By P Gosselin
Natural cycles drive our climate
The latest video by the Germany-based European Institute for Climate and Energy (EIKE) looks at CO2 and the troublesome Medieval Warm Period, which has long been a thorn for climate alarmists.
Hat-tip: Klimanachrichten
The Medieval Warm Period, the natural warm phase between 700 and 1300 AD, cannot be reproduced climate models because the simulations react primarily to CO2. Back then CO2 was not a factor because its concentration level in the atmosphere was pretty much constant. That’s why people would rather keep the Medieval Warm Period quiet.
But the facts speak for themselves. Two studies now add further pieces to our knowledge of the medieval climate.
Antarctica
In October 2023, a paper by a team of researchers led by Zhangqin Zheng from the University of Science and Technology of China in Hefei was published in the journal Quaternary Science Reviews. It deals with historical changes in the Adélie penguin population in the Ross Sea region of Antarctica and their climatic influences.
Two atmospheric-oceanic circulation patterns, the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO), have a major influence on the climate and marine ecosystems in the Ross Sea region. From a historical perspective, however, the influence of atmospheric-oceanic circulation patterns on penguin populations in this region remains unclear. The researchers analyzed sediment cores from abandoned penguin colonies on Inexpressible Island in the Ross Sea and reconstructed the changes in the populations of Adélie penguins over the past 1500 years. Zhangqin Zheng and colleagues found that the penguin population on Inexpressible Island peaked between 750 and 1350 AD, possibly due to habitat expansion in a warmer climate during the Medieval Warm Period.
After comparison with historical records of penguin populations from Cape Bird, Dunlop Island and Cape Adare, it was found that all penguin populations increased in the Ross Sea during the period 750 to 1350 AD. The population trend also coincided with extreme swings in the El Niño and SAM circulations.+
From this, the researchers concluded that SAM-ENSO could promote the inflow of circumpolar and modified circumpolar deep water into the Ross Sea and thus increase the influx of nutrient-rich deep water, together with a warmer climate, could promote the efficiency of open ocean areas, so-called polynyas, and the population increase of Adélie penguins.
The study shows the important role of ENSO and SAM as triggers of strong climate fluctuations.
These natural processes are still taking place today and have by no means ended with the start of the CO2 increase.
Poland
The other study comes from Poland. The research group led by Rajmund Przybylak from Nicolaus Copernicus University in Toruń, Poland, published their work in the journal “Climate of the Past” in November 2023. The article presents current findings on climate change in Poland for the period from 1000 to 1500 AD. This period also includes the Medieval Warm Period. The scientists first studied all available quantitative climate reconstructions that have been produced for Poland in the last two decades. They also produced four new reconstructions using three dendrochronological series and an extensive database of historical source data on weather conditions. The growth of conifers in the lowlands and mountains of Poland depends on the temperatures in the cold season, especially in February and March. All available reconstructions based on dendrochronological data refer to this time of the year. Summer temperatures were reconstructed using biological proxies and documentary evidence. However, the latter are limited to the 15th century. The winter temperature was used as a proxy for the annual temperature proxies, instead of the usual use of the summer temperature.
The Medieval Warm Period probably occurred in Poland from the late 12th century to the first half of the 14th or 15th century. All analyzed quantitative reconstructions indicate that the Medieval Warm Period in Poland was comparable or even warmer than the average temperature in the period 1951-2000.
The coldest conditions in the entire study period were recorded in the first half of the 11th century (both in winter and summer) and in the second half of the 15th century (only in winter). The greatest continentality of climate occurred in the 15th century. A good agreement was found between the reconstructions of the Polish climate and many reconstructions available for Europe.
The two new studies from Antarctica and Poland indicate that the natural climate factors still need to be much better understood in order to be able to incorporate them faithfully into climate models. Currently, the simulations do not attribute a major role to natural climate events, which is a serious mistake.
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There’s also compelling evidence that sea levels were higher prior to the neoglacial (LIA) period that came afterwards. Is there a good reconstruction of sea levels over the last 2000 years or so?
Sea levels did fluctuate with melting of ice sheets after the real Ice Age, indications on the coast of B.C. are.
I haven’t heard if money has been found to deploy better sonar equipment to investigate images from under water off of Haida Gwai that resemble stone structures to corral fish at mouth of a river. (Sonar images can mislead, as TIGHAR found out off Gardner Island searching for remains of Amelia Earhart’s airplane. Reference ‘One More Good Flight’ by Ric Gillespie.)
The Earth is still in a 2+million-year long-term ice Age, the Quaternary Glaciation, that will last until all natural ice on Earth melts. https://en.wikipedia.org/wiki/Quaternary_glaciation
The Medieval Warm Period – A global Phenomenon
If you take all of those individual proxy records and compile them into a global temperature reconstruction, you get this:
(source: Kaufman et al, 2020)
No one denies that there were regional periods of warmth during the timespan of the putative MWP, the argument is that warmth during the MWP period was not globally coherent, and so the planet as a whole never experienced temperatures comparable to today’s.
You can actually get a sense of this just by comparing the disparate timings of the many MWPs reflected in your map of individual records.
Thank you, but your 1.6 degree y axis, and the rather long flat section that mostly occurred when there were no thermometric records, the invention of the thermometer being in 1714, is supportive, without actual proof, of catastrophic global warming claims.
Anyone claiming anything about the MWP is doing so using proxy records, including the head post.
The early thermometers did not agree with each other., measured to one degree accuracy, which at that was thought great
Any temp prior to that is a guess.
Whoever put that image together is an uneducated, non scientific, a hole
How is it that the 3.5 million square miles of United States territory has somehow bucked the global hockey stick?
Richard Verney’s WUWT post from 2017 addressed that question.
The US shows warming consistent with the global trend:
If plotted alongside the reconstruction above it would be virtually indistinguishable.
Maybe the USHCN data (which almost certainly contains UHI and adjustment errors), but the 40 year trend from the other datasets doesn’t show the same trend, and there’s much more interannual variability. Even if you take only the USHCN data, the mid-latitude continental landmasses are supposed to warm much faster than the global average.
The contiguous US is warming faster than the global ocean, especially over the last 50 or so years:
(series have been smoothed to better show trend differences)
More FAKE data.
US land data as graphed is FAKE (see further up)
There were no temperature measurements for most of the ocean even in the 1950. So the ocean graph is also FAKE.
These are subsurface ocean temperatures (temperatures at depth), not sea surface temperatures (SSTs). SST measurements are numerous and global.
We have good subsurface ocean temperatures back to the 1880’s? lol.
Would we be better off if it had been cooling for 150 years?
Assuming that those curves are correct on the chart, the US was following the ocean average right up until the last ten years or so. An we’ve seen temperatures here drop recently. Such a short-term divergence isn’t very convincing. I will give you this: the UAH satellite data can capture month to month changes very well, and the Hunga Tonga eruption coupled with El Niño shows up unmistakably, giving a greater temperature trend than we had two years ago. But that’s natural variability for you…
The US land is warming faster than the global ocean across the entire length of the record:
But the difference in trend is even more stark over the past several decades:
It is simply objectively true that the contiguous US is warming faster than the global ocean.
For the last time: I mentioned that the US temperature was pretty similar until “the last ten years or so”. Let’s say 13 years give or take. The most recent years have pushed the trend up, especially the past two years. Second, I mentioned “global average” not just oceans.
Now we’re splitting hairs. The US average annual temperature has been deviating from global averages so much over the years that it prompted James Hansen to once ask, “Whither US Climate?”.
https://www.giss.nasa.gov/research/briefs/archive/1999_hansen_07/
The US is warming faster than the globe as a whole:
Hansen’s discussion in 1999 was based on the best data and methodologies they had available at the time, and the analysis necessarily ends in 1999. We can look at the same map using a more up to date and complete data set now:
The US is warming, unequivocally, and exactly in line with the pattern you articulated.
Tony Heller has shown how the historical temperature record of the Lower 48 States has been falsified to cool the 1930’s and warm the present.
Heller shows that NOAA is doing adjustments to USHCN, he doesn’t show that the adjustments are wrong.
But it’s more complicated than that, because Heller himself is making numerous questionable choices about how he’s aggregating and sampling geospatial data that introduce a lot of issue into his own analysis. He doesn’t account for station dropout, for instance – there were more stations in the USHCN in the 1930s than there are today, so counting the number of stations showing hot days is not going to be apples to apples. He also ignores changes in the observation practices in the US Coop network, where volunteers were instructed to stop recording temperatures in the afternoon and to take them in the morning instead to reduce evaporative loss for precipitation measurements. This has a big impact on the number of “hot days” counted at a station. And he just doesn’t address the uneven distribution of stations around the country at all – so all of his analyses oversample the areas of the country with the most stations.
It’s also important to note that USHCN is no longer the official long-term temperature record for the US – it was replaced by ClimDiv, which includes all GHCN stations in the US instead of the smaller USHCN subset.
Heller was actually banned from posting on this very website by Anthony Watts himself because Anthony felt he was trying to deceive people.
Yes, USHCN has undergone manic adjustments, that deliberately remove the 1930/40 peak..
The intent was to FAKE that data to match their agenda.
We know that you know that.
He doesn’t account for station dropout, for instance – there were more stations in the USHCN in the 1930s than there are today, so counting the number of stations showing hot days is not going to be apples to apples.
Nonsense. That should have no effect.
ANY “adjustment” to the data is FRAUD. Without exception, the “adjustments ” cool the past and warm the present.
If I say there were 300 stations in 1936 showing >100 degrees and 200 stations in 2021 showing >100 degrees, it matters a whole awful lot whether there were 1200 stations in 1936 and 600 stations in 2021.
Heller is conflating the number of stations showing hot days and the number of hot days that actually occurred. The latter is the thing scientists actually care about.
No the later is what climate science religion and climate activists worries about real science worries about accuracy of everything.
Isn’t it bizarre that the “adjustments” are totally linear with the increase in CO2 😉
That cannot happen by accident .
What a coincidence!
/s
This is, of course, another Heller nonsense, which has been circulating since USHCN was actually live (11 years ago). I’ve often wondered what people think those rascally scientists would achieve by adjusting proportional to CO2. It makes no sense.
In fact the explanation is simple. What Heller plots is cumulative adjustments.Since these are similar from year to year, the sum is linear with time. And CO2 increases fairly linearly with time, so of course they correlate.
Now you are simply making things as your babble was specifically addressed about 5 years ago and was exposed at Heller site.
“I’ve often wondered what people think those rascally scientists would achieve by adjusting proportional to CO2. It makes no sense.”
They would achieve keeping their jobs. Without warming they don’t have anything to study.
But how would adjusting proportional to CO2 create warming? It wouldn’t.
Imagine, for a moment, a case where the adjustments are valid and correct, and CO2 is driving the long term warming trend (not asking you to believe it, just imagine it). What would you expect this graph to look like? How would that differ from what it does look like?
It is easy
You start with a CO2 ppm curve, and adjust the temp records accordingly.
Gee whiz.
Done all the time
Even my great grandmother agrees
Clearly the temperature data has been adjusted to fit the AGW narrative, thus no coincidence, it is deliberate deception by those in charge of the temperature data, and to hell with reality! Given that we already know that CO2 has little to no effect on climate, trying to make the temperature data fit the `cause’ simply shows the level of corruption of the raw data the whole UHIE homogenization process involves.
The Trump administration should call this process out and get a more rational and ethical scientific system in place to properly record climate data and the local effects of urban warming.
‘He doesn’t account for station dropout, for instance – there were more stations in the USHCN in the 1930s than there are today, so counting the number of stations showing hot days is not going to be apples to apples.’
Up to 00:01:24 in the video he (Heller) doesn’t ‘count’ anything – he uses percentages. Nice try, though.
This is an abject failure to account for station dropout as well (although I was referring to his maps), because it doesn’t account for the geographic distribution of the station network. There will be a higher percentage of stations showing >100 degree days if there is a higher percentage of stations in hot regions of the country.
The fundamental misunderstanding that Heller propagates and that his followers all adopt is the idea that the composition of the station network is part of the thing we are trying to understand, when what scientists are trying to understand is the *climate* of the region where the station network sits.
You cannot understand the actual climate when the data you use has been manically adjusted.
There will be a higher percentage of stations showing >100 degree days if there is a higher percentage of stations in hot regions of the country.
Conversely, there will be a lower percentage of stations showing >100 degree days if there is a lower percentage of stations in hot regions of the country.
See how hopeless your attempt to smear Heller’s work is?
Right, we agree that station dropout will have a profound effect, and it matters which way it goes. Heller ignores it completely, NOAA addresses it.
You asserted station dropout had a big effect. I merely pointed out it could not explain the change.
I didn’t say it could “explain the change,” I cited it as one example of the multitude of methodological errors Heller makes.
Ok, Alan. Please advise what the general characteristics of the dropped stations are, and who’s making the decisions. For example, are they predominantly in economically depressed areas where the population has dropped?
“what the general characteristics of the dropped stations are, and who’s making the decisions”
These are volunteer stations. They cease when volunteers get old, or just get sick of it, or move on.
Another reason why USHCN was replaced by ClimDiv eleven years ago.
Even the “adjustments” get “adjusted”..
…. and go totally manic in more recent times.
Thanks for posting this. It explains a lot of the anomalous jump in USHCN temperatures in the last decade.
Fake graph. USHCN has not posted a US average of anything since it was replaced by ClimDiv 11 years ago. Any average you see was calculated by someone else, probably Heller. And he just adds thm all together without any allowance for area covered.
Even worse, he usually sums the stations adjusted, and the sum of raw. But these are totally different groups of stations. USHCN final has all the 1218 original stations; “raw” has the stations that actually reported, now down to about 700 or so. Different places, not adjustments.
Wasn’t there a climate scientist that proclaimed we needed less than 200 stations for global data?
Nick Stokes has shown that you only need 60 or so stations to get a robust estimate of global temperature change:
https://moyhu.blogspot.com/2010/05/just-60-stations.html
The issue with station dropout is not that it results in inadequate spatial coverage, it’s that it can introduce spurious trends as stations drop out.
More FAKE data.
USA was at least as warm in the 1930s/40s as it is now.
Where is the U.S. hockey stick?
https://ibb.co/Zcy4nnh
https://ibb.co/WWDLd5L
These are official NOAA temperature graphs scattered from all over rural U.S.
Nick never use real data he homogenizes them (using a method only he is expert in and different to real homogenization) and puts them thru a blender to arrived at Stokes certified data.
Actually not. For global anomaly I use unadjusted data. It makes very little difference.
A one C rise over 100 years is a REAL DANGER
Head for the hills
Doomsday is coming
Here’s a well known and shouldn’t be forgotten You Tube quote:
I received an astonishing email from a major researcher in the area of climate change he said quote we have to get rid of the Medieval Warm Period unquote
https://youtu.be/u1rj00BoItw?t=65
“You Tube quote”
You might as well attribute it to YouTube. No-one has any better idea who is supposed to have said it.
The real quote (Overpeck) is
Monckton and others paraphrased this, “we have to get rid of the Medieval Warm Period”
So it is a pretty malleable quote. But what is wrong with trying to get rid of misuse?
They (who’s “They?”) want to get rid of the 1940’s blip too.
And every month the folks at NASA’s GISTEMP change ~370 of the monthly entries back to 1880.
And Colorado University’s Sea Level Research Group C-SLRG relentlessly changed the data for satellite sea level rise until they finally could claim that they found acceleration in the altimeter record LINK that they were looking to prove. They’re now claiming it’s 0.083 mm/yr².
And oh yeah, it’s 0.083 not 0.082 or 0.084 but 0.083 mm/yr² !!
Tide gauges say 0.01mm/yr².
Has Jonathan Overpeck ever clarified why he sent that email and what he meant by “get rid of” ?
Was it Overpeck? Deming declined to say who.
As I recall, Deming did not remember who sent the email, but just remembered it as being “extraordinary”. People are saying the Overpeck email is the closest they have found in the ClimageGate emails. If others in the email chain mentioned the MWP, then it is even more clear that Overpeck was including this in his statement. Pretty clear anyway that is what he meant. We don’t have a record of ALL emails ever sent in this time period on this topic, so there may have been a different email. Deming said it had numerous people it was copied to.
There is no evidence that Overpeck said any such thing. No email has ever been produced. Deming never identified a supposed author.
Nick,
The full details are here at Climate Audit.
See Climategate email 480. 1105670738.txt
You’ve already agreed above that the real quote by Overpeck is genuine.
It says he wants to deal a mortal blow to the misuse of supposed warm period terms and myths in the literature. Doesn’t even specify the MWP.
In ‘The Hockey Stick Illusion’ Montford’s well sourced book about Climategate on page 28 he says it was Richard Lindzen who identified Overpeck as the source in
‘Climate science: is it currently designed to answer questions?’ ,29th Nov 2008 at http://arxiv.org/abs/0809.3762
That’s about fourth hand. You said Montford said Lindzen said Deming said the email came from Overpeck. But no email to see.
Ah, here we see the old Hockey Stick trick of combining proxies with modern thermometric records.
For at least 200 years (1000-1200) all the proxies show warming, worldwide.
Global Average Temperature is a nonphysical nonsense in any case.
Aka, Mike’s Nature trick.
Mr. cat: Above, Mr. Stokes goes further, suggesting even US temp records were unreliable until eleven (eleven!) years ago, kept by amateurs!! Yet these are all bundled together to create charts that visually indicate accuracy across whatever period is chosen- 200 years, 500 years, 1500 years. Any average that fits the message is more reliable than the input. Any attempt by skeptics to pick apart these charts (Heller is too good at it for these fellows) is met by the likes of AlanJ and Stokes, note Mr. J kicked off the misdirection by “averaging” proxies to dispute articles about particular proxies. He can’t let the message get obscured by facts, so he uses averaging to obscure. Broken records.
Stokes, AnalJ et al only ever use averaged, “adjusted” temperature metrics, never the raw data because the latter don’t give the results they so desperately want.
Nick presents the results of his analysis using raw, unadjusted data elsewhere in this very comment thread, and showed that it has little impact on the result.
What is the difference in uncertainty between proxy and instrument data?
Only when you cherry pick which studies you use and use a discredited statistical method to combine them.
The study I cited uses the largest database of paleoclimate records ever compiled, and it compares reconstructions compiled using multiple independent methods (each line in the graph is a different reconstruction method).
Who selected which records to include and which to exclude, and why?
Variations on a theme, guaranteed to reach the same result.
You can read a description of the selection criteria and the included datasets here:
https://www.nature.com/articles/sdata201788
Mann et al FAKED using tree ring data that was in a CO2 deficit.
Then massive averaging on both time and temperature axis to get whatever graph they wanted to get.. even turning data upside down and truncating “inconvenient” data.
There are large numbers of proxies from all around the world showing the MWP 2-3 degrees warmer than now.
Whats the error levels on a reconstruction and show us the validation points?
You can see the uncertainty interval for the reconstructions on the graph I posted above.
Which are total bullshit, Fake Data fraudster.
How to Lie with Statistics is book that was published in 1954.
The 3 largest emitters have given the middle finger to the IPCC, UN and climate activists and so CO2 levels are going to get much higher and we can all see what happens. We should be over 450ppm by 2030 and close in on 500ppm not long after 2040.
So why bother arguing you will get to see what happens first hand.
When you’re predicting apocalyptic doom and gloom it’s hugely anticlimactic and depressing when you’re proved wrong and nothing happens.
Ala the past 50 years or alarmism.
Thing is, that extra CO2 will be totally beneficial, even if the mythical warming from it does actually happen.
I really hope that people like AlanJ are ABSOLUTELY TERRIFIED by the prospect of increasing atmospheric CO2…
… because there is absolutely nothing they can do about it! 🙂
> No one denies that there were regional periods of warmth during the timespan of the putative MWP, the argument is that warmth during the MWP period was not globally coherent, and so the planet as a whole never experienced temperatures comparable to today’s.
• The MWP is not “putative.”
• These two reports show the MWP was indeed global.
• “The planet as a whole” is a canard.
Mostly tree rings which had a CO2 deficit over much of that period and are totally useless as temperature proxies.
Massive averaging on both time and temperature axis.
And it splices a concocted high resolution surface data onto the end.
IT IS A FARCE.!!
There are proxies from all around the world that show MWP being 2-3 degrees warmer than now.
Tree lines were higher up mountains, Trees and artefacts from the MWP found under retreating glaciers etc etc etc.
If you use data that non-tree ring, you get a totally different shape, which is more realistic graph which is more in line with actual history.
Is that you Michael?
This plot reflects the global warming narrative, not science.
Reliance on CO2 as the prime forcing for climate is the key in all climate models; otherwise, decarbonization of the planet is useless.
Hundreds of $trillions are at risk if the mantra is not totally supported.
The models, however, are inconsistent with climate proxies. Proxies consistently show a decline in global temperature over the past 8000 years. That makes sense in that forests, artifacts, and even people buried under the ice 6000-4000 ybp are just now appearing as the ice melts.
The climate models, driven by CO2, warm continually to the present with NO peak and NO decline possible. This model artifact was labelled the Holocene temperature conundrum (www.pnas.org/cgi/doi/10.1073/pnas.1407229111). The contention is that all proxies are WRONG and the models are correct. That assertion is the most idiotic statement in recent science publications.
So true. And yet it has it’s enthusiasts as evidenced by AJ’s comments.
You also get that if you combine multiple series that don’t respond primarily to temperature because they tend to randomly cancel out and stick series at the end that do respond to temperature because they’ve been chosen to do so.
These proxies are all thermally sensitive. You can read about proxy selection in PAGES2k descriptor linked above or in Kaufman et al, 2020.
Oh God, make it stop!
Yeah, nah. There’s no evidence for that and there never will be.
Selecting proxies based on correlation with the modern warming period is a hockeystick producing process. Oh but wait, the experts “certified” they’re temperature sensitive. They must be good then.
Not convincing.
The bolded sections describe the proxy selection process for the PAGES2k database, the vital part is what you left un-bolded:
Knowing that the proxy correlates with nearby temperature is part of the PAGES2k selection criteria, but substantially more work is done to establish the temperature sensitivity of these proxies in the first place.
Smoke and mirrors. It’s just not possible to establish whether a proxy responded to temperature throughout its existence.
Of course, these reconstructions do not offer perfect certainty, but we don’t have time machines, and we have a desire to understand past climate change, so we work within the constraints of the available data. The idea is to use many different records from many different types of paleoclimate archives and try to extract common signals.
Calling this “smoke and mirrors” is just dismissive and underscores your own ignorance of the field.
I’ve seen the various justifications for establishing whether a proxy reflects temperature and they’re just weak. Holding back verification data may sound good to a layman but its just more selection based on the temperature record.
Wider correlation? Confirmation bias.
At the end of the day the proxies give us a broad sense of climate but to suggest they’re capable of establishing fractions of degree comparisons to today’s temperatures is farcical.
NOAA says USCRN has an uncertainty of ±0.3°C. NOAA says ASOS stations have an uncertainty of +1.8°F. NIST TN 1900 shows their own station has a monthly average of Tmax has an expanded uncertainty of 1.8°C.
And people want folks to believe that 1000 year old proxies can result in resolution of one-ten thousandths of a degree? What a joke!
And you believe a proxy can show ΔT’s to the nearest ten-thousandths of a degree? Look at the graph you posted. The slope of the regression lines have a value with that resolution! THAT IS A JOKE!
USCRN stations only have an uncertainty of ±0.3°C. How some group can decide to create a temperature trend that has a 3 magnitudes smaller resolution than USCRN and convince you they are a scientific group is sad to see.
It is obvious that neither you nor they understand why significant digits are used in science.
By the way, how did you graduate high school and certainly college without learning how to properly cite the references you use?
The reconstruction shown has an uncertainty interval of >0.5 degrees C, significantly larger than the uncertainty for the instrumental record.
The uncertainties of the instrument record is much larger than that. ASOS is ±1.0°C. CRN is ±0.3°C. LIG can have an uncertainty of ±1.8°C per NIST TN 1900. These are all single measurement uncertainties as are tree rings.
The uncertainty envelope for the instrumental record is about 0.3 degrees in the earliest part of the record, and bout 0.15 degrees on average. We aren’t talking about the uncertainty of individual thermometer records or individual proxies.
So instruments used in 1850 had a 0.3°? uncertainty? You need to provide support for your assertions. Take into account that ASOS stations in the U.S. have a ±1.0° C uncertainty.
I want you to show the calculations whereby single readings are combined to reduce uncertainty.
I’m not referring to instrumental uncertainty, but to the uncertainty in the estimate of the global mean temperature anomaly, which does not equal the uncertainty of a single station measurement.
I’ve linked you to the Gistemp uncertainty analysis, you can find similar for HadCRUT in their publications.
You grunch when I show monthly averages and say they are not representative of a global average. How is a proxy any better? Don’t tell me about using globally scattered proxies, or I can show you globally scattered stations with no growth or hockey stick.
A proxy is not better than an observational record, and I’ve never said otherwise. But proxies are all we have for the pre-instrumental period.
But proxy reconstructions do represent global changes, as can be shown by verification against the observational record and comparison with other paleo-observations.
Global change averages are meaningless without knowing the statistical parameters and descriptors that are associated with the mean value.
Splicing proxies when you don’t know the absolute temperature they occurred at makes the process worthless to derive warming conclusions.
Why, because you lose the access to the parts that make up the whole.
Your graph displays nothing about actual temperatures, only perceived ΔT in the proxy.
As you should know, ΔT values do not allow one to know the absolute temperature that experienced that change.
+1.6°C ΔT at 0°C looks exactly the same as a +1.6°C ΔT at 30°C. There is no way to judge whether the base temperature is the same.
The hockey stick you show could be occurring at actual temperatures far below the temperature at the time of the MWP.
The proxies are calibrated against the instrumental record, they are on the same baseline.
Instrumental record? Where do I download the instrumental data for 1000 to 1500?
Give up, Jim. I don’t believe he has the mental capacity to understand his own argument.
If we had instrumental data for the medieval warm period we wouldn’t need to have this debate.
Yet you said, “The proxies are calibrated against the instrumental record,”.
Because they are. Thus the temperature differences are consistent across the length of the reconstruction, and directly comparable to the instrumental record.
You mean the ΔT values are consistent. That is the growth rates are similar.
That doesn’t mean the temperatures at which the change occurred are the same. You simply can not conclude from ΔT’s that the underlying temperatures are similar.
ΔT’s are not temperatures. By definition, ΔT’s are rates of change, i.e., “Δ°C/time”.
You can say that, because the proxy records and instrumental records overlap.
So you assume that if ΔT’s match for the last 100 years (or less), that they then match going backwards in time for 1000 years or more.
Do you have instrumental records for each proxy? Some are very remote and I suspect weather stations and associated data is unlikely in most cases.
If a proxy records extends, say, 1960-900, and the proxy record shows that 1960 was warmer than 900-1200, we can be confident that temperature in 900-1200 was not higher than 1960. We know that the proxy in the past doesn’t reflect a higher unknown base temperature than during the interval covered by the instrumental record because we can compare the proxy record to the instrumental record. Like… we know what today looks like, and the proxy has today.
I’m genuinely struggling to articulate this in a clear and helpful way because the concept seems so flagrantly obvious that it is difficult to see where someone might not get it.
Because you are trying to explain the unexplainable.
Just because a proxy shows a ΔT of +1.0°C at 20° in 1960 does not mean that a ΔT of +1.0°C in 900 occurred at 20°C.
A ΔT of +1.0°C could just as easily have occurred at 21°C in 900 which would mean it was warmer than 1960. Likewise, it might have occurred at 18°C which means it was colder.
You simply don’t know this information, so you can’t explain it in specific terms. It boils down to making a choice that confirms your belief, rightly or wrongly. Not very scientific.
It is why splicing anomalies is a joke. You don’t know if the baselines are similar so you can’t judge the absolute temperature.
It does, unless you’re suggesting that there was a change in the proxy’s temperature response at some point in its history (which is something you assess through careful research), because the past values are relative to the baseline of 20 degrees.
The largest problem is that trees have a pretty wide temperature range where optimum growth can occur assuming there are no confounding factors.
When I looked up bristlecone pine, the optimum temp is 65⁰F – 80F. That’s ~±8 degrees. Not a very good uncertainty when combined with current instrumental measurements.
The range of temperatures where a tree species grows is not the range of uncertainty in temperature change estimates for a single tree record, and it certainly doesn’t represent the uncertainty for a paleoclimate reconstruction derived from multiple tree records.
You’ll notice, the range is optimum, not good, not fair or poor.
That is the uncertainty range of a proxy indication. You need a reference that supports an uncertainty much smaller than that. In other words how do you discriminate what the actual temperature was within the range?
Don’t give me the standard divide by √n. Each tree ring is a single measurement of a single measurand. The uncertainties add via RSS.
Again, you’re conflating the broad ecological range of bristlecone pines with the actual precision of tree-ring-based temperature reconstructions. Trees in temperature limited environments are sensitive to temperature fluctuations, and individual specimens can provide precise and accurate estimates of temperature change over time. And scientists rarely rely on a single proxy type when making paleoclimate reconstructions, they use many different proxies (ice cores, boreholes, etc.) which show consistency with tree ring based reconstructions.
Mumbo jumbo with the hopes you can fool someone. Show us the temperature data that supports your claim of “limited environments”.
Without some scientifically supported data you are just stating your opinion. Your opinion is worth no more than any other opinion.
Are you contesting the idea that temperature can be a limiting factor to tree growth?
A lower temperature implies less sunshine for photosynthesis, so yes, temperature can be a limiting factor. What I’m contesting is how you determine the actual temperature. Do you think it is possible to discern a temperature ±1°C from an annual growth ring?
What is being determined is temperature *change*. Whether a year is warmer or colder than another.
Which confirms what I said.
You cannot justify at what absolute temperature those ΔT values occurred for the proxies.
The earth “warming” must be measured from a common earth absolute temperature. Comparing ΔT values on a standalone basis doesn’t really say much about what temperature the warming/cooling is affecting.
As I said before, knowing I accelerated 10 mph, doesn’t tell you much.
You can articulate it with a hypothetical example. So if tree rings are wider in 1960 compared to rings from trees dated to 1160 then the argument goes it’s warmer in 1960.
The problem is that the tree rings in say 1980 aren’t wider even though we “know” its even warmer. This is the divergence problem and basically tells us that tree rings aren’t good thermometers.
What you cite isn’t a hypothetical example – it’s a well known issue with the maximum latewood density of a subset of high northern latitude tree species. What you’re suggesting is that we assume similar problems might exist for other proxy types even though we have never identified them, which is unscientific.
Every tree, grass, frog and human has a range of temperature where growth is optimum. Attempting to discriminate where in that range a temperature true value occurred requires a procedure.
Show us a paper that provides not only that procedure but also how to determine the uncertainty of that true value.
You really believe this?
The hockey stick is an artifact of programming. It’s utter nonsense. All of it.
I needed a good laugh Thanks.
Correlated with the modern instrumental record and calibrated. I believe you genuinely dont understand the issue here. Can you summarise the issue and let us know why you think its a “non issue”?
Here’s my guess on your reason. You trust the scientists with no actual argument needed or given.
One is a screening step, the other is a calibration step. Can you try to articulate what your specific objection is?
You miss the most important one. After screening and calibration, where is the validation step?
The validation step comes… after… screening and calibration.
Why do you never mention absolute temperature when you discuss WARMTH?
Validation is effectively just additional screening. It’s not what you think it is in the sense of establishing correlation.
Validation is seeing how well the calibrated proxy correlates to the part of the instrumental record reserved for validation.
My immediate issue is that you don’t appear to know what the problem is with screening based on correlation with the temperature record.
I’m not really interested in a coy back and forth with you. If you want me to engage further, explain what exactly you think the problem with screening based on correlation to the temperature record is.
I’m not here to explain it to you. I’m here to establish that you dont know what it is.
I’m sorry to disappoint you.
You haven’t disappointed me.
Aw thanks, dad.
More bullshit from LiarJ the Fake Data fraudster.
A load of complete crap in other words. How can you still be so thick as to not recognize a resolution of a tenth of degree C 1000 or 2000 years ago for periods of less than a couple of centuries is laughable. And tacking on actual measured values onto that is even more laughable. You are and seemingly will always remain a gullible and very irritating idiot.
There is no doubt that the in the NH at least, the average temps were warmer than they are today. No doubt. We know this from actual tangible evidence, not just proxies.
There is also very little doubt that this phenomenon was global.
Again, you are comparing a period of 40 or 50 years or so of modern warming and looking for the same period of time globally and 1000 years ago using proxies.
You sound like a school kid after sitting through a lecture by Michael Mann.
Kaufman reversed the proxy data, turning gradual cooling into unprecedented modern warming.
But of course these are different papers, so it’s a moot point.
As you note, Kaufman et al. 2013 turned proxy data upside down. Kaufman et al. 2020 on the other hand reversed the proxy data. Different papers and different errors.
Citation, please?
https://wattsupwiththat.com/2020/08/12/mcintyre-on-kaufman-et-al-2020/
It made it into IPCC AR6.
So there was a transcription error in one of the thousands of proxy records used. Specifically how does this impact the conclusions?
In addition
http://t1p.de/mwp
Nice map but so far I haven’t been able to count up the
Red Blue Green Yellow and (grey?) flags.
Click on the flags to find the respective paper as little feature
Legend
&filter=ffF4EB37Mills et al. 2014: Lake Kyasanduka, Maramagambo Central Forest Reserve
&filter=ffDB4436Cold Air Cave, Makapansgat Valley
&filter=ffDB4436Kuhnert & Mulitza 2011: GeoB 9501
De Cort et al. 2013: Lake Bogoria, eastern flank of the Kenya Rift Valley
… 1268 weitere (and further)
Even if you could count them up, it wouldn’t tell you whether the MPW was globally warmer than today, the analysis is completely qualitative.
The climate denial is strong with this one !!
ANY proxy is qualitative, not quantitative. Proxies are NOT thermometers.
The only people who think GAT is important are Warmist shills like you.
Yeah, but Alan says that they were calibrated!! Lol.
AnalJ really believes that? He’s even dumber than I thought.
By your own stupid argument then we don’t have enough temperature sites at present to say anything globally. You would literally have to have a reading for every inch of the planet because this same stupid argument could be made.
Perhaps you could inform us of the AlanJ perfect distance each site must be apart?
Even if the Almighty came down and took you around the world during the MWP you would still cry no.
Mr. Mike: If it came to that, Mr. J would reflexively try to average that with stuff other deities might have shown him. Lotsa deities make a nice fudge!
Good article, further confirming the Medieval Warm Period (MWP) was global. The MWP and the Little Ice Age (LIA) nicely coincide with the Bray and Eddy solar cycles’ composite cycle, and since the SUN drives those cycles, the MWP and LIA must have been global events.
While the Greenland GISP2 ice core represents climate at one location on earth, I’ve found through careful spectral analysis that the variations in temperature over the Holocene can almost entirely be attributed to the Jovian planets, and because the variations can be found in carbon isotopes and in sunspot data, the sun is the main driver of Earth’s climate.
However, I think it’s unreasonable to expect that every place on earth will react in lock step if for no other reason than the imbalance between hemispheres in terms of land and oceans. I’m also not convinced that there’s enough evidence to eliminate the possibility that the sun drives climate through multiple mechanisms.
In this spectral plot the 900-year cycle most likely comes from all four Jovian planets. Given it’s distance from Earth, Isn’t it interesting how significant a role Neptune plays? Because of how the ice core is sampled, the highest credible frequency is about 0.02 yr^-1
Oh no! Contradicting the blessed revelations of Michael Mann!! All non deniers must accept that the Satanic Gasses are the only influence on temperature, and that any warming was strictly local!!!
All Good People must affirm that even though the Medieval Warm period appears everywhere one has evidence, as does the Little Ice Age, do not let such lures of Exxon deceive one from the True Path!!!
(obviously/s)
The failure of Climate Science to quantify natural variability renders climate science no better than junk science.
Statistics tells us that average +/- 3 standard deviation is normal behavior for sampled data.
So if the standard deviation in climate is for example 0.5 C, then 1.5 C or warming is fully explained as natural variability.
So no scientist alive today knows if climate change is natural or anthropogenic. They are simply guessing.
Another celebration of the universality of MWP that glides over the different timings. Any local max, whenever it happened, is alled a MWP. Here we have Antarctica 750-1350 AD (possibly!), but Poland 1200-1350 or maybe -1450 (it’s vague). What exactly is “undeniable”?
“the Medieval Warm Period in Poland was comparable or even warmer than the average temperature in the period 1951-2000”
Global temperatures in the decade to 2024 were 0.84 C warmer than that average (GISS).
The Poland paper is here
Nick,
I agree with you that these 2 papers are hardly convincing.
Geoff S
Geoff,
What are we doing up at 3am? 🙁
Just got home from the Moyhu nightclub? 🙂
Study of the wrecking of Australia by poor science and inept government. Geoff S.
False. Almost all the proxies show warming for the core period of the MWP (1000-1200).
https://wattsupwiththat.com/2018/11/03/yet-another-study-illustrates-that-the-medieval-warming-period-was-not-regional-but-global/
“the core period of the MWP (1000-1200)”
The Polish “MWP” in fact started about 1200. Coldest period was 1000-1050.
Oddly enough, the map in the WUWT post shows warming in Central and Eastern Europe for that period.
Another paper showing Poland warmer during MWP.
The MWP and LIA don’t start on the same day all over the world, therefore it can’t be a world wide event and must be ignored.
Or the same hour, minute, or second.
Asynchronous means inapplicable.
/s
These don’t even overlap. Temperature does vary naturally, and places have warm times and cooler. What happenes here is that any local warm spell between about 600 and 1500 years ago is claimed as evidence of a MWP.
False If you had bothered to read my post above, you would understand that the graph showed synchronous worldwide warmth for at least 200 years (1000- 1200).
From the OP, re Poland:
“The coldest conditions in the entire study period were recorded in the first half of the 11th century (both in winter and summer)”
That’s 1000-1050 AD
See bnice’s comment above. The first graph shows a maximum temperature around 1000 years before present.
So how does that help us? The paper featured here says that time was cold.
Do they have to?
It seems to me the argument is to imply that global warming cant happen by itself but nobody to my knowledge has attempted to find actual cold regions to balance warm regions resulting in a neat “no net energy change”
Instead what we hear is warming but non-overlapping for some regions. Generally warm, but not excessively cold in places.
The time periods don’t overlap. So what are the boundaries of the MWP? Some place is always warming somewhere.
That the earth is overall warmer and it occurred naturally. The argument that it wasn’t uniform may be great for supporting CO2 as a factor in the current warming but a naturally warmer earth for an extended period breaks the GCMs and we can’t have that, can we.
“That the earth is overall warmer”
At what time? And how do we know?
“a naturally warmer earth for an extended period breaks the GCMs”
Not true.
Better let Santer know then. He showed they can only sustain 17 years of unforced warming or cooling before reverting back towards the mean.
Not true
Its the (unintended) corollary of his paper, Separating signal and noise in atmospheric temperature changes: The importance of timescale where he finds
It isn’t a corollary at all. First it says at least 17 years. But it doesn’t say anything about reverting to the mean. It just says you see behaviours that you can’t distinguish from AGW.
Third, he’s talking about TLT, not surface.
That’s right. At 17 years the models dont continue to warm. Hence nature warming beyond 17 years implies a forcing according to that reasoning using the models.
But the simpler realisation (to save you reading and understanding the paper) must surely come from simply recognising that when the unforced models spin up, they come to an equilibrium.
Its by design.
Santer has simply found that they dont vary around that equilibrium and then hypothesises that wider variation in nature, implies the forcing.
There is certainly no equilibrium. Remember that stuff about a chaotic system, with a large energy flux running through. He does say that, observed long enough, AGW should produce a signal (trend) which would be improbable for unforced behaviour.
My turn. Not true.
A control run (ie unforced run) establishes an equilibrium where the global temperature varies around a mean.
Apparently the maximum extent to which it continues to vary up (or presumably down) is 17 years.
Then again, modern warming isn’t occurring everywhere at the same time or the same rate.
Global temperature is just a meaningless, modern construct.
Correct and so by Nicks own argument what we are seeing is not Global warming but regional warming. Both Nick and AlanJ are suffering this problem if we use there own criteria then Global warming isn’t happening.
Mr. de Boer: Yes, and if evidence of regional warming supports the message, chart it! If, not, then demand precision that is not required when the message is supported. Broken record.
Nick (and Alan),
We don’t have a comparable “Global Temperature” from the past like the one that has been constructed via thermometer measurements in the present. It’s unclear what that temperature really means or why it is important. It is local temperatures that matter most. So, we are comparing apples and oranges. But, many (poor) scientists and politicians and media folk are constantly pointing to local events occurring in quite distant places and varying from year to year and place to place and sometimes decades apart as evidence of “climate change” rather than just weather.
Since l live in England l will stick with what’s going on in Europe.
I think there are 2 factors that are causing the current warming trend in Europe, one natural the other manmade.
The natural cause.
A increasing trend over recent years of high pressure forming over the Azores and Europe especially over the late winter and spring period. Which is leading to warming due to increased air masses been sourced from the south, while at the same time cutting off the amount of colder air that can invade into Europe.
But the thing is not only does this increase in weather patterning warm up the weather, it can also warm up the climate. As the increased blocking allows clearer skies and lighter winds over the Azores and the Mediterranean Sea. Which allows the sun to warm up these waters.
The manmade cause.
Is the utter lack of care taken over the switching over of recording temps with LIG thermometers to electronic thermometers. It’s utterly trashed the consistency of the temperature record and has lead to the utter joke claims of the ‘hokey stick graph’ about the amount of warming over recent years.
I said this before and it stands: most people don’t have even a vague idea of how MWP looked like. Consider that Kiev used to have a problem with crocodiles in the nearby waterways growing numerous, large and bold enough to present a clear danger to humans, and warrant organized armed response. So, um, until there are news about small scale military operations against carnivorous reptiles at least this far North again, the whole ManBearPig noise does not even begin to seem like it may possibly deserve a serious consideration.
I am quite curios as to how a warm spell lasting a century or more could only be regional.
The air circulates the whole planet as do the oceans.
So, did western Europe, back then, exist in a glass house?
Curious minds want to know.
STORY TIP
https://apnews.com/article/climate-change-satellites-crash-earth-orbit-b21f43bbd8925d67264e41f6c24c73e1
Headline:
Study says climate change will even make Earth’s orbit a mess
It turns out that Earth’s orbit is the path taken by satellites. The headline misleads.
The concern reported is that climate change makes the upper atmosphere cooler and therefore there is less drag on orbiting junk. The result is the orbits cannot self-clean.
More good news.
We don’t need another pandemic, people will soon be dying of bloody climate boredom.
Just to settle this debate without doubt, Wikipedia (that font of all knowledge) states that –
Global average temperatures show that the Medieval Warm Period was not a global phenomenon.
That opens up a whole other vexed topic, namely the –
PROBITY
PROVENANCE
PRESENTATION
of the mythical “global average temperature” construct.
Haven’t some climate alarmists attributed the Little Ice Age (late 1300s—early 1900s ) to one form of human activity or the other? Or does such a phenomenon back then no longer count? I can also recall that a series of below-normal winters in the 1960s were explained by increasing atmospheric CO2 that resulted from the steady expansion in global industrialization fueled by the growing use of fossil fuels. The reality is that the climate panic-mongers will never miss the opportunity to utilize distortions, omissions and outright misinformation to keep whipping the lame horse about manmade global warming and environmental degradation. Except the fact that most of the world still relies heavily on oil, coal and natural gas to generate 82% of the world’s energy shows that the huge majority of businesses, industries and consumers consider energy security one of their main concerns and ignore the doomsday scenarios.
I like the dating for the MWP in the Antarctic going back to the 700’s, that agrees with Esper 2014 and northern European summer temperatures.
The Polish study is rather bizarre given that the MWP was over by the early 1200’s. Attributing the cold in the 1450’s in the Sporer Minimum, to a mystery volcanic eruption does not make sense either. Large tropical eruptions promote positive North Atlantic Oscillation conditions, leading to 1-2 milder boreal winters following the ruption.
https://cp.copernicus.org/articles/19/2389/2023/
I can throw in this short study from Austrian Palaeontologists. Just by examining tree polls and residuals of wisents (European buffalos) in caves in the Austrian mountain region “Totes Gebirge”, they come to the clear conclusion: “From this it can be concluded that the beech limit but also the forest line during the “wisent time” (6,000 to 1200 years before today – so 800 AD) was much higher and the average summer temperature had to be at least 3°C to 6°C higher than today.
“The oak boundary (boundary between colline and montane vegetation stages) today lies between 400 and 800 metres in the Northern Alpine Alps. Oaks at an altitude of 1,450m around 2,000 years ago also indicate a climate approximately 4 to 7°C warmer than today.
https://www.researchgate.net/publication/363535571_New_subfossil_findings_of_wisent_Bos_bonasus_in_caves_of_the_Northern_Calcareous_Alps_Upper_Austria