Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not involved, Stanford researchers say. See more about the Faint sun paradox here. A video clip follows.
From a Stanford University News press release.
Researchers have long wondered why water on Earth was not frozen during the early days of the planet, when the sun emanated only 70 to 75 percent as much energy as it does today. Some theorize that high levels of greenhouse gases in the atmosphere, the same mechanism cited in global warming today, were key. But new research involving Stanford scientists has a different explanation: The oceans, much larger than today, absorbed enough heat from the sun to avoid turning into ice.
BY LOUIS BERGERON
Four billion years ago, our then stripling sun radiated only 70 to 75 percent as much energy as it does today. Other things on Earth being equal, with so little energy reaching the planet’s surface, all water on the planet should been have frozen. But ancient rocks hold ample evidence that the early Earth was awash in liquid water – a planetary ocean of it. So something must have compensated for the reduced solar output and kept Earth’s water wet.
To explain this apparent paradox, a popular theory holds there must have been higher concentrations of greenhouse gases in the atmosphere, most likely carbon dioxide, which would have helped retain a greater proportion of the solar energy that arrived.
But a team of earth scientists including researchers from Stanford have analyzed the mineral content of 3.8-billion-year-old marine rocks from Greenland and concluded otherwise.
“There is no geologic evidence in these rocks for really high concentrations of a greenhouse gas like carbon dioxide,” said Dennis Bird, professor of geological and environmental sciences.
Instead, the team proposes that the vast global ocean of early Earth absorbed a greater percentage of the incoming solar energy than today’s oceans, enough to ward off a frozen planet. Because the first landmasses that formed on Earth were small – mere islands in the planetary sea – a far greater proportion of the surface of was covered with water than today.
The study is detailed in a paper published in the April 1 issue of Nature. Bird and Norman Sleep, a professor of geophysics, are among the four authors. The lead author is Minik Rosing, a geology professor at the Natural History Museum of Denmark, University of Copenhagen, and a former Allan Cox Visiting Professor at Stanford’s School of Earth Sciences.
The crux of the theory is that because oceans are darker than continents, particularly before plants and soils covered landmasses, seas absorb more sunlight.
“It’s the same phenomenon you will experience if you drive to Wal-Mart on a hot day and step out of your car onto the asphalt,” Bird said. “It’s really hot walking across the blacktop until you get onto the white concrete sidewalk.”
Another key component of the theory is in the clouds. “Not all clouds are the same,” Bird said.
Clouds reflect sunlight back into space to a degree, cooling Earth, but how effective they are depends on the number of tiny particles available to serve as nuclei around which the water droplets can condense. An abundance of nuclei means more droplets of a smaller size, which makes for a denser cloud and a greater reflectivity, or albedo, on the part of the cloud.
Most nuclei today are generated by plants or algae and promote the formation of numerous small droplets. But plants and algae didn’t flourish until much later in Earth’s history, so their contribution of potential nuclei to the early atmosphere circa 4 billion years ago would have been minimal. The few nuclei that might have been available would likely have come from erosion of rock on the small, rare landmasses of the day and would have caused larger droplets that were essentially transparent to the solar energy that came in to Earth, according to Bird.
“We put together some models that demonstrate, with the slow continental growth and with a limited amount of clouds, you could keep water above freezing throughout geologic history,” Bird said.
“What this shows is that there is no faint early sun paradox,” said Sleep.
The modeling work was done with climate modeler Christian Bjerrum, a professor in the Department of Geography and Geology, University of Copenhagen, also a co-author of the Nature paper.
The rocks that the team analyzed are a type of marine sedimentary rock called a banded iron formation.
Video: These rocks, billions of years old, tell a new story about the evolution of early Earth, Stanford researchers say.
“Any rock carries a memory of the environment in which it formed,” Rosing said. “These ancient rocks that are about 3.8 billion years old, they actually carry a memory of the composition of the ocean and atmosphere at the time when they were deposited.”
Another constraint on early carbon dioxide levels came from life itself.
In the days before photosynthetic organisms spread across the globe, most life forms were methanogens, single-celled organisms that consumed hydrogen and carbon dioxide and produced methane as a digestive byproduct.
But to thrive, methanogens need a balanced diet. If the concentration of either of their foodstuffs veers too far below their preferred proportions, methanogens won’t survive. Their dietary restrictions, specifically the minimum concentration of hydrogen, provided another constraint on the concentration of carbon dioxide in the atmosphere, and it falls well below the level needed for a greenhouse effect sufficient to compensate for a weak early sun.
“The conclusion from all this is that we can’t solve a faint sun paradox and also satisfy the geologic and metabolic constraints by having high carbon dioxide values,” Bird said.
But the theory of a lower Earthly albedo meets those constraints.
“The lower albedo counterbalanced the fainter sun and provided Earth with clement conditions without the need for dramatically higher concentrations of greenhouse gasses in the atmosphere,” Rosing said.
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wayne (16:26:04) :
Michael J. Dunn (12:45:14) :
Phillep Harding (12:02:13) :
“Michael, your point to Phillip will be greatly magnified with the correct factors:
~580 Cal/g or ~2425 kJ/kg, not 1400 J/kg
~1 Cal/g/K or ~4.2 J/g/K, not 1 J/g/K”
Dear Wayne,
My deepest apologies about the value for the heat of vaporization of water; I misread a table not only by a factor of “kilo” (k) by also by referencing the value for 300 C instead of 300 K. I’ve been in a rocky patch lately.
But you have misfired on the second number. I was giving the specific heat capacity of air, which would be warmed by any water condensation (where does the heat go?). You have given the specific heat capacity of water, which plays no role in condensation, since the water temperature does not change during the process.
Since air has about 1/1000th the density of water, this means that even a small mass of condensing water can greatly heat large volumes of air. This is known to anyone who has lived in a steam-heated dwelling. But the same effect still works in the realm of specific heat content, as can be experienced by walking through fog. Even at an equable temperature, the heat loss to the aerosol water droplets can be large, which is why fog is so chilly. (I know. I used to do a lot of horseback riding through the fog.)
This is all a footnote to the main thread of discussion, I suppose, but it does support the idea that local conditions can plausibly be the result of atmospheric heat transport processes.
@Paul Hildebrandt (06:10:47) :
“…I’m not confusing anything. Hawaii is an island, yet it is not sialic. As I stated above, if they existed, they were probably scattered and few in number. The fact that zircons of that age have not been found in their native environment argues against microcontinents. However, that does not mean that they did not exist. We just haven’t found any or they haven’t surfaced due to the stable nature of the Archean cratons….”
This is a fun topic – lots of room to wave one’s arms. I suggest Hawaii is a bad example; maybe an intraocean island arc would suit to form the calcalkaline partial melts you refer to. As to finding the pieces of microcontinents, recall that much of the Archaean in the Northern Hemisphere is covered, and we’ll probably never know what’s hidden (the SA is not all that well exposed either, and is mostly deeply weathered).
The Slave Province, where those ~4BY zircons originate, is an interesting place. It seems to be stitched together of several disparate terranes, and then this mishmash was crammed into other chunks to form the North American craton.
Here are some interesting references for those who care about such things:
http://www.mnh.si.edu/earth/text/4_1_3_1.html
2 Billion Years Ago – A Continent Is Born
Six microcontinents — some formed from Earth’s earliest continental crust — collided and stuck together to build the North American craton. The craton later became a part of three supercontinents: Laurussia, Pangaea, and Laurasia. Now it underlies 70 percent of North America. Parts of the craton contain rocks that range in age from 2.5 to 4 billion years, including Earth’s oldest-known rock. Most were highly deformed and metamorphosed as the craton was assembled.
http://geology.geoscienceworld.org/cgi/content/abstract/17/1/63
Accretion of the Archean Slave province -T. M. Kusky1
It is proposed that the high-strain zones separate four distinct terranes that have been juxtaposed during collisional orogenesis. From west to east, these include the Anton terrane, interpreted as an Archean microcontinent; the Sleepy Dragon terrane, possibly an exhumed more eastern part of the Anton terrane; the Contwoyto terrane, a westward-verging fold and thrust belt containing tectonic slivers of greenstone volcanics; and the Hackett River volcanic terrane, interpreted as an Archean island arc. The Contwoyto and Hackett River terranes represent a paired accretionary prism and island-arc system that formed above an east-dipping subduction zone. These collided with the Anton microcontinent, producing a basement nappe, expressed as the Sleepy Dragon terrane, during the main accretion event within the Slave province. The whole tectonic assemblage was intruded by late-kinematic to postkinematic granitoids.
http://geology.geoscienceworld.org/cgi/content/abstract/17/11/971
3.96 Ga gneisses from the Slave province, Northwest Territories, Canada
S. A. Bowring1, I. S. Williams2 and W. Compston2
Ion microprobe U-Pb analyses of zircons have identified the Acasta gneisses, from the westernmost Slave province, Canada, as the oldest known intact terrestrial rocks. Zircons from two samples indicate that the tonalitic to granitic protoliths of the gneisses crystallized at 3962 ±3 Ma, confirming earlier indications, from conventional zircon and Nd analyses, of the rock’s antiquity. The U-Pb analyses indicate that in addition to recent Pb loss, the zircons underwent an early episode of Pb loss and that new zircons crystallized ca. 3.6 Ga. The gneisses were derived from a source that had a long-lived enrichment in light REE, possibly from even older rocks that may be present in the Slave province.
and finally:
http://sp.lyellcollection.org/cgi/content/abstract/199/1/151
Archaean tectonics: a review, with illustrations from the Slave craton -Wouter Bleeker
The extensional and subsequent contractional evolution of granite-greenstone terrains may have occurred in the overall context of a plate tectonic regime (e.g. volcanic rifted margins, back-arc basins) but highly extended, intraplate, rift-like settings seem equally plausible. Explaining the evolution of the latter in terms of Wilson cycles is misguided. Periods of intense rifting and flood volcanism (e.g. 2.73–2.70 Ga) may have been related to increased mantle plume activity or perhaps catastrophic mantle overturn events. Although there is evidence for plate-like lateral movement in late Archaean time (e.g. lateral heterogeneity of cratons, arc-like volcanism, cratonscale deformation patterns, strike-slip faults, etc.), the details of how these plate-like crustal blocks interacted and how they responded to rifting and collision appear to have differed significantly from those in Phanerozoic time. The most productive approach for Archaean research is probably to more fully understand and quantify these differences rather than the common emphasis on the superficial similarities with modern plate tectonics.
Enjoy!
Carla (08:38:22) :
Whoaa here Group W says, “But your not on meds, Carla.”
It seems Group W runs your life. Perhaps try to get some control back and be boss over yourself.
Jim F (09:59:18) :
This is a fun topic – lots of room to wave one’s arms.
Indeed. It is also plausible that the continents have broken up and reassembled something lime 7 or 8 times over the life of the Earth.
I suggest Hawaii is a bad example; maybe an intraocean island arc would suit to form the calcalkaline partial melts you refer to.
Actually, I was using Hawaii as an example of mafic rocks forming islands. We’ve got plenty of continents to illustrate calc-alkaline rocks.
Thanks for the info. My thesis was in the Tetons working on Archean rocks. The layered gneiss there appears to be of island arc origin (for the most part), underwent granulite facies metamorphism, probably during accretion to the North American craton. It is definitely an accreted terrane.
Some very interesting comments thank you all.
I was wondering if anyone has examined Dan Bar-Zohar’s paper:
http://www.astronomy.net/forums/bigbang/messages/882.shtml
He asserts the sun in not powered by nuclear reactions, but by magnetism. It would solve the problem of a weak sun vis-a-vis the time-frame in question.
I have no opinion on this matter, just asking.
Looks like C. Karoff & H. Svensmark have been having similar thoughts…
How did the Sun affect the climate when life evolved on the Earth?
Authors: C. Karoff, H. Svensmark – Submitted on 31 Mar 2010
Abstract: “Using kappa Ceti as a proxy for the young Sun we show that not only was the young Sun much more effective in protecting the Earth environment from galactic cosmic rays than the present day Sun; it also had flare and corona mass ejection rates up to three orders of magnitude larger than the present day Sun. The reduction in the galactic cosmic ray influx caused by the young Sun’s enhanced shielding capability has been suggested as a solution to what is known as the faint young Sun paradox, i.e. the fact that the luminosity of the young Sun was only around 75% of its present value when life started to evolve on our planet around four billion years ago [and yet, paradoxically, the Earth didn’t freeze over]. This suggestion relies on the hypothesis that the changing solar activity results in a changing influx of galactic cosmic rays to the Earth, which results in a changing low-altitude cloud coverage and thus a changing climate. Here we show how the larger corona mass ejection rates of the young Sun would have had an effect on the climate with a magnitude similar to the enhanced shielding capability of the young Sun.”
Full paper here:-
http://arxiv.org/pdf/1003.6043v1
R. Gates (15:57:33) :
Everyone reading this should realize that this is just one more THEORY explaining how the so-called young-sun paradox could be explained…..
REPLY:
As far as I can see the gang here at WUWT is doing their usual job of dissecting the information and examining it. I don’t see much evidence of anyone saying . “thank you, thank you, for finally delivering the absolute truth to us, the brain dead masses.”
Frank,
Thanks for posting this video:
http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml
This was an excellent, and most illuminating presentation. Essentially gave a complete thumbnail overview of exactly why I am a 75% “warmist” and 25% sceptic.
When you deny the likeliehood of the existence of “continental land masses” and “continental crust” “at this early stage of earth’s history” except “some continental land masses may have been present at 4.4 Gya, can you describe for us exactly how you define your usage of the terms: “continental land masses” and “continental crust”?
Never forget, fence sitting is an imPALINg experience.
D. Patterson (14:12:28),
Those are the “adjusted” numbers.
The correct figures are .025% skeptic, and 99.975% true believer.
That’s my theory.
WilliMc (12:05:34) :
If the suns core is super compacted and compressed, how can nuclear reaction occur when they have to have room to “SLAM” into each other?
Being that compacted and rotating, it is possible to pop a molecule like a grape with massive pressure and friction.
Both the magnetic field on our planet and the sun would have been greater in the past then now as they were rotating faster.
Completely wrong. Land absorbs more sunlight than ocean and is thus warmer. Also, four billion years ago, the oceans barely existed. Earth’s oceans have grown through time.
In one sense it’s not that simple.
But in another sense it’s all too simple:
Attempting to go back 4+ billion years, or however old the planet is (dating is problematic), and reconstruct what was happening is…speculation…not much better than complete guess work.
Fun to do, but not very imformative…too many variables that can’t be quantified.
There is some question if Man really has any kind of handle on what the Earth was like…”in the beginning”.
Also, the desire to answer “in the beginning” type questions can lead to answers that end up sending Science in a wrong direction, which then hardens into dogmatism which can then retard scientific understanding about what is happening, now.
Understanding what the Earth’s physical relationships and dynamics are now is the most important set of questions to answer.
James F. Evans (18:03:46) :
Attempting to go back 4+ billion years, or however old the planet is (dating is problematic),
About the only thing that is not problematic about this is the dating.
If you look at the equation for methanogenesis you get:
CO2 + 4 H2 → CH4 + 2H2O
Writing out the thermodynamics you have:
delta_G_rxn = delta_G0 + RT ln Q, where in the case of methanogenesis you have:
Q = {CH4}/({CO2}{H2}^4).
Thus the energy derived from methanogensis is linearly related to the activity (concentration) of methane seen by the methanogen. As the concentration of methane increases the delta_G of the reaction increases until it is > 0, meaning the reaction is thermodynamically unfavorable.
This is what the authors mean when they are talking about the balanced diet. Since CO2 is in the denominator, an increase in CO2 also decreases the energy available from the reaction. The power of 4 on the hydrogen means also that the reaction is most sensitive to the hydrogen concentration.
Meh, I mean as the CO2 increases the energy available increases.
D. Patterson (13:40:35) :
When you deny the likeliehood of the existence of “continental land masses” and “continental crust” “at this early stage of earth’s history” except “some continental land masses may have been present at 4.4 Gya, can you describe for us exactly how you define your usage of the terms: “continental land masses” and “continental crust”?
What? That’s the best you can do? I refer you back to this post by Dr. Svalgaard in which he first brings up the term “continental.
Leif Svalgaard (12:05:26) :
The existence of 4+ Gyr old Zircon grains indicates presence of continental crust early in the Earth’s history, and there is good evidence that the Earth lost its atmosphere and hydrosphere early on and that they have been gradually added since, so the situation is not that simple.
I’m not condemning the good Doctor on the use of the word “continental”. I’m trying to keep the discussion in context. I could have used “sima” or “sial” like you to confuse the issue; However, I decided to remain in context and continue to use “continental”. I’m not quite sure why you are hung up on the semantics, but it seems rather puerile of you to get so worked up over one word. Try staying with the meat of the discussion, instead. Chill!
Leif Svalgaard (18:30:54) wrote: “About the only thing that is not problematic about this is the dating.”
It has been scientifically established that electromagnetic radiation effects radio-carbon dating, so that radiation decay rates are not necessarily linear and constant if an object has been subject to strong electromagnetic radiation, then radio-carbon dating is unreliable.
I’ll say this, however, Science has a better handle on how old the Earth is, compared to how old the Universe is — arrogant scientists not withstanding 🙂
James F. Evans (19:50:02) :
It has been scientifically established that electromagnetic radiation effects radio-carbon dating
Nonsense
I’ll say this, however, Science has a better handle on how old the Earth is, compared to how old the Universe is
More nonsense. The universe is 13.73 billion years old. The age of the Earth is estimated at 4.54 billion years, but is somewhat uncertain because there is no precise definition of what the age means. We have gone over this several times, so no need to hijack a thread again.
@David Deming (17:23:03) :
“…Also, four billion years ago, the oceans barely existed. Earth’s oceans have grown through time….”
Sez who?
.73 …ya, right. That’s the nonsense here.
James F. Evans (19:50:02) :
I’ll say this, however, Science has a better handle on how old the Earth is, compared to how old the Universe is arrogant scientists not withstanding 🙂
The 10 billion dollar collider is looking at a single big bang event. If that were the case, then all the solar systems would be of the same age and same region.
Would it not?
What about an athmosphere that was more dense earlier(warmer earth) and a warming sun that since has been depleting the athmosphere on earth and made the climate colder even if the sun has got warmer?