Ancient “Hyperthermals” a Guide to Anticipated Climate Changes
Scripps researchers document the history of sudden global warming events, impacts on marine life
By Mario Aguilera, Scripps Institute News (h/t to Dr. Leif Svalgaard)
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| Sediment samples in the lab of Richard Norris obtained by the Ocean Drilling Program reveal the mark of “hyperthermals,” warming events lasting thousands of years that changed the composition of the sediment and its color. The packaged sediment sample on the left contains sediment formed in the wake of a 55-million-year-old warming event and the sample on the right is sediment from a later era after global temperatures stabilized. |
Bursts of intense global warming that have lasted tens of thousands of years have taken place more frequently throughout history than previously believe, according to evidence gathered by a team led by Scripps Institution of Oceanography, UC San Diego researchers.
Richard Norris, a professor of geology at Scripps who co-authored the report, said that releases of carbon dioxide sequestered in the deep oceans were the most likely trigger of these ancient “hyperthermal” events. Most of the events raised average global temperatures between 2° and 3° Celsius (3.6 and 5.4° F), an amount comparable to current conservative estimates of how much temperatures are expected to rise in coming decades as a consequence of anthropogenic global warming. Most hyperthermals lasted about 40,000 years before temperatures returned to normal.
The study appears in the March 17 issue of the journal Nature.
“These hyperthermals seem not to have been rare events,” Norris said, “hence there are lots of ancient examples of global warming on a scale broadly like the expected future warming. We can use these events to examine the impact of global change on marine ecosystems, climate and ocean circulation.”
The hyperthermals took place roughly every 400,000 years during a warm period of Earth history that prevailed some 50 million years ago. The strongest of them coincided with an event known as the Paleocene-Eocene Thermal Maximum, the transition between two geologic epochs in which global temperatures rose between 4° and 7° C (7.2° and 12.6° F) and needed 200,000 years to return to historical norms. The events stopped taking place around 40 million years ago, when the planet entered a cooling phase. No warming events of the magnitude of these hyperthermals have been detected in the geological record since then.
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| Richard Norris in his lab with ancient sediments obtained by the Ocean Drilling Program reveal the mark of “hyperthermals,” warming events lasting thousands of years that changed the composition of the sediment and its color. The dark color in the large sediment core sample at left depicts the onset and aftermath of a 55-million-year-old warming event when changes in ocean temperatures altered the composition of marine life. |
Phil Sexton, a former student of Norris’ now at the Open University in the United Kingdom, led the analysis of sediment cores collected off the South American coast. In the cores, evidence of the warm periods presented itself in bands of gray sediment layered within otherwise pale greenish mud. The gray sediment contained increased amounts of clay left after the calcareous shells of microscopic organisms were dissolved on the sea floor. These clay-rich intervals are consistent with ocean acidification episodes that would have been triggered by large-scale releases of carbon dioxide. Large influxes of carbon dioxide change the chemistry of seawater by producing greater amounts of carbonic acid in the oceans.
The authors concluded that a release of carbon dioxide from the deep oceans was a more likely cause of the hyperthermals than other triggering events that have been hypothesized. The regularity of the hyperthermals and relatively warm ocean temperatures of the period makes them less likely to have been caused by events such as large melt-offs of methane hydrates, terrestrial burning of peat or even proposed cometary impacts. The hyperthermals could have been set in motion by a build-up of carbon dioxide in the deep oceans caused by slowing or stopping of circulation in ocean basins that prevented carbon dioxide release.
Norris noted that the hyperthermals provide historical perspective on what Earth will experience as it continues to warm from widespread use of fossil fuels, which has increased carbon dioxide concentrations in the atmosphere nearly 50 percent since the beginning of the Industrial Revolution.
Hyperthermals can help scientists produce a range of estimates for how long it will take for temperatures to fully revert to historical norms depending on how much warming human activities cause.
“In 100 to 300 years, we could produce a signal on Earth that takes tens of thousands of years to equilibrate, judging from the geologic record,” he said.
The scientists hope to better understand how fast the conditions that set off hyperthermals developed. Norris said that 50 million year old sediments in the North Sea are finely layered enough for scientists to distinguish decade-to-decade or even year-to-year changes.
Co-authors of the paper include researchers from the National Oceanography Centre Southampton at the University of Southampton in England and the Center for Marine Environmental Sciences, University of Bremen, Germany.
What? This minor trace gas (CO2) can cause warming? Go figure!
(sarcasm off)
Now, how will the AGW skeptics find some way to poke holes in this study?
Nothing is ruled out:
Asteroid impacts, nearby novae and supernovae, passing close/hot young star, monster solar cycles, massive rift zones (like the 2000 ft of Andesite covering the last tilt of the Sierra Nevada), Supervolcanoes… lots of things to consider. All Black Swan events in the expanse of geologic time.
RE: Scott Ramsdell: March 16, 2011 at 8:22 pm
I’ve stated several times on this site that I do not believe the mid-ocean ridge and undersea volcanoes are properly considered in climate models.
Scott,
The alarmist article the other day – “Could global warming be causing recent earthquakes?” quite possibly has it backwards.
As you note, when undersea rifts and volcanoes become more active, there could well be significant (and un-accounted) additional CO2 pumped into the deep ocean waters. Because it is deep, the release to atmosphere would take place over extended time periods, and would be smoothed; giving a long slow ramp up as we see in Mauna Loa data.
For example: The mid Atlantic rift is dead center in the undersea ‘return’ leg of the thermohaline conveyor. CO2 added there would cycle back up to the surface in the Pacific and Indian oceans centuries later. The CO2 isotope markers would give the appearance of organic origin, but would be completely independent of fossil fuel use at the surface. Slow cook heating from the bottom could also contribute to steric expansion of sea levels.
and Pamela Gray has the answer (lol, loved your comment Pamela)
Hyperthermals. Intense, sudden warmth. Reminds me of…Yep! Sounds like hot flashes to me. Gaia, Geea, or whatever her name is, needs to sit down with a bottle of chocolate wine.
Me and Nemo never seen one of them Hippothermals and we hang out down there a fair old bit. We seen a few in rivers and lagoons in Afreeca. But not in the briny.
Hope this advances the discussion, randomly.
Fascinating article. Let’s see: the Earth gets pretty warm sometimes and then gets really cold. Hmm. With all those “hyperthermal” events (someone is being hypernominous here) one would think that the Earth would have gone into the final hypercinderization process as unstoppable, feedback-induced global warming ran rampant.
But no, we got a multimillion year period of periodically freezing our asses off and dodging herds of woolly mammoths and mammoth glaciers.
So, this study begs further study. We have established that runaway global warming is not in the cards. Now, what of the flora and fauna associated with these “hyper” events? Mass extinctions or mass burgeoning? One wants to know. My guess: life went crazy on the upside, with titanotheriums and massive coral reefs and great fanged beasties that got stuck in tar pits and so forth. Glacial eras on the other hand seem to feature huge herds of a few kinds of animals.
Could some real geologists/paleontologists/geochemists/stratigraphers etc. get involved here and do some work? I mean, the “carbon dioxide” footprint described in this paper is an open invitation to loot the scientific grant system. I might even come out of retirement to do a synoptic, holistic review or two of the early Paleozoic. Maybe I could jet off to Tahiti to describe my findings.
Leif Svalgaard raised an interesting point with the link to Lake Nyos, and a few others here have touched on it, but the idea seems lost on those, ( and many others) doing the studies.
Richard Norris thinks that, “releases of carbon dioxide sequestered in the deep oceans were the most likely trigger of these ancient hyperthermal events.”
What if it’s actually the other way around? As shown in the link Dr. Svalgaard provided, events can and do, release CO2.
Considering the Earth is still a very active and rumbling planet, I’d believe this theory a lot more then the one that says mankind is influencing the climate due to Anthropogenic CO2.
Scott Ramsdell says: “…I have no doubt that periodically the undersea super volcano eruption occurs (like Yellowstone), or that the mid-ocean ridge splits far more than usual (consider a continental plate more or less round that slips all the way around rather than laterally)….”
Things like Yellowstone result where continental crust is involved in the melting. There, a mantle plume is melting whatever crustal material passes over it. For a long time that has been continental crust (in general, rock the composition of granite), which yields the siliceous melts that are involved in explosive volcanism that sends material 45,000 feet into the atmosphere and ejects hundreds or thousands of cubic kilometers of material.
Otherwise, you get something like Hawaii where a mantle plume is melting oceanic crust (in general, rock the composition of a “primitive” basalt), where the other day …gasp… they had fountains of lava 80 feet high! The viscosity of a Hawaiian basalt is several orders of magnitude less than that of a dacite magma, and further it is far less hydrous (water-bearing). The basalt flows; the dacite blows.
And yes, the Earth does speed up sometimes. The Late Cretaceous and Early Paleocene exhibited some of the greatest oceanic spreading rates that (to my knowledge) have been measured or estimated. The Atlantic Ocean opened in a flash, so to speak. The Mid-Atlantic Ridge must have stood high and proud, it was so hot and active and therefore less dense. Whether this added lots of CO2 to the atmosphere, I cannot say.
One expects these events to decline with time, as the Earth cools. The Archean Eon witnessed voluminous outpourings of komatiitic lavas – very mafic lavas with a melting point of over 1300 deg.C. Only once since then – 3 billion years ago – have we seen lavas that compare to those. Todays basalts are formed at temperatures a hundred or two hundred degrees cooler. The Earth is becoming cold and arthritic. This may have something to do with big bangs like the Japanese earthquake: things aren’t quite as fluid as they once were, and movements of great masses of rock are no longer plastic, but instead brittle failure – catastrophic movements – become the norm.
Let me get this straight; large quantities of CO2 are released from the ocean which then causes CO2 to be absorbed by the ocean causing acidification? 2-2+2=2. Am I missing something?
Question – What is the validity of the deep ocean CO2 release hypothesis? I know I’ve seen speculation about it a couple of times, but what is the evidence to show that this can happen / has happened in the past?
Regarding ” release of carbon dioxide from deep oceans”, Geologist Tim Casey seems to know his stuff. Apparently there are liquid lakes of CO2 with seawater accumulation, toward the vents. I could imagine a pressure drop (uplift) that could quickly release this as a gas.
Two interesting aspects here. At least three of these “hyperthermals” are accompanied by large carbon isotope disturbances. It has therefore always been assumed that they were caused by releases of highly fractionated carbon (e. g. biogenic methane). Carbon dioxide in the deep ocean in not highly fractionated, so it would require vast amounts to cause the observed changes. We are talking of several thousand ppms in the atmosphere here, which implies a low climate sensitivity to CO2.
Secondly, with the exception of the first (PETM) excursion, these hyperthermals are essentially invisible in the fossil record. They apparently caused no extinctions and indeed no notable changes at all in the biosphere. Indeed the Eocene when they occurred has always been considered a remarkably stable epoch with warm, equable conditions over most of the world.
The PETM excursion did cause a substantial extinction among benthic (bottom-living) foraminifers and a remarkable burst of diversification of practically everything else both in the ocean and on land.
The next major biotic crisis only comes with the strong cooling ca 35 million years ago, when continental glaciation first covered Antarctica.
“The events stopped taking place around 40 million years ago, when the planet entered a cooling phase. No warming events of the magnitude of these hyperthermals have been detected in the geological record since then.”
Nothing to do with the Laramide orogeny then……
As others have already commented this sounds like Milankovitch cycles. The strongest warming signal should be every 400,000 years but until now this periodicity has not been detected in the ice cores. Indeed this has been used to question the soundness of the theory. The next strongest should be 20000 or 40000 years but the actual strongest is around 100000 years and this has also been used to question the theory. However it now seems that in its unfrozen state (before Antarctica formed 40 million years ago) the 400000 periodicity did dominate. Similarly before the Americas joined together and cut of the circular ocean currents the next most important 20,000 year cycle was dominant.
This suggests to me that the earth is forced by these solar variations but now has natural resonances caused by the ice accumulation and restricted ocean circulation. The CO2 idea is a red herring. If they cannot find a reason why the CO2 should rise and fall every 400000 years they do not have a plausible theory. We know that it will rise and fall as a consequence of global warming so why look for something extraordinary to imply the causality is in the opposite direction.
Dr. Svalgaard, thank you for pointing out the link to the supplemental info. It is confusing though. The authors apparently “tuned” their age models to fit obliquity frequencies, but then also found substantial power spectra that fit precession and eccentricity frequencies, which (they stated) provided “independent validation of our tuning strategy”.
So the “globally widespread calcium carbonate (CaCO3) dissolution events” seem to “fit” astronomical variations, yet (the article states) they (apparently) rejected astronomical variations as a causal factor.
Very curious. I can see where using Milankovitch Cycles to establish ages would induce non-independence and multi-collinearity, so that the former cannot be used in the analysis as independent explanatory variables for the latter. But leaping to the CO2 release (oceanic turnover) as the cause is pretty speculative deduction. It’s a little bit like a trial where the strongest evidence is ruled inadmissible on technical grounds. Is this O.J. science?
PS – I find the paywall barrier to be really annoying. I tend to reject any and all papers that the System hides in that fashion.
so, does this mean that CO² has a 200,000 year atmospheric lifecycle? Oh yes I realise that it is the quatity that is taking the time to reduce itself but……
I have problems with the concept of ocean sediment quietly settling and building up for countless aeons in a specific location when, in that tme frame, continents are rent asunder and go walkabout, chains of volanoes, including those of the mid-ocean ridge, blast stuff into the atmosphere, oceans change their shape, the major currents wander about and the great mountain chain of the Himalayas is thrust on high.
Or have I missed something simple and obvious?
And tacking the obligatory man-made warming signal onto the end of the study seems a tad illogical to me.
I think most of the commenters on this thread expose thier bias by their whipjerk reaction to having to find a reason to dismiss the study. The vast bulk of commenters don’t give the impression they understand the science behind it enough to reach such a conclusion.
The various accusations of fraud against the authors of the study by a few commenters are just icing on the cake.
“Richard G says:
March 16, 2011 at 11:24 pm
Let me get this straight; large quantities of CO2 are released from the ocean which then causes CO2 to be absorbed by the ocean causing acidification? 2-2+2=2. Am I missing something?”
If the released CO2 wasn’t dissolved in the oceans then it will be. Eg:
hydrates -> atmosphere -> oceans
Paul R says:
March 16, 2011 at 8:44 pm
“There is that little scale issue again cropping up in Dick Norris’s mud study that must essentially turn mankind’s puny contribution into the Chuck Norris of molecules as usual.
Ka-ching $.”
Man’s contribution isn’t puny. CO2 levels have increased by 40% since pre-industry.
And before anyone wheels out the tired and debunked “humans only emit 3% of CO2”. That 40% increase is part of the 3% accumulating year after year after year. Adds up.
CO2 is currently at millions of year highs so claims on the internet that human CO2 emissions are somehow too small to mean anything is dishonest.
Several have pointed out logic fail in chem of oceans with evolution of co2 in this paper. Another: they have the clay layers bleached gray by ocean acidification dissolving the shells of micro-orgs caused by re-solution of evolved co2 back from the atmos, but this dissolution of shells at the same time re-evolves co2.1) How can the critters get dissolved by the re-entry of the co2 that just left? 2)the dissolution of the shells themselves evolves more co2. See how crazy you can get when you have your co2 blinkers on?
@Jeremy
They discuss Milankovich periodicities (see link Leif Svalgaard gave), but they apparently hold that these correlate with ocean carbon cycles which cause the warming. So they recruit the astronomical data to the carbon paradignm.
Mike D @ur momisugly 1:47AM
Nice.
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onion2 says: March 17, 2011 at 2:34 am
Man’s contribution isn’t puny. CO2 levels have increased by 40% since pre-industry.
And before anyone wheels out the tired and debunked “humans only emit 3% of CO2″. That 40% increase is part of the 3% accumulating year after year after year. Adds up.
CO2 is currently at millions of year highs so claims on the internet that human CO2 emissions are somehow too small to mean anything is dishonest.
The “40% increase” that “Adds up.” and your call elevate the esteem of the poor bullied CO2 molecule is just silly. CO2 is at its historic low. Plants like 1000+ppm of CO2 because they evolved in it. http://i46.tinypic.com/2582sg6.jpg
onion2, I see commonality in your posts. Do you have a set of talking points and responses at the ready? Sort of like a bible for believers with book, chapter, and verse? You have used the same or similar grammatical syntax and semantics in some of your recent responses across threads. It is an area you might want to look at in order to improve your standing as a serious debater.
eadler says:
March 16, 2011 at 8:45 pm
Latitude says:
March 16, 2011 at 7:08 pm
If CO2 is driving temperature like they claim it is. If CO2 raises temperatures to where the feedbacks tipping points cause run away global warming…
“Sexton’s explanation was gibberish.”
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Sorry eadler, I forgot to use the sarcasm annotation.
However, like most good sarcasm, it was rooted and truth. James Overland of NOAA did indeed forward a contrivance called Warm Arctic Cold Continents as an explanation for this winter’s cold. Which is odd, because at Goddard’s site, we too, independently defined the process as warmcold. My use Dr. Syme as an obscure reference to the Orwellian nature of both explanations. In fact, warmcold was contrived with Orwell’s 1984 in mind. Syme would be the co-worker of Winston Smith. “He is too intelligent. He sees too clearly and speaks too plainly.”
Both contrivances are as credible as any other explanation which was posited as an explanation for a process described in the paper.
James