Ancient global cooling gave rise to modern ecosystems

Ancient global cooling gave rise to modern ecosystems
Sediment samples taken from 17 marine locations around the world reveal a 2.5-million-year cool period beginning about 7 million years, a time of sweeping ecological changes across the planet. Credit: Herbert Lab / Brown University

Around 7 million years ago, landscapes and ecosystems across the world began changing dramatically. Subtropical regions dried out and the Sahara Desert formed in Africa. Rain forests receded and were replaced by the vast savannas and grasslands that persist today in North and South America, Africa and Asia.

Up to now, these events have generally been explained by separate tectonic events—the uplift of mountain ranges or the alteration of ocean basins—causing discrete and local changes in climate. But in a new study, a team of researchers has shown that these environmental changes coincided with a previously undocumented period of global cooling, which was likely driven by a sharp reduction in atmospheric .

The research, led by a Brown University geologist and published in Nature Geoscience, is based on a newly developed record of global spanning the past 12 million years. The record reveals a distinct period of cooler sea surface temperatures spanning 7 million to 5.4 million years ago, the end of the Miocene epoch. The global climate during the Miocene is known to have been much warmer than the present. During the cool period detected in this study, sea surface temperatures dropped to near modern levels.

"This is the first time the late Miocene has been put in a context of global sea surface temperatures, and we were surprised to see the amount of cooling we found," said Timothy Herbert, professor in the Department of Earth, Environmental and Planetary Sciences at Brown, who led the study. "In light of this , the paleobiological observations from this period start to make a lot more sense."

The new record of sea surface temperatures was derived from ocean sediment sampled at 17 different sites around the world. The sediment preserves the remains of a plankton species that varies cellular chemistry with temperature. By measuring amounts of those temperature-sensitive molecules, scientists can recreate temperature through time.

The late Miocene cool period was detected at every site sampled, in both hemispheres and in every ocean basin on the planet. The cooling was strongest toward the poles and more moderate toward the equator. That pattern, Herbert says, suggests a global atmospheric cause for the temperature decline. The most likely suspect is carbon dioxide (CO2).

"The hemispheric symmetry and the fact that cooling is much greater at the high latitudes—these are the fingerprints of CO2-related temperature change," Herbert said. "We haven't proven that it was a decline in CO2 because we're not measuring it directly, but we're making a circumstantial case for a reduction in CO2."

The cooler temperatures would likely have played a role in the drying of the subtropics in the late Miocene, the researchers say. "A cooler world—particularly a cooler ocean—would have decreased moisture in the atmosphere," Herbert said. "The hydrological cycle basically slows down with cooling."

And if the cooling was indeed driven by a reduction in atmospheric CO2, it could explain a critical shift in global vegetation that occurred during the late Miocene: the transition from forests to grassland and savanna in the of North and South America, Asia and Africa. These ecosystems are still present today. In Africa, these are the habitats associated with the evolution of our early human ancestors.

Many of the grassy plant species that began thriving during this period are "C4" plants. These species use a slightly different photosynthetic pathway than trees and other plants. The C4 pathway is more efficient in low CO2 environments. "It could be that that if CO2 declined, these C4 species were favored," Herbert said. "So we can associate that shift in vegetation with the same thing that we suspect was driving the late Miocene cooling."

It isn't clear at this point what might have driven a reduction in CO2 during this period, Herbert says. It could be that there were large-scale geological changes occurring at this time that affected the carbon cycle. Herbert's lab is looking into that possibility now.

But what is clear is that there was a significant global shift in global temperatures during the late Miocene.

"The prevailing view was that this wasn't a particularly exciting time in terms of global climate," Herbert said. "It turns out to be more interesting than people thought."


Explore further

Today's climate more sensitive to carbon dioxide than in past 12 million years

More information: Timothy D. Herbert et al. Late Miocene global cooling and the rise of modern ecosystems, Nature Geoscience (2016). DOI: 10.1038/ngeo2813
Journal information: Nature Geoscience

Provided by Brown University
Citation: Ancient global cooling gave rise to modern ecosystems (2016, September 27) retrieved 24 May 2019 from https://phys.org/news/2016-09-ancient-global-cooling-gave-modern.html
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Sep 27, 2016
It's funny how the picture illustrating climate change of seven million years ago shows land masses in their current positions.

Sep 27, 2016
So global cooling and falling CO2 led to desertification now. Could it be that it's actually a good thing we are finally coming out of a CO2 drought? Higher agricultural yields and a blooming biosphere sounds good to me...

Sep 27, 2016
So global cooling and falling CO2 led to desertification now. Could it be that it's actually a good thing we are finally coming out of a CO2 drought? Higher agricultural yields and a blooming biosphere sounds good to me...


You're an idiot. At this stage, I honestly have nothing more. This cooling period was at the end of the Miocene. Do you know how well human civilization thrived during the Miocene? It didn't. We didn't exist and the conditions of that era were not survivable for modern humans. Do you know what's going to look like the Miocene? The Anthropocene in only a few hundred years. We're heading for Miocene conditions RIGHT NOW.

You dimwit.

Sep 28, 2016
And you think I'm an idiot?

Sep 28, 2016
And you think I'm an idiot?


For advocating a return to Miocene conditions as a "good thing". Yes. Objectively, yes.

Sep 28, 2016
I advocated that? Sounds like a classic strawman to me.

Sep 28, 2016
"When the debate is lost, slander becomes the tool of the loser."― Socrates
― Socrates
To my mind the fact that you are resorting to abuse is indicative that you are losing the debate. Let me rephrase my point.
For decades now fear mongers have been claiming that a warming World with increasing CO2 will lead to widespread desertification. From the link above it seems the opposite may well be true.

Sep 28, 2016
It's funny how the picture illustrating climate change of seven million years ago shows land masses in their current positions.

Well, if you look at the simulations of where land masses were then the difference from 7 million years ago to today's positions isn't all that great
https://www.youtu...oSyVu9rk

And you think I'm an idiot?

He ain't the only one.

Sep 28, 2016
"When the debate is lost, slander becomes the tool of the loser."― Socrates
― Socrates
To my mind the fact that you are resorting to abuse is indicative that you are losing the debate. Let me rephrase my point.
For decades now fear mongers have been claiming that a warming World with increasing CO2 will lead to widespread desertification. From the link above it seems the opposite may well be true.


Excuse me, are you pretending to quote a person from whom literally NO WRITTEN MATERIALS EXIST? As an historian, I find your post offensive.

Sep 28, 2016
This comment has been removed by a moderator.

Sep 28, 2016
I apologise if I implied that just because someone made a really really really stupid comment that they are stupid

"When the debate is lost, slander becomes the tool of the loser."― Socrates
― Socrates
To my mind the fact that you are resorting to abuse is indicative that you are losing the debate. Let me rephrase my point.
For decades now fear mongers have been claiming that a warming World with increasing CO2 will lead to widespread desertification. From the link above it seems the opposite may well be true.


I have a comment you made only a few hours ago. Scroll up You, however, have a shocking strawman. Can't wait for you to prove that one.

Sep 28, 2016
It's funny how the picture illustrating climate change of seven million years ago shows land masses in their current positions.


Also, it's not a representation of Earth several millions years ago. It's a representation of the Earth today with the sites they sampled from.

You can figure out this impenetrable code using something we call a "caption".

Sep 28, 2016
Cooling dried up Sahara in the past and warming is making it greener today:
http://www.breitb...greener/

At least for Sahara region it seems like good news.

Sep 28, 2016
This comment has been removed by a moderator.

Sep 28, 2016
It's funny how the picture illustrating climate change of seven million years ago shows land masses in their current positions.

Well, if you look at the simulations of where land masses were then the difference from 7 million years ago to today's positions isn't all that great
"Continental drift connected North America to South America about three million years ago, damming up ... an express route from Atlantic to Pacific."

"This major change in ocean circulation ... led ... to ice accumulation [and] to climatic instability, with flips every few thousand years or so."

http://www.theatl...mate.htm

Sep 28, 2016
Working backward from our current situation of passing into a high energy gas cloud, one might conjecture that it was the exact opposite then; that the Earth passed from high energy into low energy and began to cool not only from the core up but from the atmosphere down. This handy scapegoat of CO2 isn't the answer for everything. Its current usefulness is as an economic vice for extracting money; I discourage science to find the CO2 answer for everything as it makes the masters of the economy happy so the grant money faucet continues to flow.

Sep 28, 2016
What the actual fuck?

Seriously, I'm officially speechless. Can't the moderators do something about these loonies?

Sep 28, 2016
What the actual fuck?

Seriously, I'm officially speechless. Can't the moderators do something about these loonies?

They allow _you_ here, don't they? :-)

Why should you be able to express your ideas and convictions while you want to deny everyone else the opportunity to express theirs.

Sep 29, 2016
Could it be that it's actually a good thing we are finally coming out of a CO2 drought? Higher agricultural yields and a blooming biosphere sounds good to me
@gregthepeg
1- plants require more than just CO2 to live

2- good for plants doesn't mean good for us

3- i suggest reading up on the studies before advocating for CO2 or even considering that higher CO2 is a good thing
start here:
http://jxb.oxford...859.full

http://science.sc...abstract

https://www.ncbi....15720649

http://www.pnas.o...abstract

http://www.plantp...abstract


Sep 29, 2016
Why should you be able to express your ideas and convictions
because his "ideas and convictions" are based on the scientific method (IOW- there's evidence)

is it really that big of a shock to come to a science site and see people who actually like science and know WTF is going on to you????

advocating for a known delusional conspiracist ideation or cult belief system is actually trolling, spamming, baiting or many other things which are not relevant to science or the site, nor is it conducive to communication unless you're starting a cult (or like zeph/reg mundy/the eu cult, need money and hits on your site)

so it comes down to advocating for or against science: leetennant is pro science and therefore has a perspective that is actually relevant to the site

whereas deniers and anti-science or pseudoscience idiots are simply providing delusion and stupidity, all without evidence, which isn't "ideas and convictions" so much as it's a recipe for a Darwin award

Sep 29, 2016
Why should you be able to express your ideas and convictions
because his "ideas and convictions" are based on the scientific method (IOW- there's evidence)
Your evidence is a trend based on suspect data.
advocating for a known delusional conspiracist ideation or cult belief system is actually trolling, spamming, baiting or many other things which are not relevant to science or the site, nor is it conducive to communication unless you're starting a cult
Exactly my point and a perfect description of your alarmist cabal.

Sep 29, 2016
Why should you be able to express your ideas and convictions
because his "ideas and convictions" are based on the scientific method (IOW- there's evidence)
Your evidence is a trend based on suspect data.
advocating for a known delusional conspiracist ideation or cult belief system is actually trolling, spamming, baiting or many other things which are not relevant to science or the site, nor is it conducive to communication unless you're starting a cult
Exactly my point and a perfect description of your alarmist cabal.


I spit on you and your kind, with your intellectual relativism and your "facts-are-just-opinions"-attitude. You people are using all the techniques of totalitarian propagandists, and it is disgusting. History will judge you harshly, and I only regret that you'll probably be dead by then so you won't suffer the consequences of your frankly EVIL actions. Disgusting, shameful and utterly devoid of honor or integrity.

Sep 29, 2016
Your evidence is a trend based on suspect data
@dusty brain TROLL
if you could prove that you would be the hero of the oil companies and you would also be rich beyond your dreams working for them

sorry, but just because you're a conspiracy theorist and don't believe reality doesn't mean the evidence is not real - that kind of belief is called schizophrenia (or religion)
Exactly my point and a perfect description of your alarmist cabal
and again: if you could prove anything you would have already done so

the scientific method isn't a special "members only" club - it's open to you to use and prove the evidence collected by scientists isn't real

your problem is that it actually requires *evidence*... and you aint got none
all ya got is your "belief" and the belief of others like you

IOW - all ya got is religion

Sep 29, 2016
the scientific method isn't a special "members only" club -
But your alarmist cabal is trying to claim it as exclusive property.


Sep 29, 2016
But your alarmist cabal is trying to claim it as exclusive property
@dustybrainTROLL
1- i am not an alarmist
2- no, they're not. scientists are just the only ones using it... because you have yet to make a post that actually uses science or evidence in any way to prove the science is wrong

more to the point: in order for you to be correct you would have to completely reinvent science and reality - which is exactly what you're doing

i don't know what, exactly, you fear, but it is definitely not allowing you to accept reality and it's causing you to ignore the evidence of AGW, etc
perhaps it has something to do with this?
http://journals.p....0075637

Sep 29, 2016
But your alarmist cabal is trying to claim it as exclusive property
@dustybrainTROLL
1- i am not an alarmist
In my book you certainly sound like an alarmist. Perhaps your connotation of "alarmist" is in error or maybe you're just another unwitting dupe of other alarmists.


Sep 30, 2016
In my book you certainly sound like an alarmist
@dustybrainedTROLL
because you believe in conspiracies. again, see: http://journals.p....0075637

Perhaps your connotation of "alarmist" is in error or maybe you're just another unwitting dupe of other alarmists
well, lets look at the definition: https://en.wikipe...Alarmism

per the definition, am i an alarmist?
nope
i follow the evidence
period
full stop

in case you didn't read that... alarmist means
Alarmism is excessive or exaggerated alarm about a real or imagined threat, such as the increases in deaths from an infectious disease.[1] In the news media, alarmism can be a form of yellow journalism where reports sensationalise a story to exaggerate small risks
make up all the labels you want, but if there isn't evidence, then it's simply wrong

i *can* demonstrate, with your own posts, that you ignore scientific evidence

Sep 30, 2016
The Stump is correct in these particular arguments, but why does he have to denigrate others with his silly abusive names?

Sep 30, 2016
to answer @STOLEN VALOR LIAR-KAM
but why does he have to denigrate others with his silly abusive names?
because of history and the evidence

historically, said user has repeatedly ignored empirical evidence and validated scientific studies for their own confirmation bias or delusion

much like *your own history* where you've ignored valid empirical evidence because you want to believe what you say is true (ya can't prove it, IOW)

if you can't produce evidence that validates your claims then it is, at best, an untested claim
at worst, it's a false claim (AKA- lie), and you've been caught in plenty of those, eh g?
http://www.auburn...ion.html

also note: they're labels

and before you get stupid and cry foul: I CAN LINK EVIDENCE

you have yet to be able to produce the same refuting my evidence based posts

Sep 30, 2016
began to cool not only from the core up but from the atmosphere down
Im trying to picture this in my mind. Im coming up empty.

Maybe this?
http://www.thenew...rth.html

Sep 30, 2016
The Stump is correct in these particular arguments, but why does he have to denigrate others with his silly abusive names?
George kamburoff - senior engineer, mcnamara techspook, manager of environments, nuke expert, world savior (I left out a few) (also pothead, VA loiterer, and psychopath)...

Likes: lying, cheating, composing false personal histories, riding his moped around the thai countryside, stolen valor (whos ever gonna know?), taking pics of his neighbors PV and telling goobers its his PV, baiting goobers, playing goobers like cheap kazoos... and also smoking pot and flushing his antipsychotics

Dislikes: goobers and people who have the unmitigated gall to make fun of him.

Dont they KNOW who he IS???


Oct 01, 2016
I spit on you and your kind, with your intellectual relativism and your "facts-are-just-opinions"-attitude. You people are using all the techniques of totalitarian propagandists, and it is disgusting. History will judge you harshly, and I only regret that you'll probably be dead by then so you won't suffer the consequences of your frankly EVIL actions. Disgusting, shameful and utterly devoid of honor or integrity.


Those are attributes of the "totalitarian propagandists" pushing apocalyptic AGW as a tool for gaining power. You're just another big, bad, internet tough guy. Someday I'd like to meet you or one of your kind in person so, with your moral and ethical relativism, and I dare you to spit on me, punk. Spitting is a form of assault, so what I do in response is just self-defense.

You say you're a "historian", which is a unanimous cabal consisting of Marxists bent on revisionism of "history" to serve the Collective.

Oct 01, 2016
The ocean current going through the arctic got clogged up with land mass. This caused cooling and drying over all. This caused C4 plants to prevail in the areas that didn't cool so much. The C4 plants produced a feedback with the cooling trend. The increase in C4 plants caused higher soil CO2 fixation rates. This led to chronically low CO2 levels since then since as it appears that C4 plants did not exist in the prior high CO2 environment.

Wiki: "Because of this extra energy requirement, C4 plants are able to more efficiently fix carbon in drought, high temperatures, and limitations of nitrogen or CO2, while the more common C3 pathway is more efficient in the other conditions."

C4 plants are an artifact of a starved system but also contribute to it over the long term

Oct 02, 2016
If you consider that the systems body has been incurring on a regular cycle of reduced energy each time, we may have the answer to our planets climate history.
http://phys.org/n...ant.html
http://solomon.as...tar.html
Note the last few pages where the author R Duncan U of Texas astrophysist., speaks to the age of magnetars and the plethora of red/brown dwarfs our science claims populate the universe.

Oct 02, 2016
The fact that this article was rushed into publication before it was ready reflects the speculative state of the whole catastrophic anthropogenic global warming scenario.

Oct 03, 2016
"Paleoclimate and archaeological evidence tells us that, 11,000-5,000 years ago, the Earth's slow orbital 'wobble' transformed today's Sahara desert to a land covered with vegetation and lakes". Starting with that the whole of this article is BS. The world has been in a general cooling phase for around 2 million or so years. During that time we have had warmer periods and today is one of them.http://www.nature...82884405

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