Guest Post By Renee Hannon
This post evaluates the relationship of global CO2 with regional temperature trends during the Holocene interglacial period. Ice core records show that CO2 is strongly coupled with local Antarctic temperature and slightly lags temperature over the past 800,000 years (Luthi, 2008). Whereas the emphasis has been on CO2 and temperature lags/leads, this study focuses on Holocene millennium trends in different latitude-bounded regions.
The Contrarian Antarctic
The Holocene is fortunate to have hundreds of proxy records analyzed by Marcott, 2013, and more recently Kaufman, 2020, to establish regional and global temperature trends. The Holocene interglacial occurs approximately during the past 11,000 years. In general, global temperature trends from proxy data show a Holocene Climatic Optimum (HCO) around 6000 to 8000 years ago and a subsequent cooling trend, the Neoglacial period, culminating in the Little Ice Age (LIA). The global mean temperature is comprised of regional trends that tend to have a concave down appearance during the Holocene shown in Figure 1a.
The exception is the Antarctic shown in red which has a concave up shape. The Antarctic reached an early Holocene Climatic Optimum between 9000 to 11000 years ago. While global and most regional temperatures were warming, Antarctic cooled to a minimum around 8000 years ago. While global and other regions show progressive cooling during the Neoglacial, the Antarctic was flat and erratic. This contrary Antarctic temperature behavior during the Holocene has also been noted by Andy May here.
Greenland and Antarctic ice core temperature anomalies derived from deuterium and/or oxygen isotopes and global proxy temperature means are shown in Figure 1b. Ice cores have high resolution over long periods of time making them a key proxy dataset. These data show similar trends to the regional compilation. However, temperature ranges tend to be larger at individual proxy sites. Smoothing of paleoclimate proxy data occurs due to averaging of multiple data types together which removes local temperature variability (Kaufman, 2023).
It’s not surprising that Antarctic temperature trends behave differently due to its unique environment. Antarctica is a continent surrounded by the Southern Ocean with a mean annual temperature of the interior between -50 to -60 deg C. Most of Antarctica is covered by a permanent ice sheet averaging 2 km in thickness. Sparse proxy data from Antarctica is predominantly from ice cores and a few marine sediments. These data comprise temperature trends in the 90oS-60oS latitude region which represent less than 10% of Earth’s surface area.
CO2 is Uniquely Synchronous with Antarctic Temperatures
CO2 gas trapped in ice bubbles show synchronous trends with local Antarctic temperature anomalies during glacial and interglacial periods over the past 800,000 years. CO2 ranges from lows of 180 ppm during glacial periods to highs of near 300 ppm during interglacial periods. Figure 2a shows the linear regression of CO2 and temperature from the EPICA Dome C ice core over the past 60,000 years that includes the Holocene interglacial and last glacial maximum. The squared regression (R2) of 0.9 is very impressive. One interesting curiosity is the Holocene interglacial period where the slope tends to flatten out and R2 decreases substantially to 0.3.
Despite the lower correlation factor for the Holocene interglacial, Figure 1a above shows that CO2 displays concave up trends like Antarctic temperature trends. CO2 reaches an early Holocene high near 275 ppm around 11,000 years ago after deglaciation. CO2 then slowly decreases by 10-15 ppm to a Holocene minimum of 260 ppm about 8000 years ago. And then, CO2 gradually increases up to 290 ppm during the Neoglacial cooling period. To note, these CO2 values are muted or smoothed due to gas trapping processes in ice and do not reflect instrumental values (Joos, 2008).
Correlation plots of Holocene CO2 versus temperature anomalies from high resolution regional proxy temperatures are shown in Figures 2b-d. They are much different than the 60,000-year Antarctic CO2 relationship in Figure 2a. The Arctic and the Northern Hemisphere regions (2c) show an inverse relationship with CO2, especially during the Neoglacial period. The tropical region (2d) shows large scatter with no statistically valid trend detected. The Southern Hemisphere, not shown, also has a low correlation with CO2. No other multi-proxy region or latitude temperature trends show a strong positive correlation with CO2 during the Holocene like the Antarctic does.
Authors have noted that CO2 has a different trend compared to global and Northern Hemisphere temperature trends. Vinos, 2022, concludes that CO2 runs opposite to global temperature trends for most of the Holocene. This CO2 asynchronous behavior and/or lack of correlation to temperature seems to be true for most regions, roughly 90% of the Earth’s surface area.
Climate Models Dominated by CO2 Forcing
Climate models fail to match global Holocene proxy temperatures known as the Holocene temperature conundrum (Liu, 2014). Models basically show a gradual increase in temperatures throughout the entire Holocene as shown in Figure 3a. While temperature proxy data shows a Holocene Climatic Optimum of 0.5 deg C around 6000-8000 years ago that climate models simply do not reproduce.
Holocene global proxy temperature trends show an inverse correlation with CO2 as plotted in Figure 3b. There are two distinct inverse trends separated by the HCO. During the Neoglacial period, proxy temperatures and CO2 show a strong negative correlation with an R2 of 0.8. Basically, as CO2 increases then global temperatures become cooler.
Temperatures from model simulations are typically controlled by changes in greenhouse gases, insolation, ice sheets, and freshwater fluxes, to name a few. Modeled temperature profiles parallel the global CO2 trend with a strong R2 of 0.7 confirming CO2 is a major model control knob. Additionally, modeled Holocene temperatures tend to resemble the contrarian Antarctic temperature trends (compare Figures 1a and 3a).
Scientists have begun to investigate the effect and possible dominance of forcings other than CO2. Zhang, 2022, modeled the effect of seasonal insolation influence and found better matches to proxy data when combining insolation with ice sheet forcing, although still not perfect. Thompson, 2022, showed that more vegetation influence in the Northern Hemisphere helps models simulate a Holocene Climatic Optimum evident in proxy data. The close relationship between CO2 and Antarctic temperature suggests that millennial variations are strongly influenced by Southern Ocean processes. Only when past forcings and the timing of their dominance are more accurately incorporated into climate simulations will models be able to predict future climate change.
Observations
Climate change is routinely claimed to be largely controlled by greenhouse gases, especially CO2. This was concluded, in part, by the strong relationship between CO2 from Antarctic ice core bubbles and local Antarctic temperature trends. While CO2 mimics Antarctic temperatures very well, ninety percent of Earth’s surface temperature trends do not demonstrate a positive correlation to CO2 during the Holocene. Arctic and Northern Hemisphere temperatures become cooler during increasing CO2 levels. Tropical proxy temperatures don’t seem to be influenced by CO2.
Model simulated temperatures which are strongly influenced by CO2 do not accurately history match Holocene global proxy temperatures and tend to largely reflect Antarctic trends. The fact that CO2 correlates well to Holocene temperatures for only the Antarctic, or <10% of our planet’s surface, yet CO2 is considered as the dominant influence on climate change is a scientific dilemma.
Download the bibliography here.
Very good report
Two comments:
The Holocene Climate Optimum proxies tell us nothing about the climate effect of adding +50% more CO2 since the mid-1800s, with manmade CO2 emissions. Unfortunately, the so called climate models (aka climate confuser games) also tell us nothing. Lab spectroscopy tells us +50% CO2 should have contributed to the warming from 1975 to 2014. The lack of global warming since 2014 tells us CO2 is NOT a climate control knob. The big problem is Ph.D. climate scientists who refuse to say “We don’t know exactly what caused the warming from 1975 to 2014, or what the global average temperature will be in 100 years”. Uncertainty is not allowed in modern climate “science”.
Holocene Politics: +1 degree C. warmer than today is good news, and bad news?
The Holocene Climate Optimum was at least +1 degree warmer than today, and it was called an optimum because +1 degree C. warmer IN THE PAST was considered to be good news! The IPCC agrees with the optimum designation.
But today the IPCC warns that +1 degree C. warmer than today IN THE FUTURE will NOT be another climate optimum — it will be a “climate emergency”.
Only a leftist organization could contradict itself like that.
https://honestclimatescience.blogspot.com/
Even with your cherry picked dates, global ter4maprures are increasing
https://www.woodfortrees.org/graph/uah6/from:2014/to:2022/trend/plot/uah6/from:2014/to:2022
We have not been this warm in 100,000 years.
Kaufman, D. S. and McKay, N. P.: Technical Note: Past and future warming – direct comparison on multi-century timescales, Clim. Past, 18, 911–917, https://doi.org/10.5194/cp-18-911-2022, 2022.
“We have not been this warm in 100,000 years.”
Not true. At least the Northern Pacific basin and Greenland were three degrees warmer than today 6000 years ago. See figures 1&2 here:
https://andymaypetrophysicist.com/2022/08/30/are-fossil-fuel-co2-emissions-good-or-bad/
Even with your cherry picked dates global temperatures show an increase.
https://www.woodfortrees.org/graph/uah6/from:2014/to:2022/trend/plot/uah6/from:2014/to:2022
We are now warmer than the past 100,000 years.
Kaufman, D. S. and McKay, N. P.: Technical Note: Past and future warming – direct comparison on multi-century timescales, Clim. Past, 18, 911–917, https://doi.org/10.5194/cp-18-911-2022, 2022.
See here, page 55, figure 4.12 and page 58, figure 4.16
https://www.researchgate.net/publication/363669186_Climate_of_the_Past_Present_and_Future_A_scientific_debate_2nd_ed
Kaufman’s reconstruction is clearly wrong. Glaciers are very sensitive to temperature changes, and they are much farther advanced today, all around the world, than they were 6000 years ago. There is no paleoclimatic data that I am aware of that suggests that 6000 years ago was cooler than today, except in Antarctica, which is only 6.7% of Earth’s surface area.
“There is no paleoclimatic data that I am aware of that suggests that 6000 years ago was cooler than today,”
In addition to Kaufman
Osman, M.B., Tierney, J.E., Zhu, J. et al. Globally resolved surface temperatures since the Last Glacial Maximum. Nature 599, 239–244 (2021). https://doi.org/10.1038/s41586-021-03984-4
When compared with recent temperature changes11, our reanalysis indicates that both the rate and magnitude of modern warming are unusual relative to the changes of the past 24 thousand years.
Bova, S., Rosenthal, Y., Liu, Z. et al. Seasonal origin of the thermal maxima at the Holocene and the last interglacial. Nature 589, 548–553 (2021). https://doi.org/10.1038/s41586-020-03155-x
Furthermore, our reconstructions demonstrate that the modern global temperature has exceeded annual levels over the past 12,000 years and probably approaches the warmth of the last interglacial period (128,000 to 115,000 years ago).
The Osman study is a blended evaluation using a climate model that incorporates proxy data. Osman also presents his proxy only data which demonstrates a Holocene climatic optimum unlike climate models and his blended model.
We are now warmer than the past 100,000 years only if you compare decadal average modern temperatures with past multi-century averages, clearly a temporal resolution issue. Geologic proxy data shows that temperatures just 6500 years ago were higher than present day. A mid-Holocene climatic optimum is supported by pollen records which show expanded grass and shrub vegetation in the African Sahara, increased temperate forest cover in Northern Hemisphere mid-latitudes and boreal forest instead of tundra in the Arctic (Thompson, 2022). Glacier and ice cap fluctuations from lake studies in the Arctic were smaller than present or absent during the early and mid-Holocene (Larocca, 2022). In a more recent publication, Kaufman, 2023, has a thorough discussion of empirical evidence at different latitudes supporting a warmer past mid-Holocene.
From Kaufman 2023
” From a large variety of available evidence, we find support for a relatively mild millennial-scale global thermal maximum during the mid-Holocene,”
What do you have that contradicts this.?
The glacial advance/retreat evidence. Much more accurate and reliable than Kaufman’s proxies. But, numerous proxies, already mentioned show the same thing. The glacial evidence is the best refutation, however. Kaufman’s conclusions are only possible by excluding most of the best evidence.
You seem to accept and reject Kaufman. Which is it?
” In a more recent publication, Kaufman, 2023, has a thorough discussion of empirical evidence at different latitudes supporting a warmer past mid-Holocene.”
“Kaufman’s conclusions are only possible by excluding most of the best evidence.”
Which part and which paper? Details matter.
There is very little of Kaufman, 2022 that I believe. Kaufman, 2023 is better, but I don’t agree with all of it.
His estimate of 0.5 deg (HCO-LIA) is very likely too low, but his list of the evidence that the HCO was warm is pretty good. The problem is you cannot estimate a global average temperature with just a few dozen inaccurate low-temporal-resolution proxies. This is a point I’ve been driving home for years. You need to choose a proxy and a location, then compare our current highly accurate measurements to the proxy at that specific location. The other way around is invalid. Besides global average surface temperature doesn’t tell you very much, since natural climate change varies so much with latitude.
This from Kaufman, 2023 is good:
“The global HTM is apparent in several compilations of globally distributed terrestrial and marine proxy datasets, including compelling evidence for global cooling over the Common Era before industrialization. Mountain glaciers worldwide generally retreated during the early and middle Holocene and readvanced thereafter. Similarly, subsurface ocean waters were probably warmer during the first half of the Holocene than during the second.”
This as accurate as we can be and states the case well.
Which part and which paper? Details matter.
Those are quotes from your .posts. Youn tell me.
I am guessing that you reject the conclusion of of Kaufman 2023.
“Global warming has reached 1 ∘C relative to the late 1800s and, in the absence of a strong reduction in greenhouse gas emissions, is on track to remain at least as warm and possibly much warmer for multiple centuries. The duration of this ongoing and upcoming global warming is on par with that of the resolution of Holocene paleotemperature reconstructions. Human-caused global warming is now exceeding the warmest multi-century period of the Holocene and thereby the envelope of temperatures under which agriculturally based society has flourished (Steffen et al., 2018). Without rapid and sustained reductions in greenhouse gas emissions, the average temperature of coming centuries will exceed 1.5 ∘C above preindustrial temperature and will therefore be warmer than the peak of the last interglacial around 125 000 years ago.”
Your quote and comments:
“Global warming has reached 1 ∘C relative to the late 1800s and, in the absence of a strong reduction in greenhouse gas emissions, is on track to remain at least as warm and possibly much warmer for multiple centuries.”
We have warmed one degree above the Little Ice Age, the coldest period in the Holocene, so this is true.
The duration of this ongoing and upcoming global warming is on par with that of the resolution of Holocene paleotemperature reconstructions. Human-caused global warming is now exceeding the warmest multi-century period of the Holocene and thereby the envelope of temperatures under which agriculturally based society has flourished (Steffen et al., 2018).”
The warming of the last 170 years exceeds the “multi-century” [averages of 200-500-year periods] variability of Holocene. Maybe, most Abrupt Climate Events (ACEs) are less than 200 years. So maybe. More likely is the HCO was warmer.
“Without rapid and sustained reductions in greenhouse gas emissions, the average temperature of coming centuries will exceed 1.5 ∘C above preindustrial temperature and will therefore be warmer than the peak of the last interglacial around 125 000 years ago.”
Pure speculation, no one has any idea how warm it was 100,000 years ago to that level of precision. However, the 1.5 deg. above the Little Ice Age is a very good thing. The Little Ice Age was the coldest and most miserable time in human history.
The LIA was NOT global.
Neukom, R., Steiger, N., Gómez-Navarro, J.J. et al. No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature 571, 550–554 (2019). https://doi.org/10.1038/s41586-019-1401-2
So what? No abrupt climate events are global, in the sense they happen everywhere at the same time. Why does that matter? Modern global warming is not global either, there are many large areas in the Southern Hemisphere especially, that are cooling, not warming. This is from AR6, Fig. 2.11(b), page 316 and Box 3.1, figure 1, page 448. Total BS argument, the LIA was real, the MWP was real, they are well documented historically.
The Great Warming: Climate Change and the Rise and Fall of Civilizations” by Brian Fagan
“A growing number of sources tell us that there was never long-lasting medieval warmth, but that between 1000 and 1200, temperatures were a few degrees warmer in some parts of the world, notably parts of China, Europe, and western North America.”
MWP was not global.
Start reading this book for free: https://a.co/a2XThu8
“We conclude that winters in which the Thames froze are not at all good indicators of the hemispheric or global mean temperatures, although well-correlated with the lowest temperatures in the local observational record, the CET. ”
Frost fairs, sunspots and the Little Ice Age
Mike Lockwood, Mat Owens, Ed Hawkins, Gareth S Jones, Ilya Usoskin
Astronomy & Geophysics, Volume 58, Issue 2, 1 April 2017, Pages 2.17–2.23, https://doi.org/10.1093/astrogeo/atx057
Published: 01 April 2017
“We conclude that winters in which the Thames froze are not at all good indicators of the hemispheric or global mean temperatures, although well-correlated with the lowest temperatures in the local observational record, the CET. ”
Who cares what they think. The Little Ice Age happened, people suffered, starved and died due to it. You can’t seriously think it didn’t happen? Millions upon millions died.
Read Behringer’s book cited in this post.
https://andymaypetrophysicist.com/climate-and-civilization-for-the-past-4000-years/
LIA happened, it was not global. It was also the time of the Age of Enlightenment, The Scientific Revolution, The Agricultural Revolution IN EUROPE.
Your history is Eurocentric.
Volcanic activity probably imitated the the LIA. You fail to mention that research..
https://ui.adsabs.harvard.edu/abs/2017AGUFMPP43D..05Z/
“…cooling has always resulted in major social upheavals, whereas warming has sometimes led to a blossoming of culture. If we can learn anything from the history of culture, it is that, even if humans were ‘children of the Ice Age’, civilization was a product of climatic warming.”
“The Great Warming: Climate Change and the Rise and Fall of Civilizations” by Brian Fagan
“Opportunity went hand in hand with misfortune. When we move beyond Europe and the North Atlantic into drier environments and lands with unpredictable rainfall, we enter a medieval world where drought cycles and even a few inches of rain could make all the difference between life and death. While Europe basked in summer warmth and the Norse sailed far west, much of humanity suffered through heat and prolonged droughts. A huge swath of the world, from much of North America through Central and South America, and far across the Pacific to northern China, experienced long periods of severe aridity. Drought cycles settled over the Saharan Sahel, the Nile Valley, and eastern Africa, creating havoc. Farmers went hungry, civilizations collapsed, and cities imploded. Archaeology and climatology tell us that drought was the silent killer of the Medieval Warm Period, a harsh reality that challenged human ingenuity to the limit. Most societies on earth were affected by medieval warming, many of them for the worse.”
The Great Warming by Brian Fagan recommended to me by the communications director of the Friends of Science.
https://ethz.ch/content/dam/ethz/special-interest/usys/ites/ecosystem-management-dam/documents/EducationDOC/Readings_DOC/The%20Great%20Warming.pdf
I bought Fagan’s book, it looks interesting and I really like books that combine history and climate, I’ve read several of them. My favorite is Wolfgang Behringer’s A Cultural History of Climate. But, I also enjoyed Cunliffe’s Europe between the oceans, 9000BC to 1000AD and Mithen’s After the Ice. All good books, but I’ve never read Fagan’s book.
Your report is very interesting. I was led to it by a link on LinkedIn.
That climate models use Antarctic ice-core data and its correlation with CO2 as a justification to use CO2 as a major temperature forcing (I hate that term “forcing”) is especially interesting since, going back to the last interglacial about 120,000 years ago, we see in that data that CO2 concentration reaches a maximum and hangs there for around 18,000 years while temperature drops by 6 to 8 degrees C. I call this a counter example. The duration is too long to be a local event, too long to be attributed to transients. With CO2 holding constant the hand waving argument of feedback loops fails.
Regards
The anthropogenic CO2 emissions are a new factor in climate change.
“Is there any merit to the studies that show that historical CO2 levels lag behind temperature, and not lead them?
Climate scientist Peter Hildebrand, Director of the Earth Science Division at NASA’s Goddard Space Flight Center, says yes, there’s merit to those studies. In the pre-industrial age, the CO2 response to temperature was that the temperature would go up and CO2 would go up. Or if the temperature went down, CO2 would go down. And the reason for that is when the temperature went up, the whole biosphere revved up and emitted CO2, and we had more CO2 in the atmosphere. So we understand that process.
In the post-industrial age, the opposite is true. Increasing CO2 in the atmosphere is leading to increased temperature. So two different things happened, one pre-industrial, where temperature was driving the CO2, and post-industrial, where CO2 was driving temperature. Which means a completely different physical-biological process is going on. And we don’t understand what the consequence of that change is.
It is a fundamental change to how the earth works and the earth’s radiation balance works. And so, we’re very concerned because we don’t see any restraining force on continued increase in temperature due to continued increase in CO2. And that’s a problem”
https://svs.gsfc.nasa.gov/11362.
Jack,
Mostly good points, but I don’t know of any evidence that “CO2 was [or is] driving temperature.” I’m sure that additional CO2 will have some effect on temperature, but it is probably very small. All we can really say is that from 1976 to 2005, CO2 and global average surface temperature are moving in the same direction. They moved in opposite directions from 1920 to 1944 and from 2016 to today.
“They moved in opposite directions from 1920 to 1944”
That is not true.
https://cdiac.ess-dive.lbl.gov/ftp/ndp030/global.1751_2014.ems
https://www.metoffice.gov.uk/hadobs/hadcrut5/
2016 is a cherry pick of a large El Nino event. to long La NIna event.
Oops, I made a mistake. I should have written 1944-1976. But 2016 to today is correct. Remember, that long term El Ninos are a cooling event. They work to move excess heat from the ocean to the atmosphere so it can more easily be expelled to space. All major natural climate shifts are associated with large El Ninos. See here:
https://andymaypetrophysicist.com/2022/08/22/the-sun-climate-effect-the-winter-gatekeeper-hypothesis-iv-the-unexplained-ignored-climate-shift-of-1997/
The two most recent climate shifts took place in 1976 (well accepted) and 1997 (still debated). Others occurred in ~1947 and ~1920. We are due for another soon.
” I should have written 1944-1976″ Rasool and Schneider (1971) identified industrial aerosols as a factor in the cooling. When the Clean Air Acts cleaned up the smog, warming resumed. Rasool and Schneider identified CO2 as contributing to warming.
That is nonsense, it is well established that the aerosol impact is greatly inflated in the models. The only evidence for anthropogenic aerosol cooling is the cooling they are supposed to explain. Models overestimate GHG warming but compensate for it by overestimating aerosol cooling (Vinos, 2022, page 183).
“it is well established that the aerosol impact is greatly inflated in the models. The only evidence for anthropogenic aerosol cooling is the cooling they are supposed to explain. Models overestimate GHG warming but compensate for it by overestimating aerosol cooling (Vinos, 2022, page 183).”
Show me the evidence for both of those assertions.
Can you read Jack? The citation is in the quote in your comment, including the page number! Don’t ask what is right in front of you!
I can read. A search on Vinos 2022 get me a wine list. What is the URL or the DOI?
Vinos, 2022 can be downloaded for free here:
https://www.researchgate.net/publication/363669186_Climate_of_the_Past_Present_and_Future_A_scientific_debate_2nd_ed
I had already given you the link in an earlier comment. It has the detailed evidence that volcanism did not cause the Little Ice Age.
The Little Ice Age was global (except for Antarctica), but it was not synchronous, in that the entire world did not cool at the same time. Although, the entire world, including Antarctica, did cool at some times between 1300 and 1850 and the whole world ocean cooled during that period.
Aerosols played no role in recent cooling events.
So we completely disagree on these points, no need to continue arguing. Read Javier Vinos’ book.
Vinosis downloaded. As a reciprocal move. please download and read Fagan..
I bought it, it looks good. We are going on holiday tomorrow, so I’ll read it on the plane.
if you like books about climate and history, I also suggest Firmament by Simon Clark.
https://www.amazon.ca/Firmament-Science-Weather-Climate-Surrounds/dp/1529362318
“And so, we’re very concerned because we don’t see any restraining force on continued increase in temperature due to continued increase in CO2.”
I see a “restraining force”, and that is the oceans which have 1000 times the heat capacity of the entire atmosphere. The highest possible ocean surface temperature in the deep ocean is thirty degrees, and in practice it rarely exceeds 28. That is the temperature that deep convection starts, which carries heat out of the ocean and into the upper troposphere. This is well documented by Newell and Dopplick, 1979.
https://andymaypetrophysicist.com/2020/11/27/ocean-temperature-update/
Andy, Steve McIntyre has discussed at length an Antarctic core that shows generally declining temperatures during the Holocene – Dome C. He also mentioned another from James Ross Island that shows a similar pattern. Does this not suggest that there is at least some uncertainty about the Holocene temperature history of Antarctica?
Dome C is plotted in figure 1 in red. It has a slight dip from 10000 to 6000BP, but is mostly flat. Antarctica is climatically isolated from the rest of the planet by the Southern Ocean, it marches to its own drummer and is unlikely to change its temperature much. But, that said, there is uncertainty.
The Holocene conundrum is well on way to being resolved by the same author who identified it.
https://www.rutgers.edu/news/important-climate-change-mystery-solved-scientists
Bova, S., Rosenthal, Y., Liu, Z. et al. Seasonal origin of the thermal maxima at the Holocene and the last interglacial. Nature 589, 548–553 (2021). https://doi.org/10.1038/s41586-020-03155-x
The antiphase of Antarctic and Greenland ice core data is nothing new. Richard Alley has discussed it in reference to the misuse of his GISP2 data and in his published papers.
https://archive.nytimes.com/dotearth.blogs.nytimes.com/2010/02/08/richard-alley-on-old-ice-climate-and-co2/
Alley is also of the view that CO2 is the “control knob”
.
Jack,
The Rutgers study you linked to is clearly incorrect, as demonstrated by glacier records from around the world, Rosenthal’s 2012 study of the Makassar strait, and Greenland ice core data. Here is more on the 30-degree ocean surface temperature limit:
“Due to the vapor pressure of water in the open tropical ocean, evaporation will limit SST to approximately 30°C, as Newell and Dopplick showed in 1978 and Willis Eschenbach and Richard Willoughby (Part 1 to Part 4) have shown at Wattsupwiththat.com.”
Go here for the links:
https://andymaypetrophysicist.com/2021/07/07/climate-sensitivity-to-co2-what-do-we-know-part-2/
Just before figure 4.
For more on Rosenthal’s study see here:
https://andymaypetrophysicist.com/2021/06/23/how-to-compare-today-to-the-past/
Rosenthal’s one site is not representative of global temperatures.
No, it isn’t and no proxy record is. The advantage of Rosenthal’s record is that it does represent the tropical and Northern Pacific, it covers much more of the surface of the Earth than any other proxy I’ve studied, and I’ve studied most of them as you can see here.
https://andymaypetrophysicist.com/2017/06/09/a-holocene-temperature-reconstruction-part-4-the-global-reconstruction/
“ The Holocene conundrum is well on way to being resolved by the same author who identified it”.
Bova’s 2021 study utilizes only a subset of proxy data restricted to latitudes of 40S-40N. Kaufman, 2023, states this about the Bova study “because low latitudes warmed less than higher latitudes during the mid Holocene, the latter must be included when estimating GMST”.