Most of the Recent Warming Could be Natural – Jennifer Marohasy

Posted: August 22, 2017 by oldbrew in climate, modelling, Natural Variation, Temperature
Tags: ,

The author notes that ‘while mainstream climate science is replete with published proxy temperature studies showing that temperatures have cycled up and down over the last 2,000 years – spiking during the Medieval Warm Period and then again recently to about 1980 as shown in Figure 12 – the official IPCC reconstructions (which underpin the Paris Accord) deny such cycles.’

We could add ‘and then says the science is settled’.
– – –
After deconstructing 2,000-year old proxy-temperature series back to their most basic components, and then rebuilding them using the latest big data techniques, John Abbot and I show what global temperatures might have done in the absence of an industrial revolution, writes Jennifer Marohasy

The results from this novel technique, just published in GeoResJ [1], accord with climate sensitivity estimates from experimental spectroscopy but are at odds with output from General Circulation Models.    

According to mainstream climate science, most of the recent global warming is our fault – caused by human emissions of carbon dioxide.

The rational for this is a speculative theory about the absorption and emission of infrared radiation by carbon dioxide that dates back to 1896.  

It’s not disputed that carbon dioxide absorbs infrared radiation, what is uncertain is the sensitivity of the climate to increasing atmospheric concentrations. This sensitivity may have been grossly overestimated by Svante Arrhenius more than 120 years ago, with these over-estimations persisting in the computer-simulation models that underpin modern climate science. We just don’t know; in part because the key experiments have never been undertaken.

What I do have are whizz-bang gaming computers that can run artificial neural networks (ANN), which are a form of machine learning: think big data and artificial intelligence. My colleague, Dr John Abbot, has been using this technology for over a decade to forecast the likely direction of particular stock on the share market – for tomorrow.   

Since 2011, I’ve been working with him to use this same technology for rainfall forecasting – for the next month and season. And we now have a bunch of papers in international climate science journals on the application of this technique showing its more skilful than the Australian Bureau of Meteorology’s General Circulation Models for forecasting monthly rainfall.

During the past year, we’ve extended this work to build models to forecast what temperatures would have been in the absence of human-emission of carbon dioxide – for the last hundred years.  

Continued here.
– – –
[1] The new paper in GeoResJ is available free of charge until 30 September 2017, at this link:

  1. reetsmeets says:

    Unbelievable theory- I think it is all true. Kindest regards RITA LAWTON

  2. Bitter&twisted says:

    Typical of the denier, Marohasy, trying to confuse us with facts.
    We don’t need no steenkin’ facts, the science is settled.

  3. oldbrew says:

    Date: 22/08/17 Jennifer Marohasy, The Spectator

  4. renewableguy says:

    Could be? But is it? What is the explanation for the recent warming of the last 150 years? Did the sun do it? No! The sun has been observed to be mildly cooling from satellite observations over the last 30+ years.

    That would be reverse correlation. So what are other natural sources that could warm the earth dramatically compared to the past 10,000 years.

    A very good explanation is ghg’s added by humans.

    [Moderation note] Integrated Sunspot number increased all the way to 2003

  5. renewableguy says:

    There are two different parameters I would like to point out in this graph. Very unlikely above and very unlikely below. This talks about climate sensitivity to a doubling of co2 from 280ppm to 560ppm co2.

    very unlikely below ranges from 1*C to 2.5*C added to average earth temperature
    very unlikely above ranges from 4*C to 8.0*C added to average earth temperature

    We have come about 1*C above the average temperature of earth from 1850. We have more warming to go and have not stopped polluting co2. The bottom is really already capped off, the top end is highly expansive in possibility.

    I’m surprised you even bring the discussion up with the need to win the AGW argument isn’t bad, when the possibility can really be horrid. If you are low risk people, you don’t go there. ou get off of fossil fuels.

  6. Bitter&twisted says:

    I do hope you are setting a good example and practicing what you preach:
    Living in a home, powered solely by wind & solar.
    Not driving a car, only eating locally-sourced food.
    No foreign holidays etc etc.

  7. oldbrew says:

    As the research says, Earth has had warming and cooling periods in the past which were unrelated to ‘fossil fuels’. This is the rule in climate history, not the exception.

    Saying today is different is an assertion not a proven fact.

  8. It wouldn’t surprise me to learn that renewableguy is profiting from the renewable energy scam, which is dependent on the climate change scam.

  9. Brett Keane says:

    rg, give us a physical science basis, not rooted in failed non-validated CMIPs. Or stop wasting our time.

  10. renewableguy says:

    Bitter&twisted says:
    August 22, 2017 at 4:08 pm
    I do hope you are setting a good example and practicing what you preach:
    Living in a home, powered solely by wind & solar.
    Not driving a car, only eating locally-sourced food.
    No foreign holidays etc etc.


    I buy 100% wind through my utility.
    I drive an electric car.
    Food, not so good.
    I take every holiday I can and I am looking for more. lol

  11. renewableguy says:

    Phillip Bratby says:
    August 22, 2017 at 5:27 pm
    It wouldn’t surprise me to learn that renewableguy is profiting from the renewable energy scam, which is dependent on the climate change scam.


    There are gigawatts of production of renewable energy around the world in replying to your assertion of scam. There are a few bad people out there and we all have to be aware. You can literally live off grid with ALMOST 100% renewable energy with fossil fuels only needed for rare backup.

    I am not making money installing or selling renewable energy.

  12. tom0mason says:

    Why are you quoting the IPCC piece?
    Jennifer made her stance on it clear on the link above (the ‘Continued here.’ link above)–

    The Intergovernmental Panel on Climate Change (IPCC) estimates warming of approximately 1°C, but attributes this all to industrialization.

    The IPCC comes up with a very different assessment because they essentially remodel the proxy temperature series, before comparing them with output from General Circulation Models. For example, the last IPCC Assessment report concluded that,

    “In the northern hemisphere, 1983-2012 was likely the warmest 30-year period of the last 1,400 years.”

    If we go back 1,400 years, we have a period in Europe immediately following the fall of the Roman empire, and predating the MWP. So, clearly the IPCC denies that the MWP was as warm as current temperatures.

    This is the official consensus science: that temperatures were flat for 1,300 years and then suddenly kick-up from sometime after 1830 and certainly after 1880 – with no decline at 1980.

  13. oldbrew says:

    Vikings grew barley in Greenland
    February 3, 2012

    A sensational find at the bottom of an ancient rubbish heap in Greenland suggests that Vikings grew barley on the island 1,000 years ago.
    – – –
    ‘The Greenland climate was a bit warmer than it is today’

  14. tom0mason says:

    And here are a few studies that show the MWP had effects in the orient …

  15. renewableguy says:

    Brett Keane says:
    August 22, 2017 at 6:39 pm
    rg, give us a physical science basis, not rooted in failed non-validated CMIPs. Or stop wasting our time.


    Empirical and computer models come within reasonable agreement with each other. One strengthens the other giving each other validation.


    Climate sensitivity from empirical observations
    There have been a number of studies that calculate climate sensitivity directly from empirical observations, independent of models.

    Lorius 1990 examined Vostok ice core data and calculates a range of 3 to 4°C.
    Hoffert 1992 reconstructs two paleoclimate records (one colder, one warmer) to yield a range 1.4 to 3.2°C.
    Hansen 1993 looks at the last 20,000 years when the last ice age ended and empirically calculates a climate sensitivity of 3 ± 1°C.
    Gregory 2002 used observations of ocean heat uptake to calculate a minimum climate sensitivity of 1.5.
    Chylek 2007 examines the period from the Last Glacial Maximum to Holocene transition. They calculate a climate sensitivy range of 1.3°C and 2.3°C.
    Tung 2007 performs statistical analysis on 20th century temperature response to the solar cycle to calculate a range 2.3 to 4.1°C.
    Bender 2010 looks at the climate response to the 1991 Mount Pinatubo eruption to constrain climate sensitivity to 1.7 to 4.1°C.

  16. The sun should have not had a cooling effect upon the climate until year 2005.

    This year ,year 2017 after following 10+ years of sub solar activity in general the solar parameters which I think are needed for a global cooling impact are now starting to be realized.

    It is a low solar, translating to an increased albedo/lower overall sea surface temperature play that I think will lead to global cooling with year 2017 being a transitional year .

    I have been calling for this for years saying if low average value solar parameters are meant following 10+ years of sub- solar activity in general the solar effect would be global cooling.

    I do not believe in the slow gradual forever climate change so many embrace.

    So many never call a turn in the climate, at best they make such a forecast for sometime in the distant future which is meaningless.

    solar parameters needed for cooling and status

    solar flux sub 90 attained

    solar wind sub 350km/sec not attained

    ap index 5 or less not attained

    euv light less than 100 units attained

    galactic cosmic ray count above 6500 units attained

    IMF 4.2 NT not attained

    solar irradiance off .15% from solar maximum high point not attained but was during the 2008-2010 solar lull .

    With the sun still having 2 or 3 years to go before minimum conditions are attained, and staying weak thereafter at least below average sub solar activity I expect the global cooling trend which has started in year 2017 I believe to continue.

  17. oldbrew says:

    Dr Marohasy writes:
    In our new paper in GeoResJ, we not only use the latest techniques in big data to show that there would very likely have been significant warming to at least 1980 in the absence of industrialisation, we also calculate an Equilibrium Climate Sensitivity (ECS) of 0.6°C. This is the temperature increase expected from a doubling of carbon dioxide concentrations in the atmosphere. This is an order of magnitude less than estimates from General Circulation Models, but in accordance from values generated from experimental spectroscopic studies, and other approaches reported in the scientific literature [9,10,11,12,13,14] — [bold added]

  18. oldbrew says:

    Why They Need To Hide The 1940’s Blip
    Posted on August 22, 2017 by tonyheller

    Troposphere temperatures show very close correlation with the Atlantic Multidecadal Oscillation (AMO) and essentially no correlation with CO2.

  19. dai davies says:

    There is a fundamental problem here that runs through all the analysis from Abbot and Marohasy to the junk science quoted by RG. It goes back to the fundamental assumption of CS that the only game in town is heat trapping in the atmosphere by radiative gasses – the greenhouse effect, GHE.

    The alternative is what N&Z labelled as the Atmospheric Thermal Enhancement, ATE. On Earth, it too is largely caused by water vapour, but there is an important difference in that the ATE is almost saturated while the GHE would increase roughly linearly with radiative gas concentration. Except that’s almost all from water vapour which is controlled by the evaporation/condensation cycle, not CO2 or us.

    It has been shown by N&Z, myself, and others that the ATE is fully capable of explaining heating above that of a planet without an atmosphere. The GHE is still just an unverified assumption. My calculations suggest that it’s negligible. Heat isn’t trapped because the atmosphere doesn’t have a lid. It leaks to space, and rapidly enough to cause little heating.

    Climate sceptics are generally still implicitly and explicitly conceding the GHE assumption. As a rough indication, anyone using the concept of climate sensitivity is probably doing so.

    I also have a problem with using proxy data. Who’s proxies? I think the only justifiable temperature data is ocean temperatures. They are real, broad geographical, temp measurements and known to cycle on scales up to millennial. They dominate atmospheric temperatures.

    My analysis of ocean surface temperatures, trying to include a linear component representing a hypothetical CO2 influence, show a maximum possible contribution for CO2 of around 0.3 C/century.

    Note that this is an upper limit. I think, for the reasons above, that all other estimates of CO2 influence should be seen the same way.


  20. renewableguy says:

    dai davies says:
    August 23, 2017 at 12:57 am

    My analysis of ocean surface temperatures, trying to include a linear component representing a hypothetical CO2 influence, show a maximum possible contribution for CO2 of around 0.3 C/century.


    I’m not familiar with your way of thinking about the climate dai. Since we live in the atmosphere and not the ocean, the trend so far is 1.75*C per century. This could change. It will most likely accelerate.


    Trend calculation: Start date: 1987 End date: 2017

    Trend: 1.75 ±0.58 °C/century (2σ)

    [Moderation note] When the ocean surface cools, air temperature follows three months later.

  21. renewableguy says:

    Salvatore del Prete says:
    August 22, 2017 at 9:54 pm
    The sun should have not had a cooling effect upon the climate until year 2005.


    The sun has slightlyy dipped in intensity and yet the earth kept warming. CO2 has been shown based in evidence to be the warming agent. The sun slightly cooling makes easier to distinguish that it is our co2 warming the earth.


    [Moderation note] Links to sks removed. Further comments containing sks links will go straight into the spam bin. Find a science website to illustrate your points.

  22. dai davies says:


    the trend so far is 1.75*C per century. This could change. It will most likely accelerate.

    I doubt it. The SST data follows a few basic cycles quite closely. Here’s an extrapolation (blue line) along with 10% variations in parameters:

    Or a close up from another model:

    If you are seriously interested, look at the Energy&Atmosphere article it comes from or the Natural Cycles article that outlines the modelling approach.


  23. dai davies says:

    Done it again 😦

    ‘ articles/Climate PP/images/SST model.gif’


  24. dai davies says:

    Doesn’t like spaces in file names? [correct – mod]

  25. tallbloke says:

    A simple model I made matches SST well with the 60yr oceanic cycles, integrated sunspot number, and CO2 lagging temperature as it always does. The best fit was obtained with a CO2 doubling value of around 0.6C, similar to Jen Marahosy’s estimate.

    The model get R^2=0.9 for monthly data since 1875. Way better than anything the IPCC CMIP models have come up with.

    My model predicts a longer delay before cooling sets in than Dai’s model does. This is due to strong el nino events occurring as the ocean sheds the excess energy it gained from the strong late C20th Sun. The ocean integrates solar energy, and releases it when the Sun diminishes. This is why SST lags behind longer term (Gleissberg cycle length) solar variation by a decade or two.

    I recommend renewableguy does some investigation of his own, rather than parroting IPCC or (ffs) the “Skeptical Science” website.

  26. tallbloke says:

  27. dai davies says:

    Interesting comparison Roger. I’m using southern SST only. That may be a difference. Both 200y and 800y cycles have started dropping which drag this century down fast.

    Integrating trig functions is same as a 90º phase shift which complicates a comparison. I started with Nicola’s sunspot model and fitted phase and magnitudes to southern SST. I assumed that SSN and SST would be out of exact resonance and shift in phase over time. That’s true, it seems, for 11y cycle. My best automated models fit that by introducing two cycles about 1y apart in period and about 130º apart in phase (~360/3?). There’s a resonance mismatch between planetary orbits and sun’s core as well as sun-ocean mismatch. Three almost-resonant systems interacting.

    Log CO2 seems strange. CO2 saturation is log against IR levels, but double NCO2 and you double absorption at the same saturation level, so I think ∆T should be roughly linear with concentration of RGs for GHE but saturated for ATE as shown in graphs in my Radiative Delay in Context article. Maybe you have shown that it ATE is dominating GHE! But it’s been a long day and I really should sleep on that one.

    It’s going to take a lot to convince me that CO2 has more than a minimal (~0.01 C) GHE. Still have zero comments on my Radiative Delay article. Which, BTW, I am making a change to when I get around to it. I’ve put a note up. Latest delay heating half what I originally calculated, about 0.15 C for whole GHE/RDE – ie mainly water vapour.


  28. dai davies says:

    Trying to crystallise where my RD analysis varies from CS. It’s the difference between looking at the atmosphere as a passive absorber and looking at is an active medium awash with collision induced radiation.

    As a passive absorber, double RGs and you reduce saturation for same IR, assumed to be just that emitted from surface. For active medium, double RGs and you double collisional IR, which is most of it above an altitude of around 50m, so saturation stays the same – give or take.


  29. oldbrew says:

    Date: 23/08/17 Chinese Academy Of Sciences

    “We found four warm epochs,” says Prof. Quansheng Ge. Data show records for the periods AD 981–1100 and AD 1201–70 are comparable to the present warm period.
    . . .
    Since 1000 CE—the period covering the Medieval Climate Anomaly, Little Ice Age, and the present warm period—temperature variations over China have typically been in phase with those of the Northern Hemisphere as a whole.
    – – –
    An increase in precipitation in the monsoonal regions of China corresponding with 20th century warming can primarily be attributed to a mega-ENSO (one significant cause of interannual-to-interdecadal variations in global SST), as well as the AMO.
    – – –
    More natural variation evidence – no industrial-scale coal/gas/oil in those days. Claims like ‘hottest year ever’ for recent times are suspect, but even if true (in the modern interglacial at least) do not prove anything about the causes.

  30. Tim Hammond says:

    Renewableguy, you commit a number of fallacies. If this warming has happened before and that wasn’t CO2, then the simplest hypothesis is that it isn’t CO2 now. You have to PROVE its CO2, not just say we don’t know anything else it could be. As for risk, that is a fallacy too. You don’t automatically avoid a risk if the definite costs of avoidance massively outweigh the potential costs if the risk occurs – I don’t pay more than the value of my house in insurance. Do you?

    And of course models tuned to past data match past data. I can do that in four lines on Excel. And then if I run that model to predict the future enough times. I will get a run that looks like the future. But a good model doesn’t need tuning, nor does it need multiple runs. So these are, by definition, poor models. When you can build a model from first principles that can “predict” the past without tuning and then can accurately predict the future in a single run, come and wake us up.

  31. oldbrew says:

    Historically CO2 levels followed temperature, never led it. Warming oceans expel some CO2, and cooling oceans absorb more. This is well-known science, part of the carbon cycle.
    – – –
    Gore’s polar bear alarmism bites the dust…

    Fat polar bears [and lots of them] drive public confidence in future of the species
    Posted on August 23, 2017

  32. oldbrew says:

    Research pair suggest global warming almost completely natural (Update)
    August 23, 2017 by Bob Yirka

    Read more at:
    – – – normally features reports of ‘warmist’ climate science, blaming CO2, dire future weather scenarios etc.