NP warming is almost 5C per century.

      • Neville says:

        Chris, UAH V6 shows 0.13 c per decade of warming since 1979 or about the same as RSS V3. The RSS tool also shows that there has been little ( RSS V 4) warming trend since 2015. Check out the latest trend data using their tool.

  • Chris Warren says:

    If souls such as Patrick Moore and others are going to tag others as “alarmists”, “scaremongers”, “disinformers” and etc than they have self-identified themselves as “denialists”. Denialists they are, denialists they remain.

    It is no use complaining if people get paid back in their own coin.

    • Don Aitkin says:

      No they haven’t at all. They have identified themselves as people who use names about other people. To deny something is religious in tone. Denying the Ascension, for example, or the divinity of Christ. Patrick Moore described his opponent in unflattering terms. That has nothing to do with the science. And science is not religion, except for believers in human-induced climate change.

      • Chris Warren says:


        Using derogatory names about people WITH THE INTENTION of opposing their views is an artefact of denialism.

        Moore has unleashed a religious chant against those who reject his crusade.

        His slander is not science and is pretty much the same spite we get from many religions against heretics, blasphemers and etc.

        Science is not religion, but denialism is.

        • spangled drongo says:

          Science is not religion, but climate science is.

          FIFY, blith.

        • spangled drongo says:

          Have you checked your local king tide levels yet, blith?

          Do get back to us when you have.

        • spangled drongo says:

          You show me yours and I’ll show you mine, blith.

          Meanwhile, I suggest you go outside and check current sea levels.

          They’re lower than they were 70 years ago:

        • Don Aitkin says:

          Chris, there is so much assertion in your post! A more reasonable person might ask you how you know what people’s intentions are, given that you were 10,000 km away from the event. Have you talked seriously and at length to Patrick Moore at any time? They might point out that the environmental movement is itself a quasi-religious one, so that the ‘religious chant’ might properly be applied to what Greenpeace, Sierra and other environmental organisations put out. Moore, being one of the early adherents of Greenpeace, and celebrated for that at the time, is after all in some position to say what has happened to that organisation. Are you? On what basis?

          Denialism is a word that you use a lot, and I doubt that many readers know what you mean by it. But that ‘denialism is religion’ is pretty far-fetched. Most of those who comment as sceptics point to evidence and data that supports their views. You mightn’t like their arguments, evidence or data, but calling them ‘denialists’ doesn’t work at all. You need not only to point to some data of your own, but show why yours is to be preferred (and not by appeals to authority).

          If I say that your contributions on these subjects suggest to me that you are a full-bottle believer in the catastrophic view of climate change, does that make me a ‘denialist’? If so, why?

        • spangled drongo says:

          Yes, blith, please explain how pointing out that there is nothing at all happening with this current warming that is any different from natural climate variability that equates to denial:

          We only do this on your behalf to stop you from further embarrassing yourself.

        • Boambee John says:


          “Using derogatory names about people WITH THE INTENTION of opposing their views is an artefact of denialism.”

          It is also an artefact of the AGW campaigners approach to sceptics, witnes your use of the derogatory term “denialism”.

          • spangled drongo says:

            Yes, BJ, and we are far too accepting of their dishonest behaviour:

            “It’s just amazing how we as a society can let global group-think ideas have fantastically large continued public traction when direct scientific observation utterly refutes the very basis of the ideas.”


          • Chris Warren says:

            Boambee John

            Be very, very clear. I do not introduce terms such as “denialism” until AFTER a particular individual has earned this appellation themselves.

            There is such a thing as “denialism” usually in other fields and waved by the likes of David Irving and Keith Windschuttle, those parading “intelligent design” and denying the moon landing.

            If you want to contest global warming science then you need new science at the same level, not the slander and defamation coming out of Curry and others.

          • spangled drongo says:

            Nearly all alarmists WRT “climate change” [such as yourself, blith] use the “denialist” term indiscriminately because it suits you to denigrate rather than debate.

            The fact that you “deny” that sceptical scientists are much more inclined to make decisions from observations rather than computer programs leaves you wide open to honest criticism.

            The term is very inappropriate but certainly applies more to alarmists than scepticts.

          • Boambee John says:


            Our discussion started with your statement that “Using derogatory names about people WITH THE INTENTION of opposing their views is an artefact of denialism.”

            I expressed the opinion that, in your view, “they earn this appellation simply by disagrreing with you? Certainly seems so, as many of those you abuse as “deniers” provided data, albeit data that you reject.”

            You demanded that I “provide any evidence where (you) have rejected data?”, and accused me of telling untruths, an assertion you repeated when, to molify you, I changed reject to ignore.

            Now you have stated that you “ignore no credible data but certainly reject the cherry picking of data that underlies so much of the denialist project.”

            Please clarify how you decide that data have been “cherrypicked”, noting that you “reject” data you consider to be such.

            Thank you, however, for acknowledging that you do “reject” some data, confirming the opinion I expressed earlier.

          • Chris Warren says:

            Boambee John

            Everyone should reject “cherrypicked” data. So what is your problem?

            Rejecting or ignoring “cherrypicked” data is NOT rejecting or ignoring data itself.

            I am very clear that your false accusation DID NOT refer to “cherrypicked” data.

            Please – no more crazy diversions.

            You should simply retract your false statement.

          • Boambee John says:

            “Everyone should reject “cherrypicked” data. So what is your problem?”
            I am certainly happy to reject “cherry picked data. You have not yet explained how you, specifically, identify it.

            You made no reference to cherry picking in your original statement. You are changing your position as you go.

          • Chris Warren says:

            Boambee John

            What on earth are you going on about?

            My issue was with YOUR falsification.

            My issue was with YOUR false statement (version 1 and version 2).

            You could have retracted them some time ago.

            Did you intend to accuse me of ignoring or rejecting ONLY cherrypicking data?

            If so, why not draft a third version? You can include the word “cherrypicking” if you like.

        • Boambee John says:


          “Be very, very clear. I do not introduce terms such as “denialism” until AFTER a particular individual has earned this appellation themselves.”

          And do they earn this appellation simply by disagrreing with you? Certainly seems so, as many of those you abuse as “deniers” provided data, albeit data that you reject.

          • Chris Warren says:

            Boambee John

            Claims such as yours that I reject data are slanderous tools of denialists.

            Please provide any evidence where I have rejected data?

            This is purely your imagination.

          • Boambee John says:

            Among others, spangled drongo regularly providrs links to a wide range of data. Your responses give no indication that you read those links.

            Personal abuse is not a valid argument, try again.

          • Chris Warren says:

            Boambee John

            So you made a deliberate falsification?

            You claimed I reject data.

            You need to retract your false statement.

          • Boambee John says:

            Change “reject” to “ignore”, for what practical difference it might make.

            Reject suggests that you consider the closerehile ignore seems closer to your apparent position.

          • Chris Warren says:

            Boambee John

            So you want to repeat your accusation in new words.

            But your claim that ignore data is just as false.

            I ignore no credible data but certainly reject the cherry picking of data that underlies so much of the denialist project.

          • spangled drongo says:

            Poor silly ol’blith. Not only conveniently ignores data and the real world [sea levels are just one instance] but then resorts to denial as defence.

        • Boambee John says:


          Read your post of 1036 on 16 June, to which I responded. It does not mention “cherry picked”. I expressed an opinion on that statement, not a statement of fact about how you decide what data you will or will not accept.

          End of conversation.

          • Chris Warren says:

            Boambee John

            You are making no sense.

            Your false accusations had nothing to do with “cherry pick” and nothing to do with an opinion on “cherry pick”.

            If you re-read your own words you will see your accusations of

            “reject data” and
            “ignore data”.

            So do you maintain or retract these statements?

          • spangled drongo says:

            Please enlighten us all on what fundamental data you refuse to reject and ignore, blith.

            For example, the IPCC 2001 WG1 Report said that the measured global temperature increase of 0.6°C ±0.2° in approximately 120 years was not natural. IOW, in excess of natural climate variability following the little ice age.

            Do you accept or reject/ignore that?

          • spangled drongo says:

            BJ, being the hypocrite he is, I don’t blame you for ending your “conversation” with our blith.

            In spite of his blithering, over the years I have yet to hear him criticise any of Hansen’s cherry picking:


  • Neville says:

    I think it’s best to forget about Chris because he’s not worth the trouble. Left wing people couldn’t care less about data, because ( in this case) they are the urgers that think everyone should agree with their CAGW mad cult .

    But does anyone remember me linking to the Royal Society ALL MODELS graph on Greenland and Antarctic SLR attribution?
    All the models were displayed showing Greenland positive and Antarctica negative for the next 300 years. So I suppose if you now believe this latest study you must throw all those previous models out the window?
    And then you must surely doubt all their other modelling studies on temp etc as well? Surely if all the negative SLR Antarctic models can be changed overnight then anything is possible?
    BTW three cheers for Zwally et al throwing a spanner in the works.

  • spangled drongo says:

    Back in 2008 James Hansen claimed that sea ice in the Arctic would be gone in summer in 5-10 years.

    And look where it is now. It’s harder to get through the NW Passage than it was in 1903:

  • BoyfromTottenham says:

    Thanks for another interesting article, Don. Unfortunately, looking at the comments, readers are as divided as ever on this subject, and do not appear to be able to make a rational argument against the skeptical side, generally resorting instead to ad-hom, authority and cherry-picking. I personally find this ‘trench warfare’ approach by the ‘true believers’ quite tiresome, but I am always impressed by your erudite and tireless efforts to enlighten and educate your readers. In my retirement I prefer arguing with sticks of timber about how they should behave as I turn them into furniture!

    PS – I noted your comment about ‘3 trillion tons of ice lost’ from the antarctic. I have noticed that this is a very common propaganda technique used by the pro-CAGW crowd to scare the masses, who often have no idea about the sheer immensity of the antarctic ice sheet, and that the air temperature above it is many tens of degrees below zero all year round ensuring that it will stay frozen for millennia unless some extra-terrestrial event supervenes.

  • spangled drongo says:

    Things got too warm for the warmists with their busybody stupidity.

    Their desire to use large blocks of “social housing” for large scale carbon reduction measures through govt-enforced insulation led to the disastrous Grenfell Tower debacle.

    They create a real catastrophe trying to prevent an imagined one: :

  • spangled drongo says:

    The crazy green schemes governments have foisted on Britain in the quest to reduce carbon emissions are mind blowing:

  • Chris Warren says:

    An example of good data. Not because of the actual numbers but the trend.

    The trend is the key.

    It seems we are experiencing massive ice-melt similar to previous inter glacial eras, when the natural causes that then applied, do not exist.

    This does not bode well for the future if GHG levels exceed levels during previous natural ice-melt episodes.

  • JimboR says:

    Don, I make no comment as to whether these ice masses are likely to disappear, but your position is not even internally consistent.

    DA: “The rubbish rejoinder came from the notion that the ice in the present Antarctic is capable of melting.”

    and in the next sentence…..

    DA: ” The correct explanations are …. ablation (evaporation) from wind.”

    i.e. melting!

    “The Antarctic ice sheet is frozen solid and can’t ‘melt’ until somewhere the temperature gets to around 1 degree C.”

    Don that is pretty silly. Cold places have summer too. Every summer it easily gets to 10C to 15C in the coastal regions of these ice masses. That’s got nothing to do with climate change, that’s summer and has been going on for centuries. Next time you find yourself in Seward AK, go for a day trip to Holgate Glacier and you’ll see massive chunks of ice calving away every day of every summer. That’s been happening since long before the industrial revolution.

    These ice masses go through annual cycles of accumulation (snow) and ablation (melt). Those who worry about these things believe the ablation phase of the cycle exceeds the accumulation phase, and will continue to for the foreseeable future. To my untrained eye, that seems at least possible. Compare that to your musings on the topic. It’s as if you think the alarmists believe we’ll all be able to gather around one weekend in summer and watch it melt away, much like you could an iceblock on the back deck. You rightly point out that’s not going to happen so conclude there’s no issue. Think decades, maybe even centuries, of continued deficits and you’ll see the problem.

    DA: “and then thought I had better do some homework. ”

    More required I’m afraid.

    • Don Aitkin says:

      Oh dear, you try so hard don’t you, Jimbo? Ablation is surface loss, of glaciers or rocks. Melting is a form of ablation, but not all ablation is melting, which is the liquefaction of something through heat. The ice masses in Antarctica lose through wind, as I said, not through heat (unless it is heat from below). Yes, temperatures as high as 15C have been recorded on the coast of the Antarctic Peninsula, but the ordinary summer temperature is below 0c most of summer. Look it up, Jimbo. Wikipedia has a sensible essay on Antarctic climate. And while you’re reading it, note how small the AP is compared with the rest of the continent. Not much sea-level increase from there. And a new article by Zwally, which I haven’t yet seen, is apparently going to say that the ice accumulation in East Antarctica offsets by a considerable amount any loss from WAIS or the AP. What have you read with your ‘untrained eye’?

      • JimboR says:

        “The ice masses in Antarctica lose through wind, as I said, not through heat”

        Why do you think wind melts ice? What difference does it make whether the ice turns to water or vapour? Either way it’s left the ice mass. Why do you think the coastal areas are warmer than the inland? What do you will happen to the inland temperatures if the ice retreats towards it?

        Nobody is suggesting we’ll be able to gather around down there on a particular date and watch the whole lot melt at once. It’s all about the ablation / accumulation balance. Your claim that it “can’t melt” is demonstrably wrong. Bits of it melt every summer.

        • Don Aitkin says:

          Oh dear, you must have been a joy to teach.The conventional AGW/Climate change scenario has CO2 raising air temperatures, melting ice and raising sea levels. But the icy winds in the Antarctic do not ‘melt’ ice. They ablate it. Wind of this kind does not melt ice, by definition (melting is liquefaction through heat). So, there’s no melting in the Antarctic except occasionally on the AP and in parts of the WAIP, but the air temperature there is usually below zero. Give it up, Jimbo. Think about it some more before you write again. The measured ice loss, if those measurements are at all correct (they are estimates) is infinitesimal. What are you trying to prove? Why?

        • JimboR says:

          Don, conventional theory has the increased heat (energy) in the system – due to the energy imbalance caused by increase CO2 levels – melting ice. It’s because of the amount of energy spent melting the ice that the temperature doesn’t go up as much as it otherwise would.

          You need to do a lot more homework on this. This is pretty basic physics.

        • JimboR says:

          And whether the ice melts into water or is turned directly into vapour makes no difference. It’s left the ice mass and and is now in the water cycle…. where it’ll turn to rain or snow. The only measure that matters is the ablation Vs accumulation balance.

      • JimboR says:

        “The ice masses in Antarctica lose through wind, as I said, not through heat ”

        I think you might be violating some pretty fundamental laws of thermodynamics there. You’re changing the state of ice without heat? Every time we get into this discussion, you consistently confuse heat (energy) with temperature. One is measured in Joules (or calories) the other in C (or F). It’s precisely because it takes heat to melt ice that iceboxes are so effective. When heat is introduced to your icebox it goes to melting the ice rather than raising the temperature of your beer.

  • spangled drongo says:

    Jimb and blith should make an effort to check evidence that is placed right under their noses upthread:


    The East Antarctic Ice Sheet (EAIS) is the largest potential contributor to sea-level rise. However, efforts to predict the future evolution of the EAIS are hindered by uncertainty in how it responded to past warm periods, for example, during the Pliocene epoch (5.3 to 2.6 million years ago), when atmospheric carbon dioxide concentrations were last higher than 400 parts per million. Geological evidence indicates that some marine-based portions of the EAIS and the West Antarctic Ice Sheet retreated during parts of the Pliocene1,2, but it remains unclear whether ice grounded above sea level also experienced retreat. This uncertainty persists because global sea-level estimates for the Pliocene have large uncertainties and cannot be used to rule out substantial terrestrial ice loss3, and also because direct geological evidence bearing on past ice retreat on land is lacking. Here we show that land-based sectors of the EAIS that drain into the Ross Sea have been stable throughout the past eight million years. We base this conclusion on the extremely low concentrations of cosmogenic 10Be and 26Al isotopes found in quartz sand extracted from a land-proximal marine sediment core. This sediment had been eroded from the continent, and its low levels of cosmogenic nuclides indicate that it experienced only minimal exposure to cosmic radiation, suggesting that the sediment source regions were covered in ice. These findings indicate that atmospheric warming during the past eight million years was insufficient to cause widespread or long-lasting meltback of the EAIS margin onto land. We suggest that variations in Antarctic ice volume in response to the range of global temperatures experienced over this period—up to 2–3 degrees Celsius above preindustrial temperatures4, corresponding to future scenarios involving carbon dioxide concentrations of between 400 and 500 parts per million—were instead driven mostly by the retreat of marine ice margins, in agreement with the latest models.

  • Chris Warren says:


    You claimed that:

    “The measured ice loss, if those measurements are at all correct (they are estimates) is infinitesimal.”

    However the data is here:

    Ice loss is not infinitesimal.

    You can find out what ablation means here:

  • JimboR says:

    Don, your obsession with whether or not the outside air temperature is above or below zero has me wondering if you think conduction is the only way of transferring heat to ice? Radiation can deliver heat to ice regardless of the surrounding air temperature. I genuinely believe you’d benefit from a refresher course on heat transfer, radiation, convection and conduction.

  • JimboR says:

    DA: “But the icy winds in the Antarctic do not ‘melt’ ice. They ablate it”

    They might seem icy to you if you’re out standing in them, but clearly if they’re evaporating (or melting) ice they’re not icy enough.

    “After studying Antarctica’s warming climate for decades, scientists are making a surprising discovery: In some places, much of that abnormal warmth is invading in the form of powerful, downhill winds called föhn (pronounced “fone”) winds. Pettit, a glaciologist from the University of Alaska in Fairbanks and a National Geographic explorer, now suspects that these winds contributed to a series of dramatic glacial collapses that have been steadily redrawing the map on the east side of the Antarctic Peninsula for the last 30 years. Föhn winds may have escaped scientists’ notice because they don’t just blow during summer—some of their most impressive heat waves actually strike in the dead of winter, eroding glaciers at a time of year that no one thought possible.”

    What is puzzling to me is why you think any of this helps your cause? The theory is that increased CO2 levels cause an energy imbalance which results in more heat in the system which results in more ablation of glaciers. Everything you’ve contributed here confirms that. It was only ever your small-mindedness that required the whole of Antarctica to be regularly sitting at 2C before ice would melt. A high school geography student has a better grasp on the cycles involved then you’re demonstrating.

  • JimboR says:

    And why are you so hung up on whether the ice melts or evaporates? It’s all ablation, it all makes the glacier smaller, and it’s all caused by heat. Whether the heat is delivered by winds in the depth of winter, or by radiation on a sunny day, or by conduction on a balmy summer’s day it’s all heat. The laws of physics tell us the only way to change the state of ice is to apply heat. You’ve somehow got it stuck in your head that the only way global warming can do that is via conduction on a balmy summer’s day. That’s your straw man, nobody else’s.

  • Don Aitkin says:

    Chris and Jimbo, discussing matters with you two is like wrestling with jelly. You shift, duck, weave, ooze away and never get to grips with anything. For the record, (i) ablation in the Antarctic is from dry cold winds. If it is caused by energy balance please tell everyone how this is done, since it is totally unclear to me, and to the literature, to the best of my reading. I do know about foehn winds, since Canberra’s weather is affected by them.
    (ii) There is no evidence that these Antarctic winds are warm. None at all. They are probably as cold as the ice around them.
    (iii) ‘it’s all affected by heat’. Show us how. Statements like that one and the other about ‘energy balance’ are just hand-waves unless you can show what the mechanisms are.
    (iv) The alleged three trillion tons of ice lost since 1992 is based on all sorts of models, satellite runs and is of course an estimate. That it was widely reported does not make it correct. Three trillion tons represents 0.1 per cent of the Western Antarctic Ice Sheet, which is 11 per cent of Antarctica, and 0.011 per cent of Antarctica. There are other estimates which say that the addition to Antarctica is greater than the supposed ice losses. In short, there is disagreement, and nobody knows. I regard a loss of 0.011 per cent of ice, even if it were real, as infinitesimal.
    (v) You seem to assume that any trend you can see will continue indefinitely. I don’t.
    (vi) My position on global warming is the null hypothesis: carbon dioxide does not have a significant effect on climate or global warming. On the evidence available, the increase in carbon dioxide levels has been good for the planet and living things in it. There is no evidence at all that there have been harmful effects. If you think there have been, you need to show what they are. What might happen in a thousand years or more does not worry me.

  • JimboR says:

    “‘it’s all affected by heat’. Show us how. Statements like that one and the other about ‘energy balance’ are just hand-waves unless you can show what the mechanisms are.”

    One man’s handwaving is another man’s physics I guess. Where do you propose the energy required to evaporate the ice comes from? Claiming “it just ablates” is handwaving.

    • Don Aitkin says:

      Jimbo, read my piece above once more. My position is that of the null hypothesis. I am not making claims about the effects of warming. I simply point out what seem to be the flaws in what is put forward by who think otherwise. If you think heat does the job, then show us the mechanism. You’re the one with the firm belief.

    • JimboR says:

      The only belief I have here is in the laws of physics. It takes heat energy to convert ice to water, and even more heat energy to convert it to vapour. Your null hypothesis appears to be that the ice converts to vapour without the need for heat energy. That’s a big call!

      • Don Aitkin says:

        Jimbo, I have no idea what you know about physics. You certainly don’t seem to know what a null hypothesis is, though I set it out above. It doesn’t require anything from me, only from you, if you want to keep going with your charade.

  • Chris Warren says:


    Please provide any evidence backing up your claim of;

    “You shift, duck, weave, ooze away and never get to grips with anything”

    Those inserting vague words such as “alleged” in front of rigorous scientific facts are the ones truly displaying such tendencies.

    People making vague statements such as:

    “There are other estimates which say that the addition to Antarctica is greater than the supposed ice losses”, without any evidence whatsoever are the ones who are shifting, ducking, weaving, oozing away and never getting to grips with anything.

    If you read my link you will see that the claim of addition of ice being greater than losses across Antarctica was referenced and it was noted:

    “The paper, like many others, disputes the findings of Zwally et al (2015), who argued that mass gains in East Antarctica were large enough to outweigh losses in the West Antarctic Ice Sheet (see also Medley et al., 2018).”

    Do you have any evidence that Zwally did not make the same level of “estimates” as you think jeopardises others you disagree with.

    Only those who shift, duck, weave, and ooze away, invent such disparaging devices.

    Claims that Antarctica is gaining ice have not survived cross examination by scientists.

    • Don Aitkin says:

      Chris, you are, how do I put it nicely, mistaken. The notion that the Antarctic has lost 3t tons of ice is not a ‘rigorous scientific fact’. It is an estimate, at odds with other estimates by other scientists. Don’t you understand that?

      ‘Claims that Antarctica is gaining ice have not survived cross examination by scientists’. Really, which ones? Where? Why are they right? How are you in a position to say so? Don’t you understand that the debates are between scientists?

  • JimboR says:

    “The ice masses in Antarctica lose through wind, as I said, not through heat”

    Don, that sentence is inconsistent with the laws of physics. Please try harder if you want to make a useful contribution here.

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