Greenland Ice Core CO2 Concentrations Deserve Reconsideration

Guest post by Renee Hannon


Introduction
Ice cores datasets are important tools when reconstructing Earth’s paleoclimate. Antarctic ice core data are routinely used as proxies for past CO2 concentrations. This is because twenty years ago scientists theorized Greenland ice core CO2 data was unreliable since CO2 trapped in air bubbles had potentially been altered by in-situ chemical reactions. As a result, Greenland CO2 datasets are not used in scientific studies to understand Northern and Southern hemispheres interactions and sensitivity of greenhouse gases under various climatic conditions.

This theory was put forward because Greenland CO2 data were more variable and different than Antarctic CO2 measurements located in the opposite polar region about 11,000 miles away. This article re-examines Greenland ice cores to see if they do indeed contain useful CO2 data. The theory of in-situ chemical reactions to explain a surplus and deficit of CO2, relative to Antarctic data, will be shown to be tenuous. The Greenland CO2 data demonstrates a response to the Medieval Warm Period, Little Ice Age, Dansgaard-Oeschger and other past climate change events. This response to past climate changes offers an improved explanation for why Greenland and Antarctic CO2 measurements differ. Further, Greenland CO2 measurements show rapid increases of 100 ppm during warm events in relatively short periods of time.

Atmospheric CO2 is More Variable in Northern Latitudes

Figure 1, from NOAA, shows atmospheric CO2 concentrations measured from the continuous monitoring program at four key baseline stations spanning from the South Pole to Barrow, Alaska. CO2 has risen from about 330 ppm to over 400 ppm since 1975 and is increasing at approximately 1-2+ ppm/year. Many scientists believe that rapidly increasing CO2 is mostly due to fossil fuel emissions.

Figure 1. Atmospheric CO2 concentrations from NOAA

Although the increasing trends from these four baseline stations appear similar, the Northern Hemispheric (NH) atmospheric CO2 concentrations are increasing slightly faster than the Southern Hemisphere (SH). Longer-term trends from all latitudes are de-seasonalized and used for calculations of the inter-hemispheric CO2 gradient and trends. During pre-industrial times the NH CO2 mean annual concentration was estimated to be 1-2 ppm higher than the SH (Stauffer, 2000). Currently, the annual mean CO2 concentration is about 5-6 ppm higher in the NH than the SH. De-seasonalized trends also show that SH CO2 lags the NH CO2 by about 2 years. For example, the annual CO2 reading at Barrow, Alaska broke 400 ppm in May 2014 whereas the annual South Pole hit 400 ppm May 2016. However, note the 1st monthly average at Barrow hit 400 ppm in April 2012 which is four years earlier than the South Pole.

Although all observation stations show that CO2 is rising, there are annual amplitude cycles reflecting seasonal differences that vary by latitude (N-S) superimposed on the overall rising longer-term trend. Figure 2 shows a graph comparing the past two years of CO2 data for Barrow, Alaska and South Pole (SPO) observatories. On the right-hand side, are global CO2 visualizations from NASA which incorporate CO2 measurements from the Orbiting Carbon Observatory spacecraft.

Figure 2. Last two years of CO2 data for Barrow, Alaska and the South Pole.

In the NH, atmospheric CO2 rises during the winter months and falls during the summer showing strong evidence of a natural biospheric signal (Barlow et. al, 2105). In NH springs and summers, CO2 concentrations decrease rapidly during a period of two months due to the growth of plants and adsorption of CO2. During autumn/fall, CO2 is released by respiration and increases. During the NH winters, there is a more stable period when the highest CO2 readings are observed. This dormant period lasts 6-7 months each year when there is less terrestrial plant growth.

Barlow, et. al calculated an increase in the NH CO2 amplitude of 0.09 ppm/yr. on detrended data. For example, NH CO2 amplitudes have increased from 14 ppm in 1975 to 18 ppm in 2019. The amplitude increase is associated with the enhanced vegetation greenness partly due to elevated warming as discussed by Yue et.al. Barlow et. al suggests the changes in CO2 uptake and release is evidence that NH vegetation may be progressively capturing more carbon during northern spring and summer as global CO2 levels increase.

The Barrow and South Pole observatories show that CO2 amplitudes in the NH are significantly larger than in the SH. A very weak amplitude of opposite polarity is seen in the SPO CO2 measurements shown by the dark gray line in figure 2. The SH CO2 amplitudes are significantly lower at only 1-2 ppm per annual cycle. The amplitude differences result in CO2 being 12-15 ppm higher in the NH than in the SH during northern winter months almost 60% of the year. This is shown in the NASA global visualizations during the dormant period. Dettinger and Ghil, 1998, suggest the smaller SH amplitudes reflect less seasonal variability due to a much-reduced terrestrial influence on CO2 concentrations. They also conclude that South Pole CO2 variations are affected mostly by marine influences such as marine upwelling and release of CO2.

CO2 Data from Greenland Ice Cores Do NOT agree with Antarctic

CO2 concentrations of trapped air in ice bubbles in Greenland and Antarctic ice cores were examined to evaluate differences between the SH and NH paleoclimate atmospheric CO2.  Antarctic ice core CO2 data is readily available and used as the key dataset for CO2 trends during interglacial and glacial periods for the SH. Surprisingly, Antarctic CO2 data are also used for NH paleoclimate CO2 trends.

Finding Greenland ice core CO2 data is extremely difficult especially in any useful format. It seems to be written out of history. There are four ice cores in Greenland; GISP2, GRIP, Camp Century, and Dye 3 with mention of atmospheric CO2 gas measurements. There is only scant data available in digital formats.

Several mid 1990’s articles have published some of the Greenland CO2 ice core data. Anklin et. al. shows Greenland GRIP and Dye 3 CO2 profiles from 5,000 to 40,000 years BP. Digital data from this study is available for GRIP CO2 concentrations in core depths. Smith et. al have published on CO2 concentrations of trapped air from the GISP2 ice core also available in core depths. Neftel et. al. published on CO2 concentrations from the Camp Century ice core compared to the Antarctic Byrd ice core. CO2 concentrations were as high as 400 ppm about 1100-1200 years ago using a dry extraction technique analyzed by laser spectrometer. Unfortunately, I am unable to located Camp Century and Dye 3 ice core CO2 data in digital format.

Figure 3. More Greenland and Antarctic CO2 data and the difference.

In 1995 Barnola et. al had recent Holocene interglacial ice core samples from both Greenland GRIP and Antarctic Siple Dome ice cores analyzed in two different laboratories, Grenoble and University of Bern. Digital data is not available; however, tables of the data are included in their publication. The results are plotted in Figure 3a. The black curve is smoothed CO2 data using Antarctica ice cores. The symbols represent Greenland GRIP CO2 from the laboratory measurements (Gren and Bern). Barnola found there is good agreement between the lab measurements on different cores in the same hemisphere. However, the measured CO2 values between Greenland and Antarctic did not agree. This discrepancy of up to 20 ppm was more than could be explained by the inter-hemispheric gradient of atmospheric CO2 concentrations.

Figure 3b shows the CO2 ppm difference between the lab measurements on the Greenland lab samples versus Antarctic samples. The present day inter-hemispheric gradient is also highlighted. Interestingly, CO2 values are in good agreement between Greenland and Antarctica from about 1600 AD to 2000 AD. However, Greenland CO2 values ranged up to 20 ppmv higher from 1600 to 900 years AD. The approximate time of the Medieval Warm Period (MWP) and Little Ice Age (LIA) are noted on the graphs.

Smith’s 1997 evaluation of CO2 in Greenland ice cores focused on the older portion, on stadials and interstadials of the Dansgaard-Oeschger (D-O) events during the glacial period. Results showed even higher CO2 variability than during the Holocene interglacial period. The warm interstadials increased on average by 50-90 ppm over a short period of 100 to 200 years. Detailed sampling over one 4-cm ice section showed three samples of CO2 higher than 400 ppm within a warm interstadial.

But there’s more: Greenland CO2 measurements are also lower than Antarctic CO2 values

CO2 concentration records from Greenland ice cores are generally higher than those from Antarctic ice cores for the same time interval. However, there are some data which show lower concentrations.  Anklin et. al. found values in the GRIP ice core that were too low compared with Antarctic records. Smith and others (1997) also found values that were too low in some samples from the cold stadial phases during the last glacial period.

In summary, the conclusions from published studies on CO2 concentrations of trapped air in ice bubbles from Greenland ice core data are surprisingly similar:

  1. CO2 concentrations in Greenland ice cores (GRIP, GISP2, Camp Century, Dye 3) are generally 20 ppm higher than Antarctic during the Holocene interglacial period younger than about 8000 years before present (BP). For older samples during the glacial period interstadials/stadials, CO2 is higher by over 50 ppm. An inter-hemisphere difference of 20-50 ppm is unrealistic and higher than present day.
  2. CO2 concentrations in Greenland ice cores show more variability than Antarctic ice core CO2 data. In addition to having higher CO2 values they also had lower CO2 values than the Antarctic data.
  3. BUT Greenland CO2 concentrations from ice cores agree well with each other and all show similar variances from Antarctic.

Condemnation of Greenland Ice Core CO2 Data

Group think – Jury’s out – One Verdict

The Greenland CO2 values are too high, too low, show more variability and most importantly do not agree with Antarctic CO2 data. Thus, something must be wrong with the Greenland ice core CO2 data. Scientists attempted to explain the potential surplus as well as depletion of Greenland CO2 values. Many technical articles and research in the mid to late 1990’s were based on a hypothesis that acid-carbonate chemical reactions in the Greenland ice bubbles created a surplus of CO2.

“The high degree of variability associated with Greenland CO2 measurements may be related to CO2 liberation from carbonates due to the dissolution by acid species in ice.” Anklin et. al, 1997 and other papers like Delmas, 1993, Barnola, et. al 1995; Smith et. al, 1997; Tschumi et. al, 2000.

Some doubts about this chemical reaction were raised because the carbonate content of ice is difficult to measure directly and so the carbonate content is estimated indirectly from the Ca2+ concentrations. Tschumi and Stauffer concluded, after completing a detailed lab study on Greenland cores, that the acid-carbonate reaction can explain only about 20% of the CO2 surplus and they suggested oxidation of organic compounds may also be responsible. Therefore, the theory to explain surplus CO2 evolved to become the result of a combination from two different chemical reactions. Additionally, they were unable to find any clear evidence to explain CO2 depletion in the Greenland ice cores. Smith et.al. also acknowledges it was unclear how reactants could be mobile in ice where diffusion is extremely slow assuming the reactions occurred after the air bubbles in ice are formed.

Surprisingly, the acid-carbonate hypothesis was accepted as valid despite the fact carbonate content in ice is difficult to directly measure, the CO2 surplus cannot be attributed to a specific chemical reaction mechanism, nor is there clear evidence for depletion of CO2 by a chemical reaction, and these chemical reactions occurred after bubble closure. This acceptance meant the discrepancy between Greenland and Antarctic ice core data was explained. Consequently, the CO2 data extracted from air bubbles in Greenland ice core data was deemed useless.

Re-examination of Greenland CO2 Measurements

One positive outcome of the Greenland CO2 variability denial is that several detailed, high density sampling studies were conducted. Figure 4 examines CO2 measurements from the Greenland GISP2 ice cores from two stadials around 45,000 years and 62,000 years BP by Smith, et. al. Note age and depth is on the vertical axis and Ca, electrical current, CO2 values, δ18O, and layer thickness are plotted on the horizontal axis.

Figure 4. CO2 measurements from the Greenland GISP2 ice cores from two stadials around 45,000 years and 62,000 years BP by Smith, et. al.

The stadials correspond to a thinner annual layer suggesting lower accumulation rates and more negative δ18O isotope signatures suggesting colder temperatures. The stadials contain the lowest concentrations of CO2, 200-240 ppm and lowest conductivity. Both stadials contain high amounts of Ca interpreted as related to dust accumulation (McGee, 2010).

The warm interstadials bounding the stadials also have unique characteristics. There is a sharp boundary where the stadial is terminated by a younger abrupt warming. Ca disappears quickly, δ18O isotopes rapidly become less negative, and CO2 increases by 50-100 ppm in a period of 50-100 years (Smith, 1997). The transition from the older preceding interstadial to the cooler stadial is more gradual. This is also reflected in more variable CO2 values and more variable conductivity or electrical current.

The chemical production of CO2 is speculated to occur with higher acidity in the ice core, which is measured by higher electrical conductivity, H+ (Smith et. al). In the younger stadial, conductivity is very low throughout the interval except at the shallowest portion less than 2358 meters. However, CO2 begins to increase at 2,377 meters more in-line with warmer δ18O isotope values.

An alternative hypothesis from these high-resolution data is that the CO2 concentrations, while more variable, do show a qualitative correlation with the ice core properties of thickness, electric current signatures, oxygen isotopes and calcium content for each unique layer and are not chemically altered. Both stadial and interstadials in the study show well-behaved patterns and similar characteristics.

Figure 5 shows the high sample density of Greenland GISP2 CO2 data, low sample density GRIP CO2 data, and Antarctic Byrd CO2 data in relation to Greenland temperature anomalies from oxygen isotopes. Age synchronization between Greenland and Antarctic ice cores was achieved by atmospheric CH4 by Ahn and Brook, 2008.

Figure 5. Greenland CO2 compared to Antarctic CO2.

Yet again, Greenland ice cores shows CO2 concentrations that tend to mimic Greenland temperature anomalies of stadial/interstadial cooling and warming periods. Large, rapid increases of CO2 occur during the rapid abrupt warming of interstadial events. As temperatures increase by 6 degrees C over a short period of 50-100 years shown at interstadial 12, the Greenland GISP2 CO2 values in blue also increase rapidly to from 200 ppm to 280 ppm. The Greenland GRIP CO2 shown in green was only randomly sampled over the D-O events but shows higher values in the interstadials when sampled of 280-300 ppm and lower values in the stadials of 220 ppm.

Note the Antarctic Byrd CO2 values in gray show a minimal response of slightly increasing CO2 in the long duration interstadials and show no increase in the short interstadials. In the longer interstadials 8 and 12, the Antarctic CO2 values do slightly rise by 10 ppm. In short interstadial 13, Greenland GISP2 CO2 rises rapidly to 260 ppm whereas the Antarctic CO2 values stay low at 205 ppm. Interstadial 11 shows Greenland GRIP CO2 values up to 300 ppm and again the Antarctic CO2 values remain around 205 ppm. Antarctic CO2 values do not show any response to interstadials 9, 10, 11 or 13.

During the cold stadials, Greenland CO2 is more similar to or slightly lower than Antarctic CO2 and averages around 190 to 200 ppm.

Antarctic CO2 Ignores Past Cold Events

Surplus CO2 can be produced by chemical reactions in theory and the necessary measured compounds (Ca, H+) are present in Greenland ice cores. However, Tschumi states that depleted CO2 cannot be explained by chemical reactions. Let’s examine the times when Greenland CO2 values are lower than Antarctic. When Greenland CO2 values drop below Antarctic values, the timing corresponds to well-known Greenland cold climate events like the Younger Dryas (YD) and Holocene interglacial 8.2 kyr event. Figure 6 compares Greenland GRIP and GISP2 CO2 to Antarctic Byrd CO2 data. Times when Greenland CO2 values are lower than Antarctic values are shaded in blue. Times when Greenland CO2 values are higher are shaded in pink.

It is obvious that Antarctic Byrd CO2 (gray line) shows no response to either the Y/D or 8.2 kyr cold events. Also obvious is the Greenland GISP2 and GRIP ice core CO2 data tell a different story. During the Holocene interglacial 8.2 kyr cold event, Greenland CO2 values drop from 270 to 210 within about 500 years and are 50 ppm lower than Antarctic CO2 values. Greenland CO2 values also show an abrupt rise after the 8.2 kyr event of 80 ppm within 200 years.

Figure 6. Greenland CO2 compared to Antarctic for Bolling-Allerod, Younger Dryas, and the 8.2 Kyr event.

The YD event was a cold period during the recent Holocene glacial to interglacial transition about 12,000 years ago. It was preceded by and interrupted the Bolling Allerod (B/A) interstadial. The YD event was barely recognized in Antarctic ice core temperatures, only 1 degree C colder. However, in Greenland ice cores the temperatures plummeted by minus 10 degrees for hundreds of years shown by the Greenland temperature anomaly above (Figure 6) in red.

The B/A interstadial and YD cold event demonstrate the qualitative correlation of Greenland CO2 values to Greenland temperature fluctuations. Greenland CO2 responds to the warmer B/A interstadial with an intermittent rise that is 20-30 ppm higher than the gradual Antarctic CO2 increase. Greenland CO2 peaks at 290 ppm and then decreases to 235 ppm during the cold YD. Contrarily, the muted Antarctic CO2 data shows a gradual rise from 250 to 270 ppm ignoring both the B/A and YD and simply responds to the gradual Holocene deglaciation. This is not surprising because Antarctic ice core temperatures derived from δ18O isotopes also show no, to only minor, temperature fluctuations during these events (not shown).

Past literature studies on Greenland Younger Dryas and the 8.2 kyr event used only Antarctic CO2 data resulting in the following observations:

  • Ahn and Brook, 2013 observed small 1-2 ppm increases of Antarctic CO2 and imply that the sensitivity of atmosphere CO2 to the Northern hemisphere cooling of the 8.2 kyr event was limited. Conversely, Greenland CO2 data shows a dramatic 80 ppm reduction within 200 years during this cold event.  
  • Lui et. al. 2012, concludes that Greenland climate during the cold YD should be substantially warmer because the increase seen in Antarctic atmospheric CO2 should be associated with an increase in surface temperature especially at high latitudes. Raynaud et. al. 2000 states that the long-term glacial Holocene increase in CO2 was not interrupted during the YD. Raynaud was surprised by this result. Marchal et. al, 1998 states that CO2 records from the Antarctic ice core shows that CO2 remained constant during the Younger Dryas cold climate event. He states this suggests the North Atlantic ocean has a minor influence on CO2.  
  • Kohler, et. al, studied the B/A using CO2 data from the Antarctic Dome C ice core which shows a CO2 increase of about 10 ppm. Their models showed that atmospheric CO2 should have increased by 20-35 ppm which is a factor of 2-3.5 greater than the CO2 data showed. As a matter of fact, Greenland CO2 does exactly that during the B/A by increasing 20-30 ppm perhaps suggesting the data is not chemically altered.

Alternative Hypotheses for Greenland Ice Core CO2 “Bad” Behavior

What if Greenland ice core CO2 data is not chemically altered and is just as accurate as the Antarctic ice core CO2 data? The Greenland ice core isotopes do express more variable CO2 fluctuations than Antarctic ice cores, but the variability appears to be synchronous with Greenland’s larger rapid temperature variations. And all the Greenland ice core CO2 data generally agrees with each other.

Seasonal bias may exist in the Greenland ice cores.

Greenland ice cores may preferentially record more northern winter CO2 readings than summer CO2 variability. Seasonality with preferential preserved winter readings can easily explain the 18-20 ppm differences observed during the recent Holocene Medieval Warm period. Recent atmospheric CO2 measurements between NH and SH observatories show up to 15 ppm differences for 6-7 months during the northern winter dormant season and 60% of the year. During the other 40% of the year, NH CO2 is transitional either increasing or decreasing due to vegetation photosynthesis or respiration and is highly variable.

Greenland CO2 Variability is Synchronous with Greenland Temperatures.
CO2 values from Greenland GISP2 and GRIP ice cores qualitatively correlate with their δ18O isotopes temperature proxies as shown in the figures above. Dye 3 and Camp Century CO2 data not presented here shows similar responses to Greenland temperatures (Anklin et. al and Neftel et. al.). This is obvious during Greenland abrupt climate changes such as the D-O events, even in short interstadials, and during the B/A. Greenland CO2 also decreases corresponding to Greenland cold events such as the YD and 8.2 kyr.

During abrupt climatic events, Greenland and Antarctica CO2 values can diverge significantly during warm interstadials with Greenland CO2 values being much higher by 75+ ppm. The interstadial warm patterns in Greenland ice cores are also amplified from Antarctic in many aspects such as temperature, dust content, methane excursions, and possibly CO2. During the Holocene 8.2 kyr event which was an abrupt cooling event, Greenland CO2 values plummeted 50+ ppm while Antarctic CO2 measurements did not recognize this event.

Greenland Ice Cores have High Gas Resolution due to High Accumulation Rates.

There are significant gas resolution differences between Antarctic and Greenland due to differences in surface temperature and snow accumulation rates. This is discussed by Ahn and Brooks, 2012 and by Middleton, 2017, 2019. Gas age samples can be younger by hundreds and up to a thousand years due to diffusion in Antarctic ice cores which have accumulation rates as low as 3 mm/yr. In Greenland where accumulations rates are much higher, gas age samples have a resolution as high as tens of years up to hundreds of years.

Middleton discusses CO2 gas sample resolutions and gas age distributions for Antarctic ice cores due to gas diffusion before bubble close off. He shows the impact of smoothing filters to match the resolution differences. Instrumental annual CO2 data should be averaged over 100+ years to compare to past Holocene Antarctic ice core CO2 values. Of course, observatories have only recorded 40 to 60 years of CO2 data. For example, Mauna Loa CO2 annual mean averaged over 60 years of data is 354 ppm compared to the reported global annual mean of 407 ppm for 2018.

CO2 Increases in Greenland Ice Cores like Methane.
It is well documented that rapid increases in methane, CH4, concentrations are synchronous with past warming events in Greenland and are more extreme than in Antarctic ice cores. Antarctic and Greenland ice core methane records both a rise during warm interstadials and a fall during stadials but with different concentrations (Blunier and Brook). They suggest significant methane increases in Greenland during past warm periods are related to increased swamp and organic releases during melting periods. During warm periods, greening of the Arctic occurs when exposed terrestrial real estate expands significantly. Photosynthesis and respiratory processes should also be in full force. If swamp and terrestrial vegetation are becoming more exposed and prolific during past warming and “greening” of the Arctic, then past CO2 should also show larger northern latitude increases like methane does.

Greenland CO2 Data Could be a Climate Game Changer

While it is possible some of the Greenland CO2 data could be contaminated, the assumption that ALL the CO2 data is chemically altered in ALL the Greenland ice cores does not explain why CO2 is so well behaved with Greenland temperatures or address the observations discussed above. It is also plausible the Greenland ice core CO2 data has more detailed resolution and higher frequency than the subdued Antarctic ice core CO2 record.

Figure 7 compares Greenland and Antarctic CO2 data over the past 50,000 years. CO2 signals preserved in the Antarctic and Greenland ice cores are significantly different. Greenland CO2 fluctuations appear synchronized with active Greenland temperature changes just as Antarctic CO2 data mimics more subdued Antarctic temperatures (not shown). Note the large data gap in digital Greenland CO2 measurements during most of the Holocene interglacial period.

Figure 7. Greenland versus Antarctica for the past 50,000 years.

The Greenland CO2 responses appear to reflect short-term centennial fluctuations whereas the Antarctic CO2 fluctuations appear to be responding to longer term millennial changes. These differences may be the result of enhanced terrestrial carbon influences in combination with oceanic releases in the Northern Hemisphere whereas the Antarctic low amplitude CO2 responses are dominated by global and Southern oceanic processes. Or simply that Antarctic ice core record has insufficient data resolution.

If the Greenland CO2 data is correct, or even qualitatively correct at best, then it needs to be re-examined and incorporated into polar interhemispheric greenhouse gas /glacial/oceanic interactions and interpretations to establish natural past atmospheric CO2 variability. Rapidly increasing CO2 values measured during this Modern Warming may not be unprecedented compared with past natural fluctuations after all.

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

References Cited
(Note – It is very frustrating to find an interesting reference that is paywalled. Many key references are from papers 25+ years old that are still paywalled).


Ahn J, and J. Brook, Atmospheric CO2 and Climate on Millennial Time Scales During the Last Glacial Period, Science 03, Vol. 322, Issue 5898, pp. 83-85, 2008. Link.

Ahn J, and J. Brook, Atmospheric CO2 over the last 1000 years: A high-resolution record from the West Antarctic Ice Sheet (WAIS) Divide ice core, Global Biogeochemical Cycles/Volume 26, issue 2, 2012. Link.

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. Link.

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. Link.

Anklin, M., J. Schwander, B. Stauffer, J. Tschumi, A. Fuchs, J.M. Bamola, and D. Raynaud, CO2 record between 40 and 8 kyr B.P. from the Greenland ice core project ice core, J Geophys. Res., 102 (CI2), 26539-26546, 1997. Link.

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. Link.

Barlow, J. M., Palmer, P. I., Bruhwiler, L. M., and Tans, P.: Analysis of CO2 mole fraction data: first evidence of large-scale changes in CO2 uptake at high northern latitudes, Atmos. Chem. Phys., 15, 13739-13758, 2015. Link.

Blunier, T and E. Brook, Timing of Millennial-Scale Climate Change in Antarctica and Greenland During the Last Glacial Period, Science, Vol. 291, Issue 5501, pp. 109-112, 2001. Link.

Delmas, R.A., A natural artefact in Greenland ice-core CO2 measurements, Tellus, 45B, 391-396, 1993. Link.

Dettinger, M., and M. Ghil, Seasonal and interannual variations of atmospheric CO2 and climate, Tellus B, 1998. Link.

Francey, R. J., Frederiksen, J. S., Steele, L. P., and Langenfelds, R. L.: Variability in a four-network composite of atmospheric CO2 differences between three primary baseline sites, Atmos. Chem. Phys., 19, 14741–14754, 2019. Link.

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

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134 thoughts on “Greenland Ice Core CO2 Concentrations Deserve Reconsideration

  1. One issue is CO2 concentrations at the surface in or downwind from an area with active or intermittently active biomass. That can deviate from overall atmospheric CO2 concentration, and do so largely unidirectionally. During a typical day in such areas, photosynthesis is making such an area a net sink of CO2 during the daytime while animals, fungi and bacteria are making such an area a net source of CO2 during the night. And during daytime, sunlight is heating the surface so convection stirs up the lowest kilometer or two of the atmosphere but during nighttime the surface air stays near the surface and CO2 accumulates. So, surface CO2 averaged during the day exceeds the overall atmospheric CO2, even in that part of the world. This effect showed up well in a study conducted at the Wisconsin Tower, with surface CO2 spiking at night much less than CO2 at the top did, daytime CO2 at the surface being more similar to CO2 at the top, and nighttime surface CO2 not spiking in the winter.

    Local or regional effects of biomass can cause surface CO2 to deviate from overall atmospheric CO2, with a strong unidirectional component of upwards when things are warm enough for the biomass to have an effect, and this does not happen when everything is frozen for hundreds of miles upwind. I suspect this has something to do with Greenland getting surface CO2 deviations upward from CO2 at Antarctica during warm periods, due to parts of Greenland that are green.

    • Excerpted from article:

      Currently, the annual mean CO2 concentration is about 5-6 ppm higher in the NH than the SH.

      Figures don’t lie, … but liars figure.

      Of course the “annual mean CO2 concentration” is higher for the NH, simply because they include the Barrow, Alaska CO2 ppm measurements in with the Mauna Loa measurements for calculating the NH annual mean average.

      Antarctica CO2 ppm measurements, which are extremely lower than the Barrow measurements, are added in with the Mauna Loa measurements for calculating the SH annual mean average which accounts for the aforesaid …… “about 5-6 ppm higher in the NH than the SH”.

      To wit : Barrow Alaska monthly mean CO2 ppm profile – annual bi-yearly cycle

      De-seasonalized trends also show that SH CO2 lags the NH CO2 by about 2 years. For example, the annual CO2 reading at Barrow, Alaska broke 400 ppm in May 2014 whereas the annual South Pole hit 400 ppm May 2016. However, note the 1st monthly average at Barrow hit 400 ppm in April 2012 which is four years earlier than the South Pole.

      It is devious, dishonest, disingenuous and utterly asinine to include Barrow, Alaska CO2 ppm measurements in with either the Mauna Loa, Hawaii or the Antarctica measurements …. simply because the Barrow observatory is located on the coast of the Arctic Ocean about 8 kl from Barrow at 71°19′ N, 156°36′ W, …… at 11 m (35 feet) above Mean Sea Level. (DUH, Mauna Loa is located at 11,000 feet above MSL)

      • Samuel,
        Barrow is not included in with Mauna Loa, it is a separate observatory. The NH and SH inter-hemispheric gradients are calculated using detrended data from all stations, not just Mauna Loa. Mauna Loa is closer to the tropics and has a trend in the middle. Below is an article that discusses the calculation of inter-hemispheric gradients. https://www.tandfonline.com/doi/full/10.3402/tellusb.v65i0.20334?scroll=top&needAccess=true

        Additionally, seasonal signatures vary by latitude where northern observatories have higher seasonal amplitudes and southern observatories have lower seasonal amplitudes. Mauna Loa Observatory has a seasonal amplitude in between.

        Barrow was used because it has the longest CO2 record closest to Greenland where the ice cores were taken and SPO is closest to Antarctic ice cores. Key point is NH CO2 rises faster and has higher amplitudes. See link for detrended data and seasonal trends.
        https://imgur.com/a/chIFwon

        • Renee – January 8, 2020 at 6:49 am

          Renee,

          Please study the three (3) different graphs noted below, …. and take note of the fact that the “annual cycles” are all the same, …… yet their CO2 amplitudes vary based on the altitude the samples are taken, ….. the average seasonal temperatures of said locations …….and their distances from the equator.

          Graph of Annual CO2 cycle at the South Pole (Antarctica) Amundsen-Scott – Elevation: 9,301ft
          https://tamino.files.wordpress.com/2012/06/spo4.jpg

          Graph of Annual CO2 cycle at the Mauna Loa Observatory, Hawaii – Elevation: 11,141 ft
          https://d1o50x50snmhul.cloudfront.net/wp-content/uploads/2007/05/dn11638-2_640.jpg

          Graph of Annual CO2 cycle at the Barrow Alaska CO2 monitoring station – Elevation: 35 ft
          https://plot.ly/~vball3ams/174/monthly-mean-co2-concentration-ppm-point-barrow-alaska.png

          Renee, why don’t you take some “CO2 samples” ….. at 11,141 ft elevation above Barrow Alaska, …. and see what ya get.

          • Samuel,
            I’m am aware of the elevation differences and have evaluated the CO2 values corrected to the Marine Boundary Layer (MBL). The red line in the link below is the correction for Barrow and SPO. SPO shows a 1.5 ppm amplitude swing and Barrow shows a 15 ppm average swing after correction. Latitude is the driver.
            https://imgur.com/a/6OleYel

          • Renee – January 8, 2020 at 2:10 pm

            SPO shows a 1.5 ppm amplitude swing and Barrow shows a 15 ppm average swing after correction. Latitude is the driver.

            Renee,

            Didn’t you mean to say …… “North latitude ONLY is the driver ”?

            Because, to wit:
            Barrow, Alaska latitude: 71°19′ N, 156°36′ W
            Amundsen-Scott -South Pole latitude: -90° 00′ 0.00″ S

            “DUH”, ….. Amundsen-Scott, South Pole, is 19° greater latitude than Barrow, Alaska, …. yet its atmospheric CO2 ppm is less than Mauna Loa CO2.

            Ya get too much “noise” taking samples that close to the surface in Barrow.

          • Ferdinand Engelbeen – January 9, 2020 at 9:16 am

            Samuel, there is hardly any difference in CO2 levels between Mauna Loa at 3,400 meter and Cape Kumukahi also on Hawaii at 7 meter height …..

            Ferdinand, there ya go again, talking “trash” at me.

            Hawaii is tropically warm, high humidity and massive amounts of “green growing” biomass sucking up CO2 from the near-surface atmosphere.

            And along with the massive amounts of “green growing” biomass you also have massive amounts of dead, rotting and decomposing biomass that is outgassing copious amounts of CO2 into the near-surface atmosphere ……. plus all the anthropogenically generated CO2.

            Plus the fact that, to wit: “ Located on the Big Island, twenty-five miles southeast of Hilo, is Cape Kumukahi, the easternmost point of the Hawaiian Islands” …. with constantly changing humidity (H2O vapor ppm) …… and thus constantly changing CO2 ppm.

          • Samuel, CO2 levels are always measured in bone dry air, after a cold freezing trap at -70°C, plays no role at all. Both Kumukahi and Mauna Loa in general receive air from the trade winds which blow East to West, thus they measure CO2 in uncontaminated air passing thousands of km over the oceans.
            Only in the afternoon it happens that Mauna Loa receives air from the valleys if there are upwind conditions and when that is noticed, the values are marked and not used for daily to yearly averages.

          • Ferdie,

            Then why doesn’t the government shut down the Mauna Loa Observatory, the South Pole Observatory, the Cape Kumukahi Hawaii Observatory and the Barrow Alaska Observatory to save scads of money….. and do their atmospheric CO2 measurements at an Observatory on the UCLA or Harvard University Campus? Or better yet, at the National Weather Service headquarters in Silver Spring, MD.

      • I looked at the Barrow CO2 graph linked by Samuel C Cogar . It appears that there is a seasonal CO2 sink in that area in the summer. I suspect the nearby part of the Arctic Ocean which is frozen over most of the time other than summer, but in the summer it is liquid but colder than most of the world’s sea surface so it is sucking CO2 out of the lowest part of the troposphere in that area. I have seen imagery from the OCO2 satellite showing CO2 being less than the overall atmospheric average in cold ocean areas where and when there is cold liquid water.

        • Donald L. Klipstein – January 9, 2020 at 10:43 am

          I looked at the Barrow CO2 graph It appears that there is a seasonal CO2 sink in that area in the summer. I suspect the nearby part of the Arctic Ocean which is frozen over most of the time other than summer, but in the summer it is liquid but colder than most of the world’s sea surface so it is sucking CO2 out of the lowest part of the troposphere in that area.

          Thank you, Donald, …… that is exactly what I believe also …… because that is what the “science” tells me.

          And the science tells me that the same “b>seasonal CO2 sink” that is associated with the ocean water in the Southern Hemisphere is the “driver” of the bi-yearly seasonal cycling of atmospheric CO2 as measured at the Mauna Loa Observatory (Keeling Curve Graph).

          The summertime cold of the Arctic Ocean is ingassing CO2 ….. at the same time as the wintertime cold of the Southern Hemisphere ocean water is ingassing CO2, ….. which causes an average 6 ppm decrease in atmospheric CO2.

  2. AAANNNNDDD:

    Why does it matter?

    The atmosphere cools the earth and BB upwelling LWIR is not possible.

    Those two statements trash the greenhouse effect.

    It’s that simple.

    It’s all science.

    • Such simplicity is not tolerated. Proper debate requires convoluted, self-contradictory, obscure statements, backed by underlying hypocrisy, ulterior motivations, and mastery of misdirection. If you cannot manage, at least, a modicum of that, then your thoughts are not worthy of attention.

      And if you really want to put some people on edge, then question all ice core data — that’s always fun.

      • Ah Ockham’s hammer – whichever explanation requires excessive convolution and complexity is likely to be politically advantageous and acceptable

      • robert,
        This scientist has questioned all the ice core data and he has the experience and credentials to do so.

        Dr Zbigniew Jaworowski’s criticism’s of the assumed reliability of IPCC graphics merging pre-industrial CO2 data from ice cores with atmospheric measurements from 20C
        http://www.mitosyfraudes.org/Calen5/JawoCO2-Eng.html

        “The basis of most of the IPCC conclusions on anthropogenic causes and on projections of climatic change is the assumption of low level of CO2 in the pre-industrial atmosphere. This assumption, based on glaciological studies, is false”
        …Determinations of CO2 in polar ice cores are commonly used for estimations of the pre-industrial CO2 atmospheric levels. Perusal of these determinations convinced me that glaciological studies are not able to provide a reliable reconstruction of CO2 concentrations in the ancient atmosphere. This is because the ice cores do not fulfill the essential closed system criteria…
        http://bit.ly/2GpdJxl

          • Yes, FE, so the story goes.

            I’ve read Jaworowski’s supposedly “completely wrong” ideas, and I’ve read Etheridge’s defense of ice-core science.

            In 2010, I did my own dive into this subject:

            https://hubpages.com/education/ICE-Core-CO2-Records-Ancient-Atmospheres-Or-Geophysical-Artifacts

            Honestly, I’m not 100% convinced either way, but I really want ice-core science to be the bastion of reliability that most people say, because I often still use its results as the basis for making certain important points.

          • Robert, the credibility of the late Dr. Jaworowski ended for me when he proposed that CO2 migrates from low levels inside the bubbles to (much) higher levels outside as the outside levels were much higher during relaxation and transport than when when the bubbles were formed…
            I have somewhere a direct mail from him that this was because melting surfaces isolate the lower layers from the atmosphere, but Neftel found just one such layer in the Siple core and calculated the average gas age based on that finding.

        • Ice core measurements for determining paleo-atmospheric CO2 ppm quantities are considered 100% accurate. RAH RAH RAH

          And how do we know that?

          Well, because the “experts” have told us that based on the following, to wit:

          it was understood in the 1960s that analyzing the air trapped in ice cores would provide useful information on the paleoatmosphere, but it was not until the late 1970s that a reliable extraction method was developed. Early results included a demonstration that the CO2 concentration was 30% less at the last glacial maximum than just before the start of the industrial age.
          https://en.wikipedia.org/wiki/Ice_core

          Shur nuff, …… makes sense to me.

          They knew for a fact that atmospheric CO2 was at 315.71 ppm in 1958, and via their “fuzzy” math they calculated that the global average atmospheric CO2 musta been about 280 ppm before the Industrial Revolution started in the mid-1700s.

          And iffen the pre-Industrial Revolution CO2 was estimated at 280 ppm, ….. then the Ice Core measurements of past CO2 ppm definitely proves that the global average atmospheric CO2 was 30% less at the last glacial maximum (22ky BP).

          Now that’s the kind of science everyone should believe in.

    • ON AVERAGE
      (This applies to all that follows. It’s simplistic, misleading and maybe just the wrong way to do it.)

      ISR of 1,368 W/m^2 arrives from the sun, plane parallel, a perspective that renders the earth a flat disc.
      (Solar luminosity divided by spherical area at orbital distance.)

      The 30% albedo leaves a net 957.6 W/m^2 ASR for the terrestrial surface.

      The spherical terrestrial surface rotating beneath the hemispherical solar heat lamp moderates, circulates and spreads that heat throughout. Now convert the discular area to a spherical area by dividing by 4 or 239.4 W/m^2 ASR.

      To maintain the thermal balance 239.4 W/m^2 must leave the spherical ToA. There are no molecules at ToA so the only way that energy can leave is by radiation, OLR.

      The S-B equilibrium temperature for 240 W/m^2 is 255 K. (Look familiar? It’s only WITH the 30% albedo.)

      Remove the atmosphere or the GHGs and the 30% albedo collapses, no clouds, no water vapor, no ice or snow, no vegetation, no oceans. As UCLA Diviner suggests, without an atmosphere the earth would be much like the moon with a 0.11 albedo.

      0.89 * 1,368/4 = 304.4 W/m^2 & 270.7 K.

      That’s 15.7 C warmer than 255 K.

      • ‘ISR of 1,368 W/m^2 arrives from the sun…’.
        If ever there was an initial assumption which was completely bogus, then that must be the best one I’ve seen.
        The sun is a star. It forms most of the mass in the galaxy. After gazing at it, worshiping it, and generally basking in it’s light and heat, we still know relatively little about how it works.
        We don’t know all that much about the energies it blasts out or about how our little planet’s magnetosphere works in it’s interactions with whatever the star throws at us.
        Quite apart from that, it is moving through the outer edge of our galaxy and our solar system is revolving around it and moving with it. Our little planet revolves around it, wobbling on it’s axis, tilting it’s faces towards it and yet we have pinned it down to 1,368 W/m^2. About the size of my garden table. On average!
        Aye, right!
        I think it’s probably a tad more complicated than that.
        What bothers me in my dotage, is the hubris of a species that believes that it can somehow stop the march of time and conserve our planet in some ‘Garden of Eden’ state. Whatever that state is conceived to be.
        At any time, a large rock, floating about in space, could put an end to us just as one of them did to 99% of all other species. Allegedly.
        So if you really want to argue with a climate catastrophe imbecile, don’t rise to the bait and argue over facts and figures. Just give them more super glue.

  3. Land based biological activity is not causing the large seasonal variations in the Arctic. The freezing and thawing of sea ice is the cause. The cold open waters of the Arctic are the big sink for CO2. A plot of sea ice concentration with time looks like their Figure 1 both in shape and timing. In contrast, the Antarctic is mostly covered with snow and ice all year and frozen water is not a sink. The sink in the SH is the cold water around the ice and snow. Freezing and thawing of that water does not cover over the sink, only shifts it somewhat to the North.

    Land based biological activity is both a source and a sink for CO2 and methane. In a mature forest, these processes tend to balance. in contrast, biological activity such phytoplankton blooms in sea water, when the sun comes up, enhances the absorbtion of CO2.

    • Fred, land based biological activity is causing most of the seasonal variability, as the total amount of CO2 drops in spring and increases in fall, opposite to temperature, thus opposite to the solubility of CO2 in seawater. That also can be seen in the opposite 13C/12C ratio change:
      http://www.ferdinand-engelbeen.be/klimaat/klim_img/seasonal_CO2_d13C_MLO_BRW.jpg
      Based on isotopes and oxygen use-release for vegetation and the solubility of CO2 in seawater with temperature, the quantities involved are about 50 GtC in and out the oceans and 60 GtC in and out vegetation over the seasons. Opposite to each other, resulting in a global 10 GtC or about 5 ppmv seasonal amplitude.

      • The temperature of the Arctic water does not change that much seasonally. The open Arctic water is always a sink. However, the amount of open water is changing greatly as the water freezes and thaws seasonally. As for the isotope ratios, the cyclical evaporation/condensation of water changes the ratios of oxygen, hydrogen, and CO2. This fractionation process occurs as water and CO2 are being transported to the Arctic. In the case of CO2, the two isotopes have slightly different vapor pressures as a function of temperature. Each cycle of evaporation from the sea surface (which releases CO2) and condensation in thunder clouds (which absorbs CO2 and returns it to the surface) slightly increases the concentration of the lighter isotope. Thus, the lighter isotope concentration increases with latitude.

        I have analyzed these data and have quantified the effects and now am in the process of writing it up on my wordpress website.

        • Fred, the main winter/summer amplitude is from the mid-latitudes where the largest temperature changes are and the largest changes in leaf volume. Isotopic changes are much larger from photosynthesis than from evaporation/uptake…

          • I’ve checked that and the greastest amplitude is above the Arctic circle and the effect of fractionation is almost directly proportional to latitude up to about 45 degrees Above 45 degrees there seems to be little additional fractionation. Above that latitude there are few thunder storms to cycle absorbtion/extraction.

          • Ferdinand,
            ”the main winter/summer amplitude is from the mid-latitudes where the largest temperature changes are and the largest changes in leaf volume”

            Are you sure about this? All the CO2 data I’ve seen shows the larger winter/summer amplitude in the Northern Hemisphere, middle amplitude in the mid-latitudes and lowest in the SH.
            Data shown here https://imgur.com/a/uuNNzrR

          • The problem with the seasonal amplitude is that there are no base stations downwind of the main forested areas, e.g. mid-latitude La Jolla takes mostly air from the Pacific Ocean, which is already mixed with the bulk of the atmosphere.
            There are some data from Southern Germany at Garmisch-Partenkirchen and other places which show at least the same seasonal amplitude as at Barrow:
            https://cdiac.ess-dive.lbl.gov/trends/co2/fra-gp.html

      • Engelbeen
        January 7, 2020 at 9:19 am

        I have it a bit hard to understand, let alone accept what is claimed in your comment as with a proper merit there.

        You see, SH is mostly all ocean, and still the same pattern there as with the NH.
        Which technically brinks us back to the problem of the proper luck of validation for such as claims, where the SH data fails and refuses to validate the claim based solely in NH data.

        Same as in the case of the Green Land data set failing and refusing to validate the Antarctica CO2 data set in the context of the long term climate.

        Oh well, I maybe misunderstand some thing important there, so will much appreciate any clarification you may offer further, especially in the consideration of so little land there in the SH, but still the same pattern in CO2 emission.
        Where actually, the man-made CO2 emissions seem to not being so heavily relied upon in your claim above.

        So, with all this vegetation and human “power” in NH, no any meaningful or considerable divergence actually there between NH and SH!!!

        Well, WUWT?

        cheers

        • Whiten,
          That is an excellent point. Remember we only have 40-60 years of instrumental data for CO2 and it’s only during a time of increasing temperatures and increasing CO2. The amplitude of the Northern Hemisphere annual response is increasing by 0.09 ppm/year with increasing CO2, which is fairly large. The swings in seasonal CO2 in the north have increased by 4 ppm since 1975. Also, the inter-hemisphere gradient between the north and south has risen from 1-2 ppm difference to 4-5 ppm. Remember we are comparing 40-60 years of instrumental data to ice core events that lasted hundreds and thousands of years.

          • Engelbeen
            January 8, 2020 at 12:39 am

            and

            Renee
            January 7, 2020 at 3:53 pm
            ——————————–

            Thank you both for your replies to my comment, appreciated.

            First thing I would like to point out to both of you, as per merit of your replies:
            “seasonal amplitude” or “seasonal CO2”.

            You see, relying in the proposition of “seasonal”, a periodic repetition,
            without considering the possibility of any effect or impact in such as,
            to be as with no any cumulative significance at all over time,
            especially when the very yearly cycles that such periods belong to,
            do not conform or hold any considerable effect or a signature of such as in any longer time periods, is quite telling.

            A seasonal variation, is just that, seasonal.

            And as both you may agree, it stands as obviously in that discrepancy between both hemispheres, simply due to the considerable land-ocean
            surface discrepancy between the both hemispheres.

            While it is understandable and acceptable to a given degree in considering ppms ( in terms of concentration) rather than in terms of CO2 emissions, while addressing such a variability condition,
            still this not quite proper and still an extrapolation…
            even while quite considerably helping and easing the point made but only up to some point.

            That seasonal variation and its amplitude have no any cumulative effect over time, either in the base yearly emissions (global or otherwise)
            or the concentration trend.

            Engelbeen.

            I am really sorry and do not like much to tell you again that you really get this things backwards.

            “If the oceans were the main cause, it would be reverse.”

            This statement of yours is a complete backwards.

            It is exactly that seasonal variation, and the discrepancy between both hemispheres in that account that actually stands as evidence of the oceans being the main cause for not saying the only one there for the CO2 global emission variation.

            You can not deny that the main base discrepancy between NH and SH is the ratio of the land area versus ocean surface.

            You see, you can not deny also, that the land area is quite “barren” and very insignificant for not saying void in the consideration of thermal emissions when compared to the oceans.
            Meaning that the NH will have a wider or more intense seasonal oceanic thermal emission variation than the SH.
            Less ocean surface more intense ocean thermal seasonal emission variation, when considering that it has to feed the same size atmosphere during the seasonal change.
            Which actually is firmly supported by the associated matching CO2 seasonal emission variation signature there… as it must.
            Meaning that there is no need what so ever in going “full climate heretic”
            by blaming biosphere for such as CO2 seasonal emission variation.

            And also when considering that the Renee’s statement:

            “Also, the inter-hemisphere gradient between the north and south has risen from 1-2 ppm difference to 4-5 ppm.”

            Holds some valid meaning, then not only the observed seasonal variation of CO2 shows that the oceans do almost all global CO2 emission, but also the climate is in a firm propagation of a cooling trend, regardless of some period of temperature increase.

            In a warming world that gradient will not increase, but in consideration of a cooling one it very much expected to do so.

            This quite a long reply, comment,
            so you guys got to do with what and how the points I tried to put forward as given.

            Open to any critique or correction, though… 🙂

            Thanks again, to both of you.

            cheers

          • Whiten,

            Sorry, but you have it backwards: land is heating much faster than ocean surface, and the amounts of CO2 captured by growing leaves in spring are far larger in the NH than what is released by the oceans. That can be seen in:
            1. The drop of CO2 levels in spring, both in the NH and smaller in the SH, as there is less land and more ocean.>
            2. The rise in 13C/12C ratio in spring, as new leaves preferentially use 12CO2, thus leaving relative more 13CO2 behind. With more CO2 release from the oceans, the 13C/12C ratio would drop, not rise.
            3. The increase in O2 in the atmosphere. New leaves produce O2 when they absorb CO2. That is much more than from the small release of O2 from warming oceans.
            Thus all evidence shows than vegetation is the main driver of the seasonal amplitude.

            For the long term changes, the seasonal amplitude is of no interest, but the mass balance and the oxygen balance show that since about 1990 there is more uptake of CO2 by the whole biosphere than release: the earth is greening.

        • Whiten,
          I think I understand your thoughts. I mostly agree with them. Seasonality CO2 is a short term cycle driven by terrestrial vegetation particularly in the North latitudes. However, the underlying longer term CO2 trend increase is due to the slower response or pulse of the ocean, although some scientists (oops 97%) believe it’s driven by human emissions.

          In my opinion, we see similar climatic CO2 patterns over the past 50,000 years. The Antarctic ice cores show the underlying oceanic influenced CO2 pulses. Whereas the Greenland CO2 rapid fluctuations suggest a combination of oceanic/terrestrial releases and intake. Perhaps in response to global oceanic changes.

          So the question becomes……what is driving the oceanic trends? In the past and now.

          • Ferdinand Engelbeen
            January 9, 2020 at 9:53 am
            —————————–

            Thank you for your consideration Ferd.
            Let me reply to your comment by addressing it backwards. 🙂

            Your statement:
            “For the long term changes, the seasonal amplitude is of no interest…”

            In consideration of the context and subject of this blog post, the seasonal amplitude supposes to be of some significant consideration, or at least that what I thought your main point was!
            Even Renee thinks that due to some rapid fluctuation effect there, that could be a significant point.

            Glad to be clarified that actually this did not happen to be the point you were trying a make, or what you were suggesting…
            but still confused here, as to what happened to be the original point or suggestion you actually trying a make then there?!!!
            As the main problem between Greenland CO2 and Antarctic CO2 stands in the consideration of long term (trend) like as long as 10k years long.

            But anyway, let see what you state next, still in the backwards addressing approach:
            “Thus all evidence shows than vegetation is the main driver of the seasonal amplitude.”

            And the vegetation activity in question, itself is mainly driven by the seasonal thermal variation, the seasons.
            Seasons are a result of a periodic thermal variation, and not driven by vegetation, and also there happens to be a gradient between the NH and SH there in consideration of seasonal thermal variation.
            So much so that in the case of the significant cooling period of LIA, it creates an argument of whether LIA was or not to be considered as a global event, where technically that gradient was increased during that period, a cooling one, not warming.

            You see, you by your own argument, by considering the initial base to be the seasonal temp variation, aka the thermal seasonal variation, still have that seasonal CO2 amplitude connected basically to the thermal amplitude and properly matching it as per the means of discrepancy and the gradient in between the hemispheres there,
            while in the same time you lack the luxury of any evidence as such in consideration of the vegetation or leafs there showing the same responding amplitude match,
            as it actually happens to depend considerably in other regional factors too.

            The vegetation and leafs do not drive the seasons.
            What drives the seasons mainly drives both, the vegetation and the seasonal CO2 emissions… where in the consideration of CO2 the connection seems more direct and more responsive to the seasonal thermal variation and its amplitude than the leafs and vegetation to the amplitude of thermal seasonal variation and the hemispheres gradient in consideration.

            No much need there for a “fake bridge” to connect CO2 variation to thermal variation. No need to go “full climate heretic”.
            A synchronicity (like between vegetation seasonal variation and the CO2 one) or a correlation in nature does not necessarily mean any direct connection or causality or dependence.

            Also you say:
            ” land is heating much faster than ocean surface,”

            In consideration of seasons, and seasonal variation, land also cools much faster, and also land has a very small thermal emission signature
            when compared to the oceanic one, for not saying completely insignificant.

            Oh well, at least I got to accept, as per the way of this reply to your comment, that I stand as a in backwards approach… 🙂

            Thank you Engelbeen.

            cheers

          • Renee
            January 8, 2020 at 4:17 pm
            ————-

            Thank you for the reply.

            As far as for the first part of your reply, any further clarification for some or any disagreement in opinion or otherwise there,
            I think you may find it at my last reply to Ferdinand Engelbeen…
            hopefully. 🙂

            In consideration of the second part,
            “the Greenland CO2 rapid fluctuations suggest a combination of oceanic/terrestrial releases and intake.”

            In my opinion, or my understanding, outside the consideration of a significant very erratic pollution, as some scientists suggest or claim,
            it may also suggest and even probably point out to a probable strong regional factor which in long term may not be erratic, but still considerably different in pattern than in Antarctic.
            One that I can think of could be the precipitations as per the pattern.
            A potential regional factor.

            Having and getting that one factor wrong, it means that there is a chance of these to ice core data, when processed, may not agree and even contradict each other significantly in the result.

            Further more, when considering that a seasonal CO2 variation does not influence or effect the CO2 atmospheric concentration in long term, and therefor considering same should hold in principle with the CO2 ice “concentration”, still in the consideration of a probable regional potential factor like precipitation, the influence and effect in the whole could be even more significant for a divergence in the ice core data.

            Anyway, just another thought. 🙂

            As for the question… “what is driving the oceanic trends? In the past and now.”

            The only answer I could offer from my position in that, with certainty from my point of view and perhaps my understanding, will be some thing like:

            Nether the RF or the famous milankovitch cycles,
            and definitely neither the man-made CO2 emissions or the Sun.
            Am sorry if this kind of answer may upset some there, but that the best I could forward as an answer, under the circumstances… 🙂

            Thanks again Renee.

            cheers

  4. As I am travelling now, I don´t have all my files here, thus can´t respond in detail, but her my first comment:

    That chemical reactions are involved in Greenland ice was made clear in the first methods used to measure CO2 in ice cores: melting the ice and extracting all air from the solution under vacuum. When they did that with Greenland ice, the CO2 level increased with the duration of the extraction: the chemical reactions simply did go on. Melting still works fine for CH4.
    One of the reasons is the volcanic eruptions from nearby Iceland, which throw up deep core highly acidic ashes.

    Second point is that Greenland is surrounded by land, Antarctica by oceans. It is known from many measurements in the past that CO2 levels over land are far more variable, depending of vegetation growth and wane in the main wind direction. Thus important changes in wind direction during colder (Little Ice Age in Europe) or warmer periods can give important local/regional CO2 changes.

    Third point is that current differences between Barrow and the South Pole are a few ppmv averaged over a year and despite the rapid increase of CO2, the South Pole has the same CO2 level only a few years later.
    Further, even for high resolution (less than 10 years), high accumulation (1.2 m/yr ice equivalent) ice cores like Law Dome, the seasonal variations are completely wiped out. Seams impossible to me that only winter season CO2 was stored, as the pores remain tens of years open for migration.

    Final point: while interesting to find out why the differences in the Greenland cores, it looks like as in the case of stomata data, where one can´t conclude anything about global CO2 data, as the CO2 data are local and at maximum regional.

    • I like your amendment to Renee Hannon’s great article. The geography would logically play a very large role in the difference and variability between Greenland and Antarctica ice core.
      More over, the kilo year variance may also be influenced by surrounding landmass being more or less covered with ice, a thing that does not apply to the Antarctic area.

      • It’s also interesting, SMB of the Greenland ice sheet can be increased by North Atlantic cyclone activity. Hurricane Nichole is a recent example.

    • Ferdinand Engelbeen

      Danke / merci / dank u wel / thank you for these explanations helping me to better evaluate the interesting head post.

      Rgds
      J.-P. D. in Germany

    • Ferdinand,
      As someone who studies CO2, I have some personal observations that may be of interest. When I was in (formerly) Point Barrow (PB) in 1967, I observed that all of the homes were heated by natural gas. Almost everyone had at least one snowmobile per family; many people owned pickup trucks. It was common practice to burn garbage outdoors in empty oil drums. The Army base used heavy equipment such as tracked vehicles (Weasels) for transportation over the sea ice and bulldozers for road creation and maintenance. The Army base also used propane to incinerate the feces from employees. While one cannot smell CO2, incinerated feces smells like burning human flesh and one rarely got a whiff of fresh air on the base. Large aircraft and ships visit Point Barrow. All of those activities produce CO2. So, I have concerns about the accuracy of CO2 measurements from PB!

      • Clyde, local contamination is surely a problem in Barrow, but as far as I know the observatory is several km from the village on a peninsula in the open ocean. All CO2 measurements are noted and stored, but only data with wind from the ocean side are used to give daily to yearly averages.
        The same for Mauna Loa where the data are not used if the wind blows over the fumaroles of the volcano or in the afternoon when upgoing winds from the valley are depleted in CO2 by photosynthesis.
        Including or excluding the contaminated data doesn´t make a difference for the average (maximum 0.1 ppmv over a year, not cummulative), it differs only in a wider noise…

      • Clyde,
        I too have had the pleasures of using the incinerator toilets at Umiat during field work. So I plotted up 5 different NH observatories and they all show large seasonal amplitude swings with Finland and Russia slightly higher. Shown in link
        https://imgur.com/a/BhFTwRi

  5. Neat, the graph of atmospheric CO2 over a year looks exactly like a capnograph tracing of a human breathing.

  6. @Nick Schroeder
    “Why does it matter? The atmosphere cools the earth and BB upwelling LWIR is not possible “

    No need to talk about radiant transfer. The sun-warmed surface heats objects it is in contact with, which includes the portion of the atmosphere, by conduction (Fourier’s Law). This relatively thin contact layer then heats up the upper atmosphere by convection. Air is a poor conductor of heat compared to rock (which is why air spaces are used to insulate buildings). But air convection is a effective mixer and speeds up the whole transfer towards equilibrium.

    Recall that a blanket, per ser , generates no heat of its own, so the atmosphere keeps the Earth warmer, just like your blanket keeps you warmer in bed than you would be without the blanket.

    • Johanus

      “No need to talk about radiant transfer. The sun-warmed surface heats objects it is in contact with, which includes the portion of the atmosphere, by conduction ?”

      “Air is a poor conductor of heat compared to rock (which is why air spaces are used to insulate buildings). ”

      Don’t you feel the contradiction, Johanus?

      The heat transfer from water/sand/soil/rock to air is so poor (25 mW/Km) that it never could be able to explain the strong convection and advection streams measured in the lower troposphere.

      Beste Grüße vom ‘Nachbarn’
      J.-P. D.

      • Yes, but I think this apparent contradiction is mitigated by several factors:
        1) Convection. Fourier’s Law states that the heat flux depends on temperature difference between the surface and air. The air becomes saturated as it heats up and will absorb less. But convection moves the heated air upwards and exchanges with cooler air to refresh the transfer. And it is not just dry air but moist convection from surface evaporation, which I believe actually “conducts” most of the surface heat to the atmosphere.
        2) Surface area. The entire surface of the earth is used as a “heat-exchanger” with the atmosphere, completely independent of gas composition. By comparison, the effective surface area for GHG absorption is vastly smaller.
        3) Latency. Smaller conductivity just means equilibrium will take longer, perhaps hours vs seconds, but eventually, if the ground is hot, the air above it will get warmer.

        I find it interesting that refrigeration engineers are using “earth-air” heat exchangers for cooling. Yes, it requires thinner tubes and more of them, compared to “earth-water”, with advantages and disadvantages. But it seems to work.
        C. T’Joen, et al., “Comparison of Earth-Air and Earth-Water Ground Tube Heat Exchangers for
        Residential Air-Conditioning Application”, https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2208&context=iracc [2012]

        ,mit freundlichen Gruessen!

  7. I look forward to the day when science recognizes that, at current levels, CO2 is nothing more than a bit player that responds to temperature changes. Then we can finally advance our understanding of climate science, and leave all this politically and agenda driven navel gazing nonsense behind.

  8. Renee, another excellent and very interesting piece of research. Very impressive, just like your previous articles.

    Particularly relevant to see how data is rejected as “wrong” if it doesn’t fit a consensus or paradigm. Previous researchers trying to explain away data as erroneous means they have thrown away useful information – a classic Type 2 error.

    Resolution, measurement support and change of variance with averaging is one of my special interests, coming from geostatistics and seismic versus well log scales. Geostatistics provides some of the tools to formally understand smooth due to change of resolution.

    Great to see you have the open mind of a true scientist!

    Regards,

    TS

  9. The Mayans’ deforestation may have also contributed. Burning the Yucatan peninsula surely contributed to CO2 increases in NH.

    • Mayans’ deforestation began about 4,000 years ago, or so it is reported. It is hard to blamed this and not consider all the other sources, including but not limited to smelting by the Sumerians, European deforestation, North American indigenous burning, original wood for buildings, sailing ships, and fuel in ‘USA’ Colonies through the “Big Cut” of Pennsylvania and into Wisconsin; also early crude iron production (also PA). Many more.

  10. A very intriguing article, thank you.

    I am glad that my good friend Ferdinand has turned up and I will just mention his duels with Beck over the latter’s findings of highly variable co2 levels dating back a century ago.

    Co2 was measured long before the observatories got into the act and the UK parliament legislated some 150 years ago to keep co2 levels down in factories. The measurements even took into account the co2 coming from the internal gas lights.

    I have asked the question before but never got an answer, at what air and sea temperature does co2 outgas frm the oceans and under what range of temperatures does it get drawn back in?does this differ according to latitude?

    Tonyb

    • tonyb

      “I have asked the question before but never got an answer, at what air and sea temperature does co2 outgas frm the oceans and under what range of temperatures does it get drawn back in?does this differ according to latitude?”

      Interesting questions, to which I also lack a valuable scientific answer.

      Rgds
      J.-P. D.

    • Tonyb, long time ago…

      There is a natural equilibrium between CO2 in seawater and CO2 in the atmosphere. At 15°C that is about 290 ppmv. That equilibrium changes with about 16 ppmv per K or °C.
      Thus at colder places CO2 is absorbed and at warmer places it is released. As that is accompanied by a continuous upwelling of waters near the equator and sinking waters near the poles, that gives a continuous flow of CO2 from equator to poles through the atmosphere of about 40 GtC/year. Still the equilibrium is the same: for the global average 15°C sea surface temperature, that is 290 ppmv, but now it is a dynamic equilibrium.

      Now humans have increased the level to 410 ppmv, that makes that the atmosphere puts more CO2 into the oceans than gets released and mainly the deep oceans take up some 2.5 GtC extra CO2 per year.

      • Ferd

        have we had ever had higher CO2 concentration at this temperature level in geological history?

        • Bob, possibly yes, during the Cretaceous era. The oceans had much higher (bi)carbonate levels in solution thus CO2 levels in the atmosphere had a higher equilibrium for higher temperatures leading to 1000-2000 ppmv in the atmosphere. Levels in the oceans dropped thanks to the drop out of carbonate shell plankton which made the beautiful cliffs one can see at many places of the earth (like South England).
          In the past at least 800,000 years that seems to stabilize and there is a nice about 8 ppmv/K ratio between Antarctic temperatures and CO2 levels. Translated to global temperatures, that is about 16 ppmv/K, not by coincidence the solubility of CO2 in the average current seawater composition…

        • Bob,

          ”have we ever had higher CO2 concentration at this temperature level in geological history?

          Neftel published a CO2 concentration of almost 400 ppm about 1100 years ago during this Holocene interglacial period. He also states “the qualitative agreement between the two concentration time series rules out the possibility of large interaction between CO2 in the bubbles and the carbonates in the ice”. That data point was removed in later publications.

          https://www.researchgate.net/profile/Albrecht_Neftel/publication/230889363_Ice_core_sample_measurements_give_atmospheric_CO2_content_during_the_past_40000_yr/links/565c1fa608ae4988a7bb6084/Ice-core-sample-measurements-give-atmospheric-CO2-content-during-the-past-40-000-yr.pdf?origin=publication_detail

        • Renee, what you don´t tell Bob is that the 400 ppmv was the median from samples at the same depth which show values between 300 and 450 ppmv. That range alone is sufficient to reject all samples, as these are clearly contaminated. Other extremes were also rejected because drilling fluid was found in the ice, which makes the samples worthless for analytic purposes. The average spread of samples at the same depth for the coldest Greenland ice core was reported around 9 ppmv for the methods used at that time (1981).
          Neftel did show in his introduction that at a certain depth, the ice was highly fractured with the possibility of contamination.

  11. There’s still an elephant in the room–bacteria. I’ve mapped in the St. Elias mtns in SW Yukon, and the Juneau Icefields in NW BC, and always seen pink algae growing on the snow in mid to late summer. Flying insects are regularly carried by updrafts to altitudes where without the updraft they cannot remain airborne and fall to the snow. Spiders find them within seconds when they fall. There is no reason for me to believe that with food (algae), and several forms of transport to get there (wind, flies and spiders–and me), that bacteria are not also present.

    As is obvious from making wine and beer, many forms of bacteria produce CO2 in varying quantities as a part of their metabolism.

    That tells me that there can be undeterminable contaminating factors trapped in ice that render ice-core CO2 data unreliable. To try to reach paleo-climatic conclusions on such data is in grave danger of just being another mann-erism, where the presence or absence of water in determining tree-ring variability was not properly considered.

    • Len Werner, it may play a role in Greenland ice due too much nearby land, but Antarctica is far more isolated. Even so, they have found bacteria even in the Vostok ice core, blown in with dust, surviving -40°C only by repairing any DNA damage. In a worst case scenario, the energy needed used about .5 ppmv CO2 in hundred thousands of years…

    • Bacteria affect the oxidation of methane to carbon dioxide and vice versa. Understanding the role of bacteria in the mineral cycle in rocks is no different to ice – just a change in the host media. I have found, and others practicising geochemical sampling have long discarded the use of CO2 and CH4 as both compounds are open to being affected by bacterial action. It maybe that the wrong elements are being analysed. Perhaps ring aromatics may be a better trace compound to analyse. Has anyone thought down these lines. If volcanic activity is suspected then Ba, Rb, Sr and possibly V become important trace elements to be considered. With new ICP-MS achieving results in the ppt range then a re-look at what is the key elements for analysis may be timely.
      Excellent comments in an excellent paper – finally some clarity of thought and results.

      • Ian, you are right for rock, but the ice core air bubbles of ancient air contain not more than 0.7 ppmv CH4. either there was much more, but then one would expect zero CH4 left or there is not enough bacterial life left at -40°C left to do the conversion. As CH4 in ice core bubbles closely follows temperatures, that probably is the case…

  12. Antarctica is ‘protected’ by circumpolar ocean and atmospheric currents. That would imply that air interchange between the south pole and the rest of the planet is much slower than for the north pole.

    Finally, the growing impact of anthropogenic activities on the atmospheric composition is well recorded in both polar regions for long-lived compounds (in particular greenhouse gases), but mostly in Greenland for short-lived pollutants. link

    Based on that, one would suppose that Antarctic data would be like Greenland data with a low pass filter applied. That’s consistent the above observation that short transient signals are observed in the Greenland data but not the Antarctic data.

    • commieBob,

      “Based on that, one would suppose that Antarctic data would be like Greenland data with a low pass filter applied.”

      My thoughts too. Your’s more elegant = shorter.

  13. The data disagree with the model.

    Clearly the data is questionable.

    Welcome to Climate “Science.”

    • Rob, in this case, the data disagree with physics, while other data series agree with physics – the solubility of CO2 in seawater. Thus at least one of the data sets is wrong. As in the case of the Antarctic cores all cores show the same values in overlapping periods, within a few ppmv, despite huge differences in temperature and accumulation, the data seems reliable. In the case of a single Greenland core, even parts of the same depths show different CO2 levels when measured…

      • Ferdinand,
        The Greenland data has been ignored for over 20 years by explaining it away with tenuous arguments for in-situ chemical alterations. The fact that Antarctic ice cores shows nearly all the same values despite huge differences in temperatures and accumulation are the reason why Greenland ice cores with their varying CO2 values deserve reconsideration. The Greenland CO2 follows these huge differences in temperature and accumulation rates, whereas Antarctic CO2 does not. The Antarctic CO2 data shows no to minimal response to well documented past climatic events such as D-O, YD, or 8.2 kyr.

        Additionally, high density sampling in Greenland cores plotted in figure 5 shows no overlapping values. They are synchronized with rapid varying temperatures. Please provide an example where the same depths show overlapping values.

        • Renee, sorry, but the influence of in-situ chemical reactions in Greenland ice cores was proven by getting more CO2 out over time when everything was melted. I have no access here to my files, but when back, I will send the reference.
          Have a look at the Greenland measurements done by two different labs: they may differ with over 10 ppmv and more for the same ice core at the same depth, which also points to contamination. The average variability in Antarctic cores for different samples at the same depth are 1.2 ppmv (1 sigma) if measured by different labs.

          • Ferdinand,
            I think your referring to the Barnola study, which I used in this article as Figure 3. The mean difference for the Greenland cores on the same samples is on the order of 2 ppmv, not 10. Also, check out the scatter for the Antarctic CO2 cores in the same study. Not much better. https://imgur.com/gallery/BnkSMyb

            How fortuitous it is to have chemically induced CO2 enhancements occur over 4000 meters of ice core with varying compounds and then chemical CO2 depletions. And have these CO2 enhancements and depletions correlate very well with past temperatures. This is the dilemma.

            I can understand severe CO2 spikes near fractured zones or areas of chemical CO2 distortion that don’t match temperatures.

          • Renee, if you look at the data around 1300, there is a difference of more than 10 ppmv between the measurements of Bern compared to Grenoble. That is for the same ice core at the same depth. If that happens with an Antarctic ice core, in all cases there was contamination with drilling fluid and/or highly disturbed ice full of cracks.
            There are several references to large changes in Greenland ice cores on very short distances which are physically impossible if that happened in the global atmosphere, but can be the result of contamination. On longer time periods, the average can be influenced by regional CO2 levels from vegetation and ice sheet formation which of course are temperature dependent…

          • Renee, if you look at the data around 1300, there is a difference of more than 10 ppmv between the measurements of Bern compared to Grenoble.

            Ferdinand,
            Yep, that is one data point, and I’m fine with eliminating a questionable data point. Yes and many of the large CO2 changes over short periods of time also correlate with rapid temperatures of the D-O events which we have not experienced present day. So, let’s re-examine the datasets and clean them up. Simply ignoring all of the Greenland CO2 data is unacceptable science.

  14. There is no overlap between Antaractic CO2 direct and proxy measurements.
    It cannot have been calibrated.
    Picking a low frequency uncalibrated proxy over a high frequency calibrated proxy like plant stomata is the definition of bad science.

    • Rob, there is a 20 year overlap (1960-1980) between the high-resolution Law Dome ice cores and direct measurements at the South Pole. They agree to within 1.2 ppmv. Ice cores with extreme differences in accumulation and temperature overlap each other with different time scales over a period of 800,000 years within 5 ppmv.
      Ice core CO2 measurements are direct measurements of CO2, not a proxy, done with the same equipment as for CO2 in the atmosphere. The only drawback is that it always is an average of several to 600 years.

      Stomata data are proxy´s and are calibrated against… ice cores CO2. They are measuring CO2 in very variable air on land, which depends of local vegetation and variations in the main wind direction. Even the main wind direction may have changed over the centuries… Thus far less reliable.

      • Ferdinand,
        “The only drawback is that it is always an average of several to 600 years.”

        Yes, the Antarctic ice cores with low snow accumulation rates tend to show gas diffusion rates more towards the 600+ years, whereas as Greenland ice cores with higher snow accumulation rates show gas diffusion rates on the order of tens of years. Not sure if any ice cores show gas averaged over several years, particularly in Antarctic.

        • Renee, two of the Law Dome cores from the summit have about 1.2 meter ice equivalent snow accumulation per year and at bubble closing depth, their average gas age spread is about 8 years. The only drawback is that the core ends at about 150 years ago when hitting bedrock. The third core (DSS) was taken more downstream and has a lower resolution, still around 20 years, but goes back over 2,000 years. Taylor Dome resolution gets about 40 years and goes back 75,000 years, etc…
          I don´t know what the resolution of the Greenland cores is, but as they reach over 100,000 years at the summit, I suppose that they are around 40 years resolution.

      • Ferdinand,
        Even the Antarctic CO2 data has been smoothed over time. The Barnola study utilized the Antarctic Siple and South Pole cores in a high density sampling program to compare to the Greenland cores in Figure 3 above. This study shows a slight increase at 1350 and now it appears to be smoothed over in more recent publications shown in the link below.
        https://imgur.com/gallery/BnkSMyb

  15. Since results from three diffents sources (Greenland ice cores, plant stomata, and chemical physical measurments) conflict with results from Antarctic ice cores, I think it’s becoming increasingly clear that the Antarctic data do not accurately reflect past CO2 values.

    I believe that a lot of problems exist, not only with the basic assumption that the air bubbles trapped actually represent the past atmospheric composition, but also with sampling and handling protocols used in obtaining, handling, and processing ice cores.

    As partial validation, I think that experiments to see what happens to CO2 being trapped in ice bubbles under pressure need to be performed under lab conditions (e.g. is the ice acting as a sempermeable membrane to CO2, cf. to a nitrogen generator).

    Regarding processing, I would hope that during drilling to obtain ice cores ,the lubricants used would be doped with fluorescent dyes so that any microfractures formed during drilling or handling of the cores could be detected.

    The waiting time of up to a year at atmospheric pressure before analysis seems problematic, couldn’t the cores be stored covered with an impermeable membrane preferably under some pressure?

    Finally, it seems to me that the presence of carbonate can reduce the CO2 concentration via CO2 + carbonate + H2O yielding bicarbonate.

    Just my twobits.
    P.S. – enjoyed the article.

    • Old Chemist
      “Since results from three different sources (Greenland ice cores, plant stomata, and chemical physical measurements) conflict with results from Antarctic ice cores, I think it’s becoming increasingly clear that the Antarctic data do not accurately reflect past CO2 values. ”

      “As partial validation, I think that experiments to see what happens to CO2 being trapped in ice bubbles under pressure need to be performed under lab conditions (e.g. is the ice acting as a semipermeable membrane to CO2, cf. to a nitrogen generator).

      Regarding processing, I would hope that during drilling to obtain ice cores ,the lubricants used would be doped with fluorescent dyes so that any microfractures formed during drilling or handling of the cores could be detected.”

      Yeah.

      A couple of twobits sometimes weigh not so much less than half a long, long article.

      Rgds
      J.-P. D.

    • Old Chemist,
      Thank you for your comments. I agree a desirable outcome would be to take another Greenland ice core to better understand past CO2 fluctuations. Methods for pressurized-preserved core samples have been used for gas hydrates. To maintain physical properties of the core samples under in situ conditions and not allow the dissociation of the gas hydrates, preservation of the samples under pressure and temperature are maintained during sampling and analyses.

      I agree with your observation that perhaps the muted Antarctic CO2 values are the questionable values. But of course, using Antarctic values helps make today’s high resolution rapid increasing CO2 values look scary.

    • Old Chemist, the value of a method in science is not measured in quantity, but in quality. Both stomata data and many of the direct measurements were taken over land, where you can find any CO2 level you (dis)like, depending of time of the day or the weather.
      Stomata data are calibrated against… ice cores, because these represent global values. Over land, there is always a positive bias of CO2 as at night CO2 levels go up by plant respiration and during the day they go down by photosynthesis, but less down as there is a better mixing with overlaying air from the bulk of the atmosphere. Continuous measuring shows some 40 ppmv and more bias over land at e.g. Giessen. That is influenced by vegetation in the main wind direction, land use changes over time, but even the main wind direction may have changed in the past between warm and cold periods, thus changing the local bias…

      In have had several years of discussion with the late Ernst Beck about the historical data, but most of these data were taken over land and show extreme variability, even within a day, so these are of no value to know the `background´ CO2 levels in the bulk of the atmosphere of that period. Only measurements taken over the oceans or coastal with wind from the seaside have value and are around the ice core values of that time:
      http://www.ferdinand-engelbeen.be/klimaat/beck_data.html

      The data from Greenland ice cores were rejected for contamination, but even if we take them at face value, there is a temperature induced bias in the data which makes that they don´t represent CO2 levels in the bulk of the atmosphere.

      So why would you replace reliable data from many Antarctic cores by unreliable data from other sources?

      • Ferdinand,
        Yes, but doesn’t the Greenland “temperature induced” bias represent the tropics and Northern Hemisphere CO2 response in the past, whereas the Antarctic CO2 in ice cores represent the CO2 response in the Southern Hemisphere or even more likely a smoothed representation of CO2. I prefer to understand what is happening in each hemisphere, not just one.

        Rubino, 2019, states this dilemma more eloquently than I.
        “There are real differences between records of the same GHG from different sites caused by atmospheric features, such as the inter-hemispheric gradient (north–south or Greenland vs. Antarctica). The inter-hemispheric gradient is different from one GHG to another, depending on the balance between, and the distribution of, sources and sinks for that specific GHG in the two hemispheres, as well as on the atmospheric circulation and the atmospheric lifetimes of the gases. There are also differences which do not reflect atmospheric changes, due, for example, ……diffusion in firn and gradual bubble close-off result in a smoothed representation of the atmospheric history in ice core gas records…..GHG records from many Antarctic sites are usually a more smoothed representation of the atmospheric history.“ https://www.earth-syst-sci-data.net/11/473/2019/essd-11-473-2019-supplement.pdf

        • Renee, If you look at the trends of current “base” stations, then there is little difference in trends between Barrow, Mauna Loa, Samoa or the South Pole. Both measure mostly oceanic air masses which are sufficiently mixed to give CO2 levels as they are in 95% of the total air mass.
          There are only two differences: the seasonal amplitude which is largest in the NH and near ground level than at altitude or the SH. That doesn’t play any role in ice cores as the smoothing of the CO2 levels in ice cores is from about a decade to about 600 years.

          The second one is from human emissions: the near constant increase in human emissions from about 1 ppmv/year in 1960 to about 4.5 ppmv/year in 2018. As 95% of human emissions are in the NH, that causes an increasing difference between NH and SH CO2 levels due to the ITCZ, which allows only a small exchange of air per year between the hemispheres (if I remember well, some 10% per year).
          http://www.ferdinand-engelbeen.be/klimaat/klim_img/acc_co2_1960_cur_4stat.jpg
          Despite the 4.5 ppmv extra per year and that only half of that is per year absorbed, thus leaving 2+ ppmv/year in the atmosphere, the difference between NH Barrow (BRW) and SH American Samoa (SMO) is only 5 ppmv, that is a lag of two years, while the time needed to reach high altitudes seems to be longer.
          Thus in my opinion, slower CO2 changes would give even less difference between the Arctic and Antarctic ice cores, except if other (regional) influences are at work…

  16. A question that came to mind was where is the temperature/CO2 lag.

    By the look of it there is a lag but much less than the normally discussed 800 years.

    Are these different swings in temperature or is this an actual change in the accepted norm.

    My eye suggests 3C for 60ppm remembering the temperatures are more variable at the poles.

  17. This essay is interesting but incomplete IMO. Although Renee Hannon does an excellent job of showing why the Greenland ice core data is unreliable, she does not adequately link the past to the present in this essay. The focus on paleo-CO2 ice core and stomata reconstructions are always with an eye towards how are they relative to today’s instrumental records. A fuller picture is obtained by examining what the two together can tell us about sources and sinks of CO2. Without that, the long tabulations of ice core-based proxy CO2 data offer no insights into the deeper understanding of what is/was going on to cause them.

    Just as the ground station temperature data is now supplemented with tropospheric and stratospheric temperature data from satellites; the ground station CO2 data, like the MLO curve (and the other station data ) that Renee Hannon shows, are now only a partial piece of the modern CO2 record. The climate alarmist community would so love to be able to ignore this ‘newcomer’ satellite temperature data and go about their SOP business of steadily adjusting the past and warming the present data to fit their modeled theories. So too they are trying to ignore what OCO-2 is telling (and has told) them about global/regional CO2 sources and sinks, even if this picture is far from complete. OCO-2 still cannot give a full picture of what is happening, but it provides clear diagnosis that present views embodied in the IPCC AR5 and earlier reports are wrong. Badly wrong.
    Renee only provided one graphic and a few sentences on this modern satellite based instrument, OCO-2, and its pivotal finding, and none of the 2017 publications that were presented in Science Magazine.

    The OCO-2 mission has provided vital insights into the failure of the Bern Model, particularly to role of the tropics in regards to being sources rather than assumed sinks in CO2.
    https://www.jpl.nasa.gov/news/news.php?release=2017-267

    It was likely a quite inconvenient message that NASA/JP highlighted the fact that (quoting NASA/JPL from OCO-2 data), “Earth’s tropical regions were the cause of the largest annual increases in atmospheric carbon dioxide concentration seen in at least 2,000 years.” That was an insight completely at odds with prior expectations and source and sink models, a fact that will be interesting to see if the IPCC is willing to honestly address this in AR6 or simply try to hand-wave it away like prior failures such as the tropical mid-tropospheric hotspot no-show in satellite and radiosonde observations.

    The Bern Model of CO2 faulty sources and sinks, and the belief that the modern rise in CO2 is entirely anthropogenic, and that it represents only half of the post-1850 anthro-emissions, underpins the IPCC’s mechanistic linkage of anthropogenic CO2 emissions to the modern instrumental records (like the MLO record). Without that base layer of support, that the CO2 is almost exclusively anthropogenic in origin, everything above that assumption on the IPCC’s anthropogenic CO2 based warming science crumbles.

    Some other “inconvient” insights from OCO-2:
    OCO-2’s orbit also allowed it to observe significant carbon dioxide signals from isolated plumes of three volcanoes on the Pacific island nation of Vanuatu. One orbit directly downwind of Mt. Yasur, which has been erupting persistently since at least the 1700s, yielded a narrow string of carbon dioxide that was about 3.4 parts per million higher than background levels — consistent with emissions of 41.6 kilotons of carbon dioxide a day. This is a valuable quantification of volcanic emissions, which are small compared to the average human emissions of about 100,000 kilotons per day.”
    source: https://www.jpl.nasa.gov/news/news.php?feature=6971

    Do the math on Mt Yasur for a year, for a century. Do the math on what its cumulative emissions have been since “the 1700’s” relative to anthropogenic CO2 emissions. Then realize Mt Yasur is certainly just one of many volcanic CO2 sources unquantified until OCO-2.

    While NASA tried to downplay that single volcanic release at 0.04% of today’s anthro-emissions of 100,000 tons/day, a deeper reflection on the fact that those continuous volcanic emission compared to past anthro emissions, and its totalities over 200+ years, and that Mt Yasur is just one volcano of likely dozens or hundreds spread across the planet of 70% ocean is quite another matter.

    Is it any wonder that the OCO-2 team has gone quiet since their pivotal 2017 publications?

    • 2nd to last paragraph of my comment:
      “…of 100,000 tons/day” is a typo-mistake on my part. Should be “100,000 kilotons/day (as per the NASA quote provided above that.)
      The math of Mt Yasur CO2 emission at 0.04% of today’s modern anthro emissions though is correct.

    • Joel
      You said, “Mt Yasur is just one volcano of likely dozens or hundreds spread across the planet of 70% ocean is quite another matter.”

      The mid-ocean ridges, vocanically active spreading centers, are a continuous chain of underwater ‘mountains’ approximately 40,000 – 50,000 miles long! We actually know very little about the density of vents or the frequency of gaseous release. We know something about them where they break the surface, and where we have accidentally stumbled on ‘Black Smokers,’ but, as with so many things about Earth, particularly in the oceans, we have scant knowledge about the details.

      I suspect that we have seriously underestimated the contribution of underwater volcanoes to the (bi)carbonate system of the oceans.

      https://en.wikipedia.org/wiki/Mid-ocean_ridge

      • Another un-quantified variable the uncertainty with which I heartily agree; I remember the Alvin dive that discovered the first ‘black smoker’. We have no idea yet how much submarine volcanic activity there is, or was, or will be; now we know that there is even volcanic activity under Antarctic ice. Such a concept was not even remotely considered when I was in university ‘learning geology’ (in quotes because what must be learned has expanded and changed so much).

        When we have such potentially large variables that can or cannot (and did or did not) contribute to something like CO2 concentrations in atmosphere and ice, what on earth are we doing considering major economic upheaval on the basis of what we think we know today? There is more unknown than is known about sources of CO2 and its effect on or response to climatic change.

      • Continuous measurements around mount Etna, one of the most active volcanoes on earth have shown that all above ground volcanoes emit about 1% of what humans emit per year. Undersea volcanoes may emit more, but play no role at all, as all CO2 is dissolved in the highly under saturated deep ocean waters under such high hydraulic pressure. Except if some large bubble reaches the surface (Bermuda triangle someone?)…

    • Joel,
      “Although Renee Hannon does an excellent job of showing why the Greenland ice core data is unreliable”.

      I think you need to re-read the article. The point of the post shows that Greenland Core CO2 data correlates well with Greenland temperatures and maybe Reliable.

      • Your words say one thing. But Figures 5, 6, 7 say something else.
        Greenland ice core CO2 is suspect. Too much interaction with NH airbornebiotic/organic confounders and volcanics in my book.

        • Joel,
          The data shows that CO2 in the NH is behaving differently than the SH during both warm and abrupt cooling periods. Greenland ice core CO2 follow Greenland temperatures. No one questions the validity of Greenland temperatures. And yes CO2 is responding to increased terrestrial and volcanic activity in combination with oceanic releases in the NH. Utilizing this data can provide a better understanding of the rapid NH land/glacial/oceanic interactions compared to the slower SH ocean responses for global climatic changes. The SH CO2 alone is not a true reflection of what is happening in the mid-northern latitudes.

  18. “They also conclude that South Pole CO2 variations are affected mostly by marine influences such as marine upwelling and release of CO2.”
    Well they sure aren’t going to be affected by seasonal variations in vegetation.

  19. I have never understood WHY CO2 concentrations should be so low in the ice core records. I would expect them to rise dramatically in warm periods (far over 300ppm) as CO2 gets released from a warming ocean. If the ice core record can be trusted, then either plant life demand for CO2 grows in proportion to CO2 availability keeping it level, or the oceans have too little CO2 dissolved in them, or oceans do not warm by much…

    Far more likely is there is a problem with Ice Core records. The CO2 is either moving, chemically reacting, or failing to be stored. How do researchers really know that CO2 is not mobile under the ice over a great amount of time? How do they know that it is not being chemically collected through slow reactions?

    There is a large rat here (ignorance), and by ignoring it we are getting a incorrect picture of CO2 in the atmosphere over time.

    Has anyone looked at how much C14 is locked up in organic chemicals (not CO2)? If carbon containing chemicals have more variance in their C14 then expected (at a given level in the Ice up to say 50,000 years old) then this would be evidence of chemical reactions continuing after burial, and gas bubbles would become depleted in CO2. If the reactions are reaching an equilibrium state at about 280 ppm, then your samples would tend to show 280 ppm as a maximum amount of CO2 available.

    I hate many proxies because they are so variable on so many things – people just assume they represent a fair and accurate picture of the thing they are studying (bias).

    • Robert, the solubility of CO2 in seawater changes with about 16 ppmv/°C around the current average 15°C sea surface temperature. That is confirmed by over 3 million seawater samples over the past centuries. For the current sea surface temperature, the equilibrium with the atmosphere would be around 290 ppmv, not 410 ppmv, which presses some 2.5 ppmv CO2/year into the oceans and vegetation.
      That is also what is seen in the 420,000 years Vostok ice core (8 ppmv/°C, but that are Antarctic temperatures, not global). Thus ice cores CO2 simply follows ancient temperatures with some (long) lag.

  20. Great article Dr Hannon, thanks.
    At some times of year eg autumn, forests generate more CO2 than cities.

    https://i.imgur.com/huRdUau.jpg

    Since there is more land and more forest in the NH than the SH, variation in forest intensity could perhaps explain higher and more variable CO2 in the NH compared to down under.

  21. Seems to me that this presentation makes a good argument that CO2 is not a well-mixed gas in the atmosphere. It seems that concentrations can vary significantly and for long periods of time. Add one more variable to the climate models.

    • Phil
      To quote President Clinton, “It all depends on what the meaning of the word ‘is’ is.” That is, “well mixed” isn’t defined! There should be a standard deviation specified for “well mixed” versus “poorly mixed.” It is generally acknowledged that the variance for water vapor is much higher than the global variance of CO2. On the other hand, both nitrogen and argon have lower variance than oxygen and CO2. So, in the final analysis, qualitatively, CO2 is neither the most or least “well mixed.” It all depends on the point one is trying to make. However, it would improve the science if numbers were used to quantify the degree of variability. Climatologists seem to have an aversion to attaching numbers to their claims.

      • So Clyde,
        What’s your hierarchy on mixing for the various key components? Well mixed to least mixed: air-Methane-CO2-water vapor? And volcanic ash…

        • Thank you for a very interesting and well-documented post.

          I think Clyde has a point here: what is meant by ‘well-mixed’? One view of well-mixed might be that an increase in the atmosphere in one area/hemisphere subsequently ‘spreads’ around the globe where the concentration and/or isotopic content eventually achieves the same levels (often claimed to be on the order of a couple of years when crossing between hemispheres). However, there are some good examples of variations with latitude, both in terms of concentration (e.g. methane) and in terms of isotopic content (e.g. 18O/16O of CO2), that cannot be explained in this way. In these cases, the differences are clearly ‘offsets’ rather than ‘lags’ and the well-mixed argument looks to be more problematic.

          The δ18O data for atmospheric CO2 are shown here: https://scrippsco2.ucsd.edu/graphics_gallery/isotopic_data/global_stations_isotopic_o18_trends.html. Clearly, the differences in values are maintained over time with no suggestion of equalisation.

          The behaviour of atmospheric methane is even clearer (NOAA data). The offsets remain constant and the trends parallel each other: https://i.postimg.cc/J0P5zJGc/1512742412-2982099.jpg.

          The globally synchronous onset of increasing atmospheric CH4 in early 2007 is remarkable: https://i.postimg.cc/rFw9YhPh/CH4-C13-by-latitude-large.jpg. Again, there is no hint of equalisation over time.

    • “Seems to me that this presentation makes a good argument that CO2 is not a well-mixed gas in the atmosphere. It seems that concentrations can vary significantly and for long periods of time. ”

      And just how does that square with Fig 1 above?

    • Phil, if you take into account that each year 20% of all CO2 in the atmosphere is exchanged with CO2 from other reservoirs and that each year humans add 4% of the total CO2 into the atmosphere (95% in the NH) and the difference between the NH and the SH measurements is not more than 2% of full scale, I find that very well mixed…

  22. The no data for Holocene interglacial in figure 7 is interesting. It it because it was not sampled, or because the warmer summers than currently melted and removed to layers?

    • another Jim,
      No data for the Holocene is lack of digital data available during this period. I did find a Camp Century Core through the Holocene with CO2 data in the Neftel, 1982 reference. However, it would be unfair to “eyeball” the values off the graph and time was in a logarithmic scale. Also, the data showed a CO2 value approaching 400 ppm, not allowed! I’m sure there is Greenland CO2 data for the Holocene, it’s just not publically available as it was deemed unreliable.

      • Renee
        When I was in the army (1966-1968) I was assigned to the Cold Regions Research and Engineering Laboratory in Hanover, New Hampshire. We had several cold rooms for working with ice cores. While it has been 50 years, I wouldn’t be surprised if they still have Greenland ice cores archived. I imagine that the library has numerous reports that never made it into the general civilian literature base.

        • Clyde,
          I would definitely be interested in finding more CO2 digital data and where that may be stored, especially during the Holocene interglacial period. It has to be out there because the graphs in the reports are not done by hand.

  23. Renee
    You said, “During autumn/fall, CO2 is released by respiration and increases.”

    It isn’t just respiration. As leaves of deciduous plants fall to the ground, they immediately start being consumed by bacteria and turned into CO2. This should drop off as the temperatures decrease mid-Winter, and then pickup again in early-Spring before the trees start to leaf out.

  24. What is the present state of data availability from ice core work?
    For many years Steve McIntyre tried to get data from Law Done in the Antarctica. Being Australian, I tried to help him and was treated like a leper. Then I took sick and lost track of events. Some comments above suggest data from more sites are hard to get.
    Also, there is the matter of proper treatment of error and its widespread lack in climate research. Surely ice core work is fundamentally important in understanding the past. Why has not the past measurement data globally been systematically compiled in an orderly data base with error bounds?
    It it plausible that some data paint an inconvenient picture and are suppressed? Geoff S

  25. What is the present state of data availability from ice core work?
    For many years Steve McIntyre tried to get data from Law Done in the Antarctica. Being Australian, I tried to help him and was treated like a leper. Then I took sick and lost track of events. Some comments above suggest data from more sites are hard to get.
    Also, there is the matter of proper treatment of error and its widespread lack in climate research. Surely ice core work is fundamentally important in understanding the past. Why has not the past measurement data globally been systematically compiled in an orderly data base with error bounds?
    It it plausible that some data paint an inconvenient picture and are suppressed? Geoff S

    • Geoff,
      What a great idea, having a comprehensive database for ice core data with depths, depth to time conversion, isotopes, temperatures, gas measurements, and standard deviations for starters. From my past experience, establishing a clean dataset is 90% of the work and the fun interpretation part 10%.

      NOAA, formerly the National Climatic Data Center (NCDC), does maintain some data but it is mostly bits and pieces from publications.

        • Thanks Ferdinand,

          I will definitely look at the CDIAC data. Also, thanks for sharing all your knowledge with us. Your comments were very insightful and informative.

          • Renee, thanks for the article, although we don’t agree on several points, the data anyway are intriguing and it looks like that CO2 on the top of the Greenland summit is influenced by temperature, where the temperature part is from a large part of the N.W. Atlantic and surrounding land, thus probably the CO2 part too. That is reasonable for the warm parts of history but not so clear for the cold intervals…

            BTW, I am back home and owe you the increase of CO2 when Greenland ice is melted for longer periods… which was gone from the Internet. But I found another one from 1995 which similar good information:
            https://www.tandfonline.com/doi/pdf/10.3402/tellusb.v47i4.16061

    • RoHa,
      If the CO2 is from Antarctic it will be a slow agonizing demise. And if it’s from Greenland it could be over quickly.

  26. Don’t know why different responding times and responding values of atmospheric CO₂,

    bound in glacier ice,

    following temperatures changes,

    between NH and SH = Greenland / Antarktis

    – should be due to chemical reactions between

    oceans outgassing CO₂ or originating from landbased fauna and other atmospheric reacting chemical compounds –

    – when obviously Greenland is surrounded by much more landmass than Antarktis

    – and landmass hosts a great amount of CO₂ exhaling fauna as well as CO₂ binding flora, directly changing atmospheric CO₂ amounts.

    No need for additional chemical reactants.

    ____________________________________

    As always, thanks for correction where I’m wrong.

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