Claim: Climate and carbon cycle trends of the past 50 million years reconciled

UNIVERSITY OF HAWAII AT MANOA

Research News

IMAGE
IMAGE: CLEVELAND VOLCANO, ALEUTIAN ISLANDS ERUPTION IN 2006. VOLCANISM IS ONE OF THE MAIN CARBON DIOXIDE SOURCES IN THE LONG-TERM CARBON CYCLE BALANCED BY WEATHERING SINKS, WHICH, AMONG OTHERS, REPRESENT IMPORTANT… view more CREDIT: NASA IMAGE COURTESY JEFF WILLIAMS

Predictions of future climate change require a clear and nuanced understanding of Earth’s past climate. In a study published today in Science Advances, University of Hawai’i (UH) at Mānoa oceanographers fully reconciled climate and carbon cycle trends of the past 50 million years–solving a controversy debated in the scientific literature for decades.

Throughout Earth’s history, global climate and the global carbon cycle have undergone significant changes, some of which challenge the current understanding of carbon cycle dynamics.

Less carbon dioxide in the atmosphere cools Earth and decreases weathering of rocks and minerals on land over long time scales. Less weathering should lead to a shallower calcite compensation depth (CCD), which is the depth in the ocean where the rate of carbonate material raining down equals the rate of carbonate dissolution (also called “snow line”). The depth of the CCD can be traced over the geologic past by inspecting the calcium carbonate content of seafloor sediment cores.

Former oceanography graduate student Nemanja Komar and professor Richard Zeebe, both at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST), applied the most comprehensive computer model of the ocean carbonate chemistry and CCD to date, making this the first study that quantitatively ties all the important pieces of the carbon cycle together across the Cenozoic (past 66 million years).

Contrary to expectations, the deep-sea carbonate records indicate that as atmospheric carbon dioxide (CO2) decreased over the past 50 million years, the global CCD deepened (not shoaled), creating a carbon cycle conundrum.

“The variable position of the paleo-CCD over time carries a signal of the combined carbon cycle dynamics of the past,” said Komar, lead author of the study. “Tracing the CCD evolution across the Cenozoic and identifying mechanisms responsible for its fluctuations are therefore important in deconvolving past changes in atmospheric CO2, weathering, and deep-sea carbonate burial. As CO2 and temperature dropped over the Cenozoic, the CCD should have shoaled but the records show that it actually deepened.”

Komar and Zeebe’s computer model allowed them to investigate possible mechanisms responsible for the observed long-term trends and provide a mechanism to reconcile all the observations.

“Surprisingly, we showed that the CCD response was decoupled from changes in silicate and carbonate weathering rates, challenging the long-standing uplift hypothesis, which attributes the CCD response to an increase in weathering rates due to the formation of the Himalayas and is contrary to our findings,” said Komar.

Their research suggests that the disconnect developed partially because of the increasing proportion of carbonate buried in the open ocean relative to the continental shelf due to the drop in sea level as Earth cooled and continental ice sheets formed. In addition, ocean conditions caused the proliferation of open-ocean carbonate-producing organisms during that period of time.

“Our work provides new insight into the fundamental processes and feedbacks of the Earth system, which is critical for informing future predictions of changes in climate and carbon cycling,” said Komar.

The researchers are currently working on new techniques to constrain the chronology of climate and carbon cycle changes over the past 66 million years.

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Mike
January 22, 2021 6:23 pm

Predictions of future climate change require a clear and nuanced understanding of Earth’s past climate.”

Yes they do! Good luck with that…

Joel O'Bryan
Reply to  Mike
January 22, 2021 6:47 pm

Merriam-Webster says:

nu·​ance | \ ˈnü-ˌän(t)s
1
: a subtle distinction or variation

Subtle would be an antonym of clear. So that wording is just a two-faced answer trying to have it both ways if you ask me.

Reply to  Joel O'Bryan
January 23, 2021 1:20 am

Subtle would not be an antonym of clear. Opaque is an antonym of clear. An antonym of ‘subtle’ would be ‘blindingly, in-your-face, obvious’.

Bryan A
Reply to  Leo Smith
January 23, 2021 1:05 pm

Obviously an attempt to pull away from Climate Change Alarmism and delve into Climate Change Subtleism

gringojay
Reply to  Mike
January 22, 2021 10:35 pm

“… (T)echniques to constrain the chronology …” is what Komar said is next. The word English word constrain is constraining the meaning of that sentence. My favorite passage is definitely “… creating a carbon cycle conundrum.”

Bryan A
Reply to  gringojay
January 23, 2021 1:08 pm

Carbon Cycle Conundrum Phacists
The new CCCP

Kevin kilty
January 22, 2021 6:35 pm

Some years ago a lecturer invited to the “Distinguish Lecture Series” at University of Wyoming gave a fascinating talk about the global volatiles budget. I wish I could recall the name of this person, and surprisingly none of the faculty I have quizzed seem to recall either the lecturer or the lecture. Perhaps someone here might know who this is…

Nevertheless, he gave quite a lot of evidence suggesting there is some unknown mechanism in volatiles moving from mantle to surface, because all known mechanisms favor the burial of volatiles in the mantle. His focus, as I recall, was mainly on chlorine and sulfur, and hissuggestion was that there might be a broad diffusion of mantle sources back to the surface. However, the talk got me to wondering about the possibilility that CO2 balance does not close and this is the reason for the secular decline over the past 50my. Subduction takes carbonates into the mantle and volcanoes are not active enough to return all the CO2 to the surface. Perhaps there is a long time lag in this part of the cycle.

Last edited 1 month ago by Kevin kilty
Joel O'Bryan
Reply to  Kevin kilty
January 22, 2021 7:02 pm

Whenever I went to a visiting guest lecture I took a black composition notebook to take notes, scribbles mostly, with bad handwriting. I was sometimes jotting things down furiously as the presenter said something or showed key points on slides. I always put the presenter name, affiliation, and date of the lecture at the top page. I still have those stacks of composition notebooks and have referred back to them occasionally to find just the kind of thing you describe here. Something would come up in conversation or lab meeting like you describe, vague recollections of some lecturer saying something we’re talking about and they’d found or observed. Those notebooks were gold.

Last edited 1 month ago by joelobryan
Joel O'Bryan
January 22, 2021 6:43 pm

“In addition, ocean conditions caused the proliferation of open-ocean carbonate-producing organisms during that period of time.”

We know that glacial periods coincide with significant atmospheric dust storms lifted from cold, drying continents. The dust plumes are carried thousands of miles by the atmosphere and settles as ocean fertilization thus providing the limiting nutrients like iron and phosphates. So open-ocean carbonate producing zooplankton should proliferate.

But since their expectations of a shoaling CCD were instead met with data showing a deepening CCD, maybe CO2 ain’t the climate control knob the climate priesthood says it is?

Chaswarnertoo
Reply to  Joel O'Bryan
January 23, 2021 3:47 am

No ‘maybe’ about it. CO2 greens and cools the planet.

Steve Keohane
Reply to  Joel O'Bryan
January 23, 2021 4:39 am

Maybe, since 90% of the time the oceans are much smaller, lower with less surface area, the carbonate producing zooplankton should proliferate, but over a smaller area, and said carbonate deposited much deeper than when we are around to take note.

Richard Page
Reply to  Steve Keohane
January 23, 2021 7:00 am

….deposited in water that we now see as deeper.

n.n
January 22, 2021 6:47 pm

50 million years of diversity. Miss a link, color it wrong, or integrate a prejudice, then your prescription diverges catastrophically.

Last edited 1 month ago by n.n
Len Werner
January 22, 2021 6:48 pm

Less carbon dioxide in the atmosphere cools Earth…”

Doesn’t this fail before it’s even got out of the gate? Hasn’t CO2 fluctuation followed but lagged temperature change throughout geologic history?

How strange to first assume a mass delusion that turns reality on its head, and then proceed with a detailed analysis from there. These are academics??

OweninGA
Reply to  Len Werner
January 22, 2021 7:33 pm

Remember, there are some ideas so idiotic that only an academic could embrace them.

Or in Orwell’s formulation: “There are some ideas so wrong that only a very intelligent person could believe in them.”

Mariner
Reply to  OweninGA
January 23, 2021 4:45 am

Socialism in general has a record of failure so blatant that only an intellectual could ignore or evade it.
Thomas Sowell

Reply to  Len Werner
January 22, 2021 7:44 pm

It’s led, lagged and not correlated… Depends on which proxies are chosen.

donb
Reply to  Len Werner
January 22, 2021 8:38 pm

@LN
There is good evidence that temperature changes preceded changes in CO2 during the glacial periods over past ~800 Myr.
However further back in time the time resolution of these two changes is difficult to determine so nothing concrete can be concluded.

Smart Rock
Reply to  Len Werner
January 22, 2021 10:56 pm

As far as I know (which isn’t that far) the only unequivocal evidence of CO2 lagging behind temperature is in the glacial-interglacial cycles of the last half million years. This is one area where the climate orthodoxy has no choice but to allow insolation fluctuations, whether they are caused by orbital cycles or “something else” to step in and take over the heavy lifting of initiating glaciation or deglaciation. That allows atmospheric CO2 to follow temperature by gassing/degassing of oceanic CO2, without violating the sanctity of CO2’s primacy as the climate driver.

The epigram “CO2 is the control knob” summarises, in five words, the entirety of climate science. But when confronting glacial cycles, the Central Committee of climate science would have to vary it a bit and say <b>”CO2 is the control knob, but there’s an on/off switch too”.</b>

Mostly they ignore glacial cycles. They just complicate the story. No ice ages in the Anthropocence; the world began in 1750.

Mickey Reno
Reply to  Len Werner
January 23, 2021 5:51 am

In the long ice core samples, cooling (reglaciation) periods began and temperatures began to fall as CO2 was hitting cyclical maximums. The relatively higher levels of CO2 did NOT prevent any cooling. And indeed, as the cooling proceeded, the CO2 lag (about 800 years) was maintained, and as the oceans eventually cooled, they absorbed more CO2, the CO2 concentrations dutifully followed the cooling cycle caused by solar/orbital/cloud/albedo changes. Read the hilarious explanation of this conundrum for the CO2 alarmists on RealClimate, and try to count up all the unknowns that their little word games employ in order to maintain the fiction that CO2 was the control knob for climate changes between glaciation and inter-glacial warming.

Tom Abbott
Reply to  Len Werner
January 26, 2021 8:42 am

“How strange to first assume a mass delusion that turns reality on its head, and then proceed with a detailed analysis from there. These are academics??”

That’s what they are doing. They are assuming the CAGW (Catastrophic Anthropogenic Global Warming) narrative that the Earth’s climate has been steadily warming since the last Ice Age and the Earth is now at the warmest point in human history, is true.

The idea that the Earth’s climate proceeds in cycles where the temperatures warm for a few decades, and then they cool for a few decades, and then warm again, has been purged from their thinking. They think this one warming period in the cycle we are currently in is the only thing that exists, and that it will continue as long as CO2 concentrations in the atmosphere increase, with the Earth getting hotter and hotter as a consequence.

So, they start out with a false assumption, and go further astray from there.

This is the essense of current Alarmist Climate Science. It’s all smoke and mirrors and unsubstantiated speculation on top of unsubstantiated speculation. It’s the darndest thing I’ve ever seen. It’s Brainwashing writ Large.

We are probably going to be disappointed at how many Republicans have fallen prey to this climate change brainwashing. They will just have to be educated. They should all be spending some time with Dr. Happer.

Biden is giving his “Climate Change” speech tomorrow, so we will be hearing the Republicans voice their opinions on the subject. That ought to be fun.

Let’s see just how over-the-top Biden’s rhetoric gets. Will he declare a National Emergency over the Earth’s climate?

markl
January 22, 2021 7:25 pm

You’ll always find what you are looking for if you lower your standards.

OweninGA
Reply to  markl
January 22, 2021 7:34 pm

Also true if you simply delete all information that goes against your theory.

Pauleta
Reply to  OweninGA
January 22, 2021 7:44 pm

Don’t have to delete, just bury it.

MarkW
Reply to  Pauleta
January 22, 2021 9:14 pm

Or adjust it

Chaswarnertoo
Reply to  MarkW
January 23, 2021 3:48 am

The adjustocene.

Editor
January 22, 2021 7:48 pm

This bit is idiotic:

Contrary to expectations, the deep-sea carbonate records indicate that as atmospheric carbon dioxide (CO2) decreased over the past 50 million years, the global CCD deepened (not shoaled), creating a carbon cycle conundrum.

It’s totally bass-ackwards. The CCD should shoal with increasing CO2. It’s supposed to deepen with increasing CO2. Although, which is the cause and which is the effect is unclear.

Joel O'Bryan
Reply to  David Middleton
January 22, 2021 8:10 pm

increasing and increasing???

Editor
Reply to  David Middleton
January 22, 2021 10:17 pm

David Middleton – I assume you mean that CCD should deepen with decreasing CO2. But in any case, I don’t think they have resolved anything – other than the observation that CCD deepened with decreasing atmospheric CO2 (I have to assume they got that right). This is how I see it: They expected to find that CCD shoaled with decreasing CO2, based on existing theory re the “CCD response to an increase in weathering rates due to the formation of the Himalayas”. When they found that CCD did the opposite of what was expected, they fiddled with the parameters until they got a match. From this it follows that they will pretty obviously fail to make the Himalayas have the opposite effect to their expected effect, and they will have to come up with some other factors that can give them what they want. They played around until they got a match using “continental ice sheets” and “open-ocean carbonate-producing organisms”. Now it would seem that they simply pumped in assumptions about the various factors until they could match observation. There may well be many other factors that they could have played with to get the same result, and there is no good reason to suppose that the factors they chose were any better or worse than the factors they didn’t choose – and bear in mind that the factors they didn’t choose include all the factors they didn’t think of. I wonder how many if those there are.

I suggest that their own paper confirms what I have said, wrt to both (a) not resolving anything and (b) not having selected the right factors: The paper’s abstract ends with “At the moment, however, our coupled modeling effort cannot reproduce the magnitude of change in all these records collectively. Similar problems have arisen in simulations of short‐term hyperthermal events during the early Paleogene (Paleocene‐Eocene Thermal Maximum), suggesting one or more basic issues with data interpretation or geochemical modeling remain.”. [my bold]

Reply to  Mike Jonas
January 23, 2021 10:15 am

Correct… Fixed below.

Reply to  Mike Jonas
January 23, 2021 10:20 am

The CCD is probably the primary control on atmospheric CO2 over the Phanerozoic Eon.

Reply to  David Middleton
January 23, 2021 10:11 am

Correction: It’s supposed to deepen with decreasing CO2.

observa
January 22, 2021 9:03 pm

Sorry I got distracted with all the new extremophiles hanging about with the dooming-
Hundreds of never-before-seen life-forms live in this 6,000-foot-deep volcano’s acid jets (msn.com)

Now where were we again? Oh yes that’s right-“oceanographers fully reconciled climate and carbon cycle trends of the past 50 million years–solving a controversy debated in the scientific literature for decades.”

January 22, 2021 9:35 pm

“Surprisingly, we showed that the CCD response was decoupled from changes in silicate and carbonate weathering rates.”

Surprising only if you are looking in the wrong place.
 

“Less carbon dioxide in the atmosphere cools Earth and decreases weathering of rocks and minerals on land over long time scales”

Mountains are thermal radiators; they typically have heights well into the direct surface thermal radiative loss to space atmospheric bypass window.
So, as the temperature of the polar surface waters dropped due to increased cold air advection following more winter heat loss to space as the Transantarctic mountains grew, more carbon dioxide was absorbed into the now cold polar deep waters around the island continent of Antarctica.
 
Consequently, less carbon dioxide would be released from these chilled deep waters on return to the equatorial surface due to ocean water thermal buffering (e.g. the Humboldt current). As the total mass of carbon dioxide sequestered in the now colder global ocean grew the Carbonate Compensation Depth was observed to deepen. The Carbonate “snow line” is therefore primarily ocean water temperature dependent. Or is it? What about the rate of biological productivity?
 
Or perhaps because the sea floor near ocean ridges is typically above the CCD. More active seafloor spreading in the Tertiary leads to shallower ridge crests and more ocean carbonate ooze sediment burial and lithic carbonate sequestration.
 
So, which dominates the CCD? Water pressure at depth which is land ice / ocean water volume dependent and also ridge crest size dependent. Decreased temperature at depth which is polar land surface icecap radiative heat loss to space dependent, or more equatorial surface water biological carbonate production. Clearly lots of moving parts here.
 

Reply to  Philip Mulholland
January 23, 2021 4:25 am

The Cretaceous Period was a time of low relief continents, high sea levels and the Tethys Ocean, a zonal tropical ocean located in the Horse Latitudes beneath the descending limb of the northern hemisphere Hadley cell. The shallow epeiric seas on the southern margins of the Tethys were warm dense bottom water generators that filled the global ocean with 16 C abyssal waters.
 
On return to the surface in the polar latitudes this warm deep water delivered heat to both the northern hemisphere Boreal Ocean, and also in the southern hemisphere to the northern coast of the still joined Austral-Antarctic continent. This warm dense saline thermohaline bottom water heat transport mechanism, driven from the Tethys, dominated the warm global climate of the Cretaceous world.
 
The modern world of the Cenozoic Era is a time of high relief continents, major mountain chains (both continental fold belts and oceanic ridges), low sea levels and the Southern Ocean, a circumpolar ocean located in the Temperate Latitudes beneath the mixing zone of the southern hemisphere Ferrel cell. To the south of the Southern Ocean lies the island ice continent of Antarctica with its buried range of the Transantarctic Mountains, the seed kernel of the modern ice age.
 
The high average elevation of the Antarctic icecap generates katabatic winds that freeze the southern margin of the Southern Ocean in winter, and generate cold dense bottom water that fills the global ocean with 4 C abyssal waters. On return to the surface in the tropical latitudes this cold deep-water circulation chills the western margins of the southern continents and also the eastern Pacific, driving the locus of the Doldrums into the northern hemisphere. This cold dense saline thermohaline bottom water transport mechanism, driven from Antarctica, dominates the cold global climate of the modern world.
 
It’s all about elevation.

Last edited 1 month ago by Philip Mulholland
gringojay
Reply to  Philip Mulholland
January 23, 2021 9:39 am

Very concise & easy to grasp presentation of it’s long view, thanx.

Reply to  Philip Mulholland
January 25, 2021 5:07 am

Philip
The presence of the meridionally bounded Atlantic ocean is also a factor.
This funnels currents from the equator toward both Arctic and Antarctic – although the latter are terminated by the Southern ocean.
In the NH it creates the unstable AMOC (Atlantic meridional overturning circulation) which behaves intermittently, adding to climate variability.
This causes superstitious hominids to ascribe malevolent causes to frequent natural climate oscillations, resulting in theocracies based on dystopian fear.

Stephen Richards
January 23, 2021 1:15 am

I apologies deeply. I read as far as the word MODEL and stopped. No point in reading beyond that

Hans Erren
January 23, 2021 1:46 am

This is a press announcenent. Where is the publication with de results?

Hans Erren
Reply to  Hans Erren
January 23, 2021 1:51 am

Here
Reconciling atmospheric CO2, weathering, and calcite compensation depth across the Cenozoic
Nemanja Komar and Richard E. Zeebe
Science Advances 22 Jan 2021:
Vol. 7, no. 4, eabd4876
DOI: 10.1126/sciadv.abd4876

https://advances.sciencemag.org/content/7/4/eabd4876/tab-figures-data

Greg
January 23, 2021 3:17 am

“Their research suggests that the disconnect developed partially because of the increasing proportion of carbonate buried in the open ocean relative to the continental shelf due to the drop in sea level as Earth cooled and continental ice sheets formed. In addition, ocean conditions caused the proliferation of open-ocean carbonate-producing organisms during that period of time.”

So, during a chat over coffee, they contrived some hypothetical excuses for the existing theory being diametrically opposed to observations.

This is not science or research, it is speculation. Actually publishing this and claiming a “reconcilliation” is farcical.

Paul of Alexandria
January 23, 2021 6:35 am

I wonder if we’re not seeing the CO2 equivalent of the “great oxidation” of 2.5 billion years ago (see https://youtu.be/H476c8UjLXY, a great video on the subject) ? That was caused by bacteria discovering photosynthesis. That episode ended in a “snowball Earth” for a while because all of the nice methane keeping the planet warm oxidized.

Now marine critters are slowly locking all that oxygen, and carbon, away again in carbonates. Could be another great extinction event, and another “snowball Earth”, creeping up on us.

phodges
Reply to  Paul of Alexandria
January 26, 2021 11:47 am

sure seems like that is where we are headed

gbaikie
January 23, 2021 11:10 am

–Predictions of future climate change require a clear and nuanced understanding of Earth’s past climate.–

Not really. Predictions of future change, beyond say, 1000 year into the future, is nearly worthless. As there other factors far more important than climate change, which can occur within a few centuries or even decades.
Within a few centuries, we might have a global nuclear war, we may discover alien civilizations, and/or space aliens could visit Earth, something significant might happen in regard artificial intelligence, we might develop a better way educating people, and so on with endless possibilities which can’t predicted but are more important
Global climate change is something that occurs very slowly- in terms of climate change nothing much has happened in last two centuries and nothing much will happen in the next two centuries- and it does require a nuanced understanding of Earth’s past climate to make such predictions.
But make a list of humans have done in last two centuries, and likely humans will as much in the next two centuries.

A moderate understanding of Earth’s climate past, indicates we are in an Ice Age and living with a world with low CO2 levels. And Ice Age is defined as having polar ice caps and a cold ocean. And there is no known factors which cause us to leave this cold global climate state
within a few centuries. With moderate understanding, it’s possible we could reach warmer time period of interglacial periods- which occurred a number of times in the past. But with current rate of sea level rise around 7″ per century, it is an unlikely thing to wish for. And the desire to return to colder condition associated with Little Ice Age, is criminally stupid.
And that politicans are pushing for criminally stupid things is hardly surprising considering their stupidity and madness over last couple of centuries.
It’s unlikely within couple centuries, we could get a global climate as cool as the Little Ice Age or as warm and warmest periods of past interglacial periods- and that about as much that needs to be predicted in terms global climate.
What is more needed is what will the idiot politicans will do, over say next couple decades.
What are they going to do about China which has been forever causing global pandemics,
and constantly mismanaging it? To mention just one aspect of “current news”?
Apparently, nothing, as is their normal non-governing wont.

Loren C. Wilson
January 23, 2021 2:22 pm

Surprisingly, the science is not quite settled yet, kind of like physics towards the end of the 1800’s.

January 23, 2021 2:37 pm

The burning question on my mind in regard to geological and palaeoclimate studies, in our current alarmist-politicised times, is simply this:

is the research community engaged in an honest search for truth? Or not?

These are intelligent and talented people. They have strong political skills also since anyone without those has the prospects of a snowflake in hell in the academic grant competing system.

I would very much like to believe that, as a whole, the research community are people who remain true to that childlike curiosity that originally led them to pursue a somewhat risky and not particularly well paid profession.

But too often one runs into obvious examples of motivated selection of evidence and motivated reasoning. Worst of all, published research seems now to mandate the unquestioned assumption of CO2 dominance of global temperature at all times past, present and future. Rather than an open mind.

The truth will still eventually be made clear. It might just take a long time.

Tom Abbott
Reply to  Phil Salmon
January 26, 2021 9:01 am

“Worst of all, published research seems now to mandate the unquestioned assumption of CO2 dominance of global temperature at all times past, present and future. Rather than an open mind.”

That *is* the worst of it. You are a pariah if you deviate from the Groupthink. Even if you don’t believe, you must conform and parrot the Groupthink.

Alarmist Climate Science = Orwell’s “1984”.

We at WUWT will probably be getting an upclose and personal look at that in the near future as the authoritrians seek to make us conform to their Groupthink, one way or another. After all it’s a National Emergency and a World Crisis.

Nope, not going to do it. Not going to conform to the Groupthink. Na-ga-da, as George H.W. Bush and a Saturday Night Live comedian, used to say. Not going to do it.

We need evidence. Groupthink be damned!

Jackie Pratt
January 25, 2021 7:56 pm

So the science is settled yet again?

“In a study published today in Science Advances, University of Hawai’i (UH) at Mānoa oceanographers fully reconciled climate and carbon cycle trends of the past 50 million years–solving a controversy debated in the scientific literature for decades.”

So I’d guess CO2 will kill the planet still?

Tom Abbott
Reply to  Jackie Pratt
January 26, 2021 9:03 am

“So I’d guess CO2 will kill the planet still?”

They don’t have any idea.

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