Most of the Recent Warming Could be Natural

This story broke while Anthony and I were eclipse hunting. ~ctm

From Jennifer Marohasy

By jennifer on August 21, 2017 in Information

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.  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 overestimations persisting in the computer-simulation models that underpin modern climate science [2].  We just don’t know; in part because the key experiments have never been undertaken [2].

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 [4,5,6].  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.

We figured that if we could apply the latest data mining techniques to mimic natural cycles of warming and cooling – specifically to forecast twentieth century temperatures in the absence of an industrial revolution – then the difference between the temperature profile forecast by the models, and actual temperatures would give an estimation of the human-contribution from industrialisation.

Firstly, we deconstruct a few of the longer temperature records: proxy records that had already been published in the mainstream climate science literature.

These records are based on things like tree rings and coral cores which can provide an indirect measure of past temperatures.  Most of these records show cycles of warming and cooling that fluctuated within a band of approximately 2°C.

For example, there are multiple lines of evidence indicating it was about a degree warmer across western Europe during a period known as the Medieval Warm Period (MWP).  Indeed, there are oodles of published technical papers based on proxy records that provide a relatively warm temperature profile for this period [7], corresponding with the building of cathedrals across England, and before the Little Ice Age when it was too cold for the inhabitation of Greenland.

I date the MWP from AD 986 when the Vikings settled southern Greenland, until 1234 when a particularly harsh winter took out the last of the olive trees growing in Germany.  I date the end of the Little Ice Age as 1826, when Upernavik in northwest Greenland was again inhabitable – after a period of 592 years.

The modern inhabitation of Upernavik also corresponds with the beginning of the industrial age.  For example, it was on 15 September 1830 that the first coal-fired train arrived in Liverpool from Manchester: which some claim as the beginning of the modern era of fast, long-distant, fossil-fuelled fired transport for the masses.

So, the end of the Little Ice Age corresponds with the beginning of industrialisation.  But did industrialisation cause the global warming?

In our just published paper in GeoResJ, we make the assumption that an artificial neural network (ANN) trained on proxy temperature data up until 1830, would be able to forecast the combined effect of natural climate cycles through the twentieth century.

We deconstructed six proxy series from different regions, with the Northern Hemisphere composite discussed here. This temperature series begins in 50 AD, ends in the year 2000, and is derived from studies of pollen, lake sediments, stalagmites and boreholes.  Typical of most such proxy temperature series, when charted this series zigzags up and down within a band of perhaps 0.4°C on a short time scale of perhaps 60-years. Over the longer nearly 2,000-year period of the record, it shows a rising trend which peaks in 1200AD before trending down to 1650AD, and then rising to about 1980 – then dipping to the year 2000: as shown in Figure 12 of our new paper in GeoResJ.

Proxy temperature record (blue) and ANN projection (orange) based on input from spectral analysis for this Northern Hemisphere multiproxy. The ANN was trained for the period 50 to 1830; test period was 1830 to 2000.

The decline at the end of the record is typical of many such proxy-temperature reconstructions and is known within the technical literature as “the divergence problem”.  To be clear, while the thermometer and satellite-based temperature records generally show a temperature increase through the twentieth century, the proxy record, which is used to describe temperature change over the last 2,000 years – a period that predates thermometers and satellites – generally dips from 1980, at least for Northern Hemisphere locations, as shown in Figure 12.  This is particularly the case with tree ring records. Rather than address this issue, key climate scientists, have been known to graft instrumental temperature series onto the proxy record from 1980 to literally ‘hide the decline’[8].

Using the proxy record from the Northern Hemisphere composite, decomposing this through signal analysis and then using the resulting component sine waves as input into an ANN, we generated a forecast for the period from 1830 to 2000.

Figure 13 from our new paper in GeoResJ shows the extent of the match between the proxy-temperature record (blue line) and our ANN forecast (orange dashed line) from 1880 to 2000.  Both the proxy record and also our ANN forecast (trained on data the predates the Industrial Revolution) show a general increase in temperatures to 1980, and then a decline.

Proxy temperature record (blue) and ANN projection (orange) for a component of the test period, 1880 to 2000.

The average divergence between the proxy temperature record from this Northern Hemisphere composite, and the ANN projection for this period 1880 to 2000, is just 0.09 degree Celsius. This suggests that even if there had been no industrial revolution and burning of fossil fuels, there would have still been some warming through the twentieth century – to at least 1980.

Considering the results from all six geographic regions as reported in our new paper, output from the ANN models suggests that warming from natural climate cycles over the twentieth century would be in the order of 0.6 to 1 °C, depending on the geographical location. The difference between output from the ANN models and the proxy records is at most 0.2 °C; this was the situation for the studies from Switzerland and New Zealand.  So, we suggest that at most, the contribution of industrialisation to warming over the twentieth century would be in the order of 0.2°C.

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.

To be clear, 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.  Through this denial, leaders from within this much-revered community can claim that there is something unusual about current temperatures: that we have catastrophic global warming from industrialisation.

To read the full article go here:

HT/Doug

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159 thoughts on “Most of the Recent Warming Could be Natural

  1. Wow, how did this paper get through and what nerve to use the proxy data to show something other than what the consensus dictates. These people need to be vilified immediately! Seriously, I wonder if there would be any difference without the tree ring data.

    • Don’t overlook that the tree ring data did not show any 1970s warming. This is mentioned in the Climategste emails.

      We know from.the satellite data that there may have been no warming from 1979 and the run up to the Super El Nino of 1997/98. There is a very slight positive trend over this about 17 year period of about 0.1 deg C but within the error bounds of measurement this is not statistically significant.

      The only statistically significant warming seen in the satellite data is the approx 0.3 deg C step change coincident upon the Super El Nino of 1997/98.

      The present ENSO cycle has yet to complete with a LA Nina so it is premature to conclude whether there is any statistically significant trend following the Super El Nino of 1997/98.

      Essentially, the satellite data shows short lived responses to Volcanoes and ENSO events all of which are natural of origin with just a large step change in temperature coincident with the Super El Nino of 1997/98.

      The more I look at the data and evidence, the more I consider that the Northern Hemisphere is no warmer today than it was in the late 1930s/early 1940s. As regards the Southern Hemisphere (and hence the globe) we just do not know since the SH is too sparsely sampled with little spatial coverage and all but no historic records/data.

      Phil Jones notes this in his 1980 paper and Hansen cooments upon this in his 1981 paper without joining issue. Further in the Climate gate emails, Phil Jones goes as far as saying that most of the SH temperatures are largely made up. He is factually correct on that call since there is such a paucity of historic data.

      • This study uses one series of proxy “temperatures” to predict another. It worked quite well. But the paper acknowledges that some of the proxies, such as tree-rings, are almost useless for determining temperature – eg, see “hide the decline”. So the study might not actually represent just temperature. It does show that there is predictability in the proxies, and the proxies do have some kind of connection with climate, so the study does seem to show that climate has predictable patterns. That’s useful, but I don’t think that the study has predicted temperature.

        Another possibility is that some of the proxies might be better than our surface temperature “measurements”. Interesting.

      • RV,
        We have tried various Australian studies. Leaving aside the noise/error problem, we can perhaps see 0.4 deg C warming 1900-2000. Less than the official 0.9 deg after homogenisation. Geoff

    • We all know that the tree ring data study was fundamentally flawed, but it had stumbled across one important fact, namely the adjusted thermometer record by the late 1990s had diverged so significantly from reality such that the merits and the extent of the adjustments made between the early 1980s and the late 1990s required re-evaluating.

      Rather than hiding the decline, Mann’s paper ought to have focused on the adjusted land based thermometer record, and examined why that record was so greatly diverging from reality. To what extent was it due to adjustments, such as station drop outs with high latitude stations dropping out, a shift from rural to urban, a continuing shift to airport stations, incorrect adjustments for UHI etc. etc

      The tree rings were telling Briffa, Mann et al that the late 1990s (prior to the effects of the Super El Nino of 1997/98 panning out) that the Northern Hemisphere was no warmer than it was in 1940, which is probably broadly correct. There is no reason why the (contiguous) US should be an outlier and it is probably no coincident that it has the best sampling and the best historic records.

      Mann could have put forward real science and something not simply of interest but something that would have greatly contributed to the science and which would have enabled it to get back on track. Mann could have enjoyed a legacy as a venerated and proper scientist, instead history will probably judge him as nothing more than a 3rd rate paddler of a cargo cult with his reputation in tatters.

  2. It’s funny how often you hear “the end of the Little Ice Age happened at the same time as the start of the Industrial Revolution.” In the AGW world, the industrialization cause the end of the ice age.

    But what if it’s the other way around?

    Suppose the end of the Little Ice Age allowed the Industrial Revolution to happen? Weather at sea improved, allowing more reliable intercontinental shipping. Rivers weren’t frozen as much, allowing internal freight movement and the construction of more canals. Snowfall didn’t block railway construction. Improved growing seasons allowed fewer farmers to grow more food, which freed up more workers (along with new tech) to make new industries.

    Et cetera, et cetera…

    • That’s what I think happened. I remember making a brief comment here years ago and someone wrote a much more eloquent reply in support.

    • Chad 🇹🇩
      Alternatively, since the industrial revolution was beginning as early as the 1700’s with the proliferation of lime kilns in England, right in the middle of the LIA, maybe industrialisation was needed due to the challenges to society of cold weather.

      In fact the industrial revolution was an inevitable continuation of the renaissance which started in the 1600s with Galileo, Vesalius and Newton etc.

      • The Industrial Revolution relied upon coal, which required steam engines to mine, then used coal in other applications.

        Coal became more important as forests were cut down during the LIA.

        The end of the Renaissance period is hotly debated, but generally considered to have occurred at some point in the 17th century. The Renaissance overlaps both the Late Middle Ages and Early Modern periods, ie from the terrible 14th to almost as bad 17th centuries, hence beginning and ending sometime between AD 1300 and 1700.

        I’d venture to say it lasted from after Giotto to before Rembrandt, but an art historian might vehemently disagree with me.

        Thus, Vesalius and Copernicus were definitely of the Renaissance, Kepler and Galileo probably, but Newton possibly not. If so, then he’s also a Reformation character, being a Puritan. Kepler would also qualify as a Reformation figure.

    • Britain was running out of trees to cut down. Maintaining a massive sail fleet of boats made of trees that had to be replaced every 20-30 years. Trees that also had to supply energy for brewing and heating of a quickly increasing population. It came at a fortuitous time for Britain and all of Europe, the Age of Sail had to come to an end in one way or another,

      • The discovery of oil also came at the right time, since the world was running out of Whales.

      • Richard, that’s a great historical point you raise.

        The repopulation of whale species in the last century, since most of the West laid down the harpoon, has been one of the great conservation success stories.

        Unfortunately, with a new whale born almost every day, it’s getting harder and harder to denialize the scientific facts: the fossil fuel industry really IS to blame for rising sea levels!

      • Richard, Brad and Ptolemy2, I’m suspect that you and all of our readers have heard it many times but, I am in your camp which believes that this combined series of natural events and the man-made response is definitive proof that John D. Rockefeller, and his Standard Oil and all their copycats, is/are what REALLY saved the whales.

        Q: With such a consensus, do any of you suspect that we can get Green Peace and their lot to join in on this message? [Note: I am not holding my breath.]

      • Ah, Got it.
        The sea level rise is attributable to thousands of extra whales, more ships of larger displacement, all the offshore wind farms and all the sediment,and trash flowing in worldwide from every river that makes it to the sea.

      • Johnny Cuyana,

        cool name. No, I don’t expect Greenpeace to thank Big Oil, begrudgingly or otherwise, ever, for saving the whales. Don’t forget your history, lest ye be doomed to reheat it:

        First ‘Green Revolution’

        From now on, civilized people will have the peace of mind that comes with knowing every drop of oil they use is sourced from ethical, nature-friendly dinosaur juice.

        Like all human progress, this is a bad thing. The new “fossil fuel industry” may have solved one problem for the planet but it will ultimately create a much graver one: anthropogenic global warming (also known as man-made climate change) skepticism.

    • Cold and hungry are a great incentive to invent something….
      …when everyone’s fed and comfortable it’s working…so why change it

    • It’s extremely important to recognize also that industrialization was not a sudden binary flip in civilization. Industrialization began, slowly, only in advanced industrialized nations of western Europe and parts of North America in 1830, but most people lived in rural areas and small areas dependent upon agriculture and natural resource extraction until well into the 20th century, and then only in the first world, while the vast majority of humans still lived off agriculture. For instance, in 1850 the farm population in the USA was 65%, and by 1916 it was still 32%. In third world nations, especially heavily populated ones like China and India, the percentages of agrarian populations were much higher for much later, until well into the second half of the 20th century

      The amount of carbon emitted is directly related to actual industrialization and use of machine power.

      So the signature left behind by industrialization should have been negligible until at least the onset of the 20th century, and very slight until the second half of the 20th century. Yet the end of the little ice age came suddenly at the end of the first quarter of the 19th century.

    • The end of the LIA made the industrial revolution possible.
      The warmer and more predictable growing season, combined with agricultural reforms, freed up workers. Workers who could now be used in the mines and factories. And Britain was lucky to have easily mined coal, to power the factories.

    • If climate science actually had to demonstrate cause and effect, rather than fallaciously conflate correlation with it, well, we might as well just start drinking Martinis right now.

  3. “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.”

    Your evidence seems to be that they say ““In the northern hemisphere, 1983-2012 was likely the warmest 30-year period of the last 1,400 years.”

    That is not denying cycles at all. That is simply saying that the temperatures over that period were likely higher than during any of the previous cycles.

    The paper looks interesting and I will certainly read it

    • seaice1, seaice1, seaice1….
      You see, when there’s a statement made, and then an EXAMPLE given….that example is directed at the previous statement. FOR EXAMPLE:

      “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.”

      You, on the other hand, had to take a sentence out of context, and then apply it to something stated three paragraphs prior to it. Whereas the paragraph that you wanted to apply that sentence to, actually explains itself: (note it even starts with the words “to be clear”….)

      To be clear, 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. Through this denial, leaders from within this much-revered community can claim that there is something unusual about current temperatures: that we have catastrophic global warming from industrialization.”

      So, the IPCC’s reconstructions are completely absent of, do not include, are apparently in opposition to/denial of the mainstream climate science that is replete (filled, full, crammed, packed, overflowing) with published proxy temperature studies that show “temperatures cycling up and down over the last 2,000 years.”…because they “essentially remodel their proxy temperature series”.

      I’m glad you’re going to read the paper. I’m sure Jennifer would be happy to help you understand any of it that isn’t “clear” to you.

      • That’s hilarious, Janice. Seaice did the same thing yesterday. If it wasn’t for altered data and strawmen, alarmists would be left with nothing to say.

      • I consider that we very much underestimate the temperatures of the past.

        On another article, Dr Roy Spencer sets out a photo of recent glacial retreat (Mendenhall Glacier) that shows that trees were growing in the area some 1000 to 2000 years ago. Viz

        These are big and established trees. Whilst the glacier has today retreated, no doubt the ground remains permafrost and nothing of significance can yet grow in the vicinity. The question that needs to answered, is how much warmer does it need to be before substantial trees will grow?

        It will take more than a few tenths of a degree of temperature rise to get rid of the permafrost. My guess is that when those trees were growing, it must have been at least 2 degrees if not several degrees warmer than today.

      • Aphan, The assertion is false anyway.

        Lots of up and down, including a high during the MWP and a low in the LIA. It is nonsense to say the IPCC denies this.

      • seaice writes

        Lots of up and down, including a high during the MWP and a low in the LIA. It is nonsense to say the IPCC denies this.

        And today’s temperatures are pretty much exactly those of the MWP according to the proxies. You have to compare like to like when making that assessment. If you look at the modern temperature record instead of what the proxies are telling you then its a straight out invalid comparison.

      • richard verney August 24, 2017 at 2:05 am
        These are big and established trees. Whilst the glacier has today retreated, no doubt the ground remains permafrost and nothing of significance can yet grow in the vicinity. The question that needs to answered, is how much warmer does it need to be before substantial trees will grow?

        Plenty of trees in the vicinity.

      • seaice1, seaice1,seaice1,

        Let’s examine what she ACTUALLY said…rather than what you “inferred” that she said:

        “(1)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,

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

        (3)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.”

        Let’s look at your charts.
        1. Yep, they look like they all estimate a warming of approximately 1C AFTER the industrial revolution.
        2.None of them actually show the temperatures past 2000, but that upward racing line does start at 1983 and does demonstrate the warmest temperatures of the last 1400 years.
        3. They do NOT show an MWP as warm as current temperatures.

        “To be clear, 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 – (1)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. ”

        1. NONE of the IPCC charts you presented show a “spike” during the MWP and then recently to about 1980 and then remaining stable or dropping a little.

        Now, you and Jennifer might have a disagreement over the word “cycle”, but I logically doubt that you both disagree with the words “up and down”. She didn’t say “the IPCC denies that the temperature fluctuates” or that the “IPCC denies that temperatures go up and down”. So I suggest that you either enjoy making yourself look foolish, or you have no idea what the dictionary definition of the word “cycle” is. (Hint….Jennifer’s paper talks about cycles….I think she refers to them as sine waves…which most scientifically literate people translate as representing cycles….)

        Oh, and one last thing. Jennifer’s charts are just proxy “measurements” from the year 50 to the year 2000. There’s no baseline to compare them to. Just simple data over time in a nice clear, high resolution. YOUR charts are “anomalies” charted over a much longer, more “blurry”/noisy period of time in relation to a specific baseline of 1961-1990. If you have no idea why it’s completely illogical/silly/dishonest to compare the two at all….much less how doing so does absolutely nothing to prove your conclusion in the least….ask someone here to help you. I’m sure someone would be happy to. I’m just here to point out flawed logic and where your own inferences are not reflected in Jennifer’s actual statements.

      • Aphan. aphan, aphan. So you acknowledge that the IPCC accepts all the variation claimed by Jennifer, but does not accept exactly the same cycles interpretation she does. Whoopy do. Some claim. All the published data is accepted by the IPCC, but they do not interpret it quite the same as I do. Some claim.

        Anyway, there is no denial of them, as this sort of fitting is quite common. Mainstream climate science accepts things like the AMO. These are well recognised in mainstream science and it is nonsense to say mainstream science denies such cycles.

      • Nice try Icey, but she specifically speaking of proxy temperature cycles….not the AMO, or bicylces, or unicycles. You’re really off your game lately with all this desperate out-of-context stuff.

    • Seaice,

      There has yet to be a single 50 year interval in the CET during the Current Warm Period to equal a number of such periods in the Medieval WP. Which is really remarkable when you consider how cooked the Met’s books are.

    • The science was settled years ago – so why spend money on climate research

      • Joe, correct you are … but, you, I and many others have been for years advocating this approach: turn off that money spigot … chasing bad money with good.

        However, our same group, ALL ALONG, has known that the efforts of these enviro-whackos were NEVER about the science; where, in reality, their [pseudo] science was only the “tool” to serve their self-serving desires of control and power.

    • Probably it should be burned along with those who create it. The only way to keep the world clean for the believers! It is sinful!

  4. So, we suggest that at most, the contribution of industrialisation to warming over the twentieth century would be in the order of 0.2°C.

    This is inline with my estimation.
    The averages of 80 million stations (correctly averaged temperatures BTW).

    • The disturbance in the early 70’s corresponds to a large shift in the number of stations.
      As you can tell I do not “normalize” or “infill”, my intention was to examine what was actually measured, not the post processed trash that is published as the GMST.

  5. most of the recent global warming is our fault .
    The use of the word fault implies that the results of global warming are not beneficial. This has never been shown.

    • To be honest, mobs and pitchforks do not require verified claims. Gore is counting on that fact.

      • Which brings up an interesting question. If mother nature is proven to be the one “at fault” will alarmists then seek ways to force the planet to reduce it’s carbon footprint? Will they insist on corks being placed in volcanic vents, both above ground and in the oceans? Will they tax states in which there is more naturally occurring CO2 than others? Will they view the planet as a malevolent place that wants to destroy all of our children’s futures?

    • ” The use of the word fault implies that the results of global warming are not beneficial. This has never been shown.”

      Nor will it ever have to be shown.

      Repeat question-begging words like “blame” ad tedium, and the public eventually takes the missing premise for granted.

      And don’t forget your Neopaganism 101:

      — Science says that most global warming (around 120-130%) is old-white-mankind’s fault

      — This doesn’t rule out that some (around negative 25%) is thanks to nature

      — But as I said… er, I mean, as science said: the bulk of it is supernatural, OK?

    • ptolemy2

      “After intense and unexpected rain fell in the north of Chile, parts of the usually arid Atacama desert have turned into a carpet of flowers.”

      Doubtless, it’s just weather.

  6. So if this technique works , it would also be interesting to see what it projects / forecasts for the next 100 years, right?

  7. There is no evidence capable of rigorous scientific inquiry that establishes that any of the warming is the result of something other than natural causes.

    The null hypothesis still stands, and is strong with this one.

    • You fail to take into account that manmade CO2 heat is “ninja heat”. That is, it is capable of defying the laws of physics, and can “hide” in the deep oceans and/or use up some of its energy melting ice and forming mega-storms. It’s worse than we thought, think of the children.

      • If it’s “ninja heat”, it’s not doing a very good job, Bruce.

        It’s hiding in plain sight, according to the science you’ve obviously failed to keep up with:

        Trenberth Travesty seen from space

        The centrepiece of Nature’s April cover story is a stunning panorama of the Trenberth Travesty stitched together from satellite imagery.

        “Using the hermeneutics of quantum gravity,” say the authors, “we are at last able to visualize this tricksy, mercurial zone of heat exchange whose 20,000-km front stretches from Cape Illusionment in autumn to The Isle of Mann in fall.”

        The latest scientists say the Travesty acts by thermal subterfuge to “launder” Kelvins from the atmosphere all the way down to the bathyclimatic ecosystem at the bottom of the sea, converting them to Hiroshimas in the process.

      • “hide” in the deep oceans

        Hiding in the deep oceans was preceded only a few years earlier by hiding the decline.
        It seems to me that most of the activity in Climate Science™ is devoted to moving the goal posts.
        Perhaps the discipline should be renamed to “Groundsman Science” . .

  8. “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 is not ‘speculative theory’ it is rock solid physics.

    • If it is ‘rock solid physics’, what is the climate sensitivity?

      That is the ‘speculative’ aspect of the theory. The passage that you quote agrees with you on every point, except the climate sensitivity, but it is the speculative nature of the climate sensitivity that keeps it from being solidly founded within Physics.

      Newton’s laws of gravitation would only be speculative theory if the acceleration due to gravity was not 9.8 m/s^2, but a value estimated to be between 5 m/s^2 and 30 m/s^2.

      • Richard says…
        “Newton’s laws of gravitation would only be speculative theory if the acceleration due to gravity was not 9.8 m/s^2, but a value estimated to be between 5 m/s^2 and 30 m/s^2.”

        Griff says…
        ” ouch”

    • Griff

      I’ll ask you again then. Why can’t it be observed in the wild if it’s such rock solid science?

    • Griff,

      If it was “rock solid physics” why did Arrhenius change his mind in 1906????

      Read it Griff-
      https://friendsofscience.org/assets/documents/Arrhenius%201906,%20final.pdf

      And then tell me what it means to the AGW theory and show me where Arrhenius states that the “science” at the time was “rock solid”.

      I like this part-
      “In a similar way, I calculate that a reduction in the amount of CO2 by half, or a gain to
      twice the amount, would cause a temperature change of – 1.5 degrees C, or + 1.6 degrees
      C, respectively.
      In these calculations, I completely neglected the presence of water vapour emitted into
      the atmosphere.”

      • However, in 1900 Knut Ångström published results from laboratory experiments (Ångström, 1900) which showed that carbon dioxide wouldn’t be very significant greenhouse gas after all. It seemed that addition of carbon dioxide didn’t have much effect to the amount of radiation going through the gas, and it also seemed that the absorption band of carbon dioxide was overlapping with the absorption band of water vapour. All this wasn’t exactly new information, however. For example Rubens & Aschkinass (1898) had already observed the overlapping of the absorption bands of carbon dioxide and water vapour and they also deduced that the atmosphere is completely opaque in the wavelength region that also included carbon dioxide. After Ångström’s study, however, it was thought that there’s much more water vapour in the atmosphere and hence it’s much more significant greenhouse gas, so it seemed that the effect of water vapour masked the possible effects from the changes of carbon dioxide concentration and therefore additional carbon dioxide wouldn’t cause more warming.

        https://agwobserver.wordpress.com/2010/03/18/when-carbon-dioxide-didnt-affect-climate/

      • “If it was “rock solid physics” why did Arrhenius change his mind in 1906????”
        He didn’t. You have quoted just the first part, where as he says, he first calculates without water vapor. When he puts it in he gets 3.9C per doubling (or halving):

        “For this disclosure, one could calculate that the corresponding secondary temperature
        change, on a 50% fluctuation of CO2 in the air, is approximately 1.8 degrees C, such that
        the total temperature change induced by a decrease in CO2 in the air by 50% is 3.9 degrees
        (rounded to 4 degrees C). “

      • Nick must have missed the comments on real world complexity and this zinger
        ….” Newton’s laws of gravitation would only be speculative theory if the acceleration due to gravity was not 9.8 m/s^2, but a value estimated to be between 5 m/s^2 and 30 m/s^2.”

      • “Nick must have missed the comments on real world complexity and this zinger”
        The claim was that Arrhenius changed his mind in 1906. He didn’t.

      • Precisely Aphan. you have hit the nail on the head. The AGW hypothesis generally ignores the influence of water. John T Houghton an original lead author for the IPCC states: “———the greenhouse effect is halted when water vapour becomes saturated with respect to ice or water” ( The Physics of the Atmospheres. 2nd. edition. ISBN o 521 33956 page 16.). Further: A quick look at the steam tables reveals that 1 Kg of water evaporated from the surface dissipates some 680 Watts/ Sq.m into the atmosphere some of which winds up in the cirrus clouds as ice, nudging the Troposphere. This level of energy transfer knocks the socks off pesky CO2, particularly as much of it ocurrs at constant temperature and rises due to the fact that gaseous water is lighter than dry air.

        In addition the root cause of this air-brushing out of water, I suspect lies in the definition of “Forcing Rate” by the IPCC which fails to comply with thermodynamic law and has thus led to a series of anomalies etc. in the logical route to the Hypothesis.
        For some 10 years I have challenged this definition but have never received any explanation for this apparent schoolboy(girl!) howler.
        To me academic rigour precludes ignoring the thermodynamic laws.

      • Nick, Nick, Nick,

        He changed his PRIOR calculation regarding the doubling of CO2 (lowered it) and then clarified/added that water vapor has TWICE the influence that CO2 does.

      • “then clarified/added that water vapor has TWICE the influence that CO2 does”
        That was always in the original calculation, as it is in modern ones. It’s now called water vapor feedback. In A’s calc, it’s little more than equal, not twice, and the bottom line is, as before, sensitivity of about 4C/doubling, as I quoted from 1906.

      • “The AGW hypothesis generally ignores the influence of water. ”
        So all those comments here about how AGW theory is wrong because it overestimates the water vapor feedback are wrong? You live and learn.

      • Yes, seaice1; estimates of water vapor feedback are demonstratively wrong: Water vapor as measured is not consistent with models. Hell, no climatic metric is consistent with models!

      • Dave Fair:
        Water vapour is very much a “will card” in this climate debate. This mainly due to the obsession with Forcing Rate which has a dubious definition. What is being ignored is its ability to transfer large amounts of energy at constant temperature. The Hydro cycle operates as a Rankine Cycle where water boils (evaporates) as the surface, expands as it rises working against gravity, dissipates unused energy in the clouds and finally is returned to earth by the gravity feed pump ( with feed heating) as rain, ice, snow etc.
        OK, within this process there are large changes in Albedo and Emissivity rapidly taking place and it is the ratio of these two that determines the radiation balance during this large vertical transfer of energy.
        No wonder it is a “Wild Card”.

      • micro6500:
        Ref: ” That’s just it, it isn’t a Wild Card, it’s a regulator, see how min T follows dew points. —98% correlation.”

        The Wild Card reference refers to the AGW concept, NOT reality. See how the traces trundle on oblivious of increasing CO2 levels. I think you may find that min T follows dew points rather than vica versa; but I’m not sure about that.
        Meanwhile the Rankine Cycle plugs on keeping a remarkably constant temperature when you consider ALL the influences in play.

      • I said Min T follows dew points. Btw, that’s what I have been talking about. It’s called Nocturnal Inversion (just found the name), and it works like a heat pipe that regulates surface cooling rates, and the Rankine Cycle is as good a description as any for the effect.
        But, co2 added it’s spectrum to the mix. So to say it doesn’t, gets you ignored. What is missed, by everyone so far, is any warming above what water vapor supports, gets radiated to space quickly, as the eclipse showed, early in the evening. It might take a few minutes longer to drop down to the temp where enough water vapor is condensing to slow cooling, but it consumes that time while the cooling rates are the highest! In exchange for less cooling at the very slowest cooling rate. It reduces thus sort of warming in the afternoon by 70-80-90% by the following morning.

        Because water vapor is temperature controlled so it temperature regulates.

      • Yes micro6500. I take your point. Well described. The specifics do get a bit complicated, however presented. Overall, however we are still left with the relative influences of CO2 and H2O. where CO2 is purported to be armed with some 1.6 Watts/sq.m with H2O having some 680 Watts/sq.m to play with. This on the global scale.
        If you were to accept that this 1.6 Watts exists; then this would be offset by a 0.5% increase in the Hydro Cycle rate, again assuming ALL other influences remain static.
        Not sure where all leads; but suspect we are both roughly on the same wavelength.

      • If you were to accept that this 1.6 Watts exists; then this would be offset by a 0.5% increase in the Hydro Cycle rate, again assuming ALL other influences remain static.
        Not sure where all leads; but suspect we are both roughly on the same wavelength.

        Yep. And even more significantly, no amount of co2 we can produce without importing carbon from else where, is going to make more than a tiny difference. The amount of water vapor there to work with is truly staggering as Harvey give humans yet another lesson on who is the boss. They are talking possibilities of over 4 to 5 feet of rain over the next week. Plus a 12′ storm surge.

    • I suppose that “physics” would be the temperature of the world in degrees Celsius as a function of Carbon Dioxide in units of parts per million. Right? That wouldn’t be speculative if such a relationship could be tested and shown to exist. It can’t and it hasn’t.

    • As already mentioned, Rock solid physics is not the IPCC’s banner statement on the ECS. Due to its broad range and low certainty, it has limited value for making policy.

      • Haw, haw, haw! Water vapor feedback (evaporation, clouds, rain, etc.) is negative. Prove otherwise.

    • Griff, Griff, Griff. SMH
      “It’s not disputed that carbon dioxide absorbs infrared radiation, what is uncertain is the sensitivity of the climate to increasing atmospheric concentrations.”
      Clearly stated and sensitivity is not rock solid physics.

    • “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 is not ‘speculative theory’ it is rock solid physics.

      Despite this being rock solid science going back to 1896, in 1971 NASA/GISS assessed the warming effect of CO2 and concluded that an 8 fold increase in CO2 would cause less than 2 degC of warming.

      This assessment was made by Schneider in conjunction with input from Hansen and was published in a peer reviewed Journal, namely Science Volume 173 (July 1971).

      It is well worth looking at their fig1. It shows temperature change in relation to change in CO2 considering the change by CO2 alone, and the change if one takes into account water vapour. Starting at 300 ppm of CO2, they assess the temperature change by CO2 reaching 2,400 ppm to be about 1.5 degC, and when one includes the feedback of water vapour this rises to approximately 2 degrees. They note that with increasing levels of CO” the rate of change reduces and by 2,400 ppm the rate of temperature change is very small indeed. They do not detail what 4,800 ppm would look like but we are talking of a few tenths of degree since their curve is becoming quite flat.

      Griff please will you
      (i) fully detail what NASA/GISS did not know (in 1970) about the physics and the radiative properties of CO2, and any water feedback implications, given that this is solid science going back to 1896.

      (ii) advise what new properties of CO2 have been discovered, when new properties of CO2 were discovered, how they were discovered which now results in CO2 having a greater warming effect than that assessed by NASA/GISS in 1970/71?

      (iii) refer us to the standard physics and chemistry text books where these new physics and radiative properties of CO2 have been set out.

      I look forward to your detailed explanation on this solid science.

      • Richard: In no way can I answer your questions, particularly as I do not have the expertise. However this could be relevant:
        Where water feedback is concerned I noted that the IPCC used a slightly different feed back equation to that of the textbook I consulted. On graphing the respective results I found that whereas the IPCC trace was very unstable, the textbook trace showed a stable but declining situation.
        I cannot comment on or explain this; so merely offer it for interest and perhaps for someone else to explain. In terms of my own bias I tend to have more faith in the textbook!! – After all, unlike scientists, engineers do have to make things that actually work don’t they?

  9. Two points:
    1. So now we’ve got dueling models. It’s like Robot Wars without the mayhem and shattered debris.
    2. This (like most studies) assumes the proxies substantially represent temperature changes over time. The divergence problem suggest this isn’t so or at least the contribution of temperature to growth of organisms is not uniform.

    • Gary,

      But that’s the beauty of proxies! They are a two edged sword. Past reconstructions using them all show a global MWP and warmer past temperatures. If they insist that they are accurate, then past reconstructions prove the AGW theory wrong. If the proxies are inaccurate, they have ZERO data to use to construct past temperatures (and thus establish a cooler past) and we all start over using only time periods after verifiable thermometer measurements were available.

      The “divergence problem” may reflect the actual truth…that temperatures are cooler rather than hotter. THAT was a problem for Michael Mann and boys…no one else. They said “it is a shame we can’t account for the LACK of warming” remember? Local proxies only apply to the temperatures in the locations they are collected in. So it’s entirely possible for them to show warming or cooling. It’s idiotic to try to convince people that a local proxy represents global temperatures.

      • Anecdotally, it’s pretty hard to say. High temperature records wee mostly set in the 30’s in many parts of the world but that is only part of the story. I recall the 60’s as being very hot in summer but also very cold winters, perhaps indicative more of humidity than heat content of the atmosphere. Climate science takes no account of any such variables that might upset their apple cart. It is a fiction that supports an assault on Western economic strength. It is mostly a creature of the Socialists whose grasp of economics is so poor that they think making wealthy countries poorer will make poor countries richer. It just doesn’t work that way. It is a mixture of politics and religion, but it isn’t science.

      • But how are those proxies calibrated? 1900-1950 with big gaps for WW1 and 2, or 1950-2000.

        Due to the rise in CO2 one would expect trees to grow faster. However NOx and SO2 emissions in the 70’s-90’s have stunted tree growth, but limestone must have dissolved faster. Use of phosphates has increased algae growth, creating ‘dead zones’. so modern silt deposits are useless.

        Everything after 1950 should be thrown out, as there are too many factors that screw up the numbers.

      • So they could not account for the lack of warming, and they had to deal with the damm blip.

        Did the proxies support the blip?

  10. Charles:

    “This story broke while Anthony and I were eclipse hunting.”

    I hope your hunt was as successful as it was humane: jugulated, bagged, tagged and mounted? Because there’s nothing more dangerous to your fellow hunters than a lightly-wounded, p!$$ed-off eclipse rampaging unaccounted-for through our National Parks.

    It’s a message worth reiterating to all, I think, as astronomical-event season officially opens: take a headshot or don’t take the shot at all; finish what you started; remember the Three X’s of Crossbow Common-Sense; and above all, happy hunting!

    • Once you get away from the hard core science community and its dependency on public funding with its corresponding corrupting influence and use tools that are common in the real world and need to work to survive you will get answer to question that are based on science and not based in political expediency. A.I. is a great tool to use to make prediction especially when you have a long historical data set and unlike all of the models being used now it’s not a question of tuning the model to the data the data creates the model by trial and error to the nth degree, doesn’t mean it always right or effective but it’s light years ahead of the complex model building process that we are using now.

  11. Sorry but garbage in = garbage out. It’s still a program it just matched an algorithm and continued it. A different algorithm may match also with different future predictions.

    • It’s a program that was only given actual, real, collected proxy data up to the year 1830, and then it was allowed to run forward to see how closely it’s calculations matched what actually happened from that point in time to the year 2000. If you want to call proxy data garbage, you’re allowed to have that opinion.

      The program as outlined in the article above, made a prediction about the years 1830-2000, and that “prediction” matched measured reality extremely closely. So “a different algorithm that might match also, with different future predictions” would be a model that did NOT match what happened between 1830 and 2000.

      That does not automatically make this model “correct” or accurate. But it makes it a heck of a lot more accurate than the IPCC’s models ever were, and it did NOT include a “hypothetical” influence from man-made CO2.

      • And that’s the key, it’s not make any hypothetical assumptions its just looking for patterns and extrapolating possibilities.

      • I think it is also good to remember the deviance current proxies have with instrumental records, which would imply similar variations in proxies where there is no instrumental record. By weather records, the temperature increased (or decreased) over the late 19th and 20th Centuries in a multi-decade set of trends, which pattern does not show in the current proxies. The 1930’s warm period and the 1940’s to 1975 cooling does not appear in the proxie records.

    • The “garbage” in many research studies unfortunately comes from deliberate cherry picking of data in many cases or reaching for a conclusion with insufficient data points. It seems to be a common thing in climate science. Michael Mann’s “hockey stick”, for instance, used quite limited and selected proxies processed through statistical manipulation that was faulty or contrived ( take your pick) to get a result that was good for his career, ensured lots more grant money and was a complete load of scientific hogwash. So I guess it depends what one calls success!

      • Sorry, I got carried away! This A.I. approach is at least more neutral in its direction, but it does depend on the accuracy of proxies. It is also empirical- either it works or it doesn’t.

  12. “This sensitivity may have been grossly overestimated by Svante Arrhenius more than 120 years ago, with these overestimations persisting in the computer-simulation models that underpin modern climate science [2]. We just don’t know; in part because the key experiments have never been undertaken [2].”

    I would like to hear more about this. When everyone talks about ‘settled science’, I thought it was the Svante Arrhenius ‘science’ they were talking about. Yet, when I read about Arrhenius and his work, he doesn’t sound very convincing. His paper reads very much like a whole lot of conclusions based on very little ‘facts’, and some of those ‘facts’ are now known to be inaccurate. Why have the key experiments never been undertaken?

    • In 1906, Arrhenius amended his prior work and admitted that he hadn’t really understood or taken into account the affects of water vapor in the atmosphere. He lowered the degree to which he thought CO2 could warm the atmosphere….and even admitted that increased CO2 would be good for animals!

      https://friendsofscience.org/assets/documents/Arrhenius%201906,%20final.pdf

      I suspect the key experiments are nearly impossible, since we don’t understand exactly how the climate works, and therefore cannot create the perfect experimental situation. I think this study is a great step in the right direction.

    • Why have the key experiments never been undertaken?

      I’ve calculated sensitivity to solar insolation by lat band for the extra-tropics.
      The units are Degree F/WDay, You can can divide it by 24 to get Degree F/W average (surface flat insolation), and multiple that by 5/9th to get Degree C/W avg.
      https://micro6500blog.wordpress.com/2016/05/18/measuring-surface-climate-sensitivity/
      You can see a large increase in sensitivity about 2000, 20-30 N Lat that explains the step in surface temps.

    • Aphan does point to a minor distortion of the history by Marohasy’s in the section quoted by Jclarke.

      The Arrhenius argument for volcanic-CO2-driven ice age cycles was mainly defeated by Ångström in papers published in 1900 and 1901 where the most powerful new evidence was the great overlap of CO2 wavelength blocking with (almost ubiquitous) water vapor. Not only Arrhenius, but most subsequent attempts to revive this solution to the mystery of the ice ages (including by Plass in the 1950s) acknowledge the overlap with water vapour, as do all the theories of CO2-emissions-driven warming from Callendar (1938) onwards. The sensitivity ‘over-estimates’ in the computer modelling are perhaps more to do with other effects that might involve negative feedback, including cloud feedback, just as Möller argued in 1961 against the early computer modelling by Plass. Some details of the controversy around 1900 and 1960 can be found in this timeline:

      https://enthusiasmscepticismscience.wordpress.com/chronology-of-climate-change-science/

  13. So, should I sell my beachfront property in Florida or not??? (note: I’ve probably got 20 years left, if lucky, to enjoy it. Of course, my heirs could enjoy it for another 50 or so)

    • Yes sell it now as quickly as you can, don’t worry about losing money just sell, buy the way I buying.

    • I will buy it…no need to get an appraisal, because this will be underwater soon. $1 seems like a fair price :)

    • Bah!

      These fools all imagine sea levels will rise so they can offer you a paltry sum.

      Florida will bake, the earth will become dry, crusty and expand thereby raising itself above any SLR. The place will be so hot it will be uninhabitable.

      Therefore I’ll take the place off your hands and I’ll accept $250,000 to relieve you of it.

      A paltry sum to save you from being fried.

  14. “So, the end of the Little Ice Age corresponds with the beginning of industrialisation. But did industrialisation cause the global warming?”

    I like to phrase this point like this:

    Was it the Industrial Revolution that let to a more favorable climate, or was it a more favorable climate that led to the Industrial Revolution?

    Kind of a chicken and egg problem …

    • Except that the 2 didn’t happen at the same time, the industrial revolution started before the end of the LIA and the modern industrial era that has had an effect on the CO2 levels that may or may not have impacted climate started after the LIA was over. They have no connection what so ever unlike the egg and the chicken.

      • Bob,

        Depends on who you ask. Most folks claim the industrial revolution started in Britain “in the late 1700s” and the average date for the LOS is “a period between the 16th to 19th centuries”.

        Temperatures reached the coldest point in the LIA ended around 1715, so temps were rising again, but not totally recovered after that. O don’t know how much closer to occurring at the same time it’s possible to get!!

      • So what caused the MWP?

        A chicken, or an egg?

        It certainly wasn’t man made CO2. Unless we all missed a super modern industrial complex that sunk into oblivion.

      • HotScot-
        According to your own fiendish brand of scientific sleight of hand, I suggest that during the MWP that the “earth became dry, crusty and expanded thereby raising itself above” the current elevation of Florida, and that the place became “so hot it was uninhabitable.”!!!

        Don’t listen to him Dave! He says he’ll save you, but I alone promised you transportation out of there!!!

  15. I like the theme of this article, which I interpret to be that analyzing time-temperature series is a better approach to predict temperatures than the construction of GCMs.

    Hoping to predict the earth’s long-term temperature by modeling a myriad of complex interactions in the solar system does not make sense. The scientific principles are not well known. The implications from CERN CLOUD experiments are that CO2 does not play a significant role in global warming, climate models used by the IPCC to estimate future temperatures are too high, and the models should be redone. A likely reason for these failures is that Newtonian physics cannot model earth processes adequately to produce practical results. The CLOUD experiments involve the application of particle physics.

    An alternate approach is to assume the solar system is a black box and to focus on modeling the output, the earth’s temperature. If one cannot model the output of a complex system, what is the likelihood that the complex system itself can be modeled? One variable, temperature, sums up the results of complex but incompletely understood processes in the solar system. Assuming these processes are periodic, then, the output, the temperature, should be a periodic function and amenable to Fourier analysis. The results might provide insight into the important processes in the solar system that influence temperature

    My simple analysis of the HadCRUT4 time-temperature data indicates a high likelihood of the beginning of an absolute decline in the global mean surface temperature trend line within the next decade. The first derivative of the temperature trend line is positive but has decreased in value every month for the past 20 years. The derivative is likely to become negative in the mid-2020s and increase in negative value well into the 2030s, i.e., the mean global surface temperature will decline.

    The sinusoidal shape of the first derivative of the trend line curve clearly displays the oscillatory behavior of the time series of temperature anomalies that is not so easily recognized from the modulated temperature series trend line curve alone. Over the last 110 years, half cycles (zero slope to zero slope) of the temperature trend line have ranged from about 18 to 57 years and averaged 38 years. I leave it to others to check out if greater focus on Fourier analysis over longer time periods has merit for forecasting. (Ref: Analysis of the Mean Global Temperature at http://www.uh.edu/nsm/earth-atmospheric/people/faculty/tom-bjorklund/)

    Comments encouraged.

  16. Jennifer Marohasy wrote:

    “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.”

    AR5 WG1 SPM p4 Section B1 Fourth bullet point actually says:

    “Continental-scale surface temperature reconstructions show, with high confidence, multi-decadal periods during the Medieval Climate Anomaly (year 950 to 1250) that were in some regions as warm as in the late 20th century. These regional warm periods did not occur as coherently across regions as the warming in the late 20th century (high confidence). {5.5}”

    Jennifer quoted only this statement from the report: “In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years (medium confidence)”

    Jennifer omitted the qualifier “medium confidence”. “Likely” means greater than 66% likelihood. If I were to roll one die, the likelihood it will show a 3 or greater is 66%. Expressing medium confidence in a “likely” statement is merely sophisticated hand waving. The IPCC is not DENYING anything about the MWP, it is saying that it has inconclusive evidence that today’s temperature is an UNSPECIFIED amount warmer. Scientists normally don’t draw conclusions based on such ambiguous data. Such conclusions normally wouldn’t be permitted in the abstract of a scientific paper. Unfortunately, policymakers probably will need to make decisions about emissions about GHGs long before paleoclimatologists have a reliable measure of the difference between the MWP and the CWP – if they ever do. So it is not unreasonable for scientists to offer policymakers their best estimate under these circumstances.

    Or it wouldn’t be unreasonable if the warmth of the MWP were important to our future. And if the scientists rebuked those who misrepresented their statements. The MWPis actually relatively unimportant. Climate sensitivity is the key issue. If climate sensitivity is high, fluctuations like the MWP and LIA will be trivial compared with what is coming.

    • @ Frank
      “If climate sensitivity is high, fluctuations like the MWP and LIA will be trivial compared with what is coming.”

      The last 20 years or so have shown that climate sensitivity to CO2 is trivial at best – huge amounts of additional CO2 from mankind have resulted in a 20 year or so period with no statistically significant increase in global temperatures. In some areas of the world temperatues have significantly declined in that period, and that doesn’t bode well for the AGW belief system.

      So there is no basis for your statement ” will be trivial to what is coming” – whatever is coming will be determined by the natural drivers of earths climate and man is not one of them to any measurable extent.

    • Frank

      Thanks for your informative reply. I’m just a layman so its hard work, but I think I kinda got the gist of it.

      My question is, as there is no credible, empirical evidence that CO2 causes global warming, isn’t that more important to mankind than climate sensitivity, indeed, doesn’t the lack of evidence negate the question of climate sensitivity altogether, at least for CO2?

      • Old England and Hot Scot: The rate of global warming for the last 40 year is 0.17 +/- 0.4 K/decade (95% ci). There has been statistically significant warming. And – now that we have experienced another strong El Nino – the rate of warming over the first 20 years of this period is essentially the same as for the last 20 years, only the confidence interval is about +/- 0.7. You can cherry-pick a lot of periods covering 2001-2012 when the warming rate was negative and longer periods when it wasn’t statistically significant. But that ended with the recent El Nino – which is why WUWT doesn’t discuss subject like it did before the recent El Nino.

        This website persists in posting information suggesting that the lack of statistically significant warming is evidence no warming has occurred. That is BS. It simply means that the noise in the GW signal makes it impossible to reject the null hypothesis of no warming for some short periods. “Absence of statistical proof warming” over short periods of time is not “proof of absence”.

        If you looked at your net worth over various periods of time, are you getting richer or not? Some months or years you may have higher expenses than others or receive one-time payments. With large fluctuations, it would be difficulty to statistically prove your wealth is increasing. If you are affluent and own a house and a 401k, the fluctuation in your net worth can be even greater. The stock market lost 40% of its value in 2008/9 and housing prices in some markets lost as much. Financial advisors don’t recommend investing money you need in the next few years in stocks, because they are too volatile. However, they will tell you that the market has always been up over any 20-year period or longer (but not statistically significantly up in all cases). So when you are saving for retirement and are planning periods several decades in the future, they recommend investing in stocks.

        In the case of climate change, we aren’t planning for the next decade. No one can be sure how much warmer it will be in a decade. Just like you can’t be sure whether it will be raining a month from today in Washington DC. During the hiatus, there was no net warming for about 12 years (with today’s revised data). Our time horizon for climate change is the next half-century or more. It will almost certainly be warmer then, and much warmer if climate sensitivity is high and we continue to emit large amounts of CO2 – which is likely.

        In 1990, the IPCC’s first report said that observed warming was comparable to the largest fluctuation in the temperature record. It has warmed nearly 0.5 degC since (0.35-0.60 degC is you want the 95% ci). So – in 1990 – they couldn’t even be sure there WAS long-term warming. However, they knew from well controlled laboratory measurements that GHGs would reduce the rate at which thermal IR escapes to space. The law of conservation of energy demands that the retained heat cause the planet to warm – though it doesn’t say how much. You don’t need to observe ANY warming to predict that rising GHGs will cause SOME warming – the question is how much? The simplest answer is the no-feedbacks climate sensitivity of about 1 degC per doubling of CO2. That isn’t catastrophic warming! The historical warming record is consistent with 1.5 to 2.0 degC of warming per doubling.

        The ignorance this site promotes about AGW is appalling. The issue is whether AGW is CAGW.

      • Frank

        That was a long road for a shortcut.

        The planet is warming, that’s clear. Is it caused by anything man does, or even CO2? Which is what the entire AGW debate revolves around and which is driving the insane march to renewables, which are harmful in almost every way imaginable.

        Lab experiments are fine to prove the AGW hypothesis, but at some point in time they must be proven in real life. No one has ever accomplished that feat. So just how long does the worlds population have to wait for evidence that CO2 causes GW? How much money must be poured down the drain before the evidence is delivered. How many people have to suffer before the evidence is available.

        During the present climate scare going back over 40 years, billions of $/£’s have been poured into climate research and no one has empirically demonstrated the underlying theory that CO2 causes warming.

        I’m no scientist, but I am a realist and a businessman. Quite why anyone would consider an unproven theory credible after the amount of money wasted over the past 40 years is quite beyond me. Yet governments across the globe are investing taxpayers money in just that. It is criminally irresponsible.

        To make matters worse, there is considerable evidence that the MWP was hugely productive with abundant crop growth allowing peasants the luxury of finding gainful employment rather than grubbing around to grow a few mangy crops to feed their family.

        And the fact is, that’s happening again right now. The planet has greened by 14% over the past 30 years but the attention of science has been seduced by the AGW hypothesis and we are not taking advantage of this abundance. Talk about fixing the roof when the sun shines?

        In the event the planet does begin to cool soon, for which there is also evidence, or heat, the question of human survivability is preposterous, we have survived worse. The the fragile ego of the scientific community is what’s at stake here, and the continuing drive for a single global political entity.

        “In the case of climate change, we aren’t planning for the next decade……………..Our time horizon for climate change is the next half-century or more.”

        What a ridiculous assertion, when it’s not known what causes global warming, or global cooling.

        “However, they knew from well controlled laboratory measurements that GHGs would reduce the rate at which thermal IR escapes to space. The law of conservation of energy demands that the retained heat cause the planet to warm – though it doesn’t say how much.”

        I’m not sure where to start with this statement. Well controlled laboratory experiments are the problem, not the solution. And as I continually point out, those lab experiments have not been demonstrated in the real world. And if the law of conservation of energy can’t say how much the planet warms by, then 0.00000000001 degrees C is as likely as 2 degrees C.

        And I’ll point out to you, what one scientist on this site pointed out to everyone here, Earth’s atmosphere exists to keeps us cool, not warm. As we enter a solar minimum, it’s job it likely to become so much easier. If you want more information on even the uncertainty of the planets fate go here and you may understand that global cooling is probably more of a threat to the human race than GW. https://judithcurry.com/2016/06/27/are-we-headed-for-a-new-solar-minimum/

  17. An odd question about this is why do the proxy temperatures show a fall after 1980 ? I don’t know if any explanation or theory has been put forwards for this – can anyone enlighten me ? Thanks

  18. What year does the data cut off? What about the criticism Zeke had on Twitter where he added the recent warming which reached 1.6 degs. higher than the first graph? He later made a correction since the reconstruction did not use tree ring data.

  19. Jennifer Marohasy wrote:

    “Proxy temperature record (blue) and ANN projection (orange) based on input from spectral analysis for this Northern Hemisphere multiproxy. The ANN was trained for the period 50 to 1830; test period was 1830 to 2000.”

    An artificial neural network with enough complexity can be fit to reproduce almost any given dataset. The S&P500 in 2020, 2025 or 2035 can be predicted from the last century of stock prices. For example, the state of the future economy will depend on how much money waste reducing carbon emissions and how serious the next market crash will be. So what Jennifer is saying is the lousy proxy data for the period 50-1830 contains information that is capable of predicting what global temperature would have done for 1830 to present and into the future. Regardless of what happened to anthropogenic aerosols – or even volcanic aerosols. Regardless of what happened to GHGs. Regardless of whether or not there is another Maunder Minimum or Grand Solar Maximum – unless the ANN has managed to “learn” about the sun’s behavior.

    What happens if one changes the structure of the ANN? What happens if the ANN is trained on the more reliable proxy data from about 600 or 1000 to 1850 or 1900 or even 1950 (before aGHGs had a major impact). The ANN will make different hindcasts and forecasts. How do we know which model is right? We don’t.

    ANNs merely find patterns in the chaotic fluctuations in imperfect RECONSTRUCTIONS of past climate (which may or may not contain signals useful for predicting the future) and projects them into the future without any understanding of the fundamental physics driving climate change.

    • “So what Jennifer is saying is the lousy proxy data for the period 50-1830 contains information that is capable of predicting what global temperature would have done for 1830 to present and into the future.”

      I missed it. Where does she say that?

      • Frank

        Mark: I cited a quote directly from Jennifer’s blog.

        Presumably that was a comment of a forum contributor. I really cant imagine JM would state: “So what Jennifer is saying is the lousy proxy data for the period 50-1830 contains information that is capable of predicting what global temperature would have done for 1830 to present and into the future.”

        If that is the case, attributing that statement to JM herself is deceitful, misleading and dishonest.

    • What would the ANN make of this imperfect data?

      We say, that’s easy. That the planet operates on about 100,000 year timescales, does not preclude it from operating also at the same time on shorter time scales.

  20. We know the hockey stick curve was produced by cherry picking data and applying (badly) and obscurely, the statistics of principal component analysis. I.e a big black box said “Hockey Stick” and that is the end of the story. Or it would have been were it not for the dogged persistence of Steve MacIntyre. The same mindset carried on up to 2017 with Arrigo’s cherry picking winkled out again by MacIntyre see https://climateaudit.org/2017/07/11/pages2017-new-cherry-pie/#more-23273

    On the Skeptic side of the debate we pride ourselves on holding our science to higher standards of integrity than the other lot.
    So I am a little bit worried that
    1) Jennifer Marhosy selected only 6 proxies that all show the MWP LIA characteristics. This obliges her to defend in advance against an accusation of cherry picking.
    2) The Neural Network stuff is another big black box and to most observers we have no idea whether it is gold dust or Mannian bias.
    It would be so sad if a MacIntyre appeared on the AGW side to blow Jennifer out of the water.

    • Alastair Gray: 1) Jennifer Marhosy selected only 6 proxies that all show the MWP LIA characteristics. This obliges her to defend in advance against an accusation of cherry picking.
      2) The Neural Network stuff is another big black box and to most observers we have no idea whether it is gold dust or Mannian bias.

      3) functions chosen to model temperature: sines and cosines, orthogonal polynomials, wavelets, etc.

      No matter what proxies you choose, functions you choose, estimation procedure you choose (lasso, least-squares with cross-validation, CNNs), a major problem is that there are not enough observations relative to (or informative about) the oscillation with an apparent period near 1000 years and no well-established mechanism to explain it. From a little before the MWP to now there is only 1 full period; for earlier peaks, the data are extremely sparse. If the temperature rise since 1885 or so is entirely driven by CO2 increase (I am not saying it is!) then we do not have even 1 full period of the hypothetical oscillation.

  21. Great article, thanks. Of course, it won’t fly for those who think that because we can accurately predict eclipses, we can accurately predict climate…but we must keep trying.

    BTW, ran into this recently, might be nice read for those who like historical proxies:

    http://www.gutenberg.org/files/55375/55375-h/55375-h.htm

    FAMOUS FROSTS AND FROST FAIRS IN GREAT BRITAIN.
    Chronicled from the Earliest to the Present Time.

    Might be interesting to compare to the MET’s “official” record…

  22. Not could be, but demonstrably is.

    Any human influence is negligible, and we don’t even know the sign, ie whether net cooling or warming. The later is essentially all urban and other heat island effects, not GHG effect. The issue is whether there are enough local heat islands to add up to a detectable global effect. If there be any, it’s only because of disproportionately weighting those areas in the global “average”.

    • Gloateus

      My understanding is that more of the planet doesn’t have measurement sites than it does. And that many of the measurement stations are subject an urban heat island effect. i also believe Judith Curry asserts that the UHI effect is negligble providing anomalies are used rather than temperatures.

      As a complete scientific thicko, I find that statement puzzling when over half the planet cant be measured and yet UHI infected sites are used to judge vast areas which don’t suffer UHI’s nor recording stations.

      We cannot possibly apply infected data to the rest of the world, homogenised or otherwise. It is pure guesswork disguised as scientific certainty.

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