New peer reviewed study discovers that when CO2 was higher in the past, not as hot as previously thought

How hot did Earth get in the past?

By Judy Holmes, Syracuse University (press release)

The question seems simple enough: What happens to the Earth’s temperature when atmospheric carbon dioxide levels increase? The answer is elusive. However, clues are hidden in the fossil record. A new study by researchers from Syracuse and Yale universities provides a much clearer picture of the Earth’s temperature approximately 50 million years ago when CO2 concentrations were higher than today. The results may shed light on what to expect in the future if CO2 levels keep rising.

clamsThe study, which for the first time compared multiple geochemical and temperature proxies to determine mean annual and seasonal temperatures, is published online in the journal Geology, the premier publication of the Geological Society of America, and is forthcoming in print Aug. 1.

ivanySU Alumnus Caitlin Keating-Bitonti ’09 is the corresponding author of the study. She conducted the research as an undergraduate student under the guidance of Linda Ivany, associate professor of earth sciences, and Scott Samson, professor of earth sciences, both in Syracuse University’s College of Arts and Sciences. Early results led the team to bring in Hagit Affek, assistant professor of geology and geophysics at Yale University, and Yale Ph.D. candidate Peter Douglas for collaborative study. The National Science Foundation and the American Chemical Society funded the research.

“The early Eocene Epoch (50 million years ago) was about as warm as the Earth has been over the past 65 million years, since the extinction of the dinosaurs,” Ivany says. “There were crocodiles above the Arctic Circle and palm trees in Alaska. The questions we are trying to answer are how much warmer was it at different latitudes and how can that information be used to project future temperatures based on what we know about CO2 levels?”

Previous studies have suggested that the polar regions (high-latitude areas) during the Eocene were very hot—greater than 30 degrees centigrade (86 degrees Fahrenheit). However, because the sun’s rays are strongest at the Earth’s equator, tropical and subtropical areas (lower latitude) will always be at least as warm as polar areas, if not hotter. Until now, temperature data for subtropical regions were limited.

The SU and Yale research team found that average Eocene water temperature along the subtropical U.S. Gulf Coast hovered around 27 degrees centigrade (80 degrees Fahrenheit), slightly cooler than earlier studies predicted. Modern temperatures in the study area average 75 degrees Fahrenheit. Additionally, the scientists discovered that, during the Eocene, temperatures in the study area did not change more than 3 to 5 degrees centigrade across seasons, whereas today, the area’s seasonal temperatures fluctuate by 12 degrees centigrade.

The new results indicate that the polar and sub-polar regions, while still very warm, could not have been quite as hot as previously suggested.

The findings are based on a chemical analysis of the growth rings of the shells of fossilized bivalve mollusks and on the organic materials trapped in the sediment packed inside the shells, which was conducted by Keating-Bitonti and her colleagues. Ivany collected the fossils from sediment layers exposed along the Tombigbee River in Alabama. The mollusks lived in a near-shore marine environment during a time when the sea level was higher and the ocean flooded much of southern Alabama. The sediments that accumulated there contain one of the richest and best-preserved fossil records in the country.

“Our study shows that previous estimates of temperatures during the early Eocene were likely overestimated, especially at higher latitudes near the poles,” Keating-Bitonti says. “The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effect—the Earth was clearly hotter during the early Eocene. Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe.”

To determine the average seasonal temperatures in the study area, Keating-Bitonti sampled the mollusk shells for high-resolution oxygen and strontium isotope analyses, which were done at SU. The Yale team analyzed shells and sediments for clumped-isotope and tetraether-lipid analysis. The results were consistent across all of the independent analytic methods. The scientists believe the multiple methods of analysis have yielded a more complete and accurate picture of ancient climate than previously possible.

The study also marks the first time clumped-isotope analysis has been used alongside traditional oxygen isotope and organic geochemical analyses in paleoclimate work. The research team is currently using the same analytical process to determine Eocene Epoch mean annual and seasonal temperatures in polar-regions.

“Clumped isotopes is a new way to measure past temperatures that offers a distinct advantage over other approaches because the technique requires fewer assumptions; it’s based on well understood physics,” Affek says. “The agreement among different methods gives us confidence in the results and enables us to use these methods in other locations, such as Antarctica.”

Keating-Bitonti recently completed a master’s degree in geology at the University of Wisconsin and will be continuing her studies at Stanford University as a Ph.D. student in the Department of Geological and Environmental Sciences, School of Earth Sciences.

###

h/t to Dr. Leif Svalgaard

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79 thoughts on “New peer reviewed study discovers that when CO2 was higher in the past, not as hot as previously thought

  1. One site, and the Global/Arctic/Antarctic temps are known????
    Kind of like, “Here let me use analytical extension to encompass the poles…” er, I’m sorry that works only in complex analysis, not in climate – back to the drawing boards guys.

  2. Like wsbriggs, I am probably more skeptical that people can gather accurate temperature data from 50-million-year-old fossilized mollusks than I am that they can gather useful data from tree rings. And because gauging the accuracy of temperature estimations of a climate 50-million years in the past is impossible, studies like this one seem like a complete waste of resources. Blech,

  3. I love this blog. We get real science in full context. Not deceptive headlines or cherry picked excerpts intended to reinforce some discredited ideological goal.

  4. Crocodiles at the North Pole. Give the polar bears something to worry about.
    There’s a good bit of web info on clumped isotopes, but I can’t imagine being able to find any kind of lipids from that long ago.

  5. “Ivany collected the fossils from sediment layers exposed along the Tombigbee River in Alabama.”
    An awfully small sample area to hang a global temperature on.
    How would they know what temperature range it was in the polar regions? From samples in Alabama.Only 2,500 miles to the south.

  6. Due to plate tectonics, the configuration of land masses and ocean basins was not the same in the Eocene as now. This means that ocean heat transport was quite different, particularly the movement of heat from the equatorial Pacific Ocean to the northern Atlantic Ocean.
    This is likely to affect the site studied more than the concentration of the CO2 in the atmosphere.

  7. They are trying to keep their jobs as they realize the kebang is falling apart might as well get into some of what the skeptics have been sayin’ singin’ all along; There have been quite a few of these articles lately from the AGW establishment. THis will proceed until all interest in the subject is stone dead by both AGW and skeptics, believers and deniers LOL. Except that it will turn to solar so the solar scientist will be hot item on the agenda in the coming years. But what is the point of funding them because nothing can be done about that one More LOL.

  8. wsbriggs,
    No, the article clearly states that they only claimed to have worked out subtropical and tropical temperatures. But since those temps are lower than or equal to what what polar temperatures were believed to be, this raises the possibility that polar temps have been overestimated. Or the new subtropical temps are wrong. Only time will tell, but the article also states that they now want to use the same technique to determine the temperature at higher latitudes. It seems your motto is “ready, fire, aim.” Read the whole article more carefully next time.

  9. The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effect—the Earth was clearly hotter during the early Eocene.
    Technically just about any CO2 should yield a “greenhouse” effect. The missing wording should say if there was an increased effect from the elevated CO2, as all the fun stuff gets invoked about CO2’s logarithmic response, response saturation, and whether feedbacks amplified or dampened the temperature response.
    Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe.
    And as “less seasonality” means lesser temperature variations, there will be less of the severe weather seen during the transitions between the seasonal cold and warm periods. Sounds good. How much more CO2 do we have to emit to get to that nicer weather?

  10. Attribution of higher temperatures 50 mya to CO2 alone forgets the effects of the geotectonic situation. Ocean currents were much different and certainly influence temperatures.

  11. “Our study shows that previous estimates of temperatures during the early Eocene were likely overestimated, especially at higher latitudes near the poles,” Keating-Bitonti says. “The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effect—the Earth was clearly hotter during the early Eocene. Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe.”
    From the paper.

  12. I guess I’m a chauvinist pig or something. As soon as I see a hyphened last name I immediately have bad thoughts,and even more after I see Wisconsin in the credentials.

  13. So what caused the atmospheric CO2 levels to rise without man made emissions and then fall without an Australian carbon tax?

  14. Every little bit of extra knowledge helps in understanding a complex system. I am intrigued that palm trees in Alaska must mean hotter temperatures than today despite their downward revision by this paper – there are palm trees in Scotland that survive today- ostensibly because of the “Gulf Stream” – I’ve seen them at Plockton which lies at about 57 degrees north and is somewhat inland sheltered from the coast – you can easily see photos of them in Google Earth.
    So finding evidence of palm trees or crocodiles in locations which appear abnormal could be explained by mechanisms other than extreme temperatures – how about a few degrees C, a warmer current than today’s gulf stream and a bit of continental drift.
    Anyway – this paper has reduced the extremes of the past back to more moderate values and helps expand our knowledge base.
    Whether CO2 is a major or minor player in climate – I’m backing minor – expanding knowledge helps keep alarmism in check.

  15. Eocene CO2 was high because of the high temperature, since the relatively weak effects of CO2 cannot alone explain any times in the past that were warmer than now. (Null hypothesis: CO2 has always been the follower, not the leader.) Rather, paleogeography & currents induced those higher temperatures, which led to higher CO2 and its weak warming, which was insufficient to prevent the cooling that came when the worldwide equatorial current was later abolished by the closing of the Tethy’s Seaway and the enclosure of the Med. The much later closing of the Strait of Panama was merely the coup de grace of WarmWorld (never to return), along with the establishment of the Circumpolar Antarctic Current.
    By the way, nowhere in this article or the abstract cited was there any mention of what the authors think was the CO2 level then. The Warmistas should plug into their silly computer models the Earth’s Eocene paleogeography & currents, along with what they fantasize as the super-powerfull BUWAHAHA Satanic CO2 and its dreaded (fictional) positive feedbacks, and watch the Eocene oceans boil. Perhaps that would expose the essential shabiness of their vaunted simulations.

  16. John of Cloverdale Perth WA says:
    July 5, 2011 at 4:57 pm
    What caused the atmospheric CO2 levels to rise was the Martians. After they wrecked Mars by playing with Doomsday devices which blew a hole into the crust we now know as Olympus Mons, they then proceeded to modify Earth correctly. Since Mars is now dead, and the secrets of the Martians died with them, any attempts at modifying Earth to satisfy paranoia over CO2 levels is likely to result in the 3rd dead Planet. Venus was the 2nd attempt, likewise a failure. Oops, we’re slap out of Planets to attempt modification, so it’s either adapt or…. Steps #9 & #10 as found on “In case of Nuclear Attack” instructions.

  17. “The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effect—the Earth was clearly hotter during the early Eocene. Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe.”
    Sweet considering the global warming slew of extreme weather predictions…

  18. How much data do some people have to see before they will finally, finally admit CO2 does not control climate?

  19. John of Perth (been there, lovely little town) asked the primary question that no one can answer.
    And the failure to be able to answer that question leaves the whole AGW argument in tatters.

  20. In my opinion studying Arctic temperatures without understanding the tilt of the earth throughout history isn’t very helpful. For instance, without knowing the precise tilt at any given period of time leave me without accurate information to make any statement whether temperatures were or were not a result of more or less sun striking Arctic areas due to earth’s tilt and less about CO2 levels, not to mention possible ice ages or warm periods. Then throw in whether or not the sun was or was not as strong as today, specific actions of sun at that given time also leaves me with a completer lack of other known factors that affect earth other that CO2.
    We do know for more than 55 million years, Ellesmere Island remained in one place while the world around it changed. Fifty-five million years ago, verdant forests grew at 75° North latitude. These wetland forests, comprised of species now primarily found in China, grew on an alluvial plain where channels meandered back and forth and periodic floods buried stumps, logs, and leaves intact. Today the forests are preserved as coal seams that outcrop on the edges …of modern Ellesmere Island, where there are no forests, and the tallest vegetation grows less than 15 cm high. Large parts of the area are polar desert, subject to intensely cold and dark winters and minimal precipitation.
    Large parts of the area are polar desert, subject to intensely cold and dark winters and minimal precipitation. That there IS climate change!

  21. “The scientists believe the multiple methods of analysis have yielded a more complete and accurate picture of ancient climate than previously possible.”
    Wellllll…..at least they didn’t use a GIGO computer model.

  22. Estimated continental positions here:
    http://en.wikipedia.org/wiki/File:Paleogene-EoceneGlobal.jpg
    —–Willis Eschenbach, take note:
    “The early Eocene Epoch (50 million years ago) was about as warm as the Earth has been over the past 65 million years, since the extinction of the dinosaurs …. There were crocodiles above the Arctic Circle and palm trees in Alaska.”
    “Eocene water temperature along the subtropical U.S. Gulf Coast hovered around 80 degrees Fahrenheit ….Modern temperatures in the study area average 75 degrees Fahrenheit”
    ———
    Gee, its almost as though there was some type of thermostat keeping the tropics at nearly a constant temperature,
    http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/

  23. So, did the level of CO2 cause the higher temperature or did the higher temperature cause the level of CO2? Discuss.

  24. “The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effect…”
    There’s that boilerplate text again. Translation: “Please don’t cut off our funding; we’re manufacturing evidence as fast as we can.”

  25. Mike McMillan says:
    July 5, 2011 at 4:06 pm
    > Crocodiles at the North Pole. Give the polar bears something to worry about.
    The certainly didn’t bother the polar bears back then, as PBs evolved only 150,000 – 130,000 years ago and crocodiles were in the arctic around 50,000,000 years earlier.

  26. None of the actual proxy temperature data for the Eocene (none that is again) shows the extreme numbers that some pro-AGW people have quoted before. Exaggeration is a big part of this science and anyone interested in the topic needs to check things out for themselves before believing the hype.
    Every now and again, a climate scientist comes along and tries to correct the hype. This study appears to be one of those. The result, however, is that the researcher’s careers are usually slowed but, at least, other researchers start using the more accurate information and eventually the record gets corrected.
    It was warmer in the Eocene – up to 6.0C warmer globally than today. Through polar amplification, the polar regions were probably up to 12.0C warmer. Equatorial regions would have been about 3.0C warmer just as this study says (the equatorial regions only change by about half of the global numbers in most studies). Through the 24 hours of sunlight in the summer, it probably got pretty warm in the polar regions in the summer but in the winter of 24 hours of darkness, it was still very cold. Some polar ice still formed in the winter.
    This is, however, one of the few periods in Earth history where 3.0C per doubling of CO2 actually works. CO2 levels were around 1,000 ppm or 2 doublings at the time. But CO2 actually rose after this warm period, reaching 1,500 ppm just as the Earth started cooling off and CO2 didn’t drop again until about 30 million years ago, after Antarctica had glaciated over and temperatures had fallen close to today’s level 4 million years earlier. ie don’t blame CO2, something else happened.

  27. There may have been crocs in the arctic, but at the N pole the sea is several km deep.

  28. I am not dismissive of this study as others are, however I’d be careful about the claim that the globe was warmer 50mill yrs ago due to higher levels of CO2.
    They have NO IDEA why the globe might have been warmer then and no idea if higher levels of CO2 drove the Ts or was the cause of higher Ts.
    If the former, then the question must be answered, “What caused the higher levels of CO2 in the first place?”

  29. “The question seems simple enough: What happens to the Earth’s temperature when atmospheric carbon dioxide levels increase?”
    =================================================
    Obviously not much………
    According to this paper, CO2 forcing has been overestimated, and that CO2 does not create as much warming as assumed……
    …and in spite of “50 million years ago when CO2 concentrations were higher than today.”
    elevated levels of CO2 could not prevent the planet from going into another ice age
    This paper is saying that CO2 is not driving the bus……………

  30. What was the atmospheric CO2 concentration 50mil years ago? Interesting that the molluscs were not dissolved by the acidic oceans we have been warned about.

  31. This seems like good science. It should impel more graduate students to sample similar Eocene fossils in (exotic) places both further north and south, and subject them to the same analyses, along with anything else that is useful. The Eocene, after all, represents the Earth’s not-so-distant future, according to the AGW crowd. Let’s get a good read on it. Wish I were still doing science. 😉

  32. If they only could determine the angle and wobble of the earth towards the sun, the distance towards the sun, the distance to the moon, the state of the sun, in relevance to the land configuration and the configuration of the other planets, as well, maybe there will be some head way as to why our climate was as it was back when great grandpa walked the earth to school.

  33. “Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe.”
    This association continues to allude me. How can CO2 increases be assigned as the driver of climate rather than the follower of temperature increases?

  34. Bill Illis says:
    July 5, 2011 at 6:25 pm

    This is, however, one of the few periods in Earth history where 3.0C per doubling of CO2 actually works. CO2 levels were around 1,000 ppm or 2 doublings at the time. But CO2 actually rose after this warm period, reaching 1,500 ppm just as the Earth started cooling off and CO2 didn’t drop again until about 30 million years ago, after Antarctica had glaciated over and temperatures had fallen close to today’s level 4 million years earlier. ie don’t blame CO2, something else happened.

    Not necessarily. It might just be appearances. The Eocene transition from the warm regime to a cold one is also a transition from a “greenhouse” state to an “icehouse” state in the extremely long term oscillations (ca. 50 – 100 my) that have marked planetary climate [see Gornitz, W. (ed.) Encylopedia of Paleoclimatology, entry on “Icehouse” (Cold) Climates]. It stands to reason that if the planet was warmer, atmospheric CO2 must have been higher simply because the oceans were warmer. It would be pretty much unavoidable. One of the points made in the encyclopedia is that “Icehouse” oceans such as at present are “well mixed.”

  35. How they can mention CO2 as a factor in early Eocene climate without mentioning that the poles could be reached by currents from the tropics, I simply don’t know.
    If polar oceans warmed to 10C, say, how much CO2 would that release (warm beer is flat)??

  36. This seems to be a rather important point about the Eocene that the tropical temperatures were not that much warmer than the present. It is a situation noted in Lindzen’s “Climate Science: Is it currently designed to answer questions?”
    “the original data analysis for the Eocene (Shackleton and Boersma, 1981) showed the polar regions to have been so much warmer than the present that a type of alligator existed on Spitzbergen as did florae and fauna in Minnesota that could not have survived frosts. At the same time, however, equatorial temperatures were found to be about 4K colder than at present. The first attempts to simulate the Eocene (Barron, 1987) assumed that the warming would be due to high levels of CO2, and using a climate GCM (General Circulation Model), he obtained relatively uniform warming at all latitudes, with the meridional gradients remaining much as they are today. This behavior continues to be the case with current GCMs (Huber, 2008). As a result, paleoclimatologists have devoted much effort to ‘correcting’ their data, but, until very recently, they were unable to bring temperatures at the equator higher than today’s (Schrag, 1999, Pearson et al, 2000). However, the latest paper (Huber, 2008) suggests that the equatorial data no longer constrains equatorial temperatures at all, and any values may have existed.”
    While the wiki article on the Eocene does say initially that the Eocene tropics was similar in climate to today, but then contradicts itself by citing, I kid you not, a giant snake as proof that the data must be wrong. Mind boggling.
    Anyway, as someone mentioned above, this is further evidence that the tropics have a tightly constrained climate.

  37. I don’t get the comments of concern about the use of a single site to make all the data. The Church of Global Warming has already shown the way, where a single tree can be used to build worldwide reconstructions of warming and CO2, and just two geographically close sites can be used to determine the rise of the oceans.
    Really, the science is settled!
    /s

  38. Baa,
    Thank you, thank you, thank you! And thank you (belatedly) for the statement about reasoning; negotiating, whatever with the person that just robbed your house (no, there is no middle ground)
    What drove the higher CO2 in the past?
    If you want a classic example of pretzel logic, read the “Skeptical Science”? sections on CO2.
    Cook says that that CO2 might not have been 4000 ppm in the Ordovician but if it was then the sun was weaker then to override (under ride?) the GHG effect. So…. does TSI (with CR or any other unknown) matter or not? Where will the funding go?

  39. Where palm trees can survive is determined not so much by exceedingly warm temperatures as by lack of freezing temps. In other words, the less seasonality, the better. Which, as the paper states, was the name of the game in the Eocene.

  40. Steve from rockwood says:
    July 5, 2011 at 7:43 pm
    Why do they keep assigning the transportation duty to a trace gas instead of the bus?
    Oh, I suppose they keep the cart in front of the horse just in case. In case of emergency, they’re all ready to beat a hasty retreat. Another theory is that, after 80 years of assigning climate change to CO2 (it started in the 1930’s), the horse is quite dead, and is being carted about in the wagon. It must be an awkward arrangement to keep up the appearances. They’re Oh for Three.

  41. Here is the salient quote: “The early Eocene Epoch (50 million years ago) was about as warm as the Earth has been over the past 65 million years, since the extinction of the dinosaurs,” Ivany says. “There were crocodiles above the Arctic Circle and palm trees in Alaska.”
    These comments are based on fossil records, and so they show that the history of natural climate variability on Earth includes severe fluctuations. Trying to attribute this retrospectively (without clear evidence, I would add) to CO2 changes is horsefeathers. The truth is that this and other studies show clearly that whatever climate fluctuations we are currently experiencing are well within the bounds of natural variability and it is not necessary to invoke human causation to explain current observations. The truth is that the AGW crowd WANTS it to be true that there is an imminent, man-caused environmental disaster just waiting to destroy us all. They don’t care about rational assessment of evidence because the “narrative” is more important than the facts.

  42. timetochooseagain says:
    July 5, 2011 at 8:09 pm “…Anyway, as someone mentioned above, this is further evidence that the tropics have a tightly constrained climate….”
    I think Willis Eschenbach explained very well the daily tropical sequence of warming, thunderstorm activity, cooling, and repeat the sequence. A warmer climate would perhaps magnify this tropical tendency, to the point that some areas might be continuously cloud-covered and thus relatively cool (like King Kong’s island!).
    I don’t know much about the Eocene, so I would be interested to know what is the sedimentary record of the period. In a system where the climate was (relatively) uniformly warm from tropics to poles, the thermohaline circulation may have ceased to operate. In which case there should be lots of black, pyritic shales in the sequence. Does anyone have any information on this?

  43. rbateman;
    Forget ‘transportation duty’, wait ’til they calculate the CO2 on the production of cement and asphalt, power generation pales! And they have already expressed violent disapproval of dirt roads here in the Rockies so the ‘logical’ end is no roads…. period.

  44. I should temper the statement ‘power generation pales’ it has provided us with the standard of living we have but…… so has concrete and asphalt and refrigerated trucks and………

  45. Clearly a fraudulent study.. We are told that increasing CO2 will make the oceans acid, so that there will be no shellfish. How can there have been any shellfish 50 million years ago when CO2 levels were much higher? The oceans would have been pure acid, unable to support any shellfish. Everyone knows shellfish have been extinct for 350 million years, since the last time CO2 levels were as low as they are today. The earth has been too hot and the oceans to acid to support life except for 350 million years ago when CO2 levels were low, and today when CO2 levels are also low. Life is only a recent development on earth, made possible by the low CO2 levels over the past few million years. [trimmed. Robt]

  46. All I know is that if the equator to pole temperature difference was much smaller it requires that latitudinal heat transfer have been much more efficient. No Thermohaline operating strikes me as the opposite. Unless the boost was entirely from atmospheric circulation. Hm, interesting…

  47. timetochooseagain says:
    July 5, 2011 at 9:38 pm
    I posted this in “tips & notes”: http://www.nature.com/ngeo/journal/v4/n7/full/ngeo1179.html#/model-data-comparison
    an article about the carbon isotope excursion related to the PETM. Interestingly, the Spitsbergen sequence discussed (a marine profile that hasn’t moved more than miles since the its formation in the Eocene) is a black, TOC-rich, pyritic mudstone that shows evidence of “anoxia” developing in the depositional basin.
    The thermohaline circulation works by having water in the tropics become dense due to evaporation: water leaves, salt stays. This denser material is transported pole-ward by the Coriolis effect; in due course it cools, becomes even denser and plunges back into the briny depths. However, it is oxygenated and therefor oxidizes the seafloor. Result: no TOC-rich, pyritic black shales (and, no oil generation potential).
    Spitzbergen is now (and in the Eocene) near the northern terminus of the thermohaline surficial flow. In the Eocene, the thermohaline sinking zone either moved south of Spitzbergen, or simply ceased to operate for a considerable length of time. If you remove temperature differentials, some phenomena don’t happen (like cooling-related density changes).

  48. Peter says: “Centigrade”? These days, it’s “Celsius.”
    Early Eocene was still using Centigrade.
    Ric Werme says: July 5, 2011 at 6:18 pm
    >Mike McMillan says: “Crocodiles at the North Pole.
    >Give the polar bears something to worry about.”
    The certainly didn’t bother the polar bears back then, as PBs evolved only 150,000 – 130,000 years ago and crocodiles were in the arctic around 50,000,000 years earlier.

    Thank you Ric. I often get the Eemian and Eocene confused.

  49. Mike McMillan says:
    July 5, 2011 at 4:06 pm
    Crocodiles at the North Pole. Give the polar bears something to worry about.

    Not unless they have very deep genetic phobias. PBs didn’t evolve until much less than 1 mya. Even Cephalogale, ancestor of all modern bears, is only half that old or less!
    😉
    By the time new crocs make the NP home, PBs will have evolved into something else altogether. Except for the ones conservationists hoard in breeding zoos somewhere.

  50. JimF says:
    July 5, 2011 at 9:05 pm
    timetochooseagain says:
    July 5, 2011 at 8:09 pm “…Anyway, as someone mentioned above, this is further evidence that the tropics have a tightly constrained climate….”
    I think Willis Eschenbach explained very well the daily tropical sequence of warming, thunderstorm activity, cooling, and repeat the sequence. A warmer climate would perhaps magnify this tropical tendency, to the point that some areas might be continuously cloud-covered and thus relatively cool (like King Kong’s island!).

    No, couldn’t happen. Needs the hot sun till afternoon to generate the rising air to make clouds. It would have to be fewer storms, less circulation, etc. because of smaller “sinks” for the heat to flow into. Much more boring altogether.

  51. Willem de Lange says:
    July 5, 2011 at 4:32 pm
    Due to plate tectonics, the configuration of land masses and ocean basins was not the same in the Eocene as now. This means that ocean heat transport was quite different, particularly the movement of heat from the equatorial Pacific Ocean to the northern Atlantic Ocean.
    =====
    You’d think so, but here’s conventional wisdom re where things were in the Eocene http://www.scotese.com/newpage9.htm. Other than a narrower Atlantic, a larger and better connected Mediterranean and Antarctica being shifted North a bit, it’s not THAT different from today. The Arctic was apparently still a poorly connected sea centered on the North Pole. Maybe circulation wasn’t that different.
    If memory serves, the scotese site has paleoclimate estimates somewhere although it isn’t immediately obvious how to get to them.

  52. General comment: I don’t really have any problem with studies like this as long as we remember that they are indicative, not definitive. We do know that lifeforms that look to be subtropical were probably thriving in the Eocene Arctic. We don’t really know for sure what the temperatures were in the Arctic, Alabama, or the tropics although we can make some somewhat educated guesses. We don’t even really know for absolutely certain where the poles were. Neither do we know what the CO2 levels were although we have some rough estimates that might be correct … or not.
    A great deal of the science I learned in high school and college in the 1950s is no longer operative. The physics has stood up well. And chemistry. Geology, on the other hand is virtually unrecognizable. And medicine … sigh … It has changed dramatically. And it is still an incoherent shambles. Frankly I’ve gotten really, really tired of people telling me what science ‘proves’. Based on past experience, my guess is that half of what science has ‘proved’ today will be unproven over the next half century. And none of us knows which half it will be.

  53. This is a nice little study that uses a relatively new isotope palaeothermometer. It is not the first study of it’s kind. For example Came et al, 2007, Nature, Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era, v449, p198-202. There will be many more such studies published over the coming years as the ‘clumped isotope palaeothermometer’ becomes more widely used as a method for determining growth temperatures for once living fossils.
    The standard 18-O isotope thermometer relies on measuring the partitioning of 18-O between calcium carbonate and the water in which the carbonate was deposited. Unfortunately such a system is usually under determined in the sense that we cannot measure the isotope composition of the water in which a particular fossil once lived. Using marine fossils we can make some assumptions about the isotopic composition of ancient oceans but these are hard to validate. The clumped isotope method relies on measuring the distribution of 18-O and 13-C in the carbonate lattice. At low temperatures the 18-O and 13-C show a slight tendency to clump together. The degree of clustering is temperature dependent and independent of the water composition in which the organism lived. The mixing thermodynamics of 18-O and 13-C are now becoming well understood theoretically and experimentally with good coherence between the 2 approaches.
    I will add a caveat. The clumped isotope method is new and has already thrown up some interesting and controversial data. The Came paper referred to above is a good example. One hypothesis for global climate evolution is that temperatures have been relatively stable, oscillating between a maxima and minima that are broadly within +/- 5 degrees or so of present day conditions (c.f. Shaviv and Veizer, 2003) and that temperatures are decoupled from atmospheric CO2 compositions. This hypothesis is supported by many thousands of 18-O analyses of Phanerozoic marine fossils. However, the Came et al study using clumped isotopes shows different temperatures to those previously estimated using just 18-O. We still don’t fully understand the origin of this discrepancy. For those interested see the online discussion of the Came et al paper at the Nature website.
    In my lab at UEA we’re carrying out similar studies to try to help understand the evolution of Earth surface temperatures throughout geologic time. It’s understandable that the early studies such as that just published focus on either hot or cold periods in Earth history. They alone however can tell us relatively little about the overall picture until a much wider range of data are available that encompass a broad palaeo-geographic and palaeo-environmental range and better temporal resolution. At the moment I’m looking for new graduate students to carry out some of this research.

  54. So basically the Sahara was no worse than it is today, Britain had a climate like Spain and Greenland was a rich and fertile place.
    All hands to the CO2 pump now!

  55. According to Prof. emerit. Jan Veizer universty of Ottwa 300 000000 years ago the CO2 content of atmosphere was at least 10 times higher as today and the earth climate was dominated by a glacial period

  56. “The question seems simple enough: What happens to the Earth’s temperature when atmospheric carbon dioxide levels increase?”
    The question is simple but wrong. The right question:
    The question seems simple enough: What’s happened to the Earth’s temperature when atmospheric carbon dioxide levels increase?
    The answer:
    The Earth’s temperature has increased.

  57. Ross, yes palm trees can survive today on the West Coast of Scotland, but only grow there because we planted them. There is no natural “reproductive route” in place today.
    The situation 50 million years ago was quite different, here there was a natural reproductive route, coupled with the fact that freezing events in the Arctic must have been very rare/non existent.

  58. So in these past eras with higher atmospheric CO2, were there corals and shellfish and arthropods? I ask because there was this National Geographic story that strongly implied the whole ocean would be as acid and fizzy as a bottle of Coke, and everything would die.

  59. Check a map of the earth 50 mya. A shallow sea where central america is now, the Med Sea connected the Atlantic and Indian Ocean (and an ocean currnet running from the Indian in the east, through the Med to the Carribean to the Pacific in the West), a massive inland sea in Asia, and no cirucm-polar current in the Antarctic as South America and Australia were practically connected to Antarctica. India still an island. No possibility this drastically different geography could have influenced the weather, er, climate?

  60. Can anyone recommend a simple ‘foundation primer’ into paleoclimate? I often see maps of Pangea and how the continents break up and move around, but it would be interesting to see that happening diagramatically, together with the likely oceanic circulations. Surely sliding all that mass around the place (not to mention ice accumulating around mountains and at poles), has to affect precession, length of day etc? How does one deconvolve all these signals to end up with consistent and reliable chronologies that allow one to reconstruct what is essentially paleogeography? There seems the real risk of building circular arguments here and so I’d assume there are reviewable foundations to the science. Where can I find them at an accessible multi-disciplinary level?

  61. “and palm trees in Alaska”
    Not all palms are tropical, there are a lot of cold hardy palms.
    Chamaerops, Trachycarpus, etc would grow in some areas of Alaska today.
    Trachycarpus is also known as the Himalayan Palm, because of where it’s from.

  62. Well, this is a Syracuse University press release. The study might or might not be a good one, but the first sentence, “…What happens to the Earth’s temperature when atmospheric carbon dioxide levels increase?” indicates that this is Syracuse U’s extreme focus. I did not find any statement about the effects of atmospheric CO2 in the abstract.
    I would be interested in studies that emerge from those universities that do not contribute heavily to political campaigns — largely these days Democratic — and that do not receive government grants with the vast majority of the funding paid to the general operating budget of the university. Are there any? I think this qualification omits Syracuse, Yale, and Stanford — oh, and probably U of Wisconsin. I would be glad for comenters here to show me where I am wrong about the funding “ethics” of our universities.
    I would also be interested, very interested, in further discussion of the proxies for temperature used, specifically delta-O-18, tetraether lipid analyses (I assume BIT – Branched and Isoprenoid Tetraether index), clumped isotope geochemistry “the study of naturally occurring, multiply-substituted isotopologues”. I had to do some research, but don’t know the science. Have they been as carefully vetted as tree rings?
    One further question — without having read the study — if these methods prove quite valuable scientifically, are younger scientists behaving honorably according to the scientific method in spite of the behaviors of many of their middle-aged priofessors? (As we can see, those educated in the time of real science, an older generation, know natural variations of “climate” and do not give in to nonsense for the purposes of keeping an elite “well funded”).

  63. Bystander says:
    July 5, 2011 at 4:41 pm
    Why bother to repeat the AGW mantra from the paper? Most people here can read. Most people here also understand it is placed there to ensure future grant funding.
    Repeating it adds nothing. Don’t waste screen space – it’s not sustainable.

  64. This would have been an interesting study if the obvious ‘CO2 causes global warming’ blah blah blah wasn’t included in the middle and the end of the article. (I paraphrased). Credibility falls when there is an obvious desire to support a particular slant through extrapolation. The mystery still stands as to whether warming (through the sun’s activities and earth’s rotation, tilt, etc) produces more CO2, or does CO2 add to warming? The evidence of the cool period during and after the onset of the industrial revolution paints evidence of the former.

  65. Dixon says:
    July 6, 2011 at 7:03 am
    Can anyone recommend a simple ‘foundation primer’ into paleoclimate? I often see maps of Pangea and how the continents break up and move around, but it would be interesting to see that happening diagramatically, together with the likely oceanic circulations. …
    ====
    Try here http://www.scotese.com/climate.htm If you find that helpful, move up to the home page for the site and prowl around. There’s quite a lot of stuff there and no particular agenda that I’m aware of.

  66. Dixon says:
    July 6, 2011 at 7:03 am
    “…Can anyone recommend a simple ‘foundation primer’ into paleoclimate?…”
    Your question veered into plate tectonics and other things (probably because its necessary). These two textbooks are about as good as it gets for the general discussion. After that, you have to read many, various papers.
    Origin and Evolution of Earth: Principles of Historical Geology
    Kent C. Condie (Author), Robert E. Sloan (Author)
    Plate Tectonics, Fourth Edition
    Kent C. Condie (Author)
    Check these out at Amazon and other booksellers. I’m not sure what the latest revision dates are.

  67. while I applaud the effort it is VERY reckless to make such generalisations from such a small data set. a single geographic data point is not representative of the whole earth. the real question that I have is: why was the co2 level so high and also what was caused the change between greenhouse conditions at this time and the icehouse condition that followed?

  68. sunsettommy says:
    July 5, 2011 at 4:11 pm
    “How would they know what temperature range it was in the polar regions? From samples in Alabama.Only 2,500 miles to the south.”
    Several people have made similar complaints. The authors talked about previous estimates of high latitude temperatures being as much as 30C in the arctic. Then they found in their analysis that it wasn’t that warm even in sub-tropical latitudes. Then they quite reasonably presumed that it couldn’t be warmer in Alaska than it was in Georgia. So they didn’t really give a temperature “range” for polar regions but rather put a cap on maximum temperature that was substantially cooler than was previously thought.
    This study is not good news for eco-warrior climate boffins. It puts maximum summer temperature in the sub-tropics at only 5F warmer than today while winter temperatures were a great deal warmer than today.
    Of course many of us have been trying to say this for years. “Global warming” from GHGs isn’t a case of everywhere on the planet getting X number of degrees of warmer. It is very unevenly distributed warming both spatially and temporally. Winters become much warmer and summers not so much. High latitudes become much warmer but low latitudes not so much. This is ideal. One couldn’t ask for a better result for living things. It’s basically the greening of the whole planet we’re talking about. What’s so bad about that?

  69. The July 2011 Scientific American has a lengthy article entitled “The Last Great Global Warming” and talks about the same period as the OP here 50-60mya.
    Interestingly the focus is on how long it took to warm up. The author, L.R. Kump, portrays the warm-up period as much slower than previously thought at 0.025C per century. It appears the eco-loons are retreating to a fall back position where that position is basically: Warming isn’t necessarily bad so long as life has plenty of time to adapt to it.
    Back in the days when the evidence was more widely acknowledged this was the global warming mantra. It wasn’t the warming so much as how fast the warming is happening and life won’t have time to adapt. Species won’t have time to adapt, evolve, or migrate. Kump goes so far as to say 50 million years ago there weren’t roads and cities blocking the migration paths northward.
    Kump bringing up roads and other manmade structures as impediments to migration it became clear he was clutching at straws. Truth will out and the CAGW meme is withering on the vine as a result. It’s all over except the crying. Once you see major players clutching at straws like Kump did it’s a done deal.

  70. John of Cloverdale Perth WA says:
    July 5, 2011 at 4:57 pm
    So what caused the atmospheric CO2 levels to rise without man made emissions and then fall without an Australian carbon tax?
    ____________________________________________________
    …. As to that Australian Carbon Tax….. Imagine the weapon that Gillard now wields!!! If the World does not bow to her magnificance, omnipotence and weird red hair….. She’ll tax the Aussie population to within an inch of it’s life….. and freeze the World solid!… Mwuhahahahahaha…..

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