Today’s Climate More Sensitive to Carbon Dioxide Than in Past 12 Million Years
Geologic record shows evolution in Earth’s climate system
The phytoplankton Emiliania huxleyi offers clues about climate past, present and future.
Until now, studies of Earth’s climate have documented a strong correlation between global climate and atmospheric carbon dioxide; that is, during warm periods, high concentrations of CO2 persist, while colder times correspond to relatively low levels.
However, in this week’s issue of the journal Nature, paleoclimate researchers reveal that about 12-5 million years ago climate was decoupled from atmospheric carbon dioxide concentrations. New evidence of this comes from deep-sea sediment cores dated to the late Miocene period of Earth’s history.
During that time, temperatures across a broad swath of the North Pacific were 9-14 degrees Fahrenheit warmer than today, while atmospheric carbon dioxide concentrations remained low–near values prior to the Industrial Revolution.
The research shows that, in the last five million years, changes in ocean circulation allowed Earth’s climate to become more closely coupled to changes in carbon dioxide concentrations in the atmosphere.
The findings also demonstrate that the climate of modern times more readily responds to changing carbon dioxide levels than it has during the past 12 million years.
“This work represents an important advance in understanding how Earth’s past climate may be used to predict future climate trends,” says Jamie Allan, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences, which funded the research.
The research team, led by Jonathan LaRiviere and Christina Ravelo of the University of California at Santa Cruz (UCSC), generated the first continuous reconstructions of open-ocean Pacific temperatures during the late Miocene epoch.
It was a time of nearly ice-free conditions in the Northern Hemisphere and warmer-than-modern conditions across the continents.
The research relies on evidence of ancient climate preserved in microscopic plankton skeletons–called microfossils–that long-ago sank to the sea-floor and ultimately were buried beneath it in sediments.
Samples of those sediments were recently brought to the surface in cores drilled into the ocean bottom. The cores were retrieved by marine scientists working aboard the drillship JOIDES Resolution.
The microfossils, the scientists discovered, contain clues to a time when the Earth’s climate system functioned much differently than it does today.
“It’s a surprising finding, given our understanding that climate and carbon dioxide are strongly coupled to each other,” LaRiviere says.
“In the late Miocene, there must have been some other way for the world to be warm. One possibility is that large-scale patterns in ocean circulation, determined by the very different shape of the ocean basins at the time, allowed warm temperatures to persist despite low levels of carbon dioxide.”
The Pacific Ocean in the late Miocene was very warm, and the thermocline, the boundary that separates warmer surface waters from cooler underlying waters, was much deeper than in the present.
The scientists suggest that this deep thermocline resulted in a distribution of atmospheric water vapor and clouds that could have maintained the warm global climate.
“The results explain the seeming paradox of the warm–but low greenhouse gas–world of the Miocene,” says Candace Major, program director in NSF’s Division of Ocean Sciences.
Several major differences in the world’s waterways could have contributed to the deep thermocline and the warm temperatures of the late Miocene.
For example, the Central American Seaway remained open, the Indonesian Seaway was much wider than it is now, and the Bering Strait was closed.
These differences in the boundaries of the world’s largest ocean, the Pacific, would have resulted in very different circulation patterns than those observed today.
By the onset of the Pliocene epoch, about five million years ago, the waterways and continents of the world had shifted into roughly the positions they occupy now.
That also coincides with a drop in average global temperatures, a shoaling of the thermocline, and the appearance of large ice sheets in the Northern Hemisphere–in short, the climate humans have known throughout recorded history.
“This study highlights the importance of ocean circulation in determining climate conditions,” says Ravelo. “It tells us that the Earth’s climate system has evolved, and that climate sensitivity is possibly at an all-time high.”
Other co-authors of the paper are Allison Crimmins of UCSC and the U.S. Environmental Protection Agency; Petra Dekens of UCSC and San Francisco State University; Heather Ford of UCSC; Mitch Lyle of Texas A&M University; and Michael Wara of UCSC and Stanford University.
-NSF-
Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Matthew Wright, Consortium for Ocean Leadership (202) 448-1254 mwright@oceanleadership.org
Related Websites
Integrated Ocean Drilling Program: http://www.iodp.org
JOIDES Resolution: http://joidesresolution.org/
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.
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Late Miocene decoupling of oceanic warmth and atmospheric carbon dioxide forcing
Jonathan P. LaRiviere, A. Christina Ravelo, Allison Crimmins, Petra S. Dekens, Heather L. Ford, Mitch Lyle & Michael W. Wara
Nature 486, 97–100 (07 June 2012) doi:10.1038/nature11200
Received 15 November 2011 Accepted 02 May 2012 Published online 06 June 2012
Deep-time palaeoclimate studies are vitally important for developing a complete understanding of climate responses to changes in the atmospheric carbon dioxide concentration (that is, the atmospheric partial pressure of CO2, pco2)1. Although past studies have explored these responses during portions of the Cenozoic era (the most recent 65.5 million years (Myr) of Earth history), comparatively little is known about the climate of the late Miocene (~12–5 Myr ago), an interval with pco2 values of only 200–350 parts per million by volume but nearly ice-free conditions in the Northern Hemisphere2, 3 and warmer-than-modern temperatures on the continents4. Here we present quantitative geochemical sea surface temperature estimates from the Miocene mid-latitude North Pacific Ocean, and show that oceanic warmth persisted throughout the interval of low pco2 ~12–5 Myr ago. We also present new stable isotope measurements from the western equatorial Pacific that, in conjunction with previously published data5, 6, 7, 8, 9, 10, reveal a long-term trend of thermocline shoaling in the equatorial Pacific since ~13 Myr ago. We propose that a relatively deep global thermocline, reductions in low-latitude gradients in sea surface temperature, and cloud and water vapour feedbacks may help to explain the warmth of the late Miocene. Additional shoaling of the thermocline after 5 Myr ago probably explains the stronger coupling between pco2, sea surface temperatures and climate that is characteristic of the more recent Pliocene and Pleistocene epochs11, 12.
PDF files
- Supplementary Information (291K) This file contains Supplementary Text, Supplementary References and Supplementary Figure 1.
Excel files
- Supplementary Data (688K) This file contains Supplementary Data used in Figure 1.
CO2 here, CO2 there, CO2 everywhere.
“In the late Miocene, there must have been some other way for the world to be warm. ”
Not a word about the times CO2 was 10 times that of today’s.
Again: shoot the arrow, then paint the target around it.
“It’s a surprising finding, given our understanding that climate and carbon dioxide are strongly coupled to each other,” Perhaps the ‘strongly coupled’ part is questionable?
This was only to be expected in the runup to the new IPCC report. The warm climate of the Miocene (and Pliocene) has always been a problem since it shows pretty conclusively that CO2 is not an important climate driver.
This paper (without any real evidence) essentially says “Yes, yes but NOW it depends on CO2, so there”
All this assumes that there is currently such a strong coupling between temperature and CO2 !
While CO2 reportedly exceeds 400 ppm for the first time ever in teh Arctic, temperatures stubornly refuse to follow suit
Game, set and match Mother Earth
Complete fantasy, but quite inventive. As the last 15 years have shown climate is exactly not coupled to changes in CO2 levels, so the premise falls flat on its face, and from a scientific point of view it makes no sense to examine their line of argument any further. For aspiring science fiction writers, it might be interesting… but I guess David Brin has depleted the Global Warming science fiction market segment already to a point that he now has to compare climate skeptics to German Landjunkers… probably his next move will be “I’m a celebrity, get me out of here”… so that market seems to be dead as well…
Hmmm… how many coauthors? Asking just to use Willis’ formula to calculate the ammount of bullshit in this… study?
So … the claim of the AGW crowd all this time has been that CO2 is the secret control, the magic temperature dial. They say that when CO2 goes up and down the climate has to, must, is required to follow. There’s no choice, they say, it’s “basic physics”.
Now these scientists are saying that no, the earth can go for millions of years with the temperature paying no attention to the CO2 levels.
Sure wish they’d make up their minds …
w.
“The scientists suggest that this deep thermocline resulted in a distribution of atmospheric water vapor and clouds that could have maintained the warm global climate.
“The results explain the seeming paradox of the warm–but low greenhouse gas–world of the Miocene,” says Candace Major, program director in NSF’s Division of Ocean Sciences.”
So water vapour isn’t a greenhouse gas?
With higher SST CO2 would be less soluble so I would expect higher atmospheric levels….so where did the CO2 go to?
Could it be warmer is better and both growing season and growth range would increase thereby locking up more CO2 in plant material?
Good grief, it’s epicycles all over again. Instead of drawing the obvious conclusion that the colder oceans of the ice age we’re in drive co2 and not vice versa, they’re clinging to AGW theory. It’s the oceans capacity for draining the atmosphere of co2 during glaciations that’s the difference to the Miocene! Draining to a level where plants are starving (during the last couple of glaciations co2 was dangerously low). . The 280 ppm level during interglacials is probably an equilibrium level where plants start to starve slightly and thus stop sucking co2 out of the atmosphere.
This paper is a good thing. Finally it is dawning on some people that CO2 isnt the only driver of climate. Maybe they’ll start to look more closely at todays ocean circulation, e.g. the PDO.
“It’s a surprising finding, given our misunderstanding that climate and carbon dioxide are strongly coupled to each other.”
There. That’s better.
P.S. Note that “strongly coupled” leaves causality open. Because of the time travel thing, you see.
“Until now, studies of Earth’s climate have documented a strong correlation between global climate [temperature?] and atmospheric carbon dioxide…”
Then this widely available reconstruction must be wrong:
http://www.americanthinker.com/%231%20CO2EarthHistory.gif
“The results explain the seeming paradox of the warm–but low greenhouse gas–world of the Miocene,”
Paradox – unless the 1.4 billion km3 of liquid water has something to do with the climate.
The real mystery is not why it was warmer in the Miocene, but instead why the Earth cooled during the Pliocene triggering regular glacial cycles. They seem to be proposing that the closing of the Panama isthmus closed down global ocean circulation of heat. In that case, we should challenge current GCM models to reproduce conditions in the Miocene by using the land distribution existing 12 million years ago !
I would say that natural climate sensitivity would be higher during ice ages than inbetween. Durable changes in avarage temperature would cause changes in ice cover at lower latitude, where any change would have far higher implications for earths albedo.
“In the late Miocene, there must have been some other way for the world to be warm.”
Because physics was just so very *different* in the late Miocene, yanno…
The first paragraph claim that warm periods in the past had high atmospheric concentrations of CO2, the converse being true as well is a lie! The Ordovician had very high atmospheric CO2 concentrations, some research claim 8000ppmv, but the Ordovician had a severe ice age.
After that false claim I left the rest especially since the writers wish us to believe that atmospheric physics changed for no apparent reason.
Richard (thick as two short planks) Black has been bigging it up at the Bullsh1t Broadcasting Corporation with his report that “team of scientists warns that life on Earth may be on the way to an irreversible “tipping point”. Who are these clowns?
http://www.bbc.co.uk/news/science-environment-18339905
As it will be another 5 billion years before this planet ends up inside the Sun, which is posited to expand to a diameter of 250 million miles; that should be quite long enough for Earth to “recover” to whatever state of pristine verdancy existed before we clever apes stood up and decided to improve our circumstances. In other word, this planet will continue to spin on its axis on its orbit around the Sun, for billions of years after we humans are extinct. Irreversible tipping point? ‘Koff.
Isn’t it strange how Richard Black looks almost the same as Michael Mann who appears also to be very similar to Gavin Schmidt? Are they actually all the same person?
“In the late Miocene, there must have been some other way for the world to be warm.”
And why not? There’s “some other way for the world to be warm” now, after all, as anyone who’s tried to correlate CO2 with anything knows.
We all know that CO2 is the only significant driver of Earth’s climate. Why is it so difficult to formalaccept that fact, simply because for a brief period “about 12-5 million years ago climate was decoupled from atmospheric carbon dioxide concentrations“? The far more important period from 1976 to 1998 demonstrates beyond all possible doubt how CO2 drives the global temperature. Obviously, in something as complex as climate, there will be brief periods when the temperature fluctuates independently of CO2. This period 12.5 million years ago was obviously one of them. The period from 1940 to 1976 was another, as was the last 14 years. But when the current brief fluctuation ends, then the temperature will continue to be driven higher by the high concentrations of CO2.
It’s that simple. Eyal Porat’s idea that they “shoot the arrow, then paint the target around it” just doesn’t stand up under this kind of argument. I think it’s called ‘argument by assertion’.
Christopher Hanley says:
June 7, 2012 at 1:07 am
//////////////////////////////////
Absolutely (although I am always sceptical of proxy recontructions).
The same lack of correlation between CO2 and temperature can be seen in the instrument record from 1850 to date. There is no correlation (sometimes even anti correlation!!) between CO2 and temperature and this is why ‘fudge’ factors such as aerosols need to be added to try and explain why temperatures fell (or plateaued) whilst CO2 levels increased.
When one further considers the ice core records which seem to suggest that CO2 lags temperature and is therefore a response not a driver to temperature change, one would consider that it is time to reconsider the basic premise as to whether as a matter of so called ‘basic’ physics CO2 controls temperature.
only thing thing they got right was the importance of ocean circulation
Sounds to me like stage setting premises covering two key bases: to permit on the one hand, a potential exit from the modeled doctrine of CO2 – temperature coupling, in order to allow a greater latitude of explanation for present day observations, and on the other, to lay ‘supported’ claim to high climate sensitivity in order to provide support for CAGW models.
It would seem, from this current publication under discussion, that ‘multiproxy strategies in paleoceanographic studies’ have come a long way since 2000 (see ref. below). Nevertheless, paleoceanography remains as uncertain a discipline as paleoclimatology. Both disciplines require considerable trust in mulitple proxies of every variable under analysis. Furthermore, the pCO2 conc. error bars (and proxies range) are sufficiently generous to permit a substantial laxity of interpretation, see Fig S1 1. Estimates of atmospheric pCO2 SUPPLEMENTARY INFORMATION Nature 486, 97–100 (07 June 2012). In this graphic representation, I personally struggle with the superimposition of a (gray) straight line across 15Myr (the full range of the x axis) that actually represents a point of ‘known’ value – pre-industrial pCO2 concentration – on a graph about ‘estimation’, and a selected known point in time (no error bars) spanning 15Myr. But then, why get in the way of marketing?
Alkenones and multiproxy strategies in paleoceanographic studies
A. C. Mix et al.
Geochemistry, Geophysics, Geosystems
Review, Volume 1, November 22, 2000 Paper number 2000GC000056, ISSN: 1525-2027
Copyright 2000
****
peeke says:
June 7, 2012 at 1:50 am
I would say that natural climate sensitivity would be higher during ice ages than inbetween. Durable changes in avarage temperature would cause changes in ice cover at lower latitude, where any change would have far higher implications for earths albedo.
****
Of course. As ice/snow extends into lower latitudes, it reflects more sunlight. Ice/snow is rather easily changeable, so now large areas of land (mostly N hemisphere) are subject to these relatively rapid albedo changes where they weren’t before. So the warmers’ whining complaints about sensitivity studies using current conditions not being able to explain ice-age conditions are absurd.
It’s ok for c02 and climate not to be linked in the Miocene when there are no coal power stations around, no tourism in the Maldives to worry about, and no Earth Hour. But what on earth are all these environmental socialists going to do if it isn’t linked in the current time period either?
This is just more epicycles to cover holes in their theory.
The complex explanation given by the authors is a candidate for Occam’s Razor. This tells us that the assumed relationship between CO2 and temperature is probably wrong.
I read about this sort of research, and my surprising finding is that people who should know better are so often surprised by findings.
Seriously, his own qualifier, “given our understanding” should probably be the tip-off. Probably a more accurate statement would have been:
“It’s a surprising finding, and one that may indicate that climate and carbon dioxide are not strongly coupled to each other, or at least not in the direction we believed.”
However, I seriously doubt that people who are committed to showing how harmful human achievement is to the planet are capable of recognizing that things aren’t nearly as dire as they believed.
Absolute BS and they know it.
The paper was probably rejected before the wording was changed to praise the appropriate comrades.
So when it was assumed that there was a correlation between paleo climate and CO2, it was proof of CO2 induced global warming, now that CO2 is not correlating with paleoclimate it is proof of CO2 induced global warming, which is proving that global warming is not falsifiable, hence it is not science but dogma.
“‘Where are the books? The poems? The plays? The goddamn operas?” So asked Bill McKibben, author and environmental campaigner, venting frustration at the cultural failure to address climate change. ” – http://www.telegraph.co.uk/earth/environment/9305638/A-cold-climate-in-the-arts-world.html
Looks like creative writing to me.
So basically, the study found that the climate was insensitive in the past, then the authors jump through hoops to say that this doesn’t contradict the belief that it is very sensitive now.
Excuse me while I suppress laughter and tears.
Willis Eschenbach says:
June 7, 2012 at 12:30 am
So … the claim of the AGW crowd all this time has been that CO2 is the secret control, the magic temperature dial. They say that when CO2 goes up and down the climate has to, must, is required to follow. There’s no choice, they say, it’s “basic physics”.
Now these scientists are saying that no, the earth can go for millions of years with the temperature paying no attention to the CO2 levels.
Sure wish they’d make up their minds …
w.
—————-
Science is hard enough but, climate science is really hard.
It’s not easy hitting a random moving target.
“It’s a surprising finding, given our understanding that climate and carbon dioxide are strongly coupled to each other,” LaRiviere says.
_______________________________________
Well LaRiviere, the scientific method says when the evidence blows a big hole in your “Understanding” then your “Understanding” is DEAD WRONG and it is time to come up with a different hypothesis. That is how science advances. Clinging to a disproven conjecture is not science.
If you and your buddies do not “Understand” that very critical part of the scientific method, it is time for you to turn in your PhDs and find another job like washing dishes in a diner.
As stated many times before and still appropriate: what a waste of time, grants, and research pursuit.
So much time, money and effort spent but so little gain, if any.
I have a database of CO2 estimates that I continually update as new estimates are made. I think I have all the estimates they used in this paper (added a couple of new ones from the paper).
[There is one series they used that I have excluded, Pagani 2010 which used a new methodology that produces CO2 estimates that are much higher than the ice cores in the period they overlap so we have to assume this methodology is not accurate – I’ve excluded another methodology, paleosols or fossil soils or pedogenic carbonates since this method has been shown to not be reliable since it depends on the time of year or season that the samples were laid down and this varies by large amounts throughout a season so it is not reliable).
So here is all the reliable CO2 estimates going back 25 million years. The authors could have extended the “decoupling” time period back to 25 million years ago. CO2 fell below 280 ppm, for perhaps the very first time, 24 million years ago and it has been there (give or take an ice age lowering it to 185 ppm and some outlier 450 ppms) ever since.
http://img338.imageshack.us/img338/5300/co2last25mys.png
CO2 going back 150 million years. If you also have the temperature estimates for the period, one would see even longer “decoupling”.
http://img138.imageshack.us/img138/2633/co2last150mys.png
CO2 going back 750 million years – more decoupling.
http://img213.imageshack.us/img213/7295/co2last750mys.png
The sources for these charts are: Antarctic Epica DomeC ice cores, Pagani 2005, Pagani 2008, Berner GeoCarb III, Royer 2004, Royer 2006, IPCC AR4, Pearson 2000, Pearson 2009, Triparti 2009, Bao 2008, Honisch 2009, Seki 2010, Beerling and Royer 2011, Bartoli 2011.
The only evidence revealed by this is the use of micro-fossils from deep-sea sediment cores dated to the late Miocene period of Earth’s history, as proxies, to demonstrate that “temperatures across a broad swath of the North Pacific were 9-14 degrees Fahrenheit warmer than today, while atmospheric carbon dioxide concentrations remained low…”
All the rest is “may be”, “must have”, “could have”, “one possibility”. Just speculation which falls down when simply tested with CO2 / temperature comparisons from the last 11,000 years.
http://wattsupwiththat.files.wordpress.com/2012/04/gisp220temperaturesince1070020bp20with20co220from20epica20domec1.gif
http://wattsupwiththat.com/2012/04/11/does-co2-correlate-with-temperature-history-a-look-at-multiple-timescales-in-the-context-of-the-shakun-et-al-paper/
Espen says:
Good grief, it’s epicycles all over again. Instead of drawing the obvious conclusion that the colder oceans of the ice age we’re in drive co2 and not vice versa, they’re clinging to AGW theory.
When the theory dosn’t account for all of the facts/observations. Then it’s time for a different theory. That is the basis of what we call “science”. Clinging to a theory regardless is more the behaviour of a “nutjob conspiracy theorist”.
It’s the oceans capacity for draining the atmosphere of co2 during glaciations that’s the difference to the Miocene! Draining to a level where plants are starving (during the last couple of glaciations co2 was dangerously low). . The 280 ppm level during interglacials is probably an equilibrium level where plants start to starve slightly and thus stop sucking co2 out of the atmosphere.
So far as many species of plant are concerned (possibly including those which have evolved CAM and C4 metabolic pathways) below 1,000 ppm is deficient. So much so that there are products available specifically to increase the level in commercial greenhouses beyond this. Humans can breath such air indefinitly. Indeed calling carbon dioxide a “greenhouse gas” makes most sense in that it is a good gas to have in a greenhouse.
The obvious conclusion is the ancestors of many living organisms (including us) were alive at a time when Earth had greater than 1,000 ppm co2 in its atmosphere.
Perry says:
Richard (thick as two short planks) Black has been bigging it up at the Bullsh1t Broadcasting Corporation with his report that “team of scientists warns that life on Earth may be on the way to an irreversible “tipping point”. Who are these clowns?
Wonder if they can explain why such “tipping points” don’t appear to have happened in the past. Thus we are around to consider their possible existance.
The scientists suggest that this deep thermocline resulted in
“The results explain the seeming paradox of the warm–but low greenhouse gas–world of the Miocene,” says Candace Major, program director in NSF’s Division of Ocean Sciences.
This is only a “paradox” is one subscribes to the erroneous idea that CO2 has a major effect on climate.This does not require that the climate has “evolved” or the laws of physics have changed, it simply requires that climate “science” evolves to encompass the critical thinking that we commonly presume is the foundation of all science.
“… a distribution of atmospheric water vapor and clouds that could have maintained the warm global climate.” Yeah, like the climate we know today.
WEIRD.
>>
Indeed calling carbon dioxide a “greenhouse gas” makes most sense in that it is a good gas to have in a greenhouse.
>>
Good line that, I’ll remember that one.
Willis Eschenbach says:
So … the claim of the AGW crowd all this time has been that CO2 is the secret control, the magic temperature dial. They say that when CO2 goes up and down the climate has to, must, is required to follow. There’s no choice, they say, it’s “basic physics”.
In which case what do physicists have to say about it? Arn’t they more qualified to comment on “basic physics” than climate scientists. (That being the approach the latter often taken when someone outside their group treads on their “turf”.)
Logically, based on their contention that oceanic circulation was an overwhelmingly strong driver of temperature trends capable of devouring whatever effects CO2 may have been capable of, they did not answer their own question: What makes ocean circulation such a weak player now? The assumption has been made that today, oceanic circulation is a benchsitter compared to eons ago.
The paper fails to answer how much capacity the previous driver (oceanic circulation) has lost to generate temperature trends. And how did it lose it? And where did it go? In order for such a tiny player (CO2) to overwhelm oceanic circulation as the power house temperature trend driver, the oceans must lose their capacity in LARGE measure. Epic fail.
“The Miocene Problem” is one that has been around for quite a while. Early on, I think there were attempts made to try to disprove the warmth of large intervals of the Miocene. That didn’t work out. The last thing on this (previous to me) was the pore size analysis on some fossil leaves in some attempt to (I think) prove the CO2 was actually higher during the Miocene.
Now, it’s the total disconnect. Great. I suppose the full article has the breakdown of the Miocene, because there’s a pretty good break around the time the Antarctic ice started accumulating. In the Gulf of Mexico depositional history, it’s basically the difference between the Upper Miocene and the Lower Miocene. In other words, even within the Miocene, you had some serious changes going on – I suspect the formation of the Antarctic ice in the middle of the Miocene was much more of an EVENT. A fast chill.
I suspect The Miocene Problem will remain just that.
However, in this week’s issue of the journal Nature, paleoclimate researchers reveal that about 12-5 million years ago climate was decoupled from atmospheric carbon dioxide concentrations. …During that time, temperatures across a broad swath of the North Pacific were 9-14 degrees Fahrenheit warmer than today, while atmospheric carbon dioxide concentrations remained low–near values prior to the Industrial Revolution.
Don’t see the low level of CO2 here: http://i46.tinypic.com/2582sg6.jpg
nor here: http://i55.tinypic.com/11awzg8.jpg
Don’t see climate coupled to CO2 either, ice cores show CO2 coupled to climate, not the other way around.
Causation or correlation?
It is causation when it supports one’s beliefs, and correlation, when it does not.
Don’t be so harsh everyone!
What these scientists are doing is trying to publish the proof that CO2 AGW is bullshit but they know that they will loose their jobs if they say so openly. These are soft bellied, scientists who’s idea of a heavy conflict is bravely sending in an unfavourable peer-review to someone’s paper.
They are not mujahideen warriors. They don’t do conflict.
So what they have to do is call it a “paradox” and then present the scientific evidence that shows “other factors” such as water vapour and cloud _may_ also have and impact. They then dress it up with the usual AGW spin in order to get it published and to ensure they get their grants for next year.
Then if 5 or 10 years time when we are all shivering our way through summers of crop failure they can come back and say: “well of course we published proof that CO2 was not the primary driver it was assumed to be as early as 2012 but no one was really ready to listen at that time. You know how slow it is to change the scientific authodoxy…”
One of my favourite examples of this is ER Thomas et al’s “unprecedented warming in Antarctica” claim
GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L20704, doi:10.1029/2009GL040104, 2009
Ice core evidence for significant 100-year regional warming on the Antarctic Peninsula
Abstract
[1] We present a new 150-year, high-resolution, stable isotope record (δ18O) from the Gomez ice core, drilled on the data sparse south western Antarctic Peninsula, revealing a ~2.7°C rise in surface temperatures since the 1950s. The record is highly correlated with satellite-derived temperature reconstructions and instrumental records from Faraday station on the north west coast, thus making it a robust proxy for local and regional temperatures since the 1850s. We conclude that the exceptional 50-year warming, previously only observed in the northern Peninsula, is not just a local phenomena but part of a statistically significant 100-year regional warming trend that began around 1900. A suite of coupled climate models are employed to demonstrate that the 50 and 100 year temperature trends are outside of the expected range of variability from pre-industrial control runs, indicating that the warming is likely the result of external climate forcing.
Received 16 July 2009; revised 4 September 2009; accepted 23 September 2009; published 24 October 2009.
Keywords: ice cores, Antarctic Peninsula, climate change.
Now, buried in the pay-walled article is a graph that shows a circa 120y “principal component” peaking around y2k. It’s not even covered in the text but it’s telling us what most readers here already know. Global warming is over for the foreseeable future.
It’s like the esoteric writings of the middle ages. There is the obvious message for the profane reader and the “hidden knowledge” only visible to the initiated.
Science has become the church that is was intended to replace. It has its monks and high priests and its secret writings. And the surfs must pay their tithes and taxes to pay for the fine robes and pot bellies.
The findings also demonstrate that the climate of modern times more readily responds to changing carbon dioxide levels than it has during the past 12 million years.
Sorry! The Bible does not allow you to change the laws of physics. Improvement needed.
Jeremiah 33
Easy-to-Read Version (ERV)25 The LORD says, “If my agreement with day and night does not continue, and if I had not made the laws for the sky and earth, maybe I would leave those people.”
When did the laws of physics change? Do I get a vote? Does the scientific method mean anything?
Jeez, this reminds me of a guy I once worked with. He claimed that the great pyramids could have easily been built by humans in ancient times because there was less gravity. Seriously, no kidding.
These people are idiots: the greatest Chemical Engineer on history made empirical ,measurements of the emissivity [=absorptivity] of CO2. It levels off at 200ppmV.
The explanation is that the IPCC’s assumption of direct thermalisation is wrong. In reality, it’s indirect and it seems that like the walls of the container at which that indirect thermalisation occurs [Tyndall’s brass tube, the PET bottle] clouds likewise reduce the CO2-specific band energy on re-emission, perhaps more so because they also getter local CO2.
It’s discussed further here:http://tallbloke.wordpress.com/2012/06/07/mdgnn-limits-on-the-co2-greenhouse-effect/#more-6600
Mike Jonas says:
It’s that simple. Eyal Porat’s idea that they “shoot the arrow, then paint the target around it” just doesn’t stand up under this kind of argument. I think it’s called ‘argument by assertion’.
It’s more like SAYING “The arrow hit the target” without even bothering with an arrow or a target…
Isn’t this paper basically just saying “It’s different this time?”
The report’s conclusions center on a measure of the amount of the earth’s land surface that has been transformed by people, from forests and prairies to uses such as cornfields and parking lots. The percentage of transformed land now stands at 43 percent, with the world’s population at seven billion.
Given this, how can any “green” politician think that “bio-fuels” are a viable solution ?
“Until now, studies of Earth’s climate have documented a strong correlation between global climate [temperature?] and atmospheric carbon dioxide…”
Ahhhh…NO!
I don’t think there has been any study of Earth’s historical climate that shows a strong correlation between global atmospheric temperatures and atmospheric CO2 levels. There have been lots of models that show such a correlation because they are programmed to do so, but the actual atmosphere does not. Granted, some studies have done a curve fit of late 20th Century temperature to the late 20th Century rise of CO2, but beyond that time frame, there are no indications of a correlation.
We do not have to go back 5 million years to find a ‘disconnect’ between temperature and CO2. Anytime other than the late 20th Century will do, including the start of the 21st Century.
If the truth sets us free…What do lies do?
“The findings also demonstrate that the climate of modern times more readily responds to changing carbon dioxide levels than it has during the past 12 million years.” Hum, since the physics and chemistry have not changed why should this be even remotely considered. The oceanic circulation patterns are variable the physics and chemistry are not. This is simply more hypothetical modeling bullshit.
Did it not occur to anyone on the Committee of Seven savants who put their names on this paper that their ‘understanding’ was plain wrong?
That’s usually a serious possibility when your experimental results conflict with established ideas.
Apparently the Biblical adage remains true: “There are none so blind as those who will not see.
/Mr Lynn
Every novel scientific discovery has a ‘wow’ factor, wherein one goes “I never would have predicted that!” And this hypothesis seems equally unlikely.
However I will play the mind game with them. The middle Miocene is noted for a dramatic cooling that caused mass extinctions, huge grass lands instead of forests, bordered by continental deserts. The cooler atmosphere simply could not absorb as much moisture as it previously did. Or so paleontologist say. The Earth is still in this phase. So shouldn’t a bit of warming be a good thing? The Earth can then get back to the good old days, when it was less sensitive to the dreaded CO2 and tropical forests were far more extensive. The central deserts were grass lands and Australia a paradise. In other words, I tend to concur with some here who surmise that these scientists are really skeptics demonstrating that atmospheric CO2 is self correcting.
TomB says:
June 7, 2012 at 8:19 am
Jeez, this reminds me of a guy I once worked with. He claimed that the great pyramids could have easily been built by humans in ancient times because there was less gravity. Seriously, no kidding.
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Sure, but since the average Egyptian worker at the time the great pyramid was built was only three inches tall, the low gravity didn’t help all that much. Once you allow folks to make up facts and adjust data to suit their needs, you end up with fourteen dimensional chess, chaos, economics, nutrition … or “climate science”.
I should think that the first response of any thinking entity confronted with this should be — are we sure that the CO2 and temperature proxies being used are any damn good? Apparently that’s not a reasonable question.
As mentioned above, no causal relationship was established. Since the work supports a vast political machine, from the perspective of government, the grant money spent and the time required for the work were not wasted.
This paper is a prime example why not everyone show receive higher education.
I think the significance of the closing of the Isthmus of Panama is overestimated. You can toggle the continents through time in Google Earth and it is clear that not much water (and certainly no deep water) was getting through there even as far back as the Eocene.
There was a better channel through Indonesia so one would expect no “warm pool” there. The Bearing passage was wider but the continental shelves remained in contact preventing deep water escape and the Aleutian Arc (closer to the strait then) would have been a further restriction.
Let’s have a look at the Miocene Earth, 14 million years ago.
http://www.scotese.com/images/014.jpg
No real ice in the Northern Hemisphere (Greenland was still Green but got very cold in the winter and there was probably some Arctic sea ice in the winter). Over the next 11 million years Greenland moved 220 kms to the northwest, (it has been moving at 2 cm/yr for the past 55 million years since splitting away from Europe). This extra 220 kms was just enough so that it became succeptible to the Milankovitch Cycle downturns and it subsequently glaciated over sometime around 3 million years ago.
The Panama Isthmus is still open, the Meditterrean-Tethys link to the Indian Ocean is still open, there is a much stronger East to West equatorial current which may have been able to completely circulate the planet at this time (rather than being directed into the Gulf Stream and Kuroshio Current as it does today). Sea level higher and much of the continents are flooded.
There is almost no savannna or desert at this time. The planet was almost completely forested. At about 8 million years ago, there appears to be a significant change in the climate where rainfall declined substantially and this marks the emergence of deserts and savannna grasslands. C4 grasses pollen is very, very low in the geologic record until 8 million years ago.
Antarctic ice is about one-half of todays level although in the next few million years, it reglaciates again. But at 14 Mya, it is mainly in the interior.
So, the Miocene planet is very, very different than the current one. It certainly has lower Albedo than the current Earth (about 27% versus 30% today) given there is less ice, more forest and more ocean. More sunlight able to warm the Earth so ti is warmer.
Simple enough explanation in my opinion (which also works for just about any other period in Earth History you want to look at). No CO2 changes are required to explain it, just continental configurations and the resulting Albedo.
*Sigh*. You forgot the “/sarc” tag. People will think you’re serious.
Mike Jonas says:
June 7, 2012 at 3:19 am
“We all know that CO2 is the only significant driver of Earth’s climate. Why is it so difficult to formalaccept that fact, simply because for a brief period “about 12-5 million years ago climate was decoupled from atmospheric carbon dioxide concentrations“? The far more important period from 1976 to 1998 demonstrates beyond all possible doubt how CO2 drives the global temperature. Obviously, in something as complex as climate, there will be brief periods when the temperature fluctuates independently of CO2. This period 12.5 million years ago was obviously one of them. The period from 1940 to 1976 was another, as was the last 14 years. But when the current brief fluctuation ends, then the temperature will continue to be driven higher by the high concentrations of CO2.
It’s that simple. Eyal Porat’s idea that they “shoot the arrow, then paint the target around it” just doesn’t stand up under this kind of argument. I think it’s called ‘argument by assertion’.”
Mike,
That is way tooooo funny! You should do stand up comedy, Sir!
Characterizing a 7 million year long late Miocene Period (from 12 million to 5 million years ago) as a “brief period” where CO2 is decoupled from climate effects is epic understatement! Then attempting a direct comparison to the truly brief 22 year long time period between 1976 and 1998 when a weak correlation existed is comedic mastery!!!! Finally, stating that we should focus on the miniscule 22 year time period as the ‘CO2 vs Climate norm’ and reject the decoupled 7 million year long period as the ‘anomoly’ rises to previously unvisited satirical flight levels! I think it should be called ‘argument by abstruse absurdity’ and your picture (as the poster child!) should be shown in the dictionary, next to the term! Well Done, Sir!
Perhaps you should add a ‘sarc’ tag to your posts though….. I find that, if I don’t, sometimes my sarcasm is misinterpreted.
MtK
gymnosperm says:
June 7, 2012 at 10:37 am
I think the significance of the closing of the Isthmus of Panama is overestimated. You can toggle the continents through time in Google Earth and it is clear that not much water (and certainly no deep water) was getting through there even as far back as the Eocene.
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I’m inclined to agree. The shallow passages would be significant for the evolution of shallow water faunas. Reef dwelling fish and invertebrates on the two sides of the isthmus probably wouldn’t diverge much until the passages closed. But I doubt the impact on climate would be great once massive — and especially deep water — exchange through the passage between North and South America was throttled down
Basically then, CO2 causes temperature rises, except during times when it doesn’t. Does that sound a bit lame to the public at large? Then add a dose of scientific jargon, call it “decoupling” and hey presto! we have waived away all that pesky conflicting evidence.
Unfortunately, we have now created a “Jekyll and Hyde” phenomenon. This schizophrenic gas, is supposed to behave perfectly rationally one day, yet subvert the laws of physics on another.
Somehow I think the one’s exhibiting dangerous signs of delusion, are these scientists, not our wonderful gas. Only in the minds of a committed zealot can such nonsense spew forth.
Bill Illis says:
June 7, 2012 at 6:04 am
….So here is all the reliable CO2 estimates going back 25 million years. The authors could have extended the “decoupling” time period back to 25 million years ago. CO2 fell below 280 ppm, for perhaps the very first time, 24 million years ago and it has been there (give or take an ice age lowering it to 185 ppm and some outlier 450 ppms) ever since.
_________________________________________
No those are not “Reliable” CO2 measurements those are the “Blessed by the Team” CO2 measurements.
To put it bluntly if CO2 went as low as 185 ppm we would not be here nor would most other animals or plants.
The atmosphere could never be below 200 ppm and have CO2 uniformly distributed without wiping out C3 plants at a minimum. The stomata data disagree with the Ice core data. ( WUWT discussion ) Dr. Zbigniew Jaworski exposed the lies surrounding the CO2 measurements and so did Beck and Dr. Tim Ball.
Here is real life data, completely divorced from the climate debate, that shows those measurements are a large crock of fertilizer.
And here is a paper that is a real kicker. It of course has the usual nod to CAGW as a get out of Pal-Review Free Card.
Gail Combs says:
June 7, 2012 at 12:23 pm
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In the ice ages, when (and I guess if) CO2 fell to 185 ppm, the broad-leafed C3 vegetation did not do very well. In fact, they died. The forests during this time are the US southeast, the Amazon at one-qaurter the current size and some of the equatorial regions only. The reason is that these areas had enough rainfall so that the C3 plants could have larger stomata and not be succeptible to drying out from envirotranspiration. The rest of the planet, however, is grassland, desert and tundra.
http://stommel.tamu.edu/~baum/paleoveg/veg-adams-big.gif
The obvious explanation is that the laws of physics have changed since the Miocene. Because obviously the radiative physics of CO2 is essential to the earth’s temperature now, but not then. At least no other explanation is conceivable, given that scientists are simply never wrong.
Okay, let me get this straight. The study discovers that CO2 and temp don’t correlate at all if you look back 5 to 12 million years, but somehow this strengthens the argument for causality (and the causality itself) in more recent times.
Could any line of “reasoning” be more completely doofus?
This study proves one thing beyond any shadow of a doubt.
It really is impossible to polish a turd.
“tty says:
June 7, 2012 at 12:21 am
This was only to be expected in the runup to the new IPCC report. The warm climate of the Miocene (and Pliocene) has always been a problem since it shows pretty conclusively that CO2 is not an important climate driver.
This paper (without any real evidence) essentially says “Yes, yes but NOW it depends on CO2, so there”
Yes.
ONLY Human CO2 emissions are a Climate Forcing and bad. CO2 emissions from Natural sources don’t count. Sounds Like a page out of Animal Farm. 🙂
Neo says: @ June 7, 2012 at 8:38 am
…..The percentage of transformed land now stands at 43 percent, with the world’s population at seven billion.”
Given this, how can any “green” politician think that “bio-fuels” are a viable solution ?
___________________________________
Very simple. It is a real easy “Follow the Money”
So an ADM contribution of over “..$3 million in unregulated “soft money” to Republican and Democratic national party committees during the past 10 years..” netted “..earnings of $1.9 billion for the year ended June 30, 2010, up $246 million over the year ended June 2009…”
Senator Richard J. Durbin, along with Congresswoman Rosa DeLauro have been dedicated to shoving a “Food Safety? Modernization” bill through Congress for the last ten or so years too. The law, passed in 2010 is designed to wipe out small family farms through massive red tape and fines.
Bill Illis says:
June 7, 2012 at 1:05 pm
Gail Combs says:
June 7, 2012 at 12:23 pm
————————-
In the ice ages, when (and I guess if) CO2 fell to 185 ppm, the broad-leafed C3 vegetation did not do very well. In fact, they died. The forests during this time are the US southeast, the Amazon at one-qaurter the current size and some of the equatorial regions only….
________________________________
I have no doubt the CO2 levels were low but not as low as the Ice Core data would put them. C3 plants include wheat, rice, daisies, petunias, roses, fruit trees, and conifers.
In the green house examples I linked to above, humidity, moisture and temperature would not be a problem for the plants and yet photosynthesis ceases at ~ 200 ppm, or if not cease it slows growth down to the point fruiting is not going to occur. During the glaciations it was also dryer than it is now. So yes I will agree CO2 probably dipped towards 200 ppm and this made the C4 and CAM mutations viable however below 200 ppm? I do not think so because photosynthesis is dependent on the partial pressure of CO2, O2, temperature and solar energy.
Also if CO2 was below 200 ppm then we would see a an abundance of C4 and CAM plants and we do not.
Last, herbivores do not like to eat C4 plants. They prefer C3. SEE: http://www.jstor.org/discover/10.2307/4215348?uid=2129&uid=3739776&uid=2&uid=70&uid=4&uid=3739256&sid=56242551443
Great spin.
A finding that decouples CO2 from temperature 12 million years ago is presented as evidence of stronger coupling today.
I hope they are paying their PR guys and girls well, they deserve it.
It also has to make you wonder about earlier periods such as Hansen’s favorite Cenozoic period 50 million years ago. Was climate sensitivity then the same as now, as 12 million years ago or something completely different. I believe the just so story makes a nice just so story when it comes to the multiple lines of evidence regarding CS, I’m skeptical that it relates in any way to reality.
Gail,
Help me out here. I think you have a really important point, but I thought that C4 plants evolved in the Tertiary in response to declining CO2 levels and their technological advance was to contain Rubisco to prevent its tendency to go oxidative. Bill Illis’s scenario for the Miocene (and the late Eocene for that matter) agrees with my own. A tremendous expansoin of C4 grasslands at the expense of C3 (dare I say K selected?) forests. Why is that not evidence of C4?
When I was a child, beginning my education in science, I was taught that in order to be considered a proper scientist one had to follow the scientific method – develop a hypothesis, determine the logical consequences of the hypothesis, test the hypothesis through experimentation and observation, and then demonstrate whether the experiment and observations support your hypothesis.
What I have seen from these people who consider themselves scientists is the development of a hypothesis, testing the hypothesis through observations of evidence from the past ( a valid assumption considering historical records), reporting that the evidence does not support their hypothesis and then inventing a reason why the evidence does not support their hypothesis. From my understanding, this is not Science.
A true Scientist would have observed that the evidence from the past does not support his hypothesis and amended or discarded his hypothesis. With the historical record showing that there are periods of time in Earth’s past where the concentration of CO2 does not correspond to Global warming, and in certain cases where it lags GW, it is obvious from a scientific point of view that the hypothesis that increased CO2 levels result in GW are completely wrong. Since there are periods where CO2 concentrations actually follow a period of GW, but there is still a strong correlation between rising CO2 levels and GW, the most logical amendment to the hypothesis would be that the increase in CO2 levels is a result of GW, not the cause of it.
I just wonder at the validity of the results published in this paper.
Both nanno- and microfossils suffer from significant changes during the post core cutting process. It has been shown that up to 80% of nannofossils can “disappear” from core material – including DSDP and OPD cores – within 2 weeks of being brought to surface and stored. This is mainly due to the breakdown of pyrite in the sediment which forms sulfuric acid, in turn generating gypsum from the carbonate of the nannofossil placoliths.
This effect has been documented in a peer reviewed paper by Self-Trail and Seefelt (2005), Core storage even for the DSDP (forerunner of the ODP) was a nightmare with molds and bacteria generating biofilms a wide range of organic acids.
Up to the present day there is no effective way to acheive accurate analysis of drilled sedimentary material, especially quantitative analysis, other than by the use of slides that have been prepared immediately following the sample’s arrival at surface, at wellsite.
As the samples in this study were collected and stored over a period of 12 years from 1990-2002, and they were probably sourced from the ODP core stores after laying there for some years, my opinion is that the derived inferences from the results are virtually invalid.
Of course, the results cannot factor in the natural selective loss of nannofossils in their post-mortem descent from the photic zone to the sea bed, which is probably in the form of concentrations in invertebrate faeces after having passed through their guts!
J.M. Self-Trail, E.L. Seefelt, 2005 Rapid dissolution of calcareous nannofossils: a case study from freshly cored sediments of the south-eastern Atlantic Coastal Plain. Journal of Nannofossil Research 27, 2, 149-158.
Michael Tremblay says:
When I was a child, beginning my education in science, I was taught that in order to be considered a proper scientist one had to follow the scientific method – develop a hypothesis, determine the logical consequences of the hypothesis, test the hypothesis through experimentation and observation, and then demonstrate whether the experiment and observations support your hypothesis.
I recall being taught something similar. Including that a conclusion that the hypothesis is wrong is perfectly valid.
What I have seen from these people who consider themselves scientists is the development of a hypothesis, testing the hypothesis through observations of evidence from the past ( a valid assumption considering historical records), reporting that the evidence does not support their hypothesis and then inventing a reason why the evidence does not support their hypothesis. From my understanding, this is not Science.
In other situations people who cling to theories which are inconsistent with the known facts tend to be called “nutters”.
A true Scientist would have observed that the evidence from the past does not support his hypothesis and amended or discarded his hypothesis.
Discarding is a radical form of “amendment” 🙂
With the historical record showing that there are periods of time in Earth’s past where the concentration of CO2 does not correspond to Global warming, and in certain cases where it lags GW, it is obvious from a scientific point of view that the hypothesis that increased CO2 levels result in GW are completely wrong. Since there are periods where CO2 concentrations actually follow a period of GW, but there is still a strong correlation between rising CO2 levels and GW, the most logical amendment to the hypothesis would be that the increase in CO2 levels is a result of GW, not the cause of it.
But an obviously incomplete theory. Since it dosn’t account for where no link can be found between temperature and CO2 level. Which appears to have been the case for most of Earth’s existence. With CO2 level changes following temperature changes only happening recently.
****
gymnosperm says:
June 7, 2012 at 10:37 am
I think the significance of the closing of the Isthmus of Panama is overestimated. You can toggle the continents through time in Google Earth and it is clear that not much water (and certainly no deep water) was getting through there even as far back as the Eocene.
****
I tend to agree w/what I’ve studied. A comprehensive paper I read yrs ago showed that the climate really didn’t cool much until ~1 million yrs after the Isthmus closed. That’s alot of ocean deep-water cycles (hundreds) for a major effect to show up. Even before that, the isthmus area was already quite shallow & deep water transfer had been cut off — only shallow surface water was moving thru. Not saying that it didn’t have an effect, just that I’m skeptical that it was the major factor. OTOH, the opening of the S American — Antarctic connection most certainly had a huge effect on Antarctica’s climate.
beng,
Interestingly Drakes Passage seems to have remained open since the Paleocene. There remains a strange tongue of ocean floor between them as testimony.
Gymnosperm:
It is very easy to conclude that since C4 plants are more efficient at photosynthesis than C3’s, falling CO2 levels was the adaptive force at work.
I don’t go along with that view. Instead, I see aridity as being the main driver.
C4 plants concentrate CO2 in their tissues (C3 plants can’t do this) and then process it .
This allows them to close their stomata after absorbing sufficient CO2 and thus reduce the amount of water needed to a minimum.
In addition, work in 2010 indicates that C4 plants were around some 14 million years earlier than previously thought which places them before the Miocene and into the Oligocene.(http://www.sciencedaily.com/releases/2010/11/101115142007.htm)
This however is still within the time frame that CO2 levels began falling from around 500ppm.
(Note also that some diatoms use C4 synthesis, indicating that this process may be very much older than we had thought.)
Given that adaptation to the environment is a prime driver of evolution, one would expect to see plants from sub-tropical margins adapt in some way to lower water availability in order to expand into drier areas. And even within sub-tropics it is possible to have very dry microclimates, so again, one would expect to see plants adapting to those conditions. The C4 pathway allows for better use of scarcer water resources.
The genus Flaveria ( family Asteraceae/Compositae – Sunflower family) ) has C3, C4 and intermediates within it, and is often used to show the development from C3 to C4 synthesis. Recently, fossillised remains of what is believed to be the progenitor of the Sunflowers have been found in Argentina, dated to around 45 million years ago, but as yet there is no evidence of C4 synthesis that long ago. Asteraceae are the largest family of plants we know of, and are distributed all over the globe, in a very wide range of habitat.
The Drake Passage opened 34.6 Mya, then closed again 27 Mya and reopened again about 13 Mya. There are a number of small plate cratons in the Passage that have been jostled around and alternatively opened, then closed the Passage to mid-depth ocean circulation (it needs to be at least 300 metres deep to get a good current going). These timelines coincide with the glacial advances and retreats in Antarctica.
http://img25.imageshack.us/img25/8785/drakepassagerestricted.jpg
Paper on the ocean current configuration prior to Australia fully separating from Antarctica and the Drake Passage opening. The Ocean Gyres kept Antarctica warm enough in the summers so that most of the snow melted. But once the Antarctic Circumpolar Current started up at 34.6 Mya, within 50,000 years, Antarctica fully glaciated over including ice shelves into the oceans. (Note that it takes some time for a rift valley separation to spread out and deepen enough for mid-depth ocean circulation to start up – as much as 10 million years).
http://www.es.ucsc.edu/~jzachos/pubs/Bijl_etal_09.pdf
Just found another paper ( paywalled) from Germany that proposes the disconnect is due to a combination of tectonic plate movement and greater vegetation cover……
“Energy balance estimates suggest that a reduction in the planetary albedo and a positive water vapor feedback in a warmer atmosphere are the dominating mechanisms to explain the temperature increase. Each of these factors contributes about one half to the global temperature rise of ∼3 K. Our results suggest that a much warmer climate during the Late Miocene can be reconciled with CO2 concentrations similar to preindustrial values”
http://www.agu.org/pubs/crossref/2011/2011GL048873.shtml
Pay your money and take your pick.
“””””……
Comments
Claim: Today’s climate is more sensitive than that of the past
Posted on June 7, 2012by Anthony Watts …..”””””
Well of course it is; nowadays, a 0.09 deg Temperature change is an earth shattering event; but millions of years ago almost nobody noticed such an insignificantr change.
The stupid! It burns!
Reblogged this on gottadobetterthanthis and commented:
As a Nature article, I assume it is paywalled, and I’ll not pay. As Willis says, “There has to be a better way to do science.” But how do they account for their assertions on the basins being different and the circulations being so significantly different? According to Dr. Scotese, this is the way the earth looked 14 Mya: http://www.scotese.com/miocene.htm . The only difference I can see is substantially higher sea level. I notice the caption for the global map indicates it would have been about the same as today starting about 20 Mya. I notice he stipulates “Antarctica was covered by ice and the northern continents were cooling rapidly.” I assume rapid means a half-dozen degrees C over about 15 million years.
How can LaRiviere et al justify claims of such magnitude over such minute differences? It seems silly at best. Primary global circulation has always been considered key to an ice-free earth. Obviously that is impossible, even with the straights (where we now have canals) somewhat open. Of course, my understanding of premodern continental configuration and circumglobal ocean circulation can be flawed and outdated, and the base theory may be wrong, but they are asserting that the ocean was different with no apparent means whereby it might have been. Dr. Scotese suggests sea level and relative land area (and especially ice) are important factors in long-term climate change. I suppose, but the effect cannot be dominant, or we would have never gotten this cold in the first place. http://www.scotese.com/moreinfo15.htm (I suppose I should allow that something may have changed to start the cooling and increasing land and ice keep causing cooling, but then why did we stop? Why have we only gotten this cold? Our current ice age is already over 2 million years running. Why have we stalled at 285 K? Why didn’t we go down to 283 K as we did many millions of years ago? Why didn’t we go even colder? Whatever it is, it sure seems a stretch to attribute significance to CO2!
Read this article for more details:
“Today’s Climate More Sensitive to Carbon Dioxide Than in Past 12 Million Years”
http://www.sciencedaily.com/releases/2012/06/120606164930.htm
especially the last eleven paragraphs.
Here is a picture of the current seafloor isochrons @ Drakes Passage. It shows the transform faults where South America and Antarctica slid past a tongue of ocean floor. The 30 ma isochron disapears in all directions (indicating closure?).
This is one of the wierdest pieces of ocean floor on the planet. Even with magnetostratiographic (Apparent Polar Wander) help, it seems speculative to assert that we really know what went on here.
http://geosciencebigpicture.files.wordpress.com/2012/06/drakes-passage.png