By Andy May
Renee Hannon (@hannon_renee) pointed out that Raphael Neukom, et al. (2019) compares the modern instrumental temperature record to the Pages2K proxy temperature record and declares that:
“… we find that the coldest epoch of the last millennium—the putative Little Ice Age—is most likely to have experienced the coldest temperatures during the fifteenth century in the central and eastern Pacific Ocean, during the seventeenth century in northwestern Europe and southeastern North America, and during the mid-nineteenth century over most of the remaining regions.”
Neukom, et al., 2019
Then, they compare this to the instrumental record since about 1900AD.
“By contrast, we find that the warmest period of the past two millennia occurred during the twentieth century for more than 98 per cent of the globe. This provides strong evidence that anthropogenic global warming is not only unparalleled in terms of absolute temperatures, but also unprecedented in spatial consistency within the context of the past 2,000 years.”
Neukom, et al., 2019
They are comparing sparse, poorly calibrated, disparate, poorly dated proxies with annual to centennial resolution to a global modern network of daily calibrated thermometer readings and their point relies on timing and accuracy. Global warming in the twentieth century was hardly uniform in any case, nearly all of it took place from 1920-1940 and 1980-2000, and temperatures in Antarctica and much of the Southern Ocean hardly changed at all, probably only 0.2°C since the late 19th century.
The location and type of Pages2K proxies used in the study are shown in their figure 1a, also our figure 1.
Figure 1 identifies some of the various types of proxies used and their locations, but it does not address the temporal resolution of the proxies or how many of them provide temperatures each year between 0AD and 2000AD. These quantities are important if we are to compare the 1,000-year-old Medieval Warming Period or the 400-year-old Little Ice Age to the thousands of daily calibrated thermometer readings we have today and make a judgement about warming or cooling spatial consistency. Figure 2 is figure 1a from Pages 2K, 2019. It provides more detail about the proxies.
Figure 3 shows the temporal resolution of the proxies in the Pages 2K 2017 version, there is no equivalent figure in the Pages 2K 2019 version. For most proxies it varies from annual (beige) to multidecadal (blues). Some of the tropical proxies have sub-annual resolution, they are coded in red in figure 3.
In figure 3, because of the colors, the high-resolution proxies shown in red look impressive, relative to the softer colors used for the lower resolution proxies. Figure 4 shows the availability of each type of proxy, it gives us a clearer picture of the temporal resolution of the Pages 2K proxy temperature reconstruction. We should remember that among the many criticisms of Marcott’s global reconstruction was that as proxies dropped out or entered it as it moved toward the modern period, their entry and exit changed the trends, also see here.
By comparing figures 2 and 3 we can see that, at least in the opinion of Pages 2K, the higher-temporal-resolution proxies are the coral proxies in orange. The coding suggests that these proxies have sub-annual resolution, as discussed in these USGS notes and these NCAR notes. But figure 4 shows that very few of these records extend back to the pre-industrial period, aka The Little Ice Age. By eyeballing figure 4 we see that we lose nearly half of the total proxy records by the middle of the Little Ice Age (~1500 to ~1600) and we lose nearly 80% by the Medieval Warm Period (~1000AD).
In the Methods section of Pages 2K (2019), they say that the sub-annual proxies were reduced to annual values by using the April-March averages in the reconstructions, which reduces the detail. They also admit that none of the reconstruction methods they tried “explicitly consider age uncertainties,” which is a fundamental problem when comparing ancient proxies to modern records.
There are other proxy problems besides their sparseness and poor temporal resolution. They are calibrated to instrumental records from the modern era. Most are organic proxies, tree rings, corals, sponges, etc. which are affected by human CO2 emissions as well as modern warming. The remaining proxies, such as lake sediments, marine sediments, borehole readings, and ice cores, often lose accuracy and/or resolution with time due to geological (that is preservation) deterioration. In addition, estimating the correct date for a sample becomes less accurate the older the sample, a problem ignored in Pages 2K. In fact, the uncertainties for all reconstruction methods and all measurements increases backward in time (Pages2K, 2019). See figure 3 in the Pages 2k 2019 supplementary materials for a visual feel of the increase in error backward in time.
Discussion
By comparing minimum and maximum proxy temperatures over the Little Ice Age (~1300 to ~1850) and comparing them to minimum and maximum modern daily instrumental measurements since 1900, Neukom, et al. would have us believe that the modern warm period is unique. We have thousands of weather stations, ocean buoys, and ARGO floats around the world today. It is well known that daily temperature extremes often exceed 30°C, which is more than 70 times the differences being estimated by Neukom, et al. as shown in figure 5, which is from their paper. These daily extremes are captured in instrumental data, but only seen occasionally, by pure chance, inaccurately, and in a very naturally smoothed way in the proxies. The proxies undersample both the high and low temperatures. Further, accuracy decreases backward in time.
The Pages 2K 2019 paper emphasizes that tree ring records are detrended which causes a loss of “multicentennial-scale temperature variability.” Variability is exactly what Neukom, et al. are trying to measure! Then Pages 2K conclude that low-resolution marine records seem to overestimate the true variance—now just how do they know the true variance? They should just say they don’t know, which is the truth of the matter.
Claims that modern warming is unusual cannot be supported with the Pages 2K dataset. This is best seen in Neukom, et al.’s figure 2 that Renee Hannon found. It is shown in figure 5.
Except for the portion of figure 5 that is after 1900AD, the globe is very sparsely sampled, but at least temperature is measured with instruments in the 20th century. Before 1700AD, the record is not only poorly sampled, but is comprised of only the low temporal resolution, poorly dated, inaccurate proxy data described above.
How do we know that the global warming observed since 1950 or so is unusual in any respect? As seen in figure 6, modern warming has not happened uniformly around the planet and some areas have cooled according to AR6 and HadCRUT5.
In warming and cooling trends, changes do not occur at the same time all over the world. Convection and atmospheric circulation assure us of that. The precision and global coverage of our measurements determines how well we see the evolution of warming or cooling. What Neukom and Pages 2K observe may simply be due to the change in accuracy, coverage, and resolution of their proxy measurements of the Little Ice Age and the Medieval Warm Period, relative to today. I would be willing to bet that the extremes seen in figure 5 are a better representation of reality than their reconstruction, and I seriously doubt they can refute that statement.
Comparisons of measurements in the modern instrumental period to ancient proxies were invalid in Mann’s notorious hockey stick, and they are still invalid. Besides, whether a change in climate is global or regional is not evidence that it is due to changing CO2 concentrations or natural. It is hard to show that global average temperature is even a valid climate metric. Air circulation patterns change all the time, especially in winter.
It is well known that the coldest period of the Little Ice Age occurred at different times in different places. It was around 1810 in the Makassar Strait in Indonesia and around 1650AD in Greenland, as shown here in figures 1 and 2.
However, the general temperature trends at both locations, over 10,000 miles apart, are similar. The effects of climate forcing, whether from the Sun or greenhouse gases, are not instantaneous everywhere at the same time. Solar energy penetrates deeply into the ocean which causes a significant delay in its climate effects, it also increases the power of solar radiation changes because solar changes accumulate in the oceans, which act as a battery. Greenhouse gas radiation does not penetrate the ocean surface, this both reduces its impact on climate relative to the Sun and reduces the delay in its effect, providing some support for Neukom’s hypothesis that more global synchronicity of climate change points toward greenhouse gas warming.
But solar-driven changes in air circulation patterns caused by ENSO, the PDO, NAO, AMO, etc. (see here) still cause regional and, sometimes global, delays in the relatively modest climatic impact of greenhouse gases.
Creating global reconstructions from proxies is foolish due to the sparseness of the proxies, their inaccuracy, and their different temporal resolutions. You can reduce resolution, but you cannot increase it. It is more meaningful to compare modern temperatures at a specific proxy location to that proxy, than to try and combine proxies into a global temperature, as discussed here.
Download the bibliography here.
Renee Hannon kindly reviewed this post.
So this didn’t happen?
Cool show! Thanks.
FJB says it’s hotter now in Cabo San Gaza than ever before.
😀😀
he knows because Emperor Maximillian told him so.
It’s faked- by climate/science deniers- using the latest AI! We had perfect weather until 1850- going back millions of years. /sarc
We should know the LIA never existed … because we’ve been told by tricky Micky Mann extinguished professor & the worlds leading ‘climb it’ sly-entist.
“but it does not address the temporal resolution of the proxies or how many of them provide temperatures each year between 0AD and 2000AD”
Proxies don’t provide temperatures at all.
Very nice Andy.
We should be long past did the Little Ice Age happen, and we should be a lot closer to here’s a high probability explanation for what caused this little, short term (in geologic timeframe) cold snap, the lowest temperatures in the last 10 thousand years. Wikepeia reports:
Wikipedia reports:
Several causes have been proposed: cyclical lows in solar radiation, heightened volcanic activity, changes in the ocean circulation, variations in Earth’s orbit and axial tilt (orbital forcing), inherent variability in global climate..
Dah? Is that any different than what encyclopedia Britanica said in 1954, seventy years ago? Since then, we’ve decided about plate tectonics, but is that it? Svensmark has a hypothesis about cosmic rays (that I consider a likely candidate) but Wikipedia apparently didn’t consider that as deserving a mention.
$billions on CO2 as the (unlikely) climate control knob, but no answer to the Little Ice Age. Incredible.
It’s all politics.
This paper makes a good case that the Little Ice Age is the result of low solar activity and a persistently negative NAO, which are probably related, and an idea I agree with. Then in the conclusions they say it is volcanism!!! Obviously because some peer-reviewer forced them to write that nonsense. Crazy world we live in.
The variable European Little Ice Age – ScienceDirect
There is nothing in the paper to support that crazy idea. For the curious, I refer them to Javier Vinos’ discussion in his book Climate of the Past, Present, and Future on Researchgate, pages 104& 180.
“This paper makes a good case that the Little Ice Age is the result of low solar activity”
And any current warming is due to HIGH solar activity, more energy reaching the surface due to cloud changes,.. and maybe a decrease in solar energy blockers like SO2.
Land surface temps are obviously also been heavily affected by the encroachment of urban heat on to a large proportion of surface sites.
Andy and Dennis (and others), think about this, what caused “Snowball Earth”? That’s Little Ice Age writ large, maybe two pulses in the earliest Paleozoic 600 – 700 million years ago. Solar variation? Greenhouse gases? Rodina breakup (first super continent breaks up). Orbital malfeasance? We don’t know. OK, how about this question: what got the earth out of the snowball condition? SUV’s? Coal-fired steel mills? What? We’re a very long way from understanding many aspects of the climate controls.
https://scitechdaily.com/when-earth-turned-to-ice-scientists-unravel-700-million-year-old-climate-puzzle/
Thanks for the reference, Clyde. I reject both of their main findings, that volcanism reduced (at that time almost all volcanism was at spreading centers, there was not any effective subduction) and that CO2 is the control knob for earth’s climate. They claim that atmospheric CO2 at 200 ppm caused Snowball Earth, but that lower level was exceeded during the heart of the last glacial cycle of the Ice Age we live in, and all records show CO2 lagging temperature. The research was funded by CO2 grant money.
“…how about this question: what got the earth out of the snowball condition?”
When talking about long eras of “hothouse” or “icehouse” Earth conditions, things like continental drift and even the planet’s rotational period are often overlooked; the focus almost always on GHGs and other things. The positions of the continental landmasses and large mountain ranges is probably 90% of the whole long-term determinate in whether we’re in a hothouse or icehouse era.
I also think that Continental Drift is not credited enough for variations in Earth’s climate, as the modification, or outright blocking, of ocean currents is a major change in weather patterns, therefore to climate changes.
Thanks Andy, nice read, here’s a couple quotes that provided a chuckle:
The statistics of extreme events show a mixed picture. Correlations with forcing factors are weak, and can only be found in connection with the “Years without a Summer”, which very often occurred after large volcanic eruptions (Seems I’ve been told volcano effects only last a few years, not hundreds of years)
Carozza et al. (2014) show that the number of publications per year containing the term LIA has risen steadily since 1970, reaching almost 100 in the year 2000 and now significantly exceeding 500 (earth wobble, volcanoes, ocean currents not unlike CO2 papers all saying the same thing).
This brings to mind the saying, “if you can’t explain the past…” which brings to mind what Yogi Berra had to say about the future:
It’s tough to make predictions, especially about the future.
If you don’t know where you are going, you’ll end up someplace else.
You can observe a lot just by watching.
The future ain’t what it used to be.
It ain’t the heat, it’s the humility.
Comment: I’m not seeing much about the future climate from the 1000 or so hours I’ve spent reading about the subject these past 20 years, other than bull feathers.
That is the problem with fascists limiting debate and enforcing consensus, science stops for the most part.
As the Soviet leaders were fond of saying, everything is in the service of the Party. That includes science.
Thanks Andy, very informative. I think that the 20th-21sr century temperature record reflects primarily the growth and urbanization of global population, the increasing concentration of thermometers in urban areas and the ballooning of the Urban Heat Island effect. There is also no doubt contribution from land use changes, natural variables (solar, ocean currents, ENSO, etc.) and maybe even CO2 concentration increase.
I remember — from a time before the global warming panic got going — learning in economic history class about the Thames river freezing over so hard that people pitched tents and held fairs on it for weeks. I would like to know if there are similar accounts in other countries. Are the climate crazies going to remove all that history as inconvenient?
I have several anecdotes (and sources) from the Little Ice Age in this post. I was particularly startled to find out that the Nile River was choked with ice for a week.
Are fossil-fuel CO2 emissions good or bad? – Andy May Petrophysicist
“similar accounts in other countries“
Searchup:
Winter Landscape Paintings by Dutch and English Masters
AND:
These Paintings Reveal How the Dutch Adapted to Extreme Weather During the Little Ice Age
As does the Medieval, Roman, Egyptian and Minoan warm periods, and the Holocene Optimum.
Recorded history, as with freezes at a given date and place, or which crops were successfully grown where, would give a much different view of the Medieval Warm Period and the Little Ice Age.
The Norse were able to do dairy farming and grow barley in Greenland circa 1000, so I really doubt any claim that it was colder then than now. Similarly, growing wine grapes in the UK was viable in the Medieval Warm, and it is just barely possible now.
Even with gmo manipulation today grapes don’t do well there.
Endless physical evidence.
There is abundant evidence of tools used by the Romans in the UK, as far north as the Hadrian Wall, which was during the Roman Warm Period, warmer than the Medieval Warm Period, warmer than the Present Warm Period
Even though CO2 has increased, it is still far below sustainability of many plants and animals
The lack of flora led to many areas turning to desert
We need more CO2 ppm
More than ‘just barely possible now’, there are almost 1,000 commercial vineyards in the UK now, mostly producing sparkling wine, Chardonnay being the most common variety. The English wines have been winning prizes in international competitions in recent years.
Only in the southern counties. During the Roman warm period vineyards were producing wine further north, between York and Carlisle.
Remains of 7 Romano-British vineyards have been found, four in Northamptonshire, one in Cambridgeshire, one in Lincolnshire and one in Buckinghamshire.
The furthest north commercial vineyard currently operating in England is Ryedale Vineyard in Yorkshire (further north than York).
Also over 40 vineyards are referred to in the Doomsday book in Southern England and there were over 100 vineyards at the time of Henry VIII (1509). English wines were hit by the phylloxera epidemic in the 19th century and further by a substantial reduction in the import tax on foreign wines which the major cause of the demise of the industry, not the weather.
Today’s grapes have been genetically enhanced to handle the cold and resist powdery mildew better in cooler climate than 1 to 2,000 years ago.
English vineyards were doing well until the introduction of phylloxera from America in the mid19th century which decimated them as it did the rest of the European vineyards. Without the genetically enhanced vines there would be no European wines.
I have two simple qualitative metrics for the MWP being warmer than now, and the LIA being colder than now.
History doesn’t mislead, unlike Mann’ hockey stick and Pages 2K.
A separate qualitative point. As you point out, the two warmings since 1900 were roughly 1920-1940, and 1980-2000 (my graphical preferences are 1920-1945 and 1975-2000). Even IPCC AR4 said in WG1 SPM fig 4 that the former was mostly natural because not enough change in CO2. News flash—natural variation did not magically stop in 1975 or 1980 even tho climate models assume it did. A major reason climate models now run hot thanks to the attribution problem baked into their unavoidable hindcast parameter tuning. Details in several long past WUWT guest posts.
“During the MWP, wine grapes were cultivated in England according to abbey records.”
So what?
Grapes are still grown in England, Scotland and Ireland now and in past decades.
Your local England wine grapes anecdote does not even come close to proving a MWP was warmer than today. A pitiful “metric”.
Viticulture, the growing of grapevines, is an expanding market within UK crop production. There are over 700 vineyards in the British Isles ranging in size greatly from small plots to large more well-known wine producers such as Bolney Estate, Denbies, Chapel Down, Nyetimber, and Ridgeview.
Grapes (Vitis vinifera) have grown well in Scotland since the first Roman landed, pulled a twig from his tunic and stuck it in the ground. Indeed, the legendary Kippen vine (variety Gros Colman) from a village near Stirling (1891 – 1964) was so healthy its owners harvested 2,000 bunches a year.
Irish wine production takes place in a small number of vineyards and wine producers the majority of which lie in County Cork, Ireland, with Lusk, North County Dublin, also producing a wine named ‘Lusca’. Ireland is officially listed as a wine producing country by the European Commission.
You didn’t account for grape that tolerate cooler weather.
When did those British wineries start? The answer will settle things – hint, not that far back!!! 1891??? That’s like yesterday in geology! That’s roughly time enough for about 200 years of warming up from the coldest depths of the Little Ice Age.
When the Romans came to the UK, wine production was started
I think their invasion philosophy was if you can’t produce wine there- don’t invade. 🙂
The Kippen vine was grown in greenhouses.
Apart from the fact that wine grapes are still cultivated in England and Wales a significant factor in the Thames freezing was the obstruction of the flow by the medieval London Bridge which was replaced in 1831.
What is the relevance of your first fact? It just demonstrates that the prevailing circumstances are favourable to wine production (weather conditions, grape varieties, economics). What happened to wine production in the centuries between the MWP and mid to late 20th century in England? And what wine was being produced in the MWP? – the majority of English wine currently produced is white with a relatively high proportion of sparkling wine.
The River Thames was also wider through central London before the embankments were built, so slower moving. But it still has to be cold for a long period for moving water to freeze over and stay frozen over for days.
In an earlier post it was claimed that: “Similarly, growing wine grapes in the UK was viable in the Medieval Warm, and it is just barely possible now.”
More than ‘just barely possible’ there are now nearly 1,000 commercial vineyards in the UK.
Your post is misleading because you didn’t account for the newer varieties that is more frost tolerant and resist powdery mildew better.
The Thames freezing is being distorted to prove a point
When were the ice fairs in London?
River Thames frost fairs –
The last great freeze of the higher Thames was in 1962–63. Frost fairs were a rare event even in the coldest parts of the Little Ice Age. Some of the recorded frost fairs were in 695, 1608, 1683–84, 1716, 1739–40, 1789, and 1814.
Not very strong evidence if a Little Ice Age.
More useful would be the CET temperature record from three land weather stations. Still only local measurements that may or may not represent a global average temperature.
The extreme cold in the 1690s during the Maunder Minimum was accompanies by some famines in Europe.
It is likely the average temperature has been warming since th 1690s.
But an average of local proxies all around the world is not accurate enough to prove that.
If the Little Ice Age never happened, then what was Frankenstein’s Monster climbing over in Mary Shelley’s novel?
(Proxy evidence, of course. But more reliable than a tree ring.)
Mrs. Frankenstein?
That was more 1816 and Mt Pinatubo than the Little Ice Age. (At least had she been in New Hampshire.)
You can not be serious, Mary Shelley wasn’t an accredited climate scientist! sarc
The rough approximate cycles in temp go back about 8000 years ….cycles of a few centuries warming followed by a few centuries cooling…..not exact clockwork but recognizable ups and downs. The data is from ice cores and deep sea bed borings. It is now….this century …..that a turn downward in temps is expected based on the past. The temp could have already topped put …or maybe a curveball and another 50 years of higher temps….nobody knows. It has been hotter in the past than now…and certainly cooler….and more CO2.
When will these people realise that the main issues with trees before the very recent (since 1900) rise in atmospheric CO2,
.. has been the constrained growth due to low CO2 levels through the MWP and any time before that.
If tree rings make up even a smallish amount of your proxies, you will end up with not finding warmer temperatures from tree ring growth going back in time before the industrial revolution.
That grow was held back from lack of available CO2.
If they can’t admit that fact, then they are effectively admitting that CO2 levels back then were at least as high as now, which destroys their whole anti-CO2 manifest !
“It is more meaningful to compare modern temperatures at a specific proxy location to that proxy, than to try and combine proxies into a global temperature”
Actually this protocol could give decently accurate results in the right situation. e.g the Tuktuyaktuk tree outside of the village by this name on the far NW Canadian Arctic coast.
This still rooted dead trunk of a 5000yr old white spruce is located about 100km north of today’s treeline and a modern white spruce of this girth is over another 100km further south. This indicates the T° at Tuk to have been 6 – 8°C warmer than now. Assuming Arctic amplification to be double the global anomaly gives at least 3°C global anomaly relative to the present!!
This is the real dendrochronology that climateer drongos studiously avoid because they prefer voodoo statistics for their dark arts. Using trees in the more common sense way, amateurs can make a good estimate by themselves and it’s easily understood by the interested lay reader.These trees occur across hundreds of thousands thousands of square kilometers of the tundra/taiga of the N. Hemisphere, charting the climate swings of the Holocene.
Ditto, for the MWP. The Canadian and Alaskan Rockies Alps, etc. have large-trunk Medieval forests peaking out from beneath the toes of mountain glaciers above the treeline! For added fun, Google the 9500 year old spruce, still alive in the taiga of Sweden! And Google ‘ redwood chunks in Ekati diamond mine (50 million years ago, now in the tundra of near-Arctic Canada.
Bleached tree stumps hundreds of yards above current bristlecone pine treeline are eloquent reminders of an earlier warm era.
So too are easily datable Viking settlements appearing out of the ice in coastal Greenland and Iceland. Estimates are that Norsemen had thriving towns and villages along those shorelines between the tenth and 14th centuries before they were engulfed in the encroaching snow and ice. No proxies necessary.
https://www.scientificamerican.com/article/viking-history-is-melting-away-in-greenland/
IMO, Vulcanism could have been a forcing mechanism of significant ice-ups. It’s already understood that Pinatubo and Krakatoa had cooling effects. Explosive “super eruptions” 30 million years ago may have precipitated the cooling transition from the Eocene to the Oligocene Epoch. These eruptions were thousands of times more powerful than any recent volcano based on what they threw out. One of several, the La Garita super is said to have ejected more than a thousand cubic miles of volcanic matter, forming a caldera in the Colorado San Juan Mountains that is miles across.
I believe that these super eruptions may have precipitated the Antarctic Glaciation.
The IPCC used to claim the global average temperature stayed in a 1 degree C. range for the thousand years before 1960. Then Mann created his Fraudulent Hockey Stink Chart that started a Three Ring Circus. The Circus probably ended today. Mann claimed only a 0.4 degree C. range for the same time period.
All those numbers are meaningless. The averaging of local proxies used to create a fake global average is not accurate enough to make such GLOBAL claims.
We have anecdotes of warmer and cooler centuries but no accurate global data to prove there were GLOBAL warm and cool periods. That does not mean such periods did not happen. It is just too far past those centuries to collect accurate data
The IPCC said in 1995 that all natural causes of climate change combined were just “noise”. That’s why they bought what Mann was selling in 1998.
Meanwhile, the predictions of global warming doom apparently began in the late 1950’s with oceanographer Roger Revere. The imaginary “threat” was specified with a consensus ECS of CO2 range in the 1979 Charney Report.
Predictions of global warming doom have no connection with any historical temperature trends.
Predictions of CAGW are calling for a new type of climate, that so far is completely imaginary — just failed CAGW predictions since 1979 with CO2 as the boogeyman.
CO2 as a boogeyman may sound silly but is VERY serious. That CO2 boogeyman justifies Nut Zero. Nut Zero is the primary strategy to morph the US into a fascist nation.
Conservatives who know more about politics than me say we are already a fascist banana republic. The two recent judgments against conservative Mark Styne (by Mann) and conservative Donald Trump (by the crazy lady) are strong evidence.
The Earth is still in a 2.56 million-year Big Ice Age named the Quaternary Glaciation with over 20 percent of the land frozen, either as permafrost or underneath the 200,000 or so glaciers in the world today.
https://en.wikipedia.org/wiki/Quaternary_glaciation
Whenever the MWP or LIA is mentioned I point to this resource on Google maps for anyone who has the time to look at over 4000 reerences
Medieval Warm Period of Google Maps
A lot of the papers refer to the MWP as the Medieval Climate Anomaly which I find a bit worrying
“daily calibrated thermometer readings”
Not sure thermometers are calibrated daily. That would be a big effort!!
Right, poor wording. I meant they are calibrated, whereas proxies are not, they are simply correlated to thermometer readings in the modern era.
To my mind how the LIA was caused is entirely inconsequential, with the data available from that period we’ll never know.
What we do know, however, is that it was a low point in humanities existence which provoked famine and disease in the northern hemisphere.
The MWP, on the other hand, proved a large step forward in mankind’s progress. Across Europe the warmer climate encouraged crop growth and consequent wealth, no matter how modest. The great Cathedrals across the continent were built, often taking 100 years and employment on these and other major projects were a welcome relief from earlier cold periods which invoked a subsistence life.
Mankind suffered under colder conditions than we have now, with lower levels of atmospheric CO2, methane, and every other atmospheric ‘pollutant’ than we have today.
Even were the MWP and LIA regional, as Mann claims, the fact is it existed in Europe and the effects of both are clear from literature and illustrations of the time.
We also have good records of both in China, India, and the Middle East.
The proxies tell us climate is always changing and the anecdotes tell us people strongly prefer warming periods.
It is amazing that the good news of more CO2 and warming is spun as bad news, and even people enjoying the warmer winters since the 1970s are frightened of more warming.
Most people dislike change, climate enthusiasts seem positively terrified of it.
It is truly bizarre.
I have a question, that I think some of you guys will know the answer.
Last week, I watched a video from Climate Discussion Nexus. In the opening discussion, alongside John Robinson, was a picture of the rings of a tree.
I was immediately struck, by the fact that the rings were not the least bit concentric. In fact, one, could have been looking at isobars for a weather forecast. On one part of the tree, the rings were close together, and on the opposite side, those same rings were widely separated.
So the question is, how do you know, that you’ve obtained the correct sample? Taken from one side, where the rings are compacted, and one might infer that those were colder/drier years, and just the opposite for a sample from the other side.
How do they ensure consistency?
Thanks
it’s impossible- and take that from a forester with 50 years experience
tree rings may have SOME correlation with temperature but also many, many other things which overwhelm the relationship with temperature
I have no idea how you could differentiate btetween the variables of rainfall, CO2 and temperature with tree rings. That’s why I call tree ring “studies” a Tree Ring Circus
Tree-rings are often assumed to approximate a circular shape, but are rarely, if ever, circular. The result has to be under- or over-estimation of historical trends.
Having seen that photo, I’d call them poxies, not proxies
Nice article Andy.
Two things. We just had a thread that discussed the U.S. corn belt not warming during the instrumental period, yet your Figure 8 shows something different. I think it illustrates how using different statistics can give different interpretations.
Lastly, these are all anomalies. By sliding all the reconstructions back and forth over even 50 years time you can probably achieve about whatever overall ΔT that you want. Added to the fact that only recently do we have temperature readings with a resolution of one-tenth of a degree, I question that we can determine from proxies that same level of accuracy.
You mention that there are areas without any warming. That pretty well damages the warmist argument that CO2 is the control knob. If cO2 is well mixed, there must be other “control knobs” at work also.
I think you are referring to figure 6, which is only from 1981 to 2020, the period of fastest modern warming. And, you are correct, the choice of starting and ending dates is critical since in the instrumental period we had both warming and cooling.
In the image at the top- they (men and animals) look like their really enjoying winter! It’s been a mild winter so far here in Wokeachusetts. Ergo, it’s an emergency! No blizzards- no sub zero (F) temps- no ice on the roads- didn’t have to burn as much fuel oil as usual- no power outages- a horrific, catastrophic, disastrous emergency! Good thing my state government has a net zero plan- so that we’ll soon get back to those missing things. And it’s awesome that there are not more than a few of those science hating, climate denying conservatives in this state. Those fools fail to appreciate the brilliance of people like Mickey Mann. PBS has a nice story about that brilliant scientist and his ordeal. /sarc
Million-dollar legal victory shines light on conservatives’ attacks on science
YouTube has comments turned off on that video. It was most likely the choice of PBS, not YouTube. They obviously would have gotten slammed so they cowardly turned off comments.
I had no idea who the Hotez guy is, even after looking him up I have little idea who he is or what he’s supposed to have done.
Nice overview on proxy data limitations. And thanks for the mention. Here’s an article that summarizes how recent temperature reconstructions used by the IPCC are downplaying uncertainty and the use of Pages 2K’s statistical reconstruction to represent the past.
“Despite the attempts in AR4 and AR5 to reflect uncertainties across multiple reconstruction efforts and to represent time-dependent uncertainties as they expanded back in time, these efforts were surprisingly abandoned in the most recent AR6 Working Group I (WG1) report in favor of a single ensemble-based reconstruction of global temperature with relatively static uncertainty bounds over the Common Era”
https://www.sciencedirect.com/science/article/pii/S0277379122001688
Thanks Renee, great paper. Figure 3, attached, is great!
I find this quote important:
“While in the tropics there is a strong correlation between boreal summer (June through August temperature) and annual temperatures, over Northern Hemisphere land regions e where the majority of available Common Era proxy data are found – mean annual temperatures and summer temperatures are relatively weakly correlated (r < 0.50, Emile-Geay et al., 2017, their Figure S6). Summer-dominated proxies therefore may not reflect the range of variability or trends in annual temperatures.” Most proxies, especially tree rings, are summer temperatures.
Andy, another study with a different approach shows how climate modelers hide the natural temperature variations.
In 2009, the iconic email from the Climategate leak included a comment by Phil Jones about the “trick” used by Michael Mann to “hide the decline,” in his Hockey Stick graph, referring to tree proxy temperatures cooling rather than warming in modern times. Now we have an important paper demonstrating that climate models insist on man-made global warming only by hiding the incline of natural warming in Pre-Industrial times. The paper is From Behavioral Climate Models and Millennial Data to AGW Reassessment by Philippe de Larminat.
The money graph is Figure 1. Anthropgenic and natural contributions. (a) Locked scaling factors, weak Pre Industrial Climate Anomalies (PCA). (b) Free scaling, strong PC
My synopsis is
https://rclutz.com/2024/01/04/climate-models-hide-the-paleo-incline/
Thanks Ron, I vote for (a).
Andy I hope you meant to choose b. OTOH the Mann verdict shows the odds heavily favor CO2 hysteria.
Yes, I meant (b).
Thanks for the synopsis, I found de Larminat’s paper hard to follow. But he makes a very important point. The paleo data, properly evaluated, supports natural warming over anthropogenic warming.
The main problem with (a) is the failure to match either the rate of warming from about 1930 to 1946 or the period of cooling (or at least a lack of warming) from 1946 to 1976. This latter period is particularly important and is easily identifiable on data published by NOAA. In addition, another reference from NOAA (select “Past Events” tab) highlights that during that period there were 3 ‘El Niño years’ and 8 ‘La Niña years’ (see link for definitions). This observation certainly points to a probable natural cause for variations in warming/cooling phases of global average temperatures.
However, there is also a problem with (b) in that it invokes a distinction between the two phases of warming with the latter one being significantly enhanced by an “anthropic contribution”. There is no evidence of the incremental atmospheric CO2 changing in 13C/12C content throughout the whole period of the graph. The net 13C/12C ratio (expressed as δ13C) of all incremental CO2 added to the atmosphere since the start of the industrial revolution and averaged over periods long enough to even out short-term variations due to ENSO and major volcanic eruptions, has not changed from -13‰. This observation, from direct measurements and from the Law Dome ice core data, very strongly suggests a common CO2 source throughout. For perspective, the δ13C value of burning fossil fuels is estimated to be around -28‰, a much lower value.
Thanks Jim, points well taken. The author’s analysis did accept the notion of CO2 radiative forcing while questioning its scale. From the paper:
” Despite the large uncertainties inherent in these calculations, the universally accepted value since remains 3.7 ± 0.5 W m –2 at doubling CO2, without the formula ever having been substantially revised since, neither in its form (log) nor in its quantification (3.7 ± 0.5 W m –2 in IPCC AR6, TS p92) [40]. Moreover, fco2 is only one of the components of the whole anthropogenic forcing. Other factors add their own uncertainties and some of which (aerosols, land use change) have antagonistic effects to GHGs.” In the end the weak anthropic result includes ECS of 1.14, well below AR6 range.
Ron, thanks for the response. Certainly (b) gives a much better match with the observations, but the δ13C issue is a bit of a hobby horse of mine! In any event, the cooling between 1946 and 1976 must have been dominated by natural variation, as per (b), because estimated emissions were growing strongly after about 1950 and especially towards the end of that period.
Incidentally, although the pause from 2001 to 2014 is a bit short to put too much emphasis on, are you aware the rate of growth in emissions was 10 times faster than the rate of growth of atmospheric CO2 over that same period (Global Carbon Budget figures). Clearly looks like another ‘disconnect’.
Thanks again Jim, this time for that last factoid. I presume you followed the intensive discussion at Climate etc. on sources of CO2
https://judithcurry.com/2023/09/26/causality-and-climate/
My summary:
https://rclutz.com/2023/10/01/co2-fluxes-are-not-like-cash-flows/
I did follow that discussion so will be very interested to read your summary – thanks for the link. I wanted to contribute to the Climate etc. discussion at the time, but had a problem registering with WP (since fixed, I hope). Instead, I emailed the lead author directly with more details of my δ13C analyses; he expressed much interest and has been pursuing that further with his own analysis.
I will revert here with any comments/questions on your summary, though it may be a day or so before I can respond.
Your summary of the paper was very good; thank you for the link. I particularly liked the quote: “As usual with climate science, conclusions are made to support a narrative or a pre-existing conviction and the complexity be damned.”
My understanding is that Mann has never divulged fully his methodology regarding his analysis and construction of the “hockey stick”; where, in other words, investigators cannot understand fully how he derived this particular result, presentation, etc.
Can anyone comment regarding whether my understanding is correct … or otherwise? TIA.
I’m not sure he ever released all his data and methods, but I think McIntyre eventually reverse engineered all of it. It is a confusing issue.
Again, thanks much … where this unknown but critical factoid may compel me toward further investigation.
Per your suggestion, I will do some looking at McIntyre’s work and then also that of Steyn; where maybe this is something that Mark has discussed in at least one of his books.
Kind regards.
Have a look on McIntyre’s ‘ClimateAudit’ site – Hampus Soderqvist did an excellent job of forensic analysis on Mann’s MBH 98 & 99 showing that Mann lied about what he did and hid the actual method and proxies for 25 years.
“the putative Little Ice Age—is most likely to have experienced the coldest temperatures during the fifteenth century in the central and eastern Pacific Ocean,”
A La Nina regime would have to be during a higher solar period, in between the centennial solar minima.
“It is well known that the coldest period of the Little Ice Age occurred at different times in different places. It was around 1810 in the Makassar Strait in Indonesia and around 1650AD in Greenland…”
1650-1654 was particularly hot in northern Europe, meaning a very positive North Atlantic Oscillation regime, which would make it colder in Greenland. The cold conditions of the Maunder Minimum for Europe were mostly confined to the 1672-1705 period. The popularised start date of 1645 for the Maunder Minimum is 20 years too early, according to my heliocentric planetary correlations, and according to Central England temperatures and weather chronicles.
Moore 2001, notes a rapid cooling at Baffin Island in 1375, it was hot in northern Europe then too.
A more extreme example is in the late 700’s, where Esper 2014, shows the warmest northern European summers of the MWP, while the Greenland GISP2 proxy is the coldest for 3450 years.
Ulric, No reconstruction can see a 4-year anomaly. Attached is the Vinther,2009 Greenland ice-core reconstruction. I think you will agree it is best since it is elevation corrected. The lowest temperature is right at 1650AD, it has 20-year resolution.
Also, there is this:
“The winter of 1657-1658 was particularly brutal. Massachusetts Bay and the Delaware River both froze over, allowing people and deer to cross on the ice. The Baltic Sea froze so hard that horses and loaded wagons could cross from Gdansk, Poland to the Hel Peninsula over 10 miles north of the city. Yet, the following summer was excessively hot in Italy and Greece.”
Are fossil-fuel CO2 emissions good or bad? – Andy May Petrophysicist
References are in the post.
There was lots of heat in Europe in the 1630-40’s too. One extreme cold winter can happen at any time, like in 763-64, with two years of baking hot summers either side. That is the true nature of the solar forcing, it operates at the scale of weather. The extreme cold winter of 763-64 was down to the heliocentric configuration of the gas giants that year. Three of them were in the same configuration with the 1657-58 winter.
I see that chart shows cooling in the early Sporer minimum, but rather warm in the very deep centennial minimum around the 1120’s which is well apparent in other proxies and in weather chronicles. And a hugely warmer late 1800’s? No I cannot agree it is the best.
Greenland is not always synchronized with Europe or North America, thus we have the North Atlantic Oscillation (Iceland/Azores), which is a key predictor of global climate.
The Little Ice Age is characterized best as a time of weather extremes and storminess. Cold times always have more extreme weather, hotter summers and colder winters, as well as more storms that are more severe. Exactly the opposite of what the alarmists will tell you. Warmer means less extreme weather, not more. This is a key point.
The attached plot from Javier’s book shows storminess as black bars. Notice the Little Ice Age is a storminess peak in Europe.
I have given examples of Greenland and Europe being anti-phase, because of the NAO, which when positive drives warmer weather in northern Europe, and cooling in Greenland.
Extreme cold winters can happen anytime, because of their discrete solar forcing. Many of the coldest have occurred outside of centennial solar minima. Generally cooler winters during centennial solar minima is normal, but less so in the current one.
Centennial solar minima see an increase in very brief Saharan plumes to Europe, due to the increase in negative NAO conditions, during otherwise generally cooler and wetter summers for NW Europe. That’s the only type of heatwave which should increase.
My old Texas history books describe how Trinity Bay, a mostly salt water body of water regularly froze in the early 1800s enough that people could walk across it – that certainly isn’t the case now or at any time after about 1830