By Kenneth Richard on 7. June 2018
It has long been established in the scientific literature (and affirmed by the IPCC) that CO2 concentration changes followed Antarctic temperature changes by about 600 to 1000 years during glacial-interglacial transitions throughout the last ~800,000 years (Fischer et al., 1999; Monnin et al., 2001; Caillon et al., 2003; Stott et al., 2007; Kawamura et al., 2007).
In contrast, two new papers cite evidence that the timing of the lagged CO2 response to temperature changes may have ranged between 1300 and 6500 years in some cases. It would appear that a millennial-scale lagged response to temperature undermines the claim that CO2 concentration changes were a driver of climate in the ancient past.
Temperature correlations between the eastern equatorial
Pacific and Antarctica over the past 230,000 years
“The EEP [eastern equatorial Pacific] stack shows persistent covariation with Antarctic temperature on orbital and millennial timescales indicating tight coupling between the two regions. This coupling however cannot be explained solely by CO2 forcing because in at least one important case, the Marine Isotope Stage (MIS) 5e–5d glacial inception, both regions cooled ∼5–6.5 thousand years before CO2 decreased. More likely, their covariation was due to advection of Antarctic climate signals to the EEP by the ocean.”
“The discovery that atmospheric CO2 covaries with Antarctic temperature and global ice volume (Lorius et al., 1990; Lüthi et al., 2008; Petit et al., 1999) has propelled CO2 to the forefront as climatic “globalizer”. However, the processes governing CO2 variability are themselves poorly understood, and likely require an oceanic/climatic trigger in the first place (Adkins, 2013; Ferrari et al., 2014; Sigman et al., 2010).”
“Antarctic ice core records are furthermore ambiguous with regard to the causal relationship between CO2 and temperature. Phase relationships show CO2 lagging behind temperature in the obliquity band (Jouzel et al., 2007) and across some major transitions (Caillon et al., 2003; Fischer et al., 1999; Kawamura et al., 2007; WAIS Divide Project Members, 2013), most prominently during the Marine Isotope Stage (MIS) 5e–5d boundary, i.e. the last glacial inception. Antarctic cooling at this time was associated with a major Milankovitch signal, and appears to have transpired almost entirely before the change in CO2 concentration. It remains unclear whether the temperature lead was restricted to Antarctica or was broader.”
Asynchrony between Antarctic temperature and CO2
associated with obliquity over the past 720,000 years
“Precise knowledge of the relationship between changes in temperature, atmospheric CO2 and solar insolation is essential to understanding Earth’s climate system. The values of a temperature proxy, the hydrogen isotopic composition (δD), in the Antarctic EDC ice core have varied in parallel with CO2 concentrations over the past 800 thousand years (kyr; r2 = 0.82). However, δD [temperature] apparently leads CO2 variations.”
“The lead is ca. 2000 years at a West Antarctic site.”
“Over the past 420 kyr, the Vostok ice core shows that the Antarctic δD temperatures lead the CO2 variations by 1.3 ± 1.0 kyr.”
“During the lukewarm interglacials (430–650 kyr BP), Antarctic δD [temperature] leads CO2 by 1900 years, and the correlation between CO2 and δD is weaker (r2 = 0.57), as determined from the EDC core.”
“Although the mechanisms underlying the coupling and the phase lags remain unclear, the Southern Ocean region, rather than Antarctica, is thought to play the central role in regulating CO2 variations. A box model, for example, estimated a ca. 60% increase in CO2 during TI that is attributable to direct and indirect temperature effects, such as changes in sea ice cover and vertical mixing in the Southern Ocean. On millennial time scales, a multi-proxy study suggests that an antiphased hemispheric temperature response to ocean circulation changes resulted in Antarctic temperatures leading global temperatures and CO2 during TI [the last glacial termination]. … [O]ur data suggest that the lead in Antarctic δD temperatures (i.e. temperature without correcting for source effects) over CO2 is partly attributable to the effects of the moisture source on δD temperatures over the past 720 kyr in the obliquity band. These results suggest that the importance of moisture source effects for the obliquity signal in δD. Thus, the source effect must be considered in future research about the relationship between Antarctic temperatures and CO2.”
“Within the obliquity frequency band, our analyses suggest that temperature variations in Antarctica have led ocean temperatures throughout the past 720 kyr. This phenomenon is most likely explained by the strong influence of local AMI on ΔT. … During TI [the last glacial termination], CO2 rose at ~18 kyr BP, which is related to the melting of the Northern Hemisphere ice sheet and the subsequent weakening of the Atlantic meridional overturning circulation (AMOC). Thus, the timing at which CO2 begins to rise during a termination would be determined by when the Northern Hemisphere ice sheet begins to melt. When eccentricity is small, the summer insolation maxima are small. Thus, if obliquity rises beyond the threshold of melting, a moderate climate forcing could cause warming enough that the southern margin of the North American ice sheet begin to retreat.”
Studies Indicating Temperature-CO2 Lag Was 600-1000 Years
“Atmospheric CO2 follows temperature changes in Antarctica with a lag of some hundreds of years.”
Southern Hemisphere and Deep-Sea Warming Led Deglacial Atmospheric CO2 Rise and Tropical Warming
“Deep sea temperatures warmed by ~2C between 19 and 17 ka B.P. (thousand years before present), leading the rise in atmospheric CO2 and tropical surface ocean warming by ~1000 years.”
“The sequence of events during Termination III suggests that the CO2 increase lagged Antarctic deglacial warming by 800 ± 200 years and preceded the Northern Hemisphere deglaciation.”
“High-resolution records from Antarctic ice cores show that carbon dioxide concentrations increased by 80 to 100 parts per million by volume 600 ± 400 years after the warming of the last three deglaciations.”
“The start of the CO2 increase thus lagged the start of the [temperature] increase by 800 ± 600 years.”
“The lag was calculated for which the correlation coefficient of the CO2 record and the corresponding temperatures values reached a maximum. The simulation yields a [CO2] lag of (1200 ± 700) yr.”
“Our chronology also indirectly gives the timing of the CO2 rise at [glacial] terminations, which occurs within 1 kyr of the increase in Antarctic temperature.”
Posted in CO2 and GHG, Paleo-climatology |
50 responses to “Scientists Find Sun-Driven Temperature Changes Led CO2 Changes By 1300-6500 Years In The Ancient Past”
Versus a single dishonest paper showing the opposite, that warmists use in their feeble counter to many papers listed here.
But, but but, CO2 goes down in ice ages proving that global warming disappears when the CO2 goes. 🤞🏼
Or something like that 😕 …. ;-(
Almost every thing I have read and every chart I have seen makes it abundantly clear that atmospheric CO2 follows temperature and not the other way around as the alarmists claim.
It seems to be entirely impossible for the skeptic mind to grasp a mechanism that can do both.
Let’s put it to a test. RAH, imagine an area that is covered with snow. Now imagine the temperature increases and melts the snow. Does the decreased albedo from this process cause the temperature to further increase (considering all other variables stay the same)?
Hopefully you’ve answered the question with “yes”. If so, what would happen if someone would spraypaint the white snow and turn it into a black snow surface? Would that cause temperatures to increase too that melts the snow?
See, so why is it so hard for skeptics to accept that CO2 concentration increases with temperature as well as CO2 concentration increases causing the temperature to increase?
What’s your point here? That so-called Greenhouse gases dominate? They do not and cannot.
Because the temperature increase or decrease was already completed 100s to 1000s of years before there was a change in the CO2 concentration. If the change happened prior to the CO2 concentration change, the likelihood of the CO2 concentration change being a cause (let alone the dominant cause) is wholly undermined.
In what way does the CO2 decline cause a temperature decline if the CO2 decline took place 5,000 to 6,500 years after the temperature had already declined back to previous levels?
Are you sure about those timelines? I hope you are not implying that the current CO2 increase is coming from a warming event 5000 to 6500 years ago, are you?
No, I’m not sure about anything involving past CO2 concentrations…for reasons detailed below. It’s highly likely our estimates of past CO2 levels are inaccurate.
The ice core data from various polar sites are not consistent with each another, and there is a discrepancy between these data and geological climatic evidence. One such example is the discrepancy between the classic Antarctic Byrd and Vostok ice cores, where an important decrease in the CO2 content in the air bubbles occurred at the same depth of about 500 meters, but at which the ice age differed by about 16,000 years. In an approximately 14,000-year-old part of the Byrd core, a drop in the CO2 concentration of 50 ppmv was observed, but in similarly old ice from the Vostok core, an increase of 60 ppmv was found. In about ~6,000-year-old ice from Camp Century, Greenland, the CO2 concentration in air bubbles was 420 ppmv, but it was 270 ppmv in similarly old ice from Byrd, Antarctica. … In the air from firn and ice at Summit, Greenland, deposited during the past ~200 years, the CO2 concentration ranged from 243.3 ppmv to 641.4 ppmv. Such a wide range reflects artifacts caused by sampling, or natural processes in the ice sheet, rather than the variations of CO2 concentration in the atmosphere. Similar or greater range was observed in other studies of greenhouse gases in polar ice.
The failure to resolve the notorious problem of why about 30 percent of man-made CO2 is missing in the global carbon cycle, based on CO2 ice core measurements, suggests a systematic bias in ice core data. It is not possible to explain the ice core CO2 record in terms of a system with time-invariant processes perturbed by a combination of fossil fuel carbon release, CO2-enhanced biotic growth, and deforestation.
Until 1985, the published CO2 readings from air bubbles in pre-industrial ice ranged from 160 to about 700 ppmv, and occasionally even up to 2,450 ppmv. After 1985, high readings disappeared from the publications. To fit such a wide range of results to the anthropogenic climatic warming theory, which was based on low pre-industrial CO2 levels, three methods were used: (1) rejection of high readings from sets of preindustrial samples, based on the credo: “The lowest CO2 values best represent the CO2 concentrations in the originally trapped ice”; (2) rejection of low readings from sets of 20th century samples; and (3) interpretation of the high readings from pre-industrial samples as representing the contemporary atmosphere rather than the pre-industrial one.
Neftel, et al. reported in 1982 rather high median CO2 concentrations in the preindustrial ice core from Byrd, Antarctica, of about 330 and 415 ppmv, with maximum value reaching 500 ppmv. However, in 1988, in the second publication on the same core, Neftel et al. did not show these high readings; the highest concentration reported was 290 ppmv, in agreement with the global warming theory.
Pearman, et al.  “on examination of the data,” rejected 43 percent of the CO2 readings from Law Dome, Antarctica core … because they were higher or lower than the assumed “correct” values. Thus, they concluded a value of 281 ppmv CO2 for the pre-industrial atmosphere.
You have made it patently clear that there is ZERO EVIDENCE that CO2 causes temperature increase… that’s just a MYTH, an unfounded ASSumption, which remains a scientifically unsupportable load of mind-numbed anti-science nonsense even after 30+ years of the AGW scam.
And YOU yourself have said that the natural rise in temperature from the solar maximum after the LIA anomaly has not caused any of the highly beneficial atmospheric CO2 increase.
“so why is it so hard for skeptics to accept that CO2 concentration increases with temperature”
Gees seb… only the other day you were adamant that temperature hadn’t caused any of the recent CO2 increase !
Can’t blame you for not getting anything I write and purposely misreading and/or misinterpreting it. It’s how you keep yourself “fake-sane” 😉
You were yapping mindlessly that humans caused 100% of the increase in atmospheric CO2,
That discounts temperature as a cause of any CO2 increase.
You have been caught yet again with your face firming planted in your own arrogant BS.
And you are so used to it, you don’t even realise it.
No AndyG55, it does not. Even the simple math of attribution seems to be beyond you. Sad.
I know simple maths is BEYOND you seb,
But Seriously ??
If its human CO2 that has caused 100% of the increase, then NONE can come from warming. Even you can’t eel you way around that, except by some weird anti-reality fantasy maths.
You can’t even manage to kneel up before your next faceplant,
Real SLAP-STICK comedy, for sure.
“It seems to be entirely impossible for the skeptic mind to grasp a mechanism that can do both.”
On the contrary it seems pretty obvious that you have difficulty understanding what has been said many, many, many times. Temperature goes up THEN Co2 goes up, temperature goes down THEN CO2 goes down.
Get it seb or do you need a coloring book and some crayons with that message in in?
By the way found any other orbital cycles that affect the climate yet?
I doubt it, as you are really not that interested. The last 100 years of scientists looking at this is wasted on you. I’m glad I never wasted my time finding these things out for you, you are too lazy to find out for yourself, set you are in your anti-science ways.
TomOmason, do you really think that this is not known by climate scientists and AGW proponents? That you somehow need to teach me that this is the case? Oh boy …
Ha, yeah right allknowing tomOmason 😉 You keep playing this role, I know what you are doing here.
“That you somehow need to teach me”
Someone needs to teach you..
.. your education is woefully lacking in many areas, especially in climate science, real science, physics, chemistry, biology, maths
The “somehow” is an issue, though.
I’m sure I wrote something else after that last sentence.
Anyway, your anti-fact AGW mantra is so firmly held, that there is NO POSSIBILITY of you EVER LEARNING anything even closely related to reality.
“TomOmason, do you really think that this is not known by climate scientists and AGW proponents? That you somehow need to teach me that this is the case?”
Yes I do, as the very basics of the variables involved in the climate and how the known ones react seem to be absent from you knowledge.
Next up water evaporates, sun shines, winds blow, ….stay tuned seb. 😉
“Ha, yeah right allknowing tomOmason 😉 “
You dislike my holding a mirror of your pomposity up to you seb. Oh dear how sad 😉
Ah that old, outmoded and simplistic “cause and effect” principle.
Fancy thinking that a temperature change could cause a lagged effect on CO2 concentration?
If CO2 leads temperature glacial to interglacial, it also should lead interglacial
The truth is completely opposite. Always with many hundred years lag concerning
interglacial to glacial.
And if you look at the saw-tooth type data, you will see that peak CO2 was ALWAYS when the temperature had started to drop.
That maximum CO2 level was totally unable to even maintain the warmer temperature, let alone cause more warming.
Yep, because it was completely in balance with the then current temperatures. It couldn’t do that even if we assigned super powers to CO2 and imagined a climate sensitivity of 100°C per doubling. That is a mathematic certainty.
However, if one does introduce extra CO2 (or other GHGs) into the atmospheres that disrupts the balance and you’ll get warming. Whether or not this warming can compensate for ice age causing orbital shifts depends on the amount of GHGs in the atmosphere.
So you subscribe to the truly bizarre theory that an increase in GHGs somehow overrides numerous other factors at play in the atmosphere, including galactic processes? The term GHG is in itself is misleading as it suggests the planet is one large glasshouse or works in that manner. It most certainly is not and does not. And you accuse the rest of us of being antiscience?
“The term GHG is in itself is misleading as it suggests the planet is one large glasshouse or works in that manner.”
But, but it is ‘like’ a sort of greenhouse.
A spinning spherical sort of greenhouse, half in cool/cold darkness, half in warm/hot light. And just about everywhere you look in this greenhouse there’s life.
A greenhouse with a huge ponds in it. A greenhouse of many invisible walls or layers, layers where the invisible walls can expand or contract under strange pressure and solar effects, a greenhouse where air forms rising convective bubbles of air to dissipate the heat, etc, etc.,
See it’s just like a greenhouse. 😀
Why would it override other factors? Do you think that we think that CO2 is the only variable influencing climate? Really?
You’ve claimed that 100% of the warming since the mid-20th century is human-caused. Doesn’t leave much room for natural factors to contribute, does it?
@SebastianH 9. June 2018 at 1:43 PM
“Do you think that we think that CO2 is the only variable influencing climate?
Come off it seb you’ve boo-hooed me at every turn when I suggest natural variations governs our climate. You have implied, by your many statements that CO2 is the climate control knob.
So what’s got you changing you tune now? Your theoretical cAGW-climate-change belief running out of gas? 😉
“if one does introduce extra CO2 (or other GHGs) into the atmospheres that disrupts the balance and you’ll get…. blah , blah…”
What a load of SCIENTIFICALLY UNSUPPORTABLE BULLCARP..
You are continuing with this NON-FACT that you KNOW you cannot provide any empirical scientific evidence for. A brain-hosed make-believe FANTASY.
It really is a PATHETIC case highlighting your TOTAL INABILITY produce anything except mindless parrot-like, FALSE, AGW mantra.
AndyG55 8. June 2018 at 8:02 PM
Yep, today Greenland hovers in the 30s and low 40s Fahrenheit and weathers snowstorms in summer. But average summer temperatures in the early Holocene (8,000 to 11,000 years ago) and Last Interglacial (116,000 to 130,000 years ago) climbed well into the 50s. Strange that so it must have been all man’s fault back then too, eh?
Are there any peer reviewed papers from the last 10 years that you know of that disagree with these and show CO2 leading Temp on some time scale?
@David Albert 7. June 2018 at 11:40 PM,
You may want to take a look at https://wattsupwiththat.com/2012/04/a-new-paper-in-nature-suggests-co2-leads-temperature-but-has-some-serious-problems/
where they have such paper from 6 years back.
Not long after that, it was exposed to be a junk paper.
The link is the 4th post of the series, the other three links to them are in link I posted.
Parrenin et al. (2013) was the first to report a synchronous change between temperature and CO2…
“Studies of polar ice cores have concluded that temperature increases during periods of rapid warming have preceded increases in CO2 by hundreds of years. Parrenin et al. present a revised age scale for the atmospheric component of Antarctic ice cores, based on the isotopic composition of the N2 that they contain, and suggest that temperature and CO2 changed synchronously over four intervals of rapid warming during the last deglaciation.”
However, this same lead author co-authored another paper that same year (2013) that said the temperature lead over CO2 is ~900 years.
Landais et al., 2013
“Antarctic temperature started increasing in phase around 136,000 years ago, but in a second phase of Termination II, from 130.5 to 129,000 years ago, the rise in atmospheric CO2 concentrations lagged that of Antarctic temperature unequivocally….At mid-slope, there is an unequivocal lead of δ15N [temperature] over CO2 of 900 ± 325 yr”
UK 9 days with basically NO WIND. !!
IPCC (2007): “Atmospheric CO2 follows temperature changes in Antarctica with a lag of some hundreds of years.”
Isn’t that particularly embarrassing considering that Antarctica seems to provide the perfect experimental set up to test the efficacy of CO2?
“Antarctica is by far the best natural control for measuring the impact of CO2 on atmospheric temperature. There are no cities, no roads, no buildings, no lakes and the air is extremely dry and cold. Antarctica is a large area of almost uniform “albedo” or reflectivity, naturally controlling for any distortion caused by the terrain. The major greenhouse gas over Antarctica is CO2, and its temperature is close to the -80°C which is close to the temperature absorbed by CO2 in the 13 & 18µ band of LWIR. Antarctica is like a giant petri dish for climate research.
What do you get when you control for water vapor and the Urban Heat Island Effect? Temperatures have actually FALLEN since 1979 in Antarctica. In fact, temperatures are actually flat over the past 50 years. CO2 has increased from 310 ppm in 1955 to 400 ppm today, and its impact on temperatures in Antarctica is immeasurable. When the impact of CO2 is isolated, and all other significant factors are controlled for, CO2 has no measurable impact on atmospheric temperatures. Antarctica temperature data proves it beyond any reasonable doubt.”
Antarctica is a pretty bad place to test this. Why? Because it is cold and sometimes colder than the sky, meaning there is not much backradiation or GHE going on in the polar regions. Those regions are warmer than they are supposed to be because of ocean currents and wind that transports energy from equator polewards.
Please don’t give any weight to blogs like co2islife. That author is pretty clueless even more so than the average pseudoskeptic.
Clueless? That’s pretty ironic coming from an enemy of truth and reason such as yourself. So you are arguing that Antarctic region is warmer due to natural factors and that the rest of the planet is warmer due, solely or largely, to anthropogenic emissions even though natural factors dominate everywhere? Come on pal, you can’t pick and choose. Either you’ve not understood nearly as much as you claim to or the theory of CAGW is invalid or perhaps both.
Nope. You’ll get it someday … maybe. This is not what I wrote, but I really get why you want to understand it this way 😉
“You’ll get it someday “
Poor seb, he thinks we will “get” the twisted change in his fantasy AGW narrative.
No-one could possibly be that lacking in cognitive rationalism to follow your anti-science BS, seb
Seb has gone beyond pure fantasy, and is heading towards hallucinogenic madness.
So then why do you attribute the Greenland ice sheet melt and Arctic sea ice losses and the high Arctic temperatures in recent decades to “not much” anthropogenic forcing? How much is “not much” — especially since you simultaneously believe that 100% of warming in recent decades is human-caused? How is 100% consistent with “not much”?
“…colder than the sky, meaning there is not much backradiation or GHE going on in the polar regions.” – …
I thought AGW was SUPPOSED to heat the warmer surface by backradiation from a colder sky. lol
Poor seb has gone WAY passed the stage of cognitive dissonance.
Poor little trollette is now in a stage of near complete cognitive mal-function.
I guess seb is saying that the “backradiation” goes upwards, or something equally bizarre.
But one can only ever but guess at what seb is trying to say, any possible rational thought is well hidden behind a camouflage of mind-numbed AGW parroting mantra.
Kenneth you maybe interested in this March 2010 paper.
Strong signature of the active Sun in 100 years of terrestrial insolation data
Institut fur Physik, TU Dortmund, Otto-Hahn-Straße 4, 44221 Dortmund, Germany
Received 23 September 2009, accepted 4 March 2010 by U. Eckern
Published online 6 April 2010
The Abstract —
And in the conclusion —
There is also an addition to this paper where they robustly answer some questions raised by not only there results, and methods but also shows improvements in data filtering.
That paper is DOI 10.1002/andp.201100171 called ‘Reply to the Comment of G. Feulner’
by Werner Weber∗
Institut f¨ur Physik, TU Dortmund, 44221 Dortmund, Germany
Received 28 July 2011, accepted 10 August 2011 by U. Eckern
Published online 20 September 2011
All-in-all it points to yet more possibilities that our knowledge of the effects of the sun on this planet and it’s climate, is not a ‘settled science’.
The IPCC’s line “The climate system is a coupled non-linear chaotic system, and therefore the long-term prediction of future climate states is not possible.” is even more apt when we do not know, understand, or deliberately fail to recognize all the parts in the chaotic system. Not that has stopped the IPCC and others, from making foolish statements, stirring up discord in the scientific community, and is trying to force people (via political agreements) to completely and expensively, change their way of life when the evidence for doing so is so obviously tainted by many non-scientific interests.
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The proponents of anthropogenic-caused global warming invariably, and ironically, DENY that the Medieval Warming Period (MWP, 1,000 years ago) was global and likely warmer than it is now. These folks acknowledge only that Europe experienced the MWP. They likely take this unjustifiable position because their computer models cannot explain a global, warmer MWP. Why? Because their models require an increasing co2 level, plus depend even more on the built-in ASSUMPTION that water vapor feedback, the actual culprit, causes 2 to 3 times the temperature increase as brought on by the increase in co2. However, co2 did not begin increasing until the 1800s, long after the MWP, so neither was there any water vapor feedback !.
With no co2 increase there is obviously also no further temperature increase provided by water vapor feedback. The MWP global temperature increase must have therefore been nothing apart from natural climate variation. It therefore becomes becomes plausible that our current warming (such as it is) may also be mostly due to NATURAL climate variation. But that, of course, conflicts with the UN’s IPCC (and other alarmists’) claim that our current warming is mostly due to the human-caused increase in co2 level, and Mann and his hockey-stick DENY that the MWP was global and likely warmer than now.
However, it’s easy to show that the MWP was indeed both global and at least as warm as now. While that says nothing about the cause of our current warming (such as it is) it speaks loudly about the credibility of the folks who DENY that the MWP was global and at least as warm as now. A significant subset of this group also insists that the “science is settled”.
A brief meta-analysis, using numerous peer-reviewed studies as well as other easily accessible data follows to demonstrate that the MWP was indeed global and at least as warm as it is now.
First, the MWP trend is conclusively shown to be global by borehole temperature data. The 6,000 boreholes scattered around the globe are not constrained to just those locations where ice core data has been used. A good discussion of the borehole data can be found at Joanne Nova’s website.
Next, the receding Alaskan Mendenhall glacier recently exposed a 1,000-year-old shattered forest, still in its original position. No trees (let alone a forest) have grown at that latitude anywhere near that site since the MWP. It was obviously significantly warmer in that part of Alaska than it is now, and Alaska is quite distant from Europe.
Finally, there have been hundreds of peer-reviewed MWP studies, and the earlier results (showing a global, warmer MWP) were reflected in earlier IPCC reports. These studies were carried out around the globe by investigators and organizations representing numerous countries. It’s curious that Mann and his cohort did not give more consideration to those study results before presenting their conflicting “hockey stick” claim. One of their own players, Phil Jones, admitted publicly that if the MWP was global and as warm as now then it is a different “ballgame”. More important, peer-reviewed studies continue to regularly show up confirming that the MWP was warmer than now.
The Greenland Temperature (gisp2) study, for example, shows, among other things, that Greenland was warmer during the MWP than it is now. Greenland is distant from both Europe and Alaska. There’s also this: https://junkscience.com/2018/06/study-ancient-greenland-was-much-warmer-than-previously-thought/
These numerous MWP studies have been cataloged at the co2science.org website. Dr. Idso, the proprietor of that website, is a known skeptic. However, the peer-reviewed studies were independently performed by numerous researchers using various temperature proxy techniques and representing many different countries. Idso is merely operating as the librarian. These studies now span several decades and new confirming investigations continue to show up regularly.
Interested readers should satisfy themselves by going to co2science.org and choosing (say) a half-dozen regions (all should be remote from Alaska, Greenland, and Europe). Focus on the subset of the MWP studies which directly address temperature. Choose at least one temperature study from each selected region. (Idso provides brief summaries but feel free to review the study in its original format.) You will find that each of the selected study sites were warmer during the MWP than now. These study results are consistent with the temperature trend exhibited by borehole data.
There are also other confirming observations which include such things as antique vineyards found at latitudes where grapes cannot be grown today, old burial sites found below the perma-frost, and Viking maps of most of Greenland’s coastline.
The MWP studies as well as various other data are all consistent with the borehole data results. This meta-study is an aggregate of straightforward peer-reviewed studies. The studies can be replicated and the research results do NOT require the use of controversial “models”, or dubious statistical machinations.
One of the “talking points” posed by alarmists, to “rebut” the claim of a global, warmer MWP is that warming in all regions during the MWP must be synchronous. Obviously the MWP studies sited herein were generally performed independently, so start and end dates of each study during the MWP will vary. However, anyone foolish enough to accept that “synchronous” constraint must also admit that our current warming would also not qualify as a global event.
For example, many alarmists go back into the 1800s when making their claims about the total global warming temperature increase. However, that ignores a three decade GLOBAL cooling period from about 1945 to 1975. That globally non-synchronous period is much more significant than just a region or two being “out of synch”.
There are also other reasons to exclude consideration of temperature increases during the 1800s. There was a significant NATURAL warming beginning around 1630 (the first low temperature experienced during the LIA) and that period of increasing temperatures ran until at least 1830 (perhaps until 1850) before co2 began increasing. However, it would have taken many subsequent decades, possibly more than a century, for co2 increase after 1830, at an average 2 ppmv per year, to accrue sufficiently before having ANY impact on thermometer measurements. Neither is there any reason to expect that the 200 years of natural and significant warming beginning in 1630 ended abruptly, after 2 centuries, merely because co2 level began increasing in 1830 at a miniscule 2ppmv per year. How much, and for how long was the temperature increase after 1830 due mostly to the continuing natural climate warming beginning in 1630?
Also, related to the “synchronous” claim, any current considerations about global warming must be constrained to a starting point after the cooling which ended in 1975, so no earlier than 1975. The global temperature began steadily increasing in 1975 and that increase basically terminated during the 1997/98 el Nino. Even the IPCC (a bureaucracy which cannot justify its mission if current warming is NATURAL) has reluctantly acknowledged yet another GLOBAL “hiatus” in temperature increase following 1998. (That’s in spite of the fact that co2 level has steadily continued increasing since it started around 1830-1850. NASA, in comparing recent candidate years for “hottest” devoted significant time to wringing its hands about differences of a few hundredths of one degree. Such miniscule differences are not significant because it is clear that the uncertainty error is at least one tenth of a degree. Some argue that the uncertainty error is as large as one degree.
So, all this current “global warming” controversy involves just over two decades, (1975 to 1998) and that warming has been followed by almost another two decades of no further statistically significant increase in temperature. But wait … ! It turns out that even the period from 1975 to 1998 apparently does not qualify as a global warming period because there were numerous “out of synch” regions and/or countries which have experienced no additional warming over durations which include the 1975-1998 span.
Another alarmist rebuttal attempt is that the MWP studies cataloged by co2science.org have been cherry-picked. (Dozens of peer-reviewed studies spanning several decades, all cherry-picked?) Readers should satisfy themselves by searching for conflicting credible peer-reviewed MWP temperature studies which have not been cataloged by co2science.org. But, keep in mind that a few stray conflicting studies will not likely have much impact, because, as the previous link demonstrates, there is no shortage of regions showing no increasing warming during the supposedly 1975-1998 global warming period.
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