The Yin and Yang of Holocene Polar Regions

Guest post by Renee Hannon

Introduction

The Arctic and Antarctic regions are different and yet similar in many ways. The Arctic has ocean surrounded by land and the Antarctic is a continent surrounded by water. Both are cold, glaciated and located at Earth’s poles some 11,000 miles apart. While sea ice has been retreating in the Arctic, it has been relatively stable in the Antarctic. This post examines surface temperature trends, solar insolation, and CO2 at the polar Arctic and Antarctic regions during the Holocene interglacial period.

Holocene Polar Temperature Trends are Out of Phase

The Holocene interglacial started about 11,000 years ago after termination of the previous glacial period. It is commonly described as consisting of an early Holocene climate optimum from approximately 10,000 to 6,000 years before present (BP, before 1950). This optimum is followed by a pronounced cooling in the mid-late Holocene referred to as the Neoglacial period which culminates in the Little Ice Age (LIA) around 1800 years AD (Lui, 2014).

Past Holocene temperature anomalies are typically estimated from ice core proxies. This post uses Arctic temperature anomalies from Agassiz-Renland isotope data corrected for elevation by Vinther, 2009 and Antarctic temperature anomalies from Dome C ice core proxies calculated by Jouzel, 2001. Temperatures are presented as anomalies relative to present day average polar temperatures. Time is shown as both years AD/BC and years before present, BP. Years BP (yr BP) is the key reference in the text. Datasets used are referenced at the end of the post.

Arctic and Antarctic Holocene temperature anomalies are shown in Figure 1. Arctic temperature anomalies show a prominent climate optimum from 10,000 to 6,000 yr BP with a brief cold interruption around 8,200 yr BP. The Neoglacial cooling is also evident where Arctic temperature anomalies steadily cool from 6,000 yr BP to the LIA as described in the literature.

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Figure 1. Temperature anomalies from Antarctic Dome C in red and Greenland Agassiz-Renland in green with a 200-year filter shown in heavy lines. Present day global temperature with 31-year filtered from Cowtan and Way shown in gray.


The Antarctic seems to be a bit more contrary from the simple Climate optimum and Neoglacial description. Antarctic does exhibit a temperature high or optimum from about 11,500 to 9000 yr BP. Masson, et. al, 2000, examined all existing Antarctic ice core records which confirm a widespread early Holocene climate optimum during this time. This early optimum is followed by cooling temperatures to a minimum around 8000 yr BP. Most core sites studied by Masson in the Antarctic display this cool minimum. Masson also recognizes a secondary Antarctic late warm optimum between 6,000 and 3,000 yr BP.

Compared to the Arctic, the Antarctic shows a much-abbreviated early climate optimum that ends just after the Arctic climate optimum begins. While the Arctic stays warm during the Holocene climate optimum 10,000 to 6000 years BP, the Antarctic experiences a cold period from 9000 to 6000 yr BP. While the Arctic shows progressive cooling during the “Neoglacial period”, the Antarctic is experiencing a second warming trend. Therefore, the Holocene climate optimum and Neoglacial period better describe the Northern Hemisphere, not the Antarctic region. The two polar hemispheres do not warm and cool together and underlying long term trends appear to be out of phase after the Antarctic early Holocene optimum.

Polar Temperature Trends are Synchronous with Local Solar Insolation

It has long been recognized that Northern Hemisphere (NH) summer solar insolation influences reconstructed ice core temperatures (Laskar, 2004). Figure 2 shows the strong Northern Hemisphere summer insolation during the early Holocene synchronous with the Arctic temperature climate optimum. In the early Holocene, northern summer insolation reaches a maximum about 9,000 years ago. Northern insolation becomes progressively weaker during the mid-late Holocene coeval to the Arctic Neoglacial cooling trend.

In this post, Northern insolation refers to the Northern Hemisphere summer (June-August) and Southern insolation refers to the Southern Hemisphere summer (December-February). Figure 2 shows both Northern and Southern summer insolation at 65 degrees latitude which are out of phase during the Holocene. In the early Holocene, Northern summer was at perihelion when Earth is closest to the sun around 9,000 yr BP, and southern summer occurred when Earth was farthest from the sun. While Northern insolation progressively declines during most of the Holocene, Southern insolation progressively increases.

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Figure 2. Arctic and Antarctic temperature reconstructions in green and red, respectively, plotted with Northern and Southern summer insolation, 65NJune and 65SDec from Laskar, 2014.

Today, northern, and southern summers are reversed from the Early Holocene. Presently, the southern summer occurs near perihelion when Earth is closest to the sun and northern summer occurs when Earth is farthest from the sun. In the future, northern insolation will continue to decline, and southern insolation which is currently strong will begin to decline.

How do Antarctic temperature trends relate to solar insolation? Masson, 2000, states that the early Antarctic climate optimum occurs at the same time as the Northern Hemispheric summer insolation optimum around 10,000 years BP. Although correct, this appears to be the only time Antarctic temperature trends display any resemblance to Northern insolation as shown in Figure 2. When Northern insolation is at an optimum around 9,000 yr BP, Antarctic temperatures are cooling towards a minimum. When Northern insolation is declining during the mid-late Holocene, Antarctic temperatures are warming or flat after the 8,200 yr BP cold period. During most of the Holocene, warming Antarctic temperature trends seems to be more aligned with increasing Southern insolation.

Holocene polar temperature trends appear to be largely synchronous and in the same direction as their local summer solar insolation. For most of the Holocene, Antarctic and Arctic temperature trends appear out of phase with each other just as Northern and Southern summer insolation are out of phase. The role of local insolation may be a strong influence on the underlying millennium-scale polar temperature trends in the polar regions.

CO2 is Synchronous with Antarctic Temperature Trends

Antarctic ice core data are routinely used as proxies for past CO2 concentrations. Antarctic CO2 data is the key dataset for paleoclimate CO2 trends during interglacial and glacial periods for the Southern Hemisphere. Surprisingly, Antarctic CO2 data is frequently used in Northern Hemisphere studies as well as compared to instrumental CO2 global trends (Ahn and Brooks, 2013, Kohler, 2011, NOAA, 2020).

Many technical articles and research from the mid-1990’s reached the hypothesis that CO2 gas in Greenland ice core bubbles were enriched by acid-carbonate chemical reactions and therefore, are unreliable (Anklin, 1995, Barnola, 1995). This theory was put forward because CO2 measurements from Greenland ice cores are more variable and generally 20-30 ppm higher than Antarctic CO2 measurements. As a result, Greenland CO2 datasets are not used in scientific studies to understand the Northern and Southern hemisphere’s interactions with and sensitivity to greenhouse gases under various climatic conditions. For a more detailed discussion on CO2 from Arctic Greenland cores, refer to my previous post here.

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Figure 3. Antarctic and Arctic temperature reconstructions plotted with Antarctic CO2 data. CO2 is from Bereiter, 2016, based on Antarctic ice cores, predominantly Dome C, during the Holocene.

Figure 3 shows CO2 data plotted with Antarctic and Arctic temperature anomalies for the Holocene. CO2 tends to be synchronous with Antarctic temperatures and out of phase with Arctic temperatures. In the early Holocene, CO2 reached 270 ppm around 11,500 yr BP. CO2, then gradually decreased to a minimum of 255 ppm around 8,000 yr BP. During most of the Holocene since 8,000 yr BP, CO2 has been increasing. This increase in CO2 parallels the increase in Antarctic temperature trends and is contrary to Arctic temperature trends which decreased during this time.

It is difficult to compare the elevated CO2 records from the present to the past since CO2 data from the Northern Hemisphere during the Holocene is not publicly available. The scant Greenland CO2 data that is publicly available shows CO2 is generally 20-30 ppm higher than Antarctic CO2 and as high as 375 ppm in the Holocene (Neftel, 1982 and Barnola, 1995). Even today, Barrow and South Pole observatories have seasonal amplitude differences resulting in CO2 being 12-15 ppm higher at Barrow than in the South Pole during northern winter months almost 60% of the year (NOAA, 2020).

Holocene Polar Correlations

Holocene polar temperature anomalies over the past 10,000 years are compared to Northern insolation, Southern insolation and CO2 using Pearson’s correlation shown in Figure 4.

The Arctic and Antarctic temperature underlying millennium trends have a negative correlation confirming they are mostly out of phase. A strong positive correlation occurs between Arctic temperature anomaly trends and Northern insolation as expected. And the Arctic temperature trends shows a strong negative correlation with Southern insolation, no surprise there. Arctic temperature trends also show a strong negative correlation with CO2.

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Figure 4. Top graph shows millennium trends using a 500-year filter for temperature anomalies. All datasets were resampled to 100-year increments. Bottom table is Pearson’s correlation coefficient for temperature anomaly, insolation, and CO2. Positive correlations are highlighted in green for the Arctic and red for the Antarctic. The correlations were performed from 10,000 years BP to present.

Antarctic temperature trends show a positive correlation with Southern Hemispheric insolation as well as with CO2 trends. These correlations are all strong, above 0.74. CO2 shows a surprisingly strong correlation with Southern insolation of 0.92. Interestingly, the Holocene Antarctic temperature anomaly trends show a strong negative correlation with Northern insolation.

Antarctic temperature proxy data is key to understanding paleoclimate trends and climatic conditions. The Southern Hemisphere is vastly under-represented in proxy data compared to the Northern Hemisphere for the Holocene and contains only about 10-15% of the proxy records. As seen in these polar comparisons, the Southern extratropics behave very differently than the Northern Hemisphere.

In conclusion, the often-overlooked Antarctic dances to a different beat than the Arctic. Antarctic and Arctic underlying temperature trends are mostly opposite in phase during the Holocene. Holocene polar temperatures trends are largely synchronous and in the same direction as their local summer solar insolation over the past 10,000 years suggesting local insolation influences the secular temperature trend of the polar regions.

The Holocene CO2 trends measured from Antarctic ice cores are coeval with Antarctic temperature trends and out of phase with Arctic temperature trends. Despite being routinely used in climate research, Antarctic CO2 is probably not representative of global and/or Arctic CO2 trends.

Acknowledgements: Special thanks to Donald Ince and Andy May for reviewing and editing this article.

References Cited:

Ahn, J, E. Brook, C. Buizert, Response of atmospheric CO2 to the abrupt cooling event 8200 years ago, Geophysical Research Letters/Volume 41, Issue 2, 2013. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013GL058177.

Anklin, M., J.M. Barnola, J. Schwander, B. Stauffer, and D. Raynaud, Processes affecting the CO2 concentration measured in Greenland ice, Tellus, Ser. B, 47, 461-470, 1995. https://onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-0889.47.issue4.6.x

Barnola, J.-M., M. Anklin, l Porcheron, D. Raynaud, l Schwander, and B. Stauffer, CO2 evolution during the last millennium as recorded by Antarctic and Greenland ice, Tellus, 47B, 264-272, 1995. https://onlinelibrary.wiley.com/doi/abs/10.1034/j.1600-0889.47.issue1.22.x

Kohler, P. G. Knorr, D. Buron, A. Lourantou, J. Chappellaz, Abrupt rise in atmospheric CO2 at the onset of the Bolling/Allerod: in-situ ice core data versus true atmospheric signals. Clim. Past, 7, 473-486, 2011. https://www.clim-past.net/7/473/2011/cp-7-473-2011.pdf

Masson, V., Vimeux, F., Jouzel, J., Morgan, V., Delmotte, M., Ciais, P., Hammer, C., Johnsen, S., Lipenkov, V. Y., Mosley- Thompson, E., Petit, J.-R., Steig, E., Stievenard, M., and Vaik- mae, R.: Holocene climate variability in Antarctica based on 11 ice cores isotopic records, Quaternary Res., 54, 348–358, 2000. https://is.muni.cz/el/1431/jaro2015/Bi8300/39087998/Masson_etal2000_climate_Antarctica_ice-core.pdf

Neftel, A, H Oeschger, J. Schwander, B. Stauffer, and R. Zumbrunn, Ice core sample measurements give atmospheric CO2 content during the past 40,000 years. Physics Institute, University of Bern. Nature Vol. 295, 1982. https://www.researchgate.net/publication/230889363_Ice_core_sample_measurements_give_atmospheric_CO2_content_during_the_past_40000_yr.

NOAA, Global Monitoring Laboratory, 2020. Visualization comparing instrumental CO2 data to past Antarctic ice core CO2 data. https://www.esrl.noaa.gov/gmd/ccgg/trends/history.html

NOAA, Global Monitoring Laboratory, 2020. Graph of Barrow, Mouna Loa, and South Pole CO2 data showing seasonal and global trends. https://www.esrl.noaa.gov/gmd/ccgg/trends/gl_trend.html

Zhengyu Liu, Jiang Zhu, Yair Rosenthal, Xu Zhang, Bette L. Otto-Bliesner, Axel Timmermann, Robin S. Smith, Gerrit Lohmann, Weipeng Zheng, OliverElison Timm. The Holocene temperature conundrum. Proceedings of the National Academy of Sciences Aug 2014, 111 (34) E3501-E3505; DOI:10.1073/pnas.1407229111, https://www.pnas.org/content/111/34/E3501

Datasets:

Arctic Agassiz-Renland temperature proxy by Vinther, 2009. ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/vinther2009greenland.txt

Dome C temperature proxy by Jouzel, 2001. https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/epica_domec/edc96-iso-45kyr.txt

Solar Insolation by Laskar, J., 2004. http://vo.imcce.fr/insola/earth/online/earth/online/index.php.

Dome C CO2 data by Bereiter, 2016. https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/antarctica2015CO2.xls

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160 thoughts on “The Yin and Yang of Holocene Polar Regions

  1. Good read but it looks like you repeated Figure 1 three times instead of the graphs reference in the text

    • Geoff, Sorry, that was my fault. I didn’t understand the way to copy image addresses in WordPress. I had to copy them to make sure they all had https addresses for firefox.

    • Leif,

      You are not scientific. Something is physically causing what is happening. Over and over.

      Your contribution is ….

      The sun is changing the planet’s temperature by modulating planetary cloud cover. Short and long term.

      Svensmark shows in the attached paper that a mechanism that modulates (increases and decreases) planetary cloud cover (high latitude regions) will cause warming in the Arctic and cooling on the Antarctic ice sheet….

      … because the albedo of the surface of the Antarctic ice sheet, is higher (more reflective) than the top of white clouds.

      Comment: The reason why this is true, is the very high speed winds over the Antarctic ice sheet, breaks the ice crystals, which creates an ice like reflective surface.

      Svensmark explains the mechanism in the attached paper and provides data …

      Which proves the sun is modulating planetary cloud cover (sun) high latitudes both poles.

      And a reduction in cloud cover causes warming in the Northern hemisphere and cooling over the Antarctic ice sheet.

      http://arxiv.org/abs/physics/0612145v1

      The Antarctic climate anomaly and galactic cosmic rays

      • David,
        There is a big missing force driving climate.

        We know the geomagnetic field, strength and direction, is changing at the same time as planetary temperature changes. This correlation is true for short and long temperature changes. i.e. The geomagnetic field strength is less in the glacial periods than in the interglacial periods.

        This fact has found by the French, a decade ago. There is a NOVA program about the finding, that the geomagnetic field is abruptly changing…

        that showed the French chalet that is used to store the 100,000 fired tiles that were gathered to find the paradoxial result. The geomagnetic field strength is abruptly changing in magnitude and direction correlating with temperature changes.

        There is no mechanism to explain what is driving the geomagnetic changes.

        And there is no explanation for very large climate changes, in the Paleo record, like the Younger Dryas. The evidence is that the YD events, they are called Henrich events, occur roughly every 6000 to 8000 years. And it is the YD events that terminate interglacial periods.

        When the temperature variation is analyzed in the frequency domain, it is found.

        The large, medium, and small changes occur at the same cyclic frequency and the large and medium events a longer frequency.

        This is a paper that finds the cyclic warming and cooling is occuring at the same frequency both poles.

        This study analyzed ice core from the Antarctic peninsula. The Antarctic peninsula’s temperature matches the Southern Sea, not the Antarctic ice sheet temperature.

        http://wattsupwiththat.files.wordpress.com/2012/09/davis-and-taylor-wuwt-submission.pdf

        Davis and Taylor: “Does the current global warming signal reflect a natural cycle”

        …We found 342 natural warming events (NWEs) corresponding to this definition, distributed over the past 250,000 years …. …. The 342 NWEs contained in the Vostok ice core record are divided into low-rate warming events (LRWEs; < 0.74oC/century) and high rate warming events (HRWEs; ≥ 0.74oC /century) (Figure). … …. "Recent Antarctic Peninsula warming relative to Holocene climate and ice – shelf history" and authored by Robert Mulvaney and colleagues of the British Antarctic Survey ( Nature , 2012, doi:10.1038/nature11391),reports two recent natural warming cycles, one around 1500 AD and another around 400 AD, measured from isotope (deuterium) concentrations in ice cores bored adjacent to recent breaks in the ice shelf in northeast Antarctica. ….

        Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper. William: As this graph indicates the Greenland Ice data shows that have been 9 warming and cooling periods in the last 11,000 years.

        http://www.climate4you.com/images/GISP2%20TemperatureSince10700%20BP%20with%20CO2%20from%20EPICA%20DomeC.gif

    • Leif, you have it exactly backwards. What Renee’s post is showing is that the solar insolation is dominating temperature changes, it just does it at different times in the two hemispheres. If CO2 were doing it, it would happen at the same time in both hemispheres.

        • It’s not solar output. It’s the variation of the angle of incidence over time.

        • Zoe, Due to Earth’s orbit and orientation, insolation at 65N and 65S can vary by 100 W/m^2 over time. You must be talking about the average at 1 AU. We are talking about insolation changes over time at specific latitudes.

      • “What Renee’s post is showing is that the solar insolation is dominating temperature changes”

        That what it looks like to me.

        I’ll be interested to see if Leif can change my mind.

      • the solar insolation is dominating temperature changes
        Solar insolation is not solar activity…
        It is amusing [but a bit a sad too] to see your knee-jerk reaction.

        • Leif, Insolation is not solar activity, very true. But, does CO2 control insolation? I think not. My reaction is not knee-jerk. Renee wrote this post, but I’ve been writing on the general subject of insolation and what affects it for many years. This post is on Earth’s orbit and orientation, there are many other factors. It is just that CO2 atmospheric concentration is not one of them.

          • “This post is on Earth’s orbit and orientation, there are many other factors. It is just that CO2 atmospheric concentration is not one of them.”

            Mmm, there’s the tell. This post purports to be about orbit and orientation. Its not really, its about how it cant be CO2. The trouble with that pea and thimble trick is the BP bit. The post explains Holocene changes… but only before 1950. However, despite CO2 being a largely post 1950 effect, your conclusion is: therefore it can’t be CO2. The whole argument falls to pieces when the tight correlation between Arctic temps, Antarctic temps, ocean temps, land temps, global temps and GHG conc. emerges in the years since 1950.

            Below, you dig yourself an even deeper hole by insisting that +-2Wm^2 in 300 years (variation from insolation changes) is “a lot”, but somehow that +3Wm^2 in 120 years of GHG forcing is not a “factor”.

            Anything but CO2, eh?

          • Fascinating how CO2 was given the power to affect the climate, but only after 1950.

            BTW, since 1950, while CO2 levels have risen at a constant rate, temperature has moved up, down and sideways, for decades at a time. Still no correlation between CO2 and temperature.

          • Loydo says:
            that +-2Wm^2 in 300 years (variation from insolation changes) is “a lot”, but somehow that +3Wm^2 in 120 years of GHG forcing is not a “factor”.

            Just above Andy May says the poles’ summer insolation varies by 100 W/m2 over the orbital cycles. That’s what this post is about, numbskull.

    • Given the very significant differences between the two poles as well as the very significant differences between the northern an southern hemisphere, why would you expect to see the same behavior, no matter what the driving force? Some climate phenomena seem to have time constants measured in centuries, if not millennia. example

      • Well,
        we are being told that CO2 is the controle knob of earth’s temperature. I.e. CO2 up = temperature up, CO2 down = temperature down, end of discussion science is settled!.

        If that were the case then temperature should go up with increasing CO2 levels no matter where you are(CO2 being ‘well mixed and all that). If both poles are out of phase wrt temperature that means CO2 is not the control knob, simple.

        Once you start having to incorporate local differences (ocean surface %, insulation, latitude, ocean currents, land use, OHC etc etc etc) to explain why some regions react differently or even opposite to the CO2 trend you are only proving that CO2 is NOT the control knob.

        So if the poles are indeed out of phase as this article seems to suggest the conclusion has to be that we can all stop worrying about CO2 emissions as they can not be anything more than noise on the signal of earths position relative to the Sun(now where did i hear that before?).

        Stay sane,

        Willem

    • Once again Leif demonstrates that when it comes to anything other than the sun, he has no interest in science.

      Since as you admit the two poles have completely different circumstances, the logical assumption would be that they would respond to changes in the sun differently. Instead you assume that your already pre-conceived position must be correct here too, and just declare that neither responds to the sun at all.

      • Solar insolation changes a lot and has different effect in the two polar regions.
        Solar activity does not change a lot and the changes in insolation completely dominates changes in solar activity as I pointed out.
        Your reaction is amusing too…

        • Leif, for once we agree. Although, I think we have a different view on “does not change a lot.” Over the last ~300 years that might mean +-2 W/m^2 to you, but “not change a lot” is more like +-5 to me. Neither value is much compared to a total of 1360 W/m^2, but to Earth’s climate it is a lot. Just some perspective. It is a matter of magnitude, but the differences are so small we can’t measure them accurately yet. The story of climate science.
          solar output

        • Loydo, That value of CO2 forcing (3.2 W/m^2) was computed with climate models by assuming that insolation variation was near zero over the time period 1750-2010. Then they subtracted “natural only” from”natural + anthropogenic” and divided anthropogenic into a few things and extracted CO2 forcing from the calculation.

          Now if the correct (in my opinion) insolation variability is used, including the correct (again my opinion) solar variability, then the 3.2 becomes close to zero. My only point is solid data does not say CO2 did it, it is just as likely that insolation variability did it. Renee’s post shows just one bit of evidence that insolation variability is more likely than CO2. Sometimes we forget that the anthropogenic CO2 forcing has never been measured, only estimated from computer models.
          More here: https://andymaypetrophysicist.com/a-short-summary-of-soon-connolly-and-connolly/

          • Andy May:\

            “solid data does not say that CO2 did it, it is just as likely that insolation variability did it”

            I agree.

            The diagram of Radiative Forcings which you show completely omits the STRONGEST positive forcing of all, which is the reduction in the amount of anthropogenic SO2 aerosols in the atmosphere due to global Clean Air efforts. Since about 1979, they have fallen by close to 100 million tons.

            (As seen in nature after every large volcanic eruption: initial cooling from the injection of SO2 into the stratosphere, then eventual warming to pre-eruption levels as the SO2 aerosols eventually settle out).

            It is a certainty that cleansing of the atmosphere is what increases insolation, NOT the accumulation of CO2 in the atmosphere.

    • Isn’t it more likely that the greater ocean surface in the Southern Hemisphere results in a greater ocean warming with the rise in S. insolation, driving CO2 outgassing?

      • John,
        “Isn’t it more likely that the greater ocean surface in the Southern Hemisphere results in a greater ocean warming with the rise in S. insolation, driving CO2 outgassing?”

        Seems like a reasonable explanation to me.

    • They depict temperature anomalies … from what base? Do we have confidence intervals for these data?The wildly oscillating lines are probably individual measurements … I don’t know enough of ice core technology, can measurements be repeated? Were they repeated? With what precision?

      • Curios George,
        The temperature anomalies are from the base of the average temperature from each polar region (-32 deg C Greenland and -55 deg C Antarctic). The wildly oscillating lines are individual measurements which are many years to decades apart. Numerous ice cores have been taken in both Greenland and Antarctica and show similar trends. Here’s a link for some basics. https://www.igsoc.org/journal/56/200/j10j201.pdf

  2. Very well written and researched post Renee. Will have to read and re-read to fully understand all the implications that this has for historical, present and future climate. If Javier is correct, then we have already committed to a future glacial ice advance from the stronger decreasing Obliquity cycle. Will this be still born and the Holocene continues, or push us into a long term negative feedback albedo loop that starts the next 100K+ year glacial advance once again? Or does CO2 over ride this now. We will probably know within a thousand years, and we are about due for this if the past interglacials are any indication. We are trending down each 1000 years it seems, just like previous interglacials.

    My first thought was we live on a bi-polar planet, with different things going on simultaneously in each (anti) arctic hemisphere and we need to fully understand the ramifications of reaching conclusions from SH data, for NH results, past present or future. Or vice versa. We can calculate much of this just from orbital mechanics, and solar insolation forcing. But many things to learn from all this. Very interesting, and I want to learn more.

    • “Or does CO2 over ride this now. We will probably know within a thousand years”

      We already know; instead of the slow cooling we would otherwise expect, we have abrupt warming. What effect will that have during an interglacial? 50% rise in CO2? No paleo record of that.

      In a thousand years we will *still* have elevated CO2 levels and rapidly melting Icecaps.

  3. What different looking graphs they would be if “present” as in Before Present, wasn’t 70 years ago. Also intertesting to note a distinct lack of a synchronous global signal for warm periods or so-called little ice ages.

    • Loydo,
      “Interesting to note a distinct lack of a synchronous global signal for warm periods or so-called little ice age”

      The focus of this post was on the underlying millennium trends. I agree the correlation of centennial signals between the polar regions within the Holocene interglacial deserves further investigation. During the glacial periods, it has been demonstrated that Antarctic and Greenlandic temperature are linked, but not in phase.
      https://science.sciencemag.org/content/322/5898/83.full

      • “The Holocene CO2 trends measured from Antarctic ice cores are coeval with Antarctic temperature trends and out of phase with Arctic temperature trends. Despite being routinely used in climate research, Antarctic CO2 is probably not representative of global and/or Arctic CO2 trends.”

        Your BP graphs only show CO2 varying by about 10% over the majority of the Holocene, enough to cause detectable differences between the poles that isn’t being swamped by insolation changes?

        In the few years *since* 1950 CO2 has jumped 30+% and everything is becoming a whole lot more synchronous. Yes the Arctic has warmed a little faster that Antarctica, but that just means the Arctic is more sensitive to a general warming, which makes sense for ocean/continent reasons mentioned in your post. Does your premise hold true for the period since 1950?

      • Loydo, Antarctic temperatures have been falling since about 2000, even though CO2 is rising rapidly. I realize that Renee did not correct “BP” her graphs, but her focus was on climate change. That is change over hundreds of years. The time since 1950 falls into some definitions of “climate.” But, many short term weather patterns, like the AMO can be longer than that, so looking at hundreds of years is more correct IMHO. If CO2 has a dominant effect, we really won’t know for sure for at least another one-hundred years.

        • “Antarctic temperatures have been falling since about 2000, even though CO2 is rising rapidly.”
          (No, they haven’t https://www.climate4you.com/images/MSU%20UAH%20ArcticAndAntarctic%20MonthlyTempSince1979%20With37monthRunningAverage.gif)

          “That is change over hundreds of years. The time since 1950 falls into some definitions of “climate.” But, many short term weather patterns…”

          Make up you mind.

          So you’re familiar with this correlation
          https://serc.carleton.edu/details/images/174582.html
          and you’ve seen this
          http://clim8.stanford.edu/CO2_1kya.jpg
          and conclude that this
          https://www.climate.gov/sites/default/files/global_temp_vs_carbon_dioxide_graph_lrg.gif
          is just an artifact, a coincidence, a trick of the light, a trivial weather pattern because things are different now, gh gasses have stopped correllating, especially human gasses, they just stopped.

          • Loydo, The UAH graph you show is from 60 deg to 85 deg. Satellites do not see the poles. The graph I showed is from actual Antarctic measurements on the surface.

            You will need to explain the point you are making with the other graphs, I don’t see it. Short term changes in temperature could just be natural cycles.

          • The trends discussed in you post are interesting and informative. But I am trying to draw a distinction between the two periods – before and after 1950 – so that the casual reader doesn’t come away with the impression that if “…CO2 trends… are… out of phase with Arctic temperature trends…” doesn’t that mean it can’t be about CO2? Or as Andy so helpfully demonstrates above: “If CO2 were doing it, it would happen at the same time in both hemispheres.

            The descent fom the Holocene optimum seems to be following an entirely predictable trajectory due to insolation cycles. The post however mentions CO2 several times, as has Andy in a few replies, but for the vast majority of the Holocene CO2 levels have been varying by only a few percent – CO2 can only have played a minor part in temperature fluxuations over the period you are discussing; up until 1950. (I am picking 1950 only out of convenience). Since then Milankovitch cycles, sunspot cycles and any other natural forcing has been swamped by an unprecented pulse of anthropogenic ghg and resulted in a sharp reversal of the trend in the subsequent 70 years. Using graphs with time scales that look like they are current but end in 1950 doesn’t make it any clearer and is potentially misleading.

            There is a pervasive culture of downplaying the impact of CO2 here, unless of course its about plant food then it really comes into its own. The links I provided above in response to Andy clearly show a tight corellation between *global* temperature and CO2 and indicate several degrees of rapid warming. I think it important to clearly distinguish between millenial, glacially slow, Milankovitch cycles, their causes and effects and AGW.

          • Loydo, 1950 to 2000 global temperatures went up rapidly for some reason, but it is only 50 years. Since 2000 CO2 has gone up a lot, why did the temperature trend stay mostly flat, except for the 2016 El Nino? You are dealing with a very short period of time. With ENSO, the AMO, the PDO and solar cycles to contend with, you can’t tell how much of an effect CO2 has. The computer models radically oversimplify and simply assume everything else is zero or near zero and assign all temperature change to CO2. Sorry, I don’t buy it.

  4. In the first graph, is temperature lagging about 2K yrs after insolation? Looks like it, but why. Thermal inertia.

    • Macha,
      “Is temperature lagging about 2K yrs after insolation”

      Great question on lags. We know that the hottest temperature is not at Summer Solstice. In the Arctic it lags summer solstice by 1 month and in the Antarctic by 1.5 months. Evaluation of lag times to insolation especially due to oceanic reaction time would interesting. This was a screening evaluation that did not evaluate lag time.

  5. I noticed a huge spike in the CO2 toward the ‘Present’. Are we tacking Mana Loa data onto proxy data?

  6. What figure 1 fails to show is the actual temperature difference between the arctic and antarctic (rather than just the anomaly). The antarctic temperature averages about -50 to -60C and the arctic about -20C, the difference being surely partly due to the fact that the antarctic has a huuuge permanent ice mass, averaging over 2 km thick and covering about 5.4 million square miles, on a larger land mass roughly centred on the south pole. Greenland is the biggest single ice mass in the arctic, but is 2000 km from the pole and covers only about 650,000 square miles, or about 12 per cent of the antarctic ice mass, while much of the rest of the north polar region is open sea. Were these simple facts not worth a mention?

    • BoyfromTottenham,
      Figure 1 is the temperature difference or anomaly from the average polar present day temperatures as stated in the text, which are quite different. Yes the impressive facts you state on the size of the Antarctic ice mass compared to Greenland help to validate the sensitivity of Greenland ice sheet variability to Northern insolation and Antarctic’s stubborn insensitivity. Thanks for the additional supportive technical information.

  7. There is no way that scientists should accept propositions that Antarctic temperatures thousands of years ago can be measured today to a tenth of a degree C. Yet, graphs like Fig 3 show such resolution. We have problems with today’s direct thermometry reaching such superb performance. Simply contrast global near surface air temperatures from competing authors. Likewise, no way can CO2 ppm from these polar regions be resolved to 1 ppm, as might be inferred from the graphs.
    There is a big gap between the high performance of a modern instrument like a mass spectrometer or IR gas analyser, on one hand, and the effects of settings and assumptions that relate such measurements to the real world. We gloss over difficulties in relating a few radioisotope measurements from gases recovered from ice, to the claimed regional historic temperatures. Safe with the knowledge that we cannot reconstruct conditions from thousands of years ago, arm wavers can proceed with impunity to make one outrageous claim after another.
    Renee, it is entirely possible (at least to me) that your whole conversation floats around with meaningless pattern within actual uncertainty limits so wide that one can create any narrative that seems subjectively reasonable. That is not proof that events happened as described.
    Have you ever attempted a comprehensive error analysis of the parts of your story, compounding their errors, to objectively arrive at a grand estimate? Do you not wonder why some of these past measurements seem to perform so well compared to today’s capabilities, before even considering the plausibility and uncertainty of the many assumptions used in the eventual conclusions?
    Geoff S

    • Geoff,

      “Ice cores are remarkably faithful recorders of past climate, providing multiple duplicated reconstructions with small and quantifiable uncertainties. Ice-core reconstructions in general do not rely on assumed quantitative time-invariance of empirical, but instead rely on assuming little more than the constancy of physical law over time.” https://www.igsoc.org/journal/56/200/j10j201.pdf.

      Ice core data is certainly not as accurate as the recent 150 years of instrumental data, no question. No one is saying this data compares so well to absolute instrumental data. This post is evaluating the underlying secular trends. Uncertainty becomes less important when investigating the relative magnitude of temperature changes rather than the absolute temperature. Proxy data do not have to be converted to units of degrees to be useful indicators of past temperature. They are useful because they attest to the timing and relative magnitude of change, which is sufficient for many statistical reconstruction methods.

      • Renee,
        Thank you for endorsing my argument by referring to Alley.
        His paper has no nmerical estimates of uncertainty, but it does have a lot of arm waving on the theme of “Look how clever my mates and I are.”
        That is my objection. Errors have to be measured, processed by methods like those from BIPM and stated numerically. Alley does not do this.
        He and you might be correct, but you have not demonstrated this.
        Geoff S

      • Renee,
        Thank you for confirming my point.
        Your reference is to Alley, a paper that shows no numbers at all about uncertainty., just many words.
        Is this not a strange choice from you to respond to an assertion of mine that more uncertainty numbers should be calculated? Geoff S

  8. you’ll be able to write a really good article in a few years where the minimum Antarctic sea ice reaches the coast or the massive ice walls. The Antarctic sea ice will then stop shrinking.
    The Arctic sea ice on the other hand will not stop shrink until it is ice free.

    Also as others have said the Antarctic has a massive thermal sink at -50°C whereas the Arctic reaches 0°C during peak summer they are not comparable areas!!!

  9. Nice article, Andy, but the AGW cult will ignore the yin-yang and claim that both North and South would’ve been cooler without CO2.

    You can’t win with them. Even if temperatures go down from now till eternity, they will claim it would drop faster without CO2.

    • Zoe, Renee wrote the article. I did some small edits and posted it, incorrectly at first! But, that was all. It is her work and she did a good job, IMHO.

        • It’s a WordPress “feature.” WordPress automatically lists the WordPress ID person who submits the article as the author. In addition to writing his own great articles, Andy “sponsors” articles by Renee and Javier.

  10. It appears that temperature and ice melt phenomena in Antarctica are mostly driven by its geological features. Even the warmth of the circumpolar deep water circulation there can be explained more easily in terms of hydrothermal vents than with ocean currents that bring heat from the tropics.

    https://tambonthongchai.com/2020/02/09/antarctica-threatens-florida/

    https://tambonthongchai.com/2020/03/22/10684/

    https://tambonthongchai.com/2019/07/16/antarctica-slr/

    • “temperature and ice melt phenomena in Antarctica are mostly driven by its geological features”

      Your links take us to quite a bit of speculation, but nothing that supports this statement. When you say “driven” it implies a ‘forcing’ caused by something changing. I understand there are rifts and volcanoes etc., but have any of them changed? What changes in these geological features can you point to that might be causing the anomalous warming/melting? Over what time frame? What is the change in W/m^2?

  11. So if the poles behave opposite does that mean that climatic effects like the little ice age or medieval warm
    period aren’t actual global but only local and restricted to one hemisphere at most?

    • Izaak,
      “So if the poles behave opposite does that mean that climatic effects like the little ice age or medieval warm period aren’t actual global but only local and restricted to one hemisphere at most?”

      The MWP as well as the Present warming has different climatic impacts at different latitudes.
      https://imgur.com/a/7b5VLVF

      • “different climatic impacts at different latitudes” sounds like a convoluted way of saying that
        the MWP didn’t exist.

        • Izaak,
          The MWP existed just as much as the Present warming. And more so in the Antarctic.

          • Renee,
            According to your graph it looks like the Antarctic warmed before the Arctic and then
            cooled just as the Arctic was warming. Suggesting that there was no significant time period when both hemispheres were warming simultaneously. Again you show that
            temperatures in the poles are anti-correlated. So how can then be a period when both
            hemispheres are warming or cooling simultaneously?

          • Izaak, You oversimplify too much. Renee’s post describes the effect of insolation changes in the higher latitudes. It is a large effect, but not the only factor. See Javier’s posts here, on my website and on Climate, Etc. for a full treatment of the other factors. Some affect the whole Earth, some only one hemisphere or the other. Some, just the North Atlantic or the Pacific. This post just covers one factor and it is hemisphere specific.

          • Izaak,
            “So how can then be a period when both hemispheres are warming or cooling simultaneously?”
            Zooming in to the past 2000 years shows that the Arctic warms much faster during centennial events like the MWP and Present than the Antarctic. They are not warming and cooling simultaneously.
            https://imgur.com/8JdJArr

  12. Renee
    A minor quibble here. You remarked, “These correlations are all strong, above 0.74.” A correlation coefficient of 0.74, strictly speaking, means that about 55% of the variance in the dependent variable is predicted or explained by the independent variable. That is, about a coin toss! If you were doing an analysis of variables, and you had two variables summing to nearly 100%, then it would be important. However, with only one independent variable, 0.74 basically says that nearly half of the variance is noise or just random. Personally, I’d reserve the term “strong” for correlations over 0.8, or pushing two-thirds.

    • Bullseye. R squared indicates percent of variation in one variable explained by the other. Correlation coefficient is just a number and is larger since it is the square root of r squared.

    • I’d reserve the term “strong” for correlations over 0.8, or pushing two-thirds.

      Since the data used is much more than N=11 (degrees of freedom), the significance level for R=.74 is .995, the highest, according to the following table excerpted from

      https://psl.noaa.gov/data/correlation/significance.html

      Significance Level
      Degrees of .950 .975 .990 .995
      Freedom
      2 1.000 1.000 1.000 1.000
      3 0.920 0.954 0.977 0.986
      4 0.833 0.891 0.936 0.956
      5 0.758 0.829 0.889 0.919
      6 0.697 0.774 0.844 0.880
      7 0.646 0.727 0.802 0.843
      8 0.605 0.685 0.764 0.808
      9 0.570 0.650 0.729 0.775
      10 0.540 0.619 0.699 0.746
      11 0.514 0.592 0.671 0.719

      • Bob
        I think that we are talking about two different things. I believe you are addressing the question of whether the cited correlation coefficient is statistically significant. I believe that one can have high significance, but low explanatory power (R^2 <0.92]. Ideally, one would want to have high significance and high explanatory power for the dependent variable.
        https://www.investopedia.com/terms/d/degrees-of-freedom.asp

        “In investing, a high R-squared, between 85% and 100%, [R>0.92] indicates the stock or fund’s performance moves relatively in line with the index. A fund with a low R-squared, at 70% or less, indicates the security does not generally follow the movements of the index.”
        https://www.investopedia.com/terms/r/r-squared.asp

        • The degrees of freedom used in climate studies are equal to the dataset duration time in months or years; r-squared isn’t involved with that, but of course a higher r-squared is preferred.

          Originally your comment and the others’ were about R, not r-squared.

          • Bob
            Generally speaking, the degrees of freedom refer to the number of samples or the number of variables used to characterize a data set.

            The original remark that prompted my response was, “Antarctic temperature trends show a positive correlation with Southern Hemispheric insolation as well as with CO2 trends. These correlations are all strong, above 0.74.”

            Yes, Renee’s remark was about R, but my response was implicitly about R^2 because that puts the R in context of utility. I’m not sure you understand. So, let me try to be clearer. On a scale of 0 to 1, (R) 0.74 seems deceptively large. However, for purposes of explanatory utility, or predictive skill, R^2 provides context. That is, until R is over about 0.9, the explanation or prediction of the variance of the dependent variable leaves a lot to be desired. That was the point I was trying to make. Just because a number is ‘big’ doesn’t mean it deserves respect.

          • There is no problem, and thanks. I have a few of those rare high R and r-squared values among my works, which I’m saving for later; hope you’ll get to see them.

  13. Renee,
    Thank you for endorsing my argument by referring to Alley.
    His paper has no nmerical estimates of uncertainty, but it does have a lot of arm waving on the theme of “Look how clever my mates and I are.”
    That is my objection. Errors have to be measured, processed by methods like those from BIPM and stated numerically. Alley does not do this.
    He and you might be correct, but you have not demonstrated this.
    Geoff S

  14. “hypothesis that CO2 gas in Greenland ice core bubbles were enriched by acid-carbonate chemical reactions and therefore, are unreliable”

    This is a theory arrived at when temperature correlations with CO2 in the Arctic ice didn’t support the dominant CO2 control knob theory of climate, much held forth by sceptics. This would appear to be another of the common practice by mainstream consensus scientists to reject unhelpful data. A big ‘tell’ (poker player term in reading other players behaviour during play) is that the data from Greenland is being withheld. Why? Because they themselves find it uncomfortably ‘unhelpful.’

    Other falsifying data has been ruthlessly altered (Karlization of the Pause) or ignored (largely), major CO2 sources are natural (Congo Basin, etc.) – OCO satellite, the Great Greening of the planet (along with burgeoning food harvests) shows the benefits of human (we would like to take all the credit having taken the blame) and natural growth in CO2 output puts this orders of magnitude larger in the benefits column for this gas, a no-no! The raw temperature records from around the world showed the 1930s to 40s to have been the hottest period of the last 100 yrs, a time before CO2 had risen significantly -US, Canada, Greenland, Iceland, Europe, Southern Africa, Paraguay, Ecuador, Australia…. all had similar shaped temperature curves. Here is one from South Africa:

    http://wattsupwiththat.files.wordpress.com/2017/01/clip_image0022.gif

    Could be the US!

  15. … CO2 data from the Northern Hemisphere during the Holocene is not publicly available. The scant Greenland CO2 data that IS publicly available …

    As written those 2 statements are incompatible / contradictory.

    Should there be a “most of” or “the vast majority of” that’s missing for some reason ?

    • Mark,
      “Should there be a “most of” that’s missing for some reason?”

      CO2 data from the Arctic is available in mid-1990 publications. CO2 measurements from Greenland ice cores showed more variability and were generally 20-30 ppm higher than Antarctic CO2 measurements. Research hypothesized that CO2 gas in Greenland ice core bubbles were enriched by acid-carbonate chemical reactions and therefore, are unreliable. After the mid-1990’s, CO2 data from Greenland ice cores were not published or not measured.

      • I did not know that, thanks for the information.

        It remains true, however, that saying “the data is not publicly available” isn’t the same as saying “for various reasons the data collected so far are considered by professionals in the field as unreliable“.

        • Mark BLR,
          I certainly was not trying to hide the hypothesis that professionals deemed Arctic CO2 as unreliable. As a matter of fact I had the courtesy to respond to your comment even though it is actually the second paragraph in my post under the section CO2 is Synchronous with Antarctic Temperature Trends. I also recommended a link for more detailed information on Greenland CO2 in this same paragraph.

          Much of the CO2 data is in the form of graphs or plots in older publications of which the digital CO2 data is not available. I do believe there is more data out there, but once the “gods of climate science” deemed it to be chemically altered, nobody dared to publish the data due to group think and/or funding peer pressure.

          • Mea culpa, I did indeed miss that section on my first “speed read” of the article.

            I still, even though I know I shouldn’t, sometimes “latch onto” specific words and phrases, assign my “default definitions” to them, and then “filter out” a lot of the rest of what I’m reading.

            Note that it is good for me to be called out when that happens …

  16. “This early optimum is followed by cooling temperatures to a minimum around 8000 yr BP. Most core sites studied by Masson in the Antarctic display this cool minimum. ”

    In fact several do show a warm spike at 8.2kyr BP, including a huge one in the Vostok ice core. Vostok also shows an extended very warm period 4700-4500 BP, which is the next coldest period after 8.2kyr BP in the GISP2 series. That interval is determined by long term solar variability, and leads to the next coldest period in GISP2 at around 775 AD, which was the warmest part of MWP for northern European summers (Esper 2014). The 8.2kyr was accompanied by fast trade winds, meaning increased La Nina, and an associated positive NAO/AO regime, driving a colder North Atlantic and hence Greenland. With wetter tropical forests due to increased La Nina and a colder North Atlantic, atmospheric CO2 levels will drop.

    SCHWABE CYCLE VARIABILITY:
    https://www.linkedin.com/pulse/schwabe-cycle-variability-ulric-lyons

  17. It’s interesting to compare Pleistocene temperature data with these Holocene data. Both the Pleistocene ice core data and the land glacial data indicate that both polar areas were in phase during the Pleistocene. Why the difference?

    It’s also interesting to note that every climate change over the past 800,000 years, including glaciations, exactly matches 10Be changes (which presumably are an indication of the strength of the solar magnetic field).

    • Interesting point Dr. Easterbrook. Could it simply be scale? Renee is dealing with data at a scale of thousands of years, you are talking about events 100 times longer. Just a thought. North/South asynchrony may not exist in longer time frames. Obliquity (~41,000 yrs) and Precession (~26,000 yrs) are largely hemispheric in their effects. Eccentricity is more global (~100,000) years.

      • Andy,

        No–the temp changes in both hemispheres are synchronous both in ice cores and in the glacial land data and at all scales.

  18. Global warming predicts that temperatures will rise with rising CO2. Climate change predicts that temperature will change with rising CO2.

    While the theory of global warming may well be wrong, it is hard to see how the theory of climate change could be wrong.

    For the theory of climate change to be wrong, temperature would need to remain constant, regardless of changes in CO2. However, as this article shows, temperatures have never been constant, regardless of CO2.

    As such, the theory of Climate Change must be correct. Temperatures must change with rising CO2.

  19. Don,
    “Both the Pleistocene ice core data and the land glacial data indicate that both polar areas were in phase during the Pleistocene.”

    What Arctic glacial datasets are you referring to for the Pleistocene suggesting the polar areas were in phase? Most of the Greenland ice cores only cover the past 40,000 years and only the Holocene interglacial.

    • Renee,

      The GISP2 core covers the past 100,000 years and there is good correlation with the last interglacial (Eemian), the last glaciation, the D/O events, and much of the Holocene. During these times the Greenland data nicely matches the Antarctic data and both are mirrored in the well-dated land records of Pleistocene glacial and nonglacial events. If you want to see the actual data, it’s in my book “The Solar Magnetic Cause of Climate Changes and Origin of the Ice Ages,” (available on Amazon.com)

      • Don,
        Thanks for the reference. I didn’t realize the GISP 2 core covered the Eemain period. I did look at GISP 2 over the Holocene relative to the Dome C. GISP2 is flatter during the Holocene climate optimum relative to the Agassiz-Reland, NGRIP, and GRIP data. The centennial events are much more pronounced in GISP2 including the 8.2 kyr event. And the centennial events do appear to match between Antarctic Dome C and GISP2 data. However, the longer term millennium trends appear to be different. A quick plot is here, years AD. https://imgur.com/a/4s4NA5J.

        Concerning the last glacial period, I do recall a paper by Ahn and Brooks that Age synchronization between Greenland and Antarctic ice cores through atmospheric CH4 variations reveals that Antarctic and Greenlandic temperature are linked, but not in phase. https://science.sciencemag.org/content/322/5898/83.full

        I’d appreciate your thoughts on the plot and/or the paper. Many thanks for your input and discussion.

        • Renee,

          I’ve looked at the data for all of the ice cores and decided to use data from the Antarctic EPICA and Vostok cores as best suited for my purposes. The EPICA core data covers the last 800,000 years and the Vostok data covers 400,000 years. If you put the Vostok curve over the EPICA curve they are practically identical, giving one confidence in the dataset. I use GISP2 because it’s the longest and Minze Stuive (who made the isotope measurements with Peter Grootes) is a friend of mine, and I have his entire raw data set so I can plot any interval I want.

          If you haven’t looked at the EPICA and Vostok data, I’d recommend you do so. The easiest way is to just look in my book. I blow up short sections of these curves to look at the details and they reveal a remarkable story. I looked at every temp change for the past 800,000 years and compared the data to changes in 10Be levels and was astonished to find that EVERY temp change was mirrored by comparable changes in 10Be, even very short, abrupt temp changes during the late Pleistocene D/O events. Since 10Be a function of the strength of the solar magnetic field, that means solar magnetism drives the Earth’s climate. Take a look at the data in my book and you will be surprised.

          I looked in detail at the Holocene temp changes (and 10Be) in the EPICA, Vostook, and GISP2 data, which seem to differ from the curves you posted. Don’t know why.

          Anyway, let me know what you think about all this. Interesting stuff!

          Don

          • Don,
            Yes, I do like the Vostok, EPICA Dome C (EDC) and EPICA Dronning Maud Land (EDML) isotope records. The EDML is a much shorter time frame of only 130,000 years, but they all overlay nicely as you point out. There is that annoying spurious data point on Vostok around 8200 yrs.

            I haven’t looked at 10Be but plan to read your research regarding its relationship to the solar magnetic field. I also appreciated your reference in my previous post to your 2016 paper that showed data from Greenland weather stations and the high temps during the 1940 warm period.

    • Correction. Greenland ice cores go back about 100,000 years and cover the last Glacial period and Holocene interglacial period.

    • The NH and SH were clearly out of phase in the run up to Holocene inception.

      The Bolling-Allerod (Northern hemisphere warming at 14,600 yrs ago) and Younger Dryas (subsequent 1000 yr cold interval) were features of the last deglaciation driven by oceanographic processes. The deglaciation starting as early as 22yrs ago led by warming in Antarctica. The general picture is one of steady changes in Antarctica contrasting with unstable fluctuations in the NH driven by the Atlantic Meridional Overturning Circulation (AMOC).

      About 22 kYa (thousand years ago) Antarctica started warming. The slow oceanic warming caused by peaking obliquity was hoovered to Antarctica by deep ocean circulation. The NH at the same time slightly cooled. So already the NH and SH were acting reciprocally.

      At about 14 kYa the “Bolling-Allerod” (BA) happened, i.e. the NH abruptly warmed, as evidenced by Greenland cores. This was accompanied by a reciprocal pause and slight reversal in the (already long established) gradual Antarctic warming – the bipolar seesaw again. This episode is referred to as the “Antarctic cold reversal”.

      At the time of the BA there was a sharp rise in global sea level – 20 meters in 500 years. Weaver et al 2003 (link below) show that this was caused by a collapse of the gradually warming Antarctic ice sheet. The resulting pulse of fresh meltwater from Antarctica had the long range effect of speeding up the AMOC and the gulf stream in the NH, bringing rapid warming to the NH and the BA. The bipolar seesaw continued – as the NH became sharply warmer, there followed in the SH the Antarctic cold reversal where temperatures went slightly into decline.

      However down in the deep ocean, ongoing century-scale interactions between the SH and NH caused – about a thousand years later – an abrupt stoppage of the AMOC and the gulf stream. In fact the cuplrit was Antarctic Intermediate water (AAIW) – see again Weaver et al. With the interruption of the gulf stream the NH went cold again – the Younger Dryas. In response – by now you get the picture – the Antarctic returned to gradual warming.

      Eventually, after about 1000 years of NH cold with no gulf stream (the YD) the after-effects of the huge Antarctic ice sheet collapse finally subsided allowing the AMOC and the gulf stream to resume. Now followed an exception to the bipolar seesaw – both NH and SH warmed together, around 12 kYa. This marked the final end of the last glacial and the Beginning of the Holocene.

      http://home.sandiego.edu/~sgray/MARS350/deglaciation.pdf

      https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/97GL02658

      • Phil,
        Nice synopsis of the deglaciation episode and the NH and SH interactions during this significant event.

  20. This post makes the important observation that global CO2 atmospheric concentration up till the industrial age has been dominated by SH and Antarctic temperatures. Figure 3 makes this clear.

    This provides further evidence that the primary source of CO2 atmospheric changes is thermal equilibrium between CO2 in the ocean and atmosphere according to Henry’s law of gas solubility and temperature. There is more water in the SH than the NH. Therefore as figure 3 above shows, atmospheric CO2 follows the temperature of the SH more than that of the NH. A lot more.

    This fact is very important as it exposes a trick used by Skakun and other authors in arguing that temperature change at Holocene inception, 15-10,000 years ago, followed and thus was driven by CO2. This sleight of hand employed the difference between NH and SH in temperature change at Holocene inception, together with some clever data shuffling. In the NH there was a “false start” to the Holocene, with rapid warming 14,500 years ago in the Bolling Allerod excursion followed by a fall to cooler temperature in the North Atlantic during the 1000-year Younger Dryas (YD). After the YD Holocene warming resumed in the NH while the SH has been steadily warming since 22kya.

    During the YD global atmospheric CO2 continued to rise, because the SH oceans were still warming. The SH was not much affected by the YD. In general the effect of the YD was to shift forward in time the NH start of the Holocene. What Shakun and co-perpetarators did was define the onset of the Holocene by a large number of (largely biological) proxies of temperature biased toward the NH, while comparing this to the CO2 concentration that – as we have already seen – is driven mostly by SH ocean temperature. The result is the SH-following CO2 increase slightly preceding NH-biased temperature increase and a suprious (but very influential) conclusion being drawn that somehow Holocene warming from the last glacial maximum was being driven by CO2 increases (coming from God knows where).

    http://geoscience.wisc.edu/geoscience/wp-content/uploads/2010/07/Shakun_Carlson_QSR_2010.pdf

    It is notable that Shakun’s paper does show the Southern Ocean’s (Antarctic) temperatures as well as rising CO2 – as Renee shows in figure 3 above. But Shakun et al put the two in different figures – fig 1 and fig 7, far apart in the paper, and no comment is made as to their similarity.

    It is very important to understand that global CO2 concentration (excluding human influence) is dominated by the Southern Ocean and SH. This combined with understanding the inter-hemispheric seesawing of temperatures at Holocene inception, shows that changes in ocean water temperature precede and are causative of atmospheric CO2 rise, not the other way around.

    • Phil,
      Yes, Shakun’s paper was very misleading. It’s also very disappointing that CO2 measurements from Antarctic ice cores are the only paleo CO2 dataset we have. I believe it is not completely representative of global CO2. Antarctic CO2 conditions are dominated by the Southern ocean as you point out and oceanic process are a longer-term underlying driver of climatic conditions.

      I wish scientists would have continued to gather CO2 from Greenland ice cores even with all its warts. The scant Greenland CO2 available shows more variability and may be suggesting both oceanic as well as shorter-term terrestrial CO2 fluctuations. It’s a missing piece of the CO2 puzzle that would help explain or at least put into better context the present day centennial increase in CO2.

      • Renee
        A lot of the original work done in Greenland was by scientists with the US Army Cold Regions Research and Engineering Laboratory (formerly SIPRE), in Hanover, New Hampshire. There have been a lot of changes wrought in the staffing and mission since I was stationed there in 1966 & 1967. I wouldn’t be surprised to discover that there are a lot of reports archived in the library that never made it into the general literature. You might want to consider soliciting the lab to see if you might be allowed to have access to unpublished reports.

          • Renee
            The lab is (or at least was) unique in that it had a number of cold rooms where cores could be worked on without melting. They also archived retrieved cores there. However, after more than 50 years, I’d be concerned about gases diffusing out of the ice at low pressures. So, I don’t know whether or not they could offer physical resources to be analyzed with modern instrumentation.

            Shortly before mustering out of the Army, I considered an opportunity to go to Antarctica for a drilling program that was being planned. However, there was a buildup going on in Vietnam, and knowing how the military worked, I was concerned that if I extended my tour I might end up in Vietnam instead of Antarctica. Besides, when I came back I probably wouldn’t have had a wife any longer. The bottom line is that CRREL might also have had some Antarctic cores in storage. If you are in a position to do some research, it might be worthwhile to try to determine what, if anything, remains at the lab.

          • Clyde,
            What an interesting background. Yeah, you are right about cores being too old to be resampled for gas analysis. But I’d take any old reports or CO2 data not published yet.

            I did email Ed Brooks at OSU several months ago and sent him my Greenland CO2 article. I asked him for any Greenland CO2 data he was aware of. No response.

            I’d consider sponsoring or donating to a university research project that would compile and re-examine Greenland ice core CO2 data. Perhaps it would lead to additional ice core data gathering directly targeting CO2 investigation.

      • Phil,
        There is some value, of course, to more data. The biggest downside about stomatal data is it tends to exhibit localized CO2 influences. But that can also be said about tree ring data, which is extensively used as Northern Hemisphere climate temperature proxy data.

        If I had a choice, I would extensively re-sample the Greenland ice cores for CO2 analyses. And secondly, drill a new Greenland ice core and use the best technology available to preserve and sample for CO2 data.

  21. Beware of crazy climatologists rewriting history, such as the bogus Minoan Warm Period. A pair of super solar minima from 1360 BC and 1250 BC drove the decline and demise of several civilisations including the Minoans. And that was super warm in Greenland because of a negative NAO/AO regime. The centennial scale noise in GISP2 is the inverse of solar variability, the coldest periods were the warmest in the mid latitudes. During the 8.2kyr event there were expansions of village settlements in Serbia, the Indus, and in England with wheat growing and the earliest known boatyard. 2700-2500 BC saw the onset of city building worldwide, that’s the real Minoan warm period, that’s when they and many others flourished from. That’s two of the three coldest periods in GISP2 during the Holocene. The warm spike in GISP2 from around 1000 AD was the Oort solar minimum, but one should ask then why the following centennial minima in Richard Alley’s series do not show as warmer spikes. It looks rather fishy to me. It’s all too easy to get the polar seesaw upside down in relation to solar variability with the wrong idea about GISP2.

    https://media.springernature.com/m685/springer-static/image/art%3A10.1038%2Fs41598-017-13246-x/MediaObjects/41598_2017_13246_Fig2_HTML.jpg

  22. How about a new hypothesis: the co2 levels in the ice cores are a result of a fractional distillation process which fractionated the co2 concentration to a ppm equilibrium level which is temperature dependent, this would explain the close correlation between the temperature and co2 concentration for both Antarctic and Greenland ice cores? This would explain the lag of co2 to temperature and the apparent rise in co2 concentration in recent decades. The evidence from both hemisphere ice cores supports this although the mechanism is elusive although Jawarovski (sorry about the spelling) hints at something like this happening and other research shows that other trace gases fractionate in the ice cores.

  23. Renee I enjoyed your analysis, but I think solar activity has more influence over time than orbital. Different regions respond at slightly different levels of solar energy and have different lags due to basin size, land locations, and ocean currents:

    https://i.postimg.cc/SR0zNCwt/Sun-Ocean-and-Ice.jpg

    The 1935-2004 solar modern maximum profoundly affected the ocean, sea ice, Greenland, and CO2.

    • Bob,
      Nice montage. I agree there are different lags in different geographical regions. Did you do any analysis comparing solar activity to the Southern Hemisphere or Antarctic temperatures over the past thousands of years?

      I’ll defer to Leif on this one. His comment above “Solar insolation changes a lot and has different effect in the two polar regions. ….the changes in insolation completely dominates changes in solar activity”.

    • “The 1935-2004 solar modern maximum profoundly affected the ocean, sea ice, Greenland, and CO2.”

      But the AMO and Greenland is always warmer during centennial solar minima. While during the strongest solar wind conditions of the space age, the AMO was at its coldest. The had to be weakening of the solar wind from 1925 for the AMO to warm, irrespective of what sunspot numbers were doing.

        • Bob Weber:

          You state “the solar output and the solar wind are definitely connected, but the solar output is directly controlling the long-term climate warming/cooling, not the solar wind”

          This is not correct.

          I have done an analysis of the Central England Temperatures Instrumental data set, which spans the years 1659-present, and find no evidence of any solar variability affecting the climate.

          What IS affecting the climate is varying amounts of SO2 aerosols in the atmosphere, primarily from volcanic eruptions.

          https://www.Osf.io//b2vxp/

          • … and find no evidence of any solar variability affecting the climate.

            Burl you made me make another revision! just to show you I am correct 😉

            The CET (Fig. 3c) cools @ SN<90.8, making 10 indices on my list, and there are more climate indices in the same sunspot range not on those charts that could fill many pages.

            https://i.postimg.cc/brnCm9zp/Sun-Climate-BE-levels.jpg

            SO2 volcanic aerosols are short-term and easily over-powered by solar forcing

            https://i.postimg.cc/C55TwXGp/Solar-vs-Volcanic-Cooling.jpg

          • Bob Weber:

            Regarding your post of May 30, 8:05 pm, where you attempted to show that you were correct.

            You need to download and study the link that I provided.

            You will see that all of my comments are fully supported by the data, and you need to wrap your mind around them, as uncomfortable as that may be.

          • Burl wrote:
            “I have done an analysis of the Central England Temperatures Instrumental data set, which spans the years 1659-present, and find no evidence of any solar variability affecting the climate.”

            Well you cannot be looking in the right place as much of the variability in CET is solar driven at the scale of weather, and modulated by the AMO which is also solar driven

            “What IS affecting the climate is varying amounts of SO2 aerosols in the atmosphere, primarily from volcanic eruptions.”

            Large eruptions typically follow much colder N Hem winters, and slightly warm 1-2 following winters through a positive influence on the NAO, and slightly cool 1-2 subsequent summers. So weather effects volcanoes and then the eruptions effect the weather, but they don’t cause colder CET winters.

          • Ulrich Lyons:

            You need to view the link which I provided.

            Central England temperature excursions precisely match the temperature effects of volcanic eruptions, increasing when there are no eruptions, and decreasing when there is a VEi4 or larger eruption.

        • Bob wrote:
          “The AMO responded to the Modern Maximum similarly as well, cooling SN<89.3"

          Sunspot has little to do with it, AMO variability is an inverse response to the solar wind strength.

          • Ulric,

            Sunspots, the long-term TSI proxy, TSI, and the IMF ie solar wind co-vary with the sun’s magnetic field, and inversely with cosmic rays.

            Solar wind negative Bz events are irregular and short-lived, w/o effect on tropics, where AMO heat derives – same reason Svensmark’s cosmic ray cloud theory is bunk – no effect on the tropics where warming/cooling is TSI/insolation driven.

            The AMO as a solar accumulation function has it’s own long-term tempo due basin size.

          • Bob writes:
            “Sunspots, the long-term TSI proxy, TSI, and the IMF ie solar wind co-vary with the sun’s magnetic field, and inversely with cosmic rays.”

            Not so, there were major lows in the solar wind at sunspot maximums in 1969 and 1979-80, after which the major lows shifted to about a year past sunspot minimum in 1997 and 2009. Which is why the AMO anomalies have shifted from being in phase with sunspot cycles during the cold AMO phase, to anti-phase with sunspot cycles during the warm AMO phase.

            https://snipboard.io/l6eKs2.jpg

          • The reason why Svensmark’s ideas are wrong is because weaker solar wind drives warmer ocean phases which then reduce low cloud cover.
            Weaker solar wind causes negative NAO/AO states which are directly associated with slower trade winds, that’s why there is an increase in El Nino conditions during centennial solar minima. Negative NAO/AO states directly drive warm AMO anomalies via ocean gyres in the North Atlantic effecting the overturning rates. And then there is a ~8 month lagged positive feedback from El Nino episodes driving major AMO warm pulses.

  24. EPICA CO2 lags temperature by 400-600yr with a Millenial Sensitivity of 7.8ppm/C @ R=.9, R^2=.8:

    https://i.postimg.cc/DzprcYXP/Epica-Ice-Core-CO2-lags-Temp.jpg

    The annual perihelion insolation pulse peaks in January over the southern ocean, ultimately driving CO2:

    https://i.postimg.cc/HnRtZKPP/Annual-CO2-Cycle-driven-by-Sun-and-Ocean.jpg

    The sun’s early year warming of Nino34 then first affects Antarctic sea ice, then Arctic sea ice:

    https://i.postimg.cc/zBmD5Q78/Nino34-vs-Sea-Ice-Extent.jpg

    The main reason the Antarctic CO2 isn’t the best overall is the larger expanse of ice-free cold waters ringing the Antarctic sea ice and shores that continually sink more CO2 than the Arctic cold waters which don’t sink anything in comparison when covered with ice.

    • Bob,
      Thanks for confirming that Antarctic CO2 isn’t the best overall measurement to use. Unfortunately, it’s the only CO2 data available before 1960 instrumental data and is frequently used as a past comparison to global present day CO2.

    • As evidenced by the seasonal variation in CO2 draw-down and replenishment, which shows minimal time lag, I’d say that the time lag you cite is an argument for the oceans being the primary source of atmospheric CO2, given the known slow, deep currents with a recycle time of hundreds of years.

  25. Could local solar insolation be the missing link?
    “the mechanisms that are responsible for generating the anti-correlation of the northern and southern hemisphere warrants further investigation. This phenomenon requires substantial changes in net hemispheric air-sea heat exchanges”
    https://www.nature.com/articles/s41467-020-15754-3

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