Three Graphs

News Brief by Kip Hansen — 30 November 2019

 

featured-imageA recent study in Oceanography, the Official Magazine of The Oceanography Society, titled  “Atlantic warming since the Little Ice Age” [.pdf here], is interesting in its entirety, with an Abstract as follows:

 

“Radiocarbon observations suggest that the deep Atlantic Ocean takes up to several centuries to fully respond to changes at the sea surface. Thus, the ocean’s memory is longer than the modern instrumental period of oceanography, and the determination of modern warming of the subsurface Atlantic requires information from paleoceanographic data sets. In particular, paleoceanographic proxy data compiled by the Ocean2k project indicate that there was a global cooling from the Medieval Warm Period to the Little Ice Age over the years 900−1800, followed by modern warming that began around 1850. An ocean simulation that is forced by a combined instrumental-​proxy reconstruction of surface temperatures over the last 2,000 years shows that the deep Atlantic continues to cool even after the surface starts warming. As a consequence of the multicentury surface climate history, the ocean simulation suggests that the deep Atlantic doesn’t take up as much heat during the modern warming era as the case where the ocean was in equilibrium at 1750. Both historical hydrographic observations and proxy records of the subsurface Atlantic are needed to determine whether the effects of the Little Ice Age did indeed persist well after the surface climate had already shifted to warmer conditions.”

Those interested in the relationships between deep Atlantic Ocean water temperature, surface Atlantic water temperature, and possible effect on climate — and, of course, effects of atmospheric climate on deep Atlantic Ocean temperature and the ocean’s heat uptake and release — should read the whole paper.

Of particular interest for today’s Climate Debate are these three graphs — the first two of which are simply copied from the paper itself, including their captions:

two_millenia

This first graph shows the Ocean2K reconstruction of global surface temperatures  (anomaly with baseline 15 CE — broad black trace) and on the right-hand side, various modern regional Atlantic Ocean surface water temperatures.

The second graph:

1850_to_2015

This is the view we are accustomed to seeing in the Climate Debate — the global surface temperature anomaly (some baseline — in this case 15 CE) with a starting point around 1850 (some start a bit later, 1890).  Note that it is “Identical to Figure 1, but restricted to the years 1850−2015.”  The starting point is picked to represent “the start of the Modern Industrial Era”.

Now an annotated version of the second graph:

Annotated_difference

Here we have the second graph 1850-2015, with the global Average Surface Temperature anomaly (again — baseline 15 CE)  but I have dropped in a smaller window, on the left, bringing forward  the Roman Warm Period and the Medieval Warm Period (MWP) — the years 100-800 CE (same scale) — to illustrate the difference between the peak Global Average Surface Temperature (GAST)  of the Medieval Warm Period to the most current GAST on the graph (2015).

This exposes the ubiquitous trick of the Climate Debate, in which Global Temperatures are [almost] always shown only from the depths of the Little Ice Age (clearly marked on the first graph by Gebbie), resulting in images similar to Gebbie’s Figure 2 — despite the fact that most 2 millennia reconstructions clearly show the Roman and Medieval Warm Periods as generally in the same range as the Modern Warm Period.   Given the acknowledged range of error  in any temperature reconstruction and in modern estimates of global surface temperatures (today, in absolute temperatrures,  around +/- 0.5ºC  or a range of 1ºC)  — there may be little, if any,  significant-to-the-global-environment difference  between the two periods.

The Medieval Warm period did not result in a “Climate Catastrophe”  and the [iffy] little additional 0.2°C  seen today  is very unlikely to spark a modern Climate Catastrophe either.

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Author’s Comment:

A great deal of the polarization in the Climate Debate  is based on this little trick of data presentation — using a starting date  known to represent a low point  in some data set of a measurement which the author wishes to show has increased to a present high.  Failure to show the full context of the data is a type of data falsification.

Kudos to Geoffrey Gebbie for including both graphs in his paper.

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134 thoughts on “Three Graphs

  1. Change the Y axis scale to -3C to +3C and it becomes almost a flat line. For visuals it is all about how the data is presented. The temperature anomaly maps are the best. You can put the bright reds, oranges to show the positives and pale blues to show the negatives and where do your eyes focus?

    Also pay attention to what each color represents. It easy to make +1C look much more menacing and expansive than -1C just by color selection. I saw an instance where the colors were reversed (reds showing colder, blue showing warmer). The two maps side by side where completely different to the eye although they showed the same data.

    • rbabcock ==> Yes, there are many many ways to bias the visual presentation of data. The use of colors, red, to depict the “danger” of slightly warmer temperatures, or the use of deep blues to make slight cooling appear dangerously cold.

      There are very good books on visual presentation — and a lot of clever propagandists well trained in the topic. (It’s not just in CliSci either — every science field has their share — and politics of course).

      • Back in the Jurassic when I was in school I was introduced to a little paperback book entitled “How To Lie With Statistics” which showed this and a host of other techniques to skew data representation. It was intended as a cautionary book, to inform you about what to look out for. Now, I think it has become a how to manual for distorting data in all forms. They’ve added the words “For Fun And Profit” to the end of the title.

      • true in general, but I don’t see any propagandist use of colours here.

        I have no idea whether any of this hold water at this stage but in the paper , fig 5 is the most interesting. It shows deep ( up to 2km ) OHC varying twice as fast as surface (0-700m) OHC.

        If the data is to be believed, this shows that it is not dominated by convection, conduction or eddy diffusion but by some other process circumventing simple thermodynamics. It seems most likely this is ocean currents, cold, dense saline water descending in the Arctic and overturning being the major means of heat transport between ocean and surface.

        This is something we do not understand and is not part of the “basic physics” of GCMs. If they are lacking such a fundamental component of energy balance, any match to hindcasts is simply fortuitous ( or more likely rigged via “tuning” various illconstrained parameters ).

        • Yes, yes, yes! The warning of the Atlantic started 100 years before a CO2 influence was even possible, clearly showing the natural variability that exists on Earth. The warning since 1950 is, if anything, less than the warming before 1950.

          This study, like thousands of others, is evidence that natural climate change rules and the human influence is not even necessary to explain observations.

          Man made climate change science is, and always had been, a bunch of politically driven crap!

        • Even in a small lake the circulation is complex. We measured a bunch of things in our coastal BC lake that supplies community water in preparation for upgrading. In summer the surface 4 m had a progressive decrease in temp and oxygenation, then a short reversal followed by decreasing temperatures to an anoxic bottom. In early winter temperatures were similar all the way to 10 m, but oxygenation decreased with depth. Dissolved carbon (from peat) was pretty homogeneous at both times. A local geologist spoke of the summer to winter changes as ‘the lake turning over’ as the surface cooled in fall. The actual changes look like a much more complex process, and there was no indication of oxygenated surface waters reaching the bottom layers.

          You would need a great deal of multi-year data to sort out the Atlantic circulation.

        • Greg ==> Didn’t mrean to imply that there was any propagandistic use of colors in this paper or in the graphs from it. That was a reference to Babcock’s “The temperature anomaly maps are the best. You can put the bright reds, oranges to show the positives and pale blues …..”

          I agree that the underlying data in the full paper are of great interest to understanding the as-yet-not-understood relationships between deep ocean currents and surface climate.

      • Kip, I’m a little confused by your “MWP” peaking in 600 AD. This was the “dark ages” which corresponded to the coldest period between the roman WP and MWP, at least in the centres of civilisation at the the time.

        One may expect heat loss from OHC to result in warming of the surface climate, this is not at all simple and I don’t see that the paper shows what you are trying to make it show.

        • Greg ==> If all the temperature reconstructions agreed with one another, this would all be easier. 600 CE is a bit early for the MWP, which seems to show up a few hundred years early on this particular reconstruction. These early Warm Periods are similar in magnitude to the Modern Warm Period. The difference may be in the baseline (15 CE).

          See this wiki link for the divergence between reconstructions….sources listed at the bottom. At least one other reconstruction shows a peak at 600-700 CE. In that Wiki image, it is the Dark Red trace that we are most used to seeing — it is from Moberg (2005) (seems to be mislabeled in the Wiki text–but definitely from Moberg).

          • “These early Warm Periods are similar in magnitude to the Modern Warm Period.”

            Not true, look at own your link. I’m not saying they didn’t happen, but the more detail we get the more the LIA and early Warm Periods are shown to be far less significant than the temperature excursions of today. Not only far less widespread and far less uniform – different regions eperienced fluctuation decades even centuries apart – but far weaker, *maybe* not an order of “magnitude” weaker, but no comparison.
            They happened, but just not like many here wished they happened.

            So no, not even close to true. And no, one ice core from Greenland is not the same.

      • “Yes, there are many many ways to bias the visual presentation of data.”

        With that in mind, maybe you could show us what the top chart would like if the time intervals along the x-axis were kept constant throughout?

        • Snape ==> The graphs are copied from the original paper….the different time scale is due t the authors focus on the last 150 years or so, their own data — Figure 2 — starts in 1880.

          • Kip
            As mentioned, In figure 2 the author focuses on the more recent time period.

            But in figure 1, for comparison, the years 0 to 1750 are placed on the same grid as the years 1750 to present, but using different time scales along the x-axis.

            This creates a visual misrepresentation of the data.

          • Snape ==> The original Figure 1 shows a break (double vertical line) to separate the two portions of the graph with the differing time scales. I would not have done it that way, but there you have it.

  2. “Given the acknowledged range of error in any temperature reconstruction and in modern estimates of global surface temperatures (today, in absolute temperatrures, around +/- 0.5ºC or a range of 1ºC)…”

    Since many of the surface stations may be giving higher readings than they should due to UHI and siting problems, shouldn’t that really be something along the lines of + 0.5C / -0.7C or maybe more? I have a problem believing the error is the same in both directions, but maybe that is just me?

    • JohnWho ==> The figure “+/- 0.5°C” is quoted from Gavin Schmidt. It is the norm to state a range of possible error this way. Some disciplines use error bars in which the error range is shown by whiskers above and below the mean, with the mean not being necessarily centered (common in medical studies).

      An example here.

      • There are many metrologists that would argue that there is no way to measure even an Olympic size swimming pool to an accuracy of 0.2C. Claiming that proxies can provide temperatures a millennium ago to an accuracy of 0.2C by showing graphs with that level of precision is approaching fraud.

        • These are as usual anomalies rather than temperatures. I’m slightly at a loss as to what the error bar therefor is as it is comparing two data points each with perhaps different error ranges.

          But if the 1850 temperature is say +/_ one degree then there is no anamoly is there, unless the anamoly is greater than one degree?

          And I struggle to believe the 1850 temperature is accurate to less than one degree. So is this all just nonsense?

          • In 1850 there were probably less than 116 weather observations sites in the world the entire Southern Hemisphere had less than a dozen, most of those were in Australia and New Zealand.
            https://notrickszone.com/2019/08/23/earth-surface-temperature-data-too-scant-no-certainty-southern-hemisphere-stations-show-cooling-since-1880/

            So can anybody really think that there is any way to be accurate within 5DegC for any guessed temperature anomalies from the 10 or 12 observations for the entire Southern Hemisphere?
            Anomalies from what?

            Presenting graphs based on tenths of a degree is either abject ignorance or deliberate misstatement {cough}. There is no middle ground.

          • Phoenix44
            The Rule of Thumb for subtracting numbers with different precision is to be guided by the number(s) with the least precision. That is, if you are subtracting a number with one significant figure to the right of the decimal point from a number with three significant figures to the right of the decimal point, you only retain 1 significant figure to the right of the decimal point in the difference.

            https://sciencing.com/use-significant-figures-addition-subtraction-2323698.html

          • The use of numbers with this precision is absolutely unethical. For visual presentations there need to be “shadows” showing the uncertainty and a statement of the absolute uncertainty in the text.

            My biggest gripe is adding digits of precision through averaging. This is totally unscientific, violates all rules of significant digits, and shows either ignorance or a lack of ethics.

            Massaging data thru averaging and statistical machinations in order to get a number that you can use in a paper should never be allowed.

          • @ clipe
            November 30, 2019 at 7:56 pm

            The point is that if you want to show the anomaly between an 1850 observation an accuracy of one degree with an observation from an automated system providing observation accurate to 2 decimal places, the anomaly should only be shown to a degree precision. The result should also show an error bar of +/-0.5C.

            Note that with proxy temperatures the accuracy is probably +/- 5C which makes a comparison of the graphs above a mathematical exercise with no real world validity.

          • clipe
            I was responding to to the remark by Phoenix44, “I’m slightly at a loss as to what the error bar therefor is as it is comparing two data points each with perhaps different error ranges.”

            What is your point?

    • The problem that goes hand-in-hand with undercorrected UHI is the ongoing massive loss of cooler rural stations and their data. In a sleight of hand ruse, such a loss allows copious interpolative infilling with UHI contaminated urban station data.

  3. Whatever caused the fall from the Medieval Warm Period and the rise out of the Little Ice Age had nothing to do with our insignificant power to add or detract. Further, the rise began before CO2’s rise, which means it is not the cause and, indeed, is consistent with previous records.

      • Kip
        Have you seen the work by the Connollys on radiosonde data that shows CO2 warming is very slight? ( See http://www.oprj.net for analyses of 20 million radiosondes that indicate the hypothesis is false.) Also consider Harde and Berry on the small amount of the CO2 change that is anthropogenic and your statement of “anthropogenic CO2 may be helping raise temperatures a bit in the present” should likely read “a tiny bit”. To me these works are part of the evidence you were waiting for at the end of your linked series but are disproving the AGW hypothesis you were examining.

        • DMA ==> Well, one paper probably will not be sufficient to disprove the AGW hypothesis — although it is “weakening” evidence. There’s a lot of that.

          Still waiting for evidence, one way or the other. Despite the public mania, the evidence for the AGW hypothesis has not been getting stronger -=-= rather the contrary.

          Thanks for the link!

      • Kip, as meaningless as “average temperature” of the Earth is, what tome scale are you referring to? Since the Ice Age began, the “average” is MUCH lower than it is now.

    • ….. the fall from the Medieval Warm Period and the rise out of the Little Ice Age had nothing to do with

      Scissor, ….. right you are …….. and that is one of the reasons why M Mann et el tried to eliminate the MWP.

  4. The lag suggests that the stabilisation time scale, that is the time it takes to attain a dynamic equilibrium if everything remains the same as it is now, is of the order of centuries. Yet the turnover time for the major ocean currents (their extent/speed) is of the order of years. Why this discrepancy? Are the currents deep down some kind of river with little heat exchange with the rest of the waters they find themselves in? If so, why?

    • Ed Zuiderwijk ==> The study of Ocean Currents and their effects on climate where humans live — Earth’s land surface — is a very very young scientific field and there is little really sound knowledge about it. The paper that is the source of the first two graphs in this news brief are from a study on exactly that topic, thus might be a good read and give some answers to your question.

      There is no doubt that there are connections between the cold deep oceans and the surface climate — exactly how it all works in the real world is what many oceanographers are studying.

      • Kip
        I believe that CO2 IR emissions are not absorbed by water to heat it (see the linked article below) and therefore cannot be responsible for hiding the warming as claimed. This would make the temperature of the oceans entirely natural. On top of that, water at the same temperature and under the same pressure has about 3300 times as much heat as air because of the specific heat of the two substances and their respective specific gravities. This means that the air has very little chance of changing the temperature of the oceans. The reverse is the case. By the ocean in the summer the breeze from the ocean is cool. The air has not warmed the water but the reverse has occurred.
        Really, some physics introduced into the AGW debate would be refreshing!
        http://www.warwickhughes.com/blog/?p=87
        John

        • jpm ==> Only the skin sea surface absorbs any IR — you are correct. But in the tropics, the air and the water exchange heat — from warmer air to cooler water and vice versa. my understanding is that wind, waves, and currents cause mixing in the top layer of the ocean and currents (up, down, and lateral) take some of the heat energy to deeper layers.

          • Kip
            What you describe is not AGW in action, which requires IR transfer as I understand it, but natural warming of the water and as I mentioned above the atmosphere has very little chance of warming the seas because of the difference in SG & specific heat of the two substances! The warming of the oceans is not caused by AGW but natural radiation from the sun, UV and visible radiation.
            John

    • Why assume there is ever equilibrium? In a complex, non-linear, chaotic system, everything affects everything, so equilibrium is very hard to achieve. There may be times when it looks like equlibrium, particularly if you use a single, gross metric (global average temperature say) but in detail it is not equilibrium as the billions of individual elements of the climate are different and still changing.

      It’s like throwing a billion dice – you’d see the same numbers come up a lot but the dice would always be different.

    • “Ed Zuiderwijk November 30, 2019 at 7:05 am

      The lag suggests that the stabilisation time scale, that is the time it takes to attain a dynamic equilibrium if everything remains the same as it is now, is of the order of centuries. Yet the turnover time for the major ocean currents (their extent/speed) is of the order of years.

      Why this discrepancy? Are the currents deep down some kind of river with little heat exchange with the rest of the waters they find themselves in? If so, why?”

      Because the dispense of appropriate heat through the atmosphere / ocean-water-body takes: centuries.

    • Incorrect assignment; hopefully right here:

      “Ed Zuiderwijk November 30, 2019 at 7:05 am

      The lag suggests that the stabilisation time scale, that is the time it takes to attain a dynamic equilibrium if everything remains the same as it is now, is of the order of centuries. Yet the turnover time for the major ocean currents (their extent/speed) is of the order of years.

      Why this discrepancy? Are the currents deep down some kind of river with little heat exchange with the rest of the waters they find themselves in? If so, why?”

      Because the dispense of appropriate heat through the atmosphere / ocean-water-body takes: centuries.

  5. I had a physics professor who required us to plot data on a graph scaled to zero. This helped us understand the actual magnitude of what we were looking at and understand signal versus noise a little. While this might not be appropriate in plotting past surface and ocean temperature data and reconstructions, perhaps we could plot the trend against daily and seasonal variability to help people understand how small the changes are that are being derived from the data versus natural variation. It’s a bit like finding gravity waves when the signal is much smaller than the noise.

    • Loren ==> You are right about scales — they can be used to exaggerate or diminish effects. In the original study, from which the graphs are copied, the top-to-bottom scale represent only 1.5°C — narrower than the comfort temperature range recommended for modern offices — and less than most people can easily experience and identify.

  6. Much of the expected warming is not due to CO2, but feedbacks. Feedbacks are a function of temperature, so they would operate irrespective of CO2 level. The question then is, why didn’t feedbacks continue to warm the planet during the MWP, or at any other time in geologic history, for that matter.

    • Strong CO2-GHG theory as implemented via the modern GCMs makes a very specific prediction that is unique to the hypothesis – the presence of and continued amplification of a mid-troposheric (centered @ ~8.5km alt) warm spot temp anomaly in the tropics relative to the surface anomaly.
      The lack of its (the warm spot) detection by satellite and Radiosonde is an utter failure of strong CO2-GHG theory. The climate scammer community continues to hand-wave away this failure. It is one of several reasons Schmidt, Mann, and their ilk refuse to debate knowledgeable skeptics. Their strong GHG theory is becoming increasingly untenable and defensible save their massive on-going surface station data manipulations. A manipulation which only makes the lack of the hotspot that much more glaring. Sort of a tangled-web outcome when one endeavors to deceive.

      • The concept of “greenhouse” gas is simply wrong. The method of deriving the influence on surface temperature is wrong.

        Atmospheric water vapour rises and falls annually. The outgoing long wave radiation rises and falls annually. Each millimetre of water column increases OLR by approximately 2W/sq.m so they are POSITIVELY correlated. It is the exact opposite of the fairy tale.
        https://1drv.ms/b/s!Aq1iAj8Yo7jNg1ITK3Yk3q3yhL3_

        Every person with their brain in gear need to make an effort to stop the unscientific nonsense.
        The distribution of water over the surface of the earth is the reason for the life friendly temperature over most of the surface. Nothing to do with “greenhouse” gas. The average temperature of the moon is around 200K. Nothing like the proposed average 255K radiating temperature of Earth.

      • Indeed, if the surface data suddenly warmed, the current CO2 hypothesis would be falsified. I think their lack of an alternative hypothesis that blames capitalists keeps their thumbs off the scales.

    • That, Tom, goes straight to the heart of the matter. The much vaunted ‘feedback on water vapour’ should not only work when the temperature increases due to, purportedly, CO2, but also on a random fluctuation due to a change of water vapour content itself. The crucial aspect is the initial temperature increase, not what caused it. And the fact that we do not and did not ever see such a run-away feedback on water vapour alone, even with an ample supply of water, tells us that the proposed mechanism does not work. That it is nonsense. The fact that is an important aspect in climate models tells you therefore that those models are fundamentally flawed.

    • Some climate feedbacks are a function of temperature, but others are a function of CO2.

      In Systems Science or engineering, a “feedback” or “feedback loop” is a mechanism through which the output of a system loops around or “feeds back,” and affects an input to the same system (which, in turn, affects the output, which affects the input, etc.).

      For example, when the thermostat in your house detects that the temperature is getting too cold, it turns on the furnace to raise the temperature. That’s a (manmade) feedback system: The temperature causes a change in thermostat & furnace behavior, which, in turn, causes a change in temperature.

      Feedback mechanisms (or simply “feedbacks,” for short) are grouped into two categories: positive & negative. That doesn’t mean good vs. bad. It means amplifying (positive) vs. attenuating/reducing/stabilizing (negative).

      A positive feedback is one which causes a same-direction response, so it tends to increase (amplify) the effect of a change in input.

      A common misconception is that positive feedbacks necessarily “run away,” and make a system unstable. That is incorrect. Positive feedbacks of less than 100% don’t make a system unstable.

      For example, consider a linear system with a positive 10% (i.e. +1/10) feedback from the output to the input. An input change of 1.0 will “feed back” +10%. That’s added to the input, causing it to become, effectively, 1.1. The “.1” (additional part) is also then amplified by 10%, becoming .11, etc. The +10% feedback ends up, in the long term, asymptotically approaching 11.11111…% (i.e., +1/9 = ×10⁄9) amplification.

      Similarly, a +20% (i.e. 1/5) linear feedback causes a +25% (i.e., +1/4 = ×1.25) amplification, a +33⅓% (i.e. 1/3) feedback causes a +50% (i.e. +1/2 = ×1.5) amplification, and a +50% (i.e. 1/2) feedback causes a +100% (i.e. +1 = ×2) amplification.

      In general, in a linear system, a feedback ƒ causes a “compounded” net amplification (or attenuation, if ƒ is negative) which multiplies the original effect by 1/(1-ƒ). Here’s a diagram:

      https://sealevel.info/linear_feedback_system_diagram2.html

      For example, if ƒ = +20% then net amplification = 1/(1-ƒ) = 1/(1-0.2) = 1.25×.

      (Caveats: In practice, delays in the feedback path may mean that the full amplification effect of a positive feedback isn’t immediately seen. Also, these calculations assume linearity, but most systems are not perfectly linear, though many are approximately linear over input & output ranges of interest.)

      A negative feedback is something which causes an opposite-direction response, and thereby reduces the magnitude of the effect of the change. (Exception: if there are delays in the feedback path, very strong negative feedback can cause oscillations in the system, but that’s beyond the scope of this little primer.)

      The thermostat in your home is an example of a negative feedback mechanism (albeit a highly nonlinear one). It reduces the effect on indoor temperature of input changes, like changes in the weather, or someone leaving a window open.

      Negative feedbacks abound in nature, especially in biological systems, such as your own body. E.g., if your body overheats, you will sweat in reaction to your elevated body temperature. Evaporation of perspiration cools your body: a negative feedback.

      “Course corrections” are another example: When you are driving your car, and it drifts toward the edge of the road, in reaction to that drift you reflexively nudge the steering wheel toward the center of the road: a negative feedback.

      As noted above, in general, in a linear system, a feedback ƒ causes a “compounded” net effect on the output of 1/(1-ƒ). So, for example, if ƒ =-25% then net attenuation = 1/(1-ƒ) = 1/(1+0.25) = 0.8×, i.e., a 20% reduction in the effect on the system output.

      I have what is intended to be a comprehensive list of climate feedbacks, confirmed and speculated, on my web site, here:

      https://sealevel.info/feedbacks.html

      • “For example, consider a linear system with a positive 10% (i.e. +1/10) feedback from the output to the input. An input change of 1.0 will “feed back” +10%. That’s added to the input, causing it to become, effectively, 1.1. The “.1” (additional part) is also then amplified by 10%, becoming .11, etc. The +10% feedback ends up, in the long term, asymptotically approaching 11.11111…% (i.e., +1/9 = ×10⁄9) amplification.”

        Check your math again.

        It appears you have an amplifier with a gain of 1 and a feedback loop with a gain of 0.1.

        You start off with an input of 1 which generates a feedback of 0.1.
        The input then becomes 1.1 which gives an output of 1.1 which feeds back 0.11. Thus your input becomes 1.11. The output goes to 1.11 which when fed back becomes .111. Thus the input goes to 1.111 and so does the output. The feedback becomes 0.1111 forcing the input to 1.1111. Et cetera, et cetera, ….

        The output never stops growing. It may grow in increments you can’t measure but it never stops growing. Technically that *is* a runaway condition. You simply can’t dismiss that fact by saying you can’t measure it. The same thing happens with any positive feedback value, be it 0.2, 0.3, etc.

    • Ed Zuiderwijk, Tom’s “Much of the expected warming is not due to CO2, but feedbacks. Feedbacks are a function of temperature, so they would operate irrespective of CO2 level.

      The question then is, why didn’t feedbacks continue to warm the planet during the MWP, or at any other time in geologic history, for that matter.”
      ____________________________________

      YOUR “fact that we do not and did not ever see such a run-away feedback on water vapour alone, even with an ample supply of water”

      refers to a however needed “ample supply of water”

      – when that “ample supply of water” is already there” : the whole body of water on Earth.

      There is nothing “more”.

  7. I used to belong to the Oceanography Society, some quite a time ago. Too many societies, too many journals. They even published my letter about a subject that I don’t recall, have to check to see how stupid it was, but editor was very professional and remarked that they don’t get many letters that explore the subject or something like that. I check them out now and then, last I recall was one incomplete analysis, one editorial complaint that they couldn’t get students to go to sea much any more, and a very good page after the oil spill in small print about all the species of oil biodegraders in the ocean, very impressive. Going to sea in the old days was how you got checked out, fortunately I loved it, but can’t say I never got seasick. Too many apparently now need the experience.

    Anyway, the abstract is not all that bad, at least admitting to the Medieval Warm Period and the need for historical hydrographic observations. However, the devil is in the details, and they simulate that the ocean is still rather cool at depth, a place they know the least about.

    • HD ==> Well, I don’t get seasick (under anything that could be described as normal conditions) and have spent 1/2 of my adult life living on the sea in boats and ships (including 2 weeks recently, albeit with my youngest son as Captain). And, I agree, it is a shame fewer young people “run off to sea” these days and fewer are interested in the great adventure that the sea represents.

      The ARGO program is returning a lot of interesting contemporary data but we have only abject guesses about the past temperatures of the oceans with historical records only of some sketchy surface data from ships — probably not even accurate to a few degrees.

      • Kip,
        As you know, there are two kinds of sailors: those that have been [seasick] and those who will be.

        All it takes is the right set of conditions. With many thousands of miles under my keel, (like you) I haven’t gotten seasick… yet.

        I always enjoy your pieces here on WUWT. Thank you!

        • John ==> I did, once, as the stress effects of a near sinking event in a storm wore off, my stomach happily gave up its load. Wsa never sure if it was the adrenaline let-down or the boat motion.

          • Kip
            One time I went on a chartered salmon fishing boat out of the SF Bay. I was having the time of my life standing on the bow as we porpoised west. Once we got past the Golden Gate Bridge, and got into what they call the Potato Patch, the swells were so high the masts on the nearby boats would momentarily disappear. I started to feel a little queasy and cold, so I went behind the cabin to get out of the wind. There I was breathing the diesel fumes and felt worse. I went down below, and the smell of mildew was even worse than the diesel fumes. It kept getting worse and I bolted up the stairs to the deck to start chumming for salmon. It was so bad that I thought I was going to die. Then I was afraid I wasn’t going to die! Finally, after I had attracted all the salmon that I could with the contents of my stomach, the captain announced that it was too rough to fish. He turned around and headed back towards SF. After getting on land, it took me several hours to get back to feeling normal. It was then that I decided that I didn’t have the “Right Stuff” to be an astronaut. I had given it all to the salmon.

        • LOL, I have been a yachtsman for +40 years and have never been sea-sick. That said I have had crew before that have been so sick as to be incapacitated.

  8. Looking along the time axis (x – abscissa) where the data stops at 2010 CE, our Modern Warm Period is “living on borrowed time.”
    The climate barkers at NASA/GISS were banking on this when James Hanson started the CO2 scam in his 1988 Senate testimony. My guess is he figured they had a 30-40 year window from about 1980 to pull off carbon taxes and a war on fossil fuels before they couldn’t conceal a decline in GAST. He and the rest were figuring on a 2000-2010 “peak oil” to give them the economic leverage to pull it off.
    Fast forward 30 years. Given the US energy dominance, a world awash in affordable oil and gas and China’s and India’s skyrocketing CO2 emissions, it is only now with massive data set tampering that it will be possible for the climate scam to keep its legs. But with trillions of dollars at stake, and political power dreams on the line, they are giving it their best shot with a climate propaganda campaign like nothing else ever unleashed on a population. If it weren’t for an open internet and the rise of blogs like WUWT and independent news internet outlets, they’d probably have succeeded circa 2010.

    • “They” aren’t that smart now, so I doubt that they were that smart then (with regard to knowing about a 30-40 year window), and at the time they really did think that oil would run out or at least its production would shortly peak.

      The anti-fossil fuel movement has continued unabated, of course. With regard to climate, however, there probably was an about course consensus correction from cooling to warming based on real belief.

      The desire for power and money is also a constant driver.

      • Scissor, if by “they” you mean James Hansen, he began his career as a professional fear-meister in the late ’60s, pushing the Malthusian global cooling meme with financial backing, I suppose, from the Club of Rome. Same agenda though: to deindustrialize the West.

        Ten years later, it was obvious the planet had started warming — not headed to another LIA as expected after projecting the past into the future — and so the rhetoric shifted to AGW.

        Fool me once, etc.

    • Latitude ==> Well, its a smallish ocean…. Actually, the Atlantic dominates the weather and climate of Europe and I believe we know more about the Atlantic and its currents than any other of the oceans.

      There does seem to be a lot of media attention on the Pacific in recent years.

    • Chaamjamal ==> Thanks for the link to that interesting analysis — and particularly the BIBLIOGRAPHY which lists many of the important papers on the topic.

    • Wow – it must be costing the oil companies a fortune to underwrite all this CO2 busting research!

      It could be that natural variation simply stopped about 170 years ago and all climate change since has been the result of CO2. That is as realistic as the concept of “greenhouse” gas.

  9. A “just so” story that tries to make the fact that there are phase angles (lags) between top of ocean and deep ocean temperature signals into an ” unprecedented eureka!” insight.

    Of course, they see a “fingerprint” proving the ocean was “in equilibrium” before 1880.

    Dubious, that.

    • Dave Miller ==> Yes, quite right about the dubious “equilibrium” claim. The Earth’s climate is made up to two non-linear chaotic dynamical systems — the atmosphere and the oceans — coupled to one another. Neither is nor will be “in equilibrium” — nor has been.

      Such assumptions of equilibrium are not scientifically supportable.

      • Kip,

        We see the equilibrium point as we swing past it, every time. Every spike on the graph is a tipping point where we reverse direction and swing back toward equilibrium, overshoot and then swing back again. Negative feedback in action.

        • WBWilson ==> You may be right — but every peak and valley do not necessarily represent a passed equilibrium and a return towards it. See my series on Chaos here at WUWT. . . there is no reason to believe that the climate has reached (ever) an equilibrium. It may have a couple of semi-stable [strange] attractors.

  10. As an Instrument and Control Engineer responsible for tuning the process control systems for Coal and Nuclear powered electric generating stations it was obvious that essential all of the process systems lag the change in energy input.
    One only need look at the daily local temperature curve. The coldest time of the day is usually an hour or so AFTER sun rise, unless because of a rapidly moving front. It amazes me that climate scientists and “meteorologists” do not understand that the temperature of the ocean is going to lag by centuries. The mass of the medium, water, is orders of magnitude greater than the atmosphere.

    • v. ==> Your combined graph shows how much uncertainty there is about the early part of the last 150 years GAST. Gavin, who is showing Sea surface Temps, has it declining until about 1910! before the rise to the highs of the 30s and 40s.

    • My house gradually loses heat, slowly, until the furnace starts up, and it regains all that heat in a few minutes. The oceans act as a heat storage unit, that gradually loses heat stored in deeper layers as the atmosphere remains colder than the surface temp of the oceans. When the sun becomes more active over a multi-cycle span, the opposite happens. The oceans warm in layers, because the quick response of the atmosphere is warmer than the water surface layers, so the oceans store more heat, than they lose.
      If the sun begins a quiet phase, we will need every source of energy we can find to keep the cold at bay, and food production at a sufficient level.

      • It is the air in your house that has heated up quickly. The mass of all the objects in your house still need to be rewarmed and will suck up the warmth from the air until reaching equilibrium.

    • And the change from about 450 -550 in the proxy data is very similar to the measured changes of the recent centuries. 200 years of measurements would only fit in one cell of the proxy data. Much of the range would be “averaged out” by the proxy process. Multi-decade variations are smoothed by radiocarbon analysis, but are noticeable trends in the modern record.

  11. Case of ‘hide the decline’ cones to mind
    http://www.vukcevic.co.uk/GSST.htm
    Red graph was published by Gavin Schmidt in 2011 on RC
    http://www.realclimate.org/index.php/archives/2011/07/revisiting-historical-ocean-surface-temperatures/comment-page-2/

    Notes:
    – Anomaly axis shifted by 0.2C – not relevant to analysis.
    – Gavin’s graph shows that in two 30 year periods i.e. 1910-1940 rise in GSST is equal to that of 1980-2010.
    Gavin’s graph shows 30 year decline 1880-1910. Are we heading for another 30 year decline starting in the near future.

  12. A point unfortunately generally ignored in all these discussions, yet able to be understood with just some high school level knowledge of statistics, is the point that the range of temp data over the past 2000 yrs is just a matter of ~ 1degC. Using the very rough, but commonly used approximation that 1 SD is ~ 1/4th the range recorded, then all observations recorded over the last 2 millennia fall within +/-2 SD of the mean, ie–
    ~ 67% chance that all observations are just random variation about the mean….Add in the observational error of proxy studies (gotta be a couple degrees) and the +/- 0.5deg error in recent instrumental readings and one has to wonder, as long as we’re at it, how many angels can dance on the head of a pin?

    • guidoLaMoto == > As to angels, I always default to Douglas Adams’ “42”.

      I have written extensively here on the falacious lack of proper error ranges — both in published means and in original measurements.

  13. This contribution is not very quantitative, but it comes from a very relable source :Oxford Archaeology South , who have published a series of monographs on “Thames through Time” (paleolithic to the modern age).
    In the section on the medieval Rural Landscape they say:

    -“Vine cultivation appears to have reached its greatest extent in England between about
    1100 and 1220, when frosts were rare after the beginning of May, average summer
    temperatures were a degree or two warmer than today and Septembers were usually warm and
    dry. Even during the climatic optimum of the early middle ages there were occasional bad years
    when the grapes failed to ripen fully. They were then usually pressed and fermented to make
    verjuice, a kind of sharp vinegar used in cooking and pickling. The accounts of the gardener of
    Abingdon Abbey record no income from grapes in 1412–13, since they had all been retained
    in the infirmary for making verjuice. During the 13th century, some vineyards began to fall out
    of use, and the decline accelerated considerably during the 14th century. The vineyard at
    Tidmarsh seems to have gone out of use by 1305, when the holdings of John de Tidmarsh on
    his death included a dwelling with a garden ‘without the court which is called Wynherd’ (VCH
    1923, 434); there is no evidence that the manorial vineyard recorded there in 1239 was ever
    cultivated again.”-

    • Chris ==> I’d have to see a very much more rigorous analysis to draw your conclusion. You may be right — but I certainly would make a claim based solely on that graph.

  14. “bringing forward the Roman Warm Period and the Medieval Warm Period (MWP) — the years 100-800 CE (same scale) — to illustrate the difference between the peak Global Average Surface Temperature (GAST) of the Medieval Warm Period to the most current GAST on the graph (2015).”

    As Greg noted above, it isn’t either. The inset ends with the coronation of Charlemagne in 800. The MWP is normally reckoned to start about 950 ad. And the main peak is in the Dark Ages.

    It conforms to the local convention that the MWP is any peak, any time. And of course was worldwide (whenever it happened).

    • Nick ==> I’ll repeat my previous answer on this point:

      ” If all the temperature reconstructions agreed with one another, this would all be easier. 600 CE is a bit early for the MWP, which seems to show up a few hundred years early on this particular reconstruction. These early Warm Periods are similar in magnitude to the Modern Warm Period. The difference may be in the baseline (15 CE).

      See this wiki link for the divergence between reconstructions….sources listed at the bottom. At least one other reconstruction shows a peak at 600-700 CE. In that Wiki image, it is the Dark Red trace that we are most used to seeing — it is from Moberg (2005) (seems to be mislabeled in the Wiki text–but definitely from Moberg).”

    • I don’t trust any of the proxies to 1) actually show temperature, 2) have anywhere near the purported accuracy. They’re wild guesses.

      • Jeff ==> If I was ablke to insert images here, I would pop in the image from wiki showing the disagreement between differing proxies of the last 2k years temperature.

        https://commons.wikimedia.org/wiki/File:2000_Year_Temperature_Comparison.png

        The graph is “faked” in that it splices on the [supposed] thermometer record on the right hand side as if it relates directly in scale to the proxies….which it does not.

        Other versions

        https://commons.wikimedia.org/wiki/File:Holocene_Temperature_Variations.png

        https://commons.wikimedia.org/wiki/File:1000_Year_Temperature_Comparison.png

        Each version is accompanied by links to the sources for each of the proxy reconstructions.

        None of them come scientifically close to being accurate representations of temperatures in numeric form — they may have some relevance in relative temperatures — but not numerically — certainly not to 1/10ths of a degree C. That is a ridiculous idea — entirely unsupportable scientifically.

        So, I agree with you. And I agree with S. Mosher who famously stated:

        “The global temperature exists. It has a precise physical meaning. It’s this meaning that allows us to say…The LIA was cooler than today…it’s the meaning that allows us to say the day side of the planet is warmer than the nightside…The same meaning that allows us to say Pluto is cooler than Earth and Mercury is warmer.” [ source ]

        There, he has it right in a nutshell — but that’s all that we can really say…..

  15. In a roughly 2000 year time period, ending in 1980, we see temperature anomalies swing between -0.4C and +0.4C. A total range of just 0.8 C

  16. Given the acknowledged range of error in any temperature reconstruction and in modern estimates of global surface temperatures (today, in absolute temperatures, around +/- 0.5ºC or a range of 1ºC) — there may be little, if any, significant-to-the-global-environment difference between the two periods.

    In other words, “indistinguishable from zero”.

  17. Got to-
    “An ocean simulation that is forced by a combined instrumental-​proxy reconstruction of surface temperatures over the last 2,000 years shows..”
    and the eyes glazed over as usual but perseverance is a virtue-
    “As a consequence of the multicentury surface climate history, the ocean simulation suggests..”
    “Both historical hydrographic observations and proxy records of the subsurface Atlantic are needed to determine…”

    One warming measure to rule them all and that’s SLR geologically and our tide gauges that dismiss all their other poxy proxies academic tea leaf readings and political seances-
    https://www.ncdc.noaa.gov/news/what-are-proxy-data
    Call me when it begins to drop and I’ll join the preppers.

    In the meantime keep an eye out for the giant asteroids for me. That’s the one big downside of fossil fuels. It fostered the exponential growth of the non-productive classes. Talk about surplus value. Marx would turn in his grave at it all.

  18. What I find a little disconcerting is the complete exclusion of submarine tectonic activity when ocean temperatures are discussed. It is assumed that all rising water temperatures have a solar origin. For example the Atlantic rift has been recorded pumping out cubic miles of methane gas, what else is it discharging? The latest information in geology circles is that tectonic activity occurring between New Guinea and the Solomon Islands initiates the El Nino cycle. The oceans make up 71% of the Earth’s surface and average depth is 4000 meters. We only have 3000 buoys covering millions of square kilometres and effectively know stuff all. I know all the money is in the study of atmospheric science and the “renewable industries”, but if there was a little bit of honesty in”climate science” then serious studies would be also looking at volcanic activity in the oceans and maybe the ‘renewables’ wouldn’t cost us the Earth.

    • Christine ==> Sorry for the delayed response — I started to do some research for papers on the topic — but was interrupted by real life.

      There are studies on sub-oceanic volcanic activity. Such activity, as well as hot water vents, etc, do, of course, warm the ocean locally — they must — heat always always (almost) travels from warmer to colder.

      AGW activist sites publish blog posts poop-pooping the idea that there is any measurable effect. Also see here.

      We really know very little about ocean temperatures at the present time — in 20 or 30 years, we may have enough data to make some educated guesses about it.

  19. I suppose this point is not new:
    That the early data for the global temp readings will not have been an average of the recent 7 sources.

    Would the readings from the period prior to 1870 be representative of just one or two of the 7 regions – rather than being a fair representation of the whole area?

    If they aren’t comparable then the graph doesn’t show anything.

    • McBryde ==> The authors present the two as sort-of separate graphs – in Fig 1 — a double vertical line indicates both a change in time scale and a change from reconstruction of temps to “measured” temperatures.

      One has to read the whole study to understand what they are getting at.

  20. Atlantic warming since the Little Ice Age:
    https://tos.org/oceanography/article/atlantic-warming-since-the-little-ice-age

    Radiocarbon observations suggest that the deep Atlantic Ocean takes up to several centuries to fully respond to changes at the sea surface.

    You would expect the deep ocean circulation with a cycle time of several millennia, to indeed respond slowly at depth to any changes at the surface. Not surprising that the data confirm this.

    This does not stop alarmist scientists claiming that “missing” warming heat is somehow hiding in the deep ocean. That – miraculously – less than a century of surface warming is suffusing the abyssal ocean depths with disastrous warming.

    This is like a cosmologist proposing that a part of the universe outside of our “light cone” is influencing earth. This is impossible – outside of our light cone, light cannot travel to earth during the history of the universe. As the R.E.M. song put it, “you can’t get there from here”.

    The deep ocean is not in causal contact with the surface in real time. It takes centuries and millennia for changes of temperature and insolation at the surface to reach the deep ocean via changes in downwelling patterns.

    Water in the deep ocean can be defined in n terms of “age” in years since its “formation” by downwelling from the surface. This age can reach 3-4000 years in places like the North Pacific.

    The atmospheric nuclear bomb tests in the 1950’s and 1960’s have provided a valuable opportunity for a tracer study, using tritium (^3H, half life ) to directly map in 4D the Thermohaline circulation starting from the most important site of downwelling in the Northern Hemisphere, the Norwegian Sea.

    If eddys from surface wind were mixing seawater down the the bottom, then deep water would not have this old “age” of thousands of years. In general the thermocline is a barrier to vertical mixing.

    Alarmists snatching at the deep ocean as a place to domicile their missing warming, only shows that they are ignorant and contemptuous of oceanography.

  21. Epilogue:

    This essay is just to highlight the paper of interest and point out this paper shows it was as warm in the past in the Common Era as it is now.

    Some readers have pointed out that the paper’s reconstruction shows the Roman and medieval Warm Periods either conflated or with the MWP a bit early. While it is not my reconstruction — thus not mine to defend — I have supplied a link in Comments above (twice) that indicates that “reconstructions” are not measurements and that the generally disagree with one another — sometimes to a great degree.

    Fussing about differing guesses as to past GAST, when we cannot adequately measure and calculate the present GAST, is a fools errand — nonetheless, it is interesting to see what different groups of researchers come up with.

    Thanks for reading!

      • David ==> Steven Mosher sums up our ability to measure Global Average Surface Temperature:

        “The global temperature exists. It has a precise physical meaning. It’s this meaning that allows us to say…The LIA was cooler than today…it’s the meaning that allows us to say the day side of the planet is warmer than the nightside…The same meaning that allows us to say Pluto is cooler than earth and mercury is warmer.”

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