From NSF: Significant Role of Oceans in Onset of Ancient Global Cooling
 Aerial view of the drillship JOIDES Resolution.
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May 26, 2011
Thirty-eight million years ago, tropical jungles thrived in what are now the cornfields of the American Midwest and furry marsupials wandered temperate forests in what is now the frozen Antarctic.
The temperature differences of that era, known as the late Eocene, between the equator and Antarctica were half what they are today.
A debate has been ongoing in the scientific community about what changes in our global climate system led to such a major shift from the more tropical, greenhouse climate of the Eocene to modern and much cooler climates.
New research results published in this week’s issue of the journal Science, led by Rensselaer Polytechnic Institute scientist Miriam Katz, are providing some of the strongest evidence to date that the Antarctic Circumpolar Current (ACC) played a key role in the shift.
“What we have found is that the evolution of the Antarctic Circumpolar Current influenced global ocean circulation much earlier than previous studies have shown,” said Katz. “This finding is particularly significant because it places the impact of initial shallow ACC circulation in the same interval when the climate began its long-term shift to cooler temperatures.”
There has been a debate over the past 40 years on what role the Antarctic Circumpolar Current had in the past cooling trend.
“These climate changes are one of the most significant shifts in Earth’s history, from early Cenozoic ‘greenhouse’ climates to the mid- to late Cenozoic ‘icehouse’ that saw repeated massive glaciations of the polar regions,” said Candace Major, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences.
The research was funded by NSF in partnership with the Integrated Ocean Drilling Program, and its predecessor programs, the Ocean Drilling Program and Deep Sea Drilling Project.
“The work by Katz and colleagues is the first to demonstrate that the basic structure of currents associated with modern ocean circulation has existed for the past 33 million years,” said Major.
Previous research had placed the development of the deep ACC–greater than 2,000 meters water depth–in the late Oligocene, approximately 23-25 million years ago.
That’s well after the global cooling pattern had been established.
Katz and colleagues have placed the global impact of the ACC at approximately 30 million years ago, when it was still just a shallow current.
Oceans and global temperatures are closely linked. Warmer ocean waters result in warmer air temperatures and vice versa.
In the more tropical environs of the Eocene, ocean circulation was weaker and currents more diffuse.
As a result, heat was more evenly distributed around the world. That resulted in fairly mild ocean temperatures worldwide.
Today, ocean temperatures vary considerably and redistribute warm and cold water around the globe.
“As the global ocean currents were formed and strengthened, the redistribution of heat likely played a significant role in the overall cooling of the Earth,” Katz said.
No current is more major than the ACC, scientists believe.
Often referred to as the “mixmaster” of the ocean, the ACC thermally isolates Antarctica by preventing the warm surface waters of subtropical gyres from passing through.
The ACC instead redirects some of that warm water back toward the north Atlantic, creating Antarctic Intermediate Water.
This blocking of heat enabled the formation and preservation of the Antarctic ice sheets, according to Katz.
The circumpolar circulation, Katz concludes, was responsible for the development of the modern four-layer ocean current and heat distribution system.
Katz looked at the uptake of several elements’ isotopes, or variants, in the fossil skeletons of small planktonic organisms found in ocean sediments.
Using the drillship, the fossil organisms, known as benthic foraminifera, were brought up from beneath the sea-floor in long cores of sediments.
The foraminifera incorporated certain elements and isotopes, reflecting environmental conditions at the time.
By analyzing the ratios of these elements and isotopes, researchers were able to reconstruct past environmental conditions. They looked at isotopes of oxygen and carbon, along with ratios of magnesium versus calcium.
Analysis of these isotopes showed the earliest evidence for Antarctic Intermediate Waters, which circulates as a consequence of the ACC.
This finding is the first evidence of the effects of shallow ACC formation.
The results place the ACC’s global impact much closer to the time when Antarctica separated from South America, creating a gateway.
It had previously been thought that currents moving through this gateway could not be strong enough at such shallow depths to affect global ocean circulation.
“By reconstructing the climates of the past, we can explore Earth system responses to current climate change,” Katz said.
Katz is joined in the research by Benjamin Cramer of Theiss Research; J.R. Toggweiler of Geophysical Fluid Dynamics Lab/NOAA; Chengjie Liu of Exxon Mobil Exploration Co.; Bridget Wade of University of Leeds; and Gar Esmay, Kenneth Miller, Yair Rosenthal, and James Wright of Rutgers University.
-NSF-
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Who’d’ve thunk it? The movement of a fluid 5,000X as massive as the atmosphere affects the climate in a massive way….
Whooops!
So the conclusion that the climate change WAS caused by the oceans, but we can now, having proved this, examine how the oceans will ‘respond’ to climate change which is NOW caused by us?
Fail!
Funny how they again leave the sun out of the equation. What they observe is the result. Could the sun output might have played a role in it, maybe?
Whenever climate change and the word greenhouse is tied to work, what comes to mind is using the pieces of an incomplete puzzle with another puzzle and claiming the pieces and picture produced fits.
Jerome writes,
“So the conclusion that the climate change WAS caused by the oceans, but we can now, having proved this, examine how the oceans will ‘respond’ to climate change which is NOW caused by us?
Fail!”
The failure is in your head, not the science. Climate changes for many reasons, on many time scales. This particular article describes change on the time scale of continental drift!
Right now, on a time scale of decades and less, we’re the ones poking the atmosphere with 6 new gigatons of CO2 per year.
If Exxon is involved, no matter what the results, the findings will be considered tainted by the “consensus”.
The story………..
CO2 levels dropped, causing a drop in temperatures that made the ice in Antarctica possible….
….and we discovered that by mining foraminifera
That didn’t exist because of ocean acidification
And, we know enough to predict the future climate……………
Tell me again what FOIA’s are for?
“As the global ocean currents were formed and strengthened, the redistribution of heat likely played a significant role in the overall cooling of the Earth,” Katz said.
You cannot have a zero-sum game resulting in less heat. Either more heat escaped or less heat entered the system, or both. It’s a nice start, but the conclusions are incomplete without mechanism, hypothetical or otherwise.
What is troubling is that if Antarctica became isolated, then the rest or the Planet must then be warmer than the Eocene.
But according to the internet conspiracy theorists, the Piri Reis map portrays the area now known as Queen Maud land in an ice-free state, presumably charted by the Atlanteans before the great flood, and a map fragment was handed down through several cultures until it wound up in the portuguese cartographers hands. Sorry I just find these theories way more entertaining than popular sci-fi.
Good stuff. The most pressing question, what were the processes responsible for causing such a nosedive in the earths climate between the end of the Eocene and today? Antartica has been more or less in the same position over the pole thru the Cenezoic, yet temperate zone flora apparently thrived within a few hundred KM of the pole. By the Miocene and ever since, Antartica has been locked under ice.
“Thirty-eight million years ago, tropical jungles thrived in what are now the cornfields of the American Midwest and furry marsupials wandered temperate forests in what is now the frozen Antarctic.”
Must have been quite an interesting forest given there’s little to no sunlight for six months and then little to no darkness for six months.
Global temperatures dropped 2.0C and Antarctica glaciated over within 150,000 years of this event.
Just before the start-up of the Antarctic Circumpolar Current, this is what the continental configurations and the ocean currents looked like. Ocean gyres from the mid-latitudes kept Antarctica warm enough, at least in the summer, to melt most of the snow and ice. It was still a frozen wasteland in the winter.
http://img35.imageshack.us/img35/8862/antoceancurrents35m.jpg
The isolation of Antarctica in an extreme polar climate by the start-up of the Antarctic Circumpolar Current resulted in the Albedo of the Earth (the amount of sunlight reflected back to space) increasing from about 27.2% to 29.8% which is just the right amount to drop global temperatures by 2.0C.
A nice picture was taken by Apollo 17 in December 1972 why demonstrates why this occured. The big white spot at the South Pole (reflecting 85% of the sunlight versus 60% 35 Mya when it was not glaciated) is Antarctica.
http://a.imageshack.us/img826/4568/antarcticaas1714822727.jpg
Most of the pro-AGW climate researchers try to tie the event to a draw-down of CO2 and do not discuss the Antarctic Circumpolar Current at all. But this is the history of CO2 and global temperatures over the last 45 Mys. No correlation to CO2 at all.
http://img824.imageshack.us/img824/4927/tempco245mlefttoright.png
Here are some of the other continental drift and geographic change which occurred over the period which more accurately reflect what was happening in the climate.
http://img204.imageshack.us/img204/695/tempgeog45m.png
Steve R says
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The most pressing question, what were the processes responsible for causing such a nosedive in the earths climate between the end of the Eocene and today?
———/
Plate techtonics. They affect the trajectory of ocean currents. Then other factors come into play such as iced-over regions reducing the absorption of visible light from the sun.
BillI llis says
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No correlation to CO2 at all.
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On these time scales a lot is going on that affects both temperature and CO2 concentrations outside of the CO2-temperature feedback loop. E.g. Rock weathering, movement of continents affecting ocean currents, volcanic activity, biological activity etc.. It is not clear to me that the “fast” CO2-temperature feedback loop would be visible on these kinds if graphs just because of the timescale mismatch.
@lazyteenager 606pm
You should submit that paragraph to Nature to be published. Brilliant critical thinking.
There’s some stuff here worth earmarking. –AGF
Oceans and global temperatures are closely linked. Warmer ocean waters result in warmer air temperatures and vice versa.
Warmer ocean waters result in warmer air temperatures—I buy that. But vice versa? The air temperature would have to be pretty hot to warm ocean waters to any significant degree … right?
This paper makes the source I posted in “Tips” all that more interesting:
ALARMIST GLOBAL WARMING MODELS VS THE GEOLOGICAL RECORD
Pierre Jutras
http://www.smu.ca/academic/science/geology/bios/documents/ALARMISTGLOBALWARMINGMODELSVSTHEGEOLOGICALRECORDHongKong2007.pdf
This is a model in which plate tectonics is the predominant contributor to greatly increased quantities of CO2 in the atmosphere during times of rapid continental drift (more subduction and recycling of CO2) or far less CO2 during times of plate collisions and “supercontinent” formation (less subduction and sequestration of CO2). Overlain on this is second-order effects of the Croll-Milankovitch cycles of eccentricity, obliquity and precession, and further effects of the placement of large land masses in polar regions and athwart oceanic basins (e.g., exactly the subject of the above paper).
As the author plots it out, high CO2 eras (greenhouse eras) exhibit great diversity in life forms, while low CO2 eras (ice ages) show mass extinctions and lack of biological diversity. We’re in one of the latter phases, and a mitigating factor is to INCREASE the CO2 content of the atmosphere by burning our hydrocarbon fuels.
Now, he sees times of high CO2 as being relatively warm; low CO2 as relatively cold. In fact, the geologic record shows that. But, contrary to alarmist belief, there is no “runaway heating” and warmer is conducive to life rather than a threat.
JimF says: Check it out. Great geological arm waving, and yet I think his position is coherent.
LazyTeenager says:
May 26, 2011 at 6:24 pm
It is not clear to me that the “fast” CO2-temperature feedback loop would be visible on these kinds if graphs just because of the timescale mismatch.
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These are ALL the reliable estimates, on the same timescale. I haven’t run across an estimate which puts CO2 dropping to 300 ppm from 1,400 ppm at the glaciation boundary.
There is only a drop about 2 Mys after the Antarctic glaciation. Even then, at 31 Mya, it is only a drop to 900 ppm from 1,400 ppm after which it went back up to 1,200 ppm, 800,000 years later.
There are 100 individual CO2 estimates between 36 Mya and 30 Mya so that should be good enough to determine if CO2 really fell to the 300 ppm level which the Antarctic glaciation would require (if CO2 is the primary mechanism in the climate).
It didn’t. Co2 didn’t get down to 300 ppm until about 25 Mya, about 2 Mys after most of the Antarctic glaciers had melted back already. The timelines say CO2 played no part in the glacier development.
““As the global ocean currents were formed and strengthened, the redistribution of heat likely played a significant role in the overall cooling of the Earth,” Katz said.”
I agree with Mr Bateman. It’s a zero-sum game. How could the redistribution of the heat within the earth’s sphere have caused the total sum of heat to drop. Makes no sense to me.
So lets dam the ocean currents and hey presto a warming planet?Let us restore Axel Heiberg Island to its former forested glory.Sarc of course but there is no shortage of useless protoplasm thro out our governments to throw into the breech.
@Madman2001 says:
May 26, 2011 at 7:51 pm
Maybe you should read the paper rather than RBateman. They explain a situation in which we went from temperate conditions globally with small, diffuse oceanic currents to one in which we have much cooler (overall) conditions, big differences in sea temperatures over moderate distances, and big warm and cold currents impinging on various continental masses. That, and a significant increase in global albedo, and who knows what else.
It would appear this earth is extraordinarily complex. Which AGW model do you think full explores and properly calculates this complexity?
I wish I could remember, but I think it was Joe D’Aleo who pointed out the possibility that there is link from seismic activity to weather. The Antarctic circumpolar current is throttled by the Drake Passage at the end of S America. There are volcanoes there. A little bit of seismic choking in the Drake Passage would strengthen the Humboldt Current and start a La Nina. Does anyone know if this is being investigated anywhere?
The most interesting detail:
1) “initial shallow ACC circulation”
2) “when it was still just a shallow current”
3) “This finding is the first evidence of the effects of shallow ACC formation.”
4) “It had previously been thought that currents moving through this gateway could not be strong enough at such shallow depths to affect global ocean circulation.”
sky, if you are around, please succinctly tell us what you believe would have driven this shallow current.
“JimF says: Check it out. Great geological arm waving, and yet I think his position is coherent.”
Just read the paper myself, and I concur. Step back and look at the bigger picture, and it can become so much clearer.
Ice Age Taxes? Just say NO!!!