UF research gives clues about carbon dioxide patterns at end of Ice Age
GAINESVILLE, Fla. — New University of Florida research puts to rest the mystery of where old carbon was stored during the last glacial period. It turns out it ended up in the icy waters of the Southern Ocean near Antarctica.
The findings have implications for modern-day global warming, said Ellen Martin, a UF geological sciences professor and an author of the paper, which is published in this week’s journal Nature Geoscience.
“It helps us understand how the carbon cycle works, which is important for understanding future global warming scenarios,” she said. “Ultimately, a lot of the carbon dioxide that we’re pumping into the atmosphere is going to end up in the ocean. By understanding where that carbon was stored in the past and the pathways it took, we develop a better understanding of how much atmospheric carbon dioxide the oceans can absorb in the future.”
Scientists know that during the transition from the last glacial period to the current inter-glacial period about 14,000 years ago, carbon dioxide levels rose very quickly at the same time that the age of the carbon dioxide in the atmosphere fell, as measured by radiocarbon data. That suggests carbon dioxide had been stored in the ocean and suddenly released, she said.
One idea holds that it was building up in the Southern Ocean around Antarctica, where extensive sea ice on the surface of the ocean initially prevented the exchange of gasses into the atmosphere, Martin said. The other possibility is that the same process occurred in the Northern Hemisphere with ice sheets in the North Pacific Ocean, she said.
In her lab, Martin and lead author Chandranath Basak, a UF graduate student in geological sciences; Keiji Horikawa, a UF postdoctoral fellow in geological sciences; and Thomas Marchitto, a University of Colorado geology professor, studied that question by using a technique to measure isotopes of neodymium, a rare earth element not commonly found in marine sediments but preserved in microscopic fossil fish teeth. The isotopic signature of a water mass, which is captured in the fish teeth, reflects the location where the water mass came from, she said.
“It’s essentially what we call a water mass tracer,” Martin said. “You can tell where the water masses have formed and where they have moved to by using this tracer.”
The researchers took samples that had been shown to have old carbon in them and measured the neodymium isotopes on fish teeth from the sediments to see if they could reconstruct whether they had come from the North Pacific or the Southern Ocean, she said.
“When we did this, we got a signal that looks very much like the Southern Ocean,” she said. “It implies that all the carbon was being stored in the Southern Hemisphere and as the ice sheet melted back, it released that carbon dioxide into the atmosphere, causing part of the big increase in carbon dioxide and introducing old carbon back into the atmosphere.”
By giving information about environmental conditions during the last glacial period, the research findings can help scientists to reconstruct what the world was like at that time, she said.
The implications are that while large amounts of carbon could be stored in the ocean when there was a great deal of sea ice, the opposite is the case in a world that is warming, with less ice, which allows more carbon dioxide to be released into the atmosphere, Martin said. Thus, in a warming scenario the oceans may not be able to store as much carbon dioxide as they could under glacial conditions
The oceans are a critical part of the carbon dioxide cycle, Martin said. “The oceans have 60 times more carbon dioxide in them than the atmosphere, so when we worry about what’s happening with carbon dioxide in the atmosphere, we often look to the oceans as a potential source or sink.”
The concentration of carbon dioxide in the atmosphere during the glacial periods was about 200 parts per million, compared with 280 parts per million during a typical interglacial period, Martin said. Today that level has soared to about 380 parts per million, she said.
The time period that encompasses the last glacial period to the current interglacial period when carbon dioxide levels went up very quickly is often referred to as the “mystery interval” because scientists hadn’t known where the carbon was stored, Martin said.
“Now we have a better understanding of how the system worked,” she said.
One wonders how the sea life down there tolerated all that extra carbon resulting in “ocean acidification”.
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Paul Deacon, Christchurch, New Zealand says:
October 25, 2010 at 8:05 pm
R. Gates says:
October 25, 2010 at 4:39 pm
This is the common logical falacy that is propagated by many AGW skeptics. Namely that a temperature rise prior to CO2 increases proves that CO2 cannot cause warming. Yes, rises CO2 levels follow temperature increases in many instances in the geological record, but then once the CO2 begins to increase, it functions to extend and amplify the warming. Furthermore, it is glaciation that serves to increase CO2 levels through a slowing of the hydrological cycle. To say that a rise in CO2 can not affect an increase in global temperatures simply because is sometimes lags a rise in temperature is one of the biggest logical fallacies that I see coming from the skeptical community. CO2 can act as a positive feedback to a general warming that may have been initiated through astrononomical (i.e Milankovitch) or other natural cycles.
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R Gates – please point me to one or more periods in the paleo-climate record when you believe that the above positive feedback as described by you caused a catastrophic runaway increase in atmospheric temperatures.
Thanks.
_____
I am not a subscriber to “catastrophic” runaway increases in atmospheric temperatures through AGW…i.e. there is no “C” in front my general agreement with AGW, so I can’t site you any period that such has occurred. Eventually, as the CO2 levels increase to the point that the hydrological cycle is at an extreme end, we would get lots of weathering of rock with lots of CO2 being removed from the atmosphere, and this would naturally bring the system back into balance. One could even imagine this “accleration” of the hydrological cycle would even slow down the antropogenic output of CO2 as well as a curious side effect. But of course, the natural wearing down of rock and “scrubbing” of CO2 from the atmosphere occurs over millions of years, but even that is still a blink of the eye in the billions of years the earth has existed.
So, while I do, in general believe that humans are impacting the oceans, eco-systems, atmosphere, and other life sustaining systems of the earth in various negative ways, that could lead to some very unfortunate circumstances for humans, sub specie aeternitatis (to use Spinoza out of context), such impacts of humans, and the human race in general are but a brief ghost like phantoms moving across the unimaginably long landscape of earth’s history and life and the earth will always find a way long after we are gone.
“To say that a rise in CO2 can not affect an increase in global temperatures simply because is sometimes lags a rise in temperature is one of the biggest logical falacies …”
I didn’t say “Co2 can not affect an increase in global temperatures…”. Maybe it can. But maybe it didn’t.
What I was implying is that it is possible that the current increase in CO2 (or part of it) is caused by the warming of the oceans. It’s not all man-made.
The same about global warming. Since the earth did warm in the past due to other reasons, unrelated to CO2, maybe some of the warming, at least in the last years, is also caused by other factors.
FijiDave says:
October 25, 2010 at 6:21 pm
…
“Billions of dollars, quadrillions of man-hours, squadrillions of words, and there is still an argument over whether or not twelve man-made carbon dioxide molecules per one million molecules of air is catastrophically heating the atmosphere?”
Love the post, but I think you may want to say twelve CO2 molecules per one hundred thousand molecules of air.
Brian W says:
October 26, 2010 at 7:29 am
” This article is nothing but an AGW inspired pseudoscientific mess designed to convince under a cloud of confusion. Pure crap! Its even crap on crap.”
In other words, a typical AGW article.
BWD
Enneagram says:
October 26, 2010 at 8:29 am
Magnetite grains were found at the nasal bones, years ago by an English anthropologist, who analyzed hundreds of female and male skulls, finding that men’s facial bones had much more iron than women (That’s women usually give wrong directions 🙂 )
Which, we find, is quite attractive! And its cute how they take so long to get ready too! 😀
R. Gates says:
October 25, 2010 at 4:39 pm
This is the common logical falacy that is propagated by many AGW skeptics. Namely that a temperature rise prior to CO2 increases proves that CO2 cannot cause warming.
_________________________________________________________
The fallacy is in the theory that CO2 is the cause of the 20th century warming. The major greenhouse gas is water vapour not CO2. It has 95 times the warming effect of CO2 while CO2’s warming effect decreases logarithmitically. Increases of CO2 above the current level would not cause any significant warming.
If what you theorise is true, then the planet would have had a runaway warming> heating>burning up many millions of years ago. But that never happened and will only happen when the sun decides to blow up in some billions of years in the future.
The amount of CO2 dissolved in the oceans is 50 times that in the atmosphere. So, if a tiny warming of the oceans due to ANY cause were to release 2% of the oceans’ CO2, this would mean a doubling of the atmospheric CO2 in simplistic terms, but then feedbacks are so complicated.
@tallbloke says:
October 26, 2010 at 11:50 am
Perhaps a telluric current was finding the copper pipes to be a quicker path! 🙂
Mr. Watts:
Doesn’t high school physics show that increasing the atmosphere concentration of CO2 cause an increase in the greenhouse effect?
You stated:
“What’s news is that this team confirmed the southern ocean was the main sink then. This finding also points to why CO2 lags temperature in paleoclimate temperature and CO2 reconstructions.”
This is not the first time a study has been issued on this subject.A May 2010 study, described below, previously identified the southern ocean as a major carbon sink that is capable of producing a “burp” of CO2 into the atmosphere.
Skinner, L.C., Fallon, S. Waelbroeck, C., Michel, E. and Barker S., ‘Ventilation of the deep Southern Ocean and deglacial CO2 rise’ is published in Science on 27 May 2010.
Scientists Detect Huge Carbon ‘Burp’ That Helped End Last Ice Age
http://www.sciencedaily.com/releases/2010/05/100527141959.htm
Excerpt:
ScienceDaily (May 28, 2010) — Scientists have found the possible source of a huge carbon dioxide ‘burp’ that happened some 18,000 years ago and which helped to end the last ice age.
The results provide the first concrete evidence that carbon dioxide (CO2) was more efficiently locked away in the deep ocean during the last ice age, turning the deep sea into a more ‘stagnant’ carbon repository — something scientists have long suspected but lacked data to support.
According to Dr Skinner: “Our results show that during the last ice age, around 20,000 years ago, carbon dioxide dissolved in the deep water circulating around Antarctica was locked away for much longer than today. If enough of the deep ocean behaved in the same way, this could help to explain how ocean mixing processes lock up more carbon dioxide during glacial periods.”
But changes in Earth’s orbit could only have acted as the ‘pace-maker of the ice ages’ with help from large, positive feedbacks that turned this solar ‘nudge’ into a significant global energy imbalance.
Changes in atmospheric CO2 were one of the most important of these positive feedbacks, but what drove these changes in CO2 has remained uncertain.
Scientists think more CO2 was locked up in the deep ocean during ice ages, and that pulses or ‘burps’ of CO2 from the deep Southern Ocean helped trigger a global thaw every 100,000 years or so. The size of these pulses was roughly equivalent to the change in CO2 experienced since the start of the industrial revolution.
If this theory is correct, we would expect to see large transfers of carbon from the ocean to the atmosphere at the end of each ice age. ”
In 2007 the IPCC noted the CO2 lag in FAQ 6.1
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-6-1.html
BigWaveDave says:
October 26, 2010 at 8:13 pm
Thanks your kind comment.
“Love the post, but I think you may want to say twelve CO2 molecules per one hundred thousand molecules of air.”
Not wanting to be pedantic, but if there are 390 molecules of CO2 in in 1,000,000 molecules of air in the atmosphere (390 ppmv), and anthropogenic CO2 is 3.2% of that 390 ppmv, then 390*3.2% = 12.45.
Or, have I, like an old draught horse, got my blinkers on too tight, and not seeing something which I ought?
Cheers