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.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Leif Svalgaard (12:36:52) :
gkai (12:28:22) :
just by chance because both the greenhouse and albedo are independent from solar output
For the Svensmark enthusiasts: the early solar wind was 100-1000 times a vigorous back then so few galactic cosmic rays would have made it to the Earth, so no low clouds [and higher albedo] due to them…
~
And what kind of interstellar medium would the sun have been embedded in then. Very hot, hot, medium, cool or cold would you say..?
Like somehow ah this should matter somewhere in the history of this planet. Well, maybe not in this particular instance. Yeah right, doesn’t make a difference. Can anyone tell me exactly what proportions of what were in the interstellar medium at the time?
It’s madness I tell you, madness. hahahhahahhahahhahaha
There had to be lower Albedo (as well as more greenhouse gases).
The chart at the beginning from Kastings shows that solar irradiance reaching the Earth has increased since the Sun reached main sequence maturity by about 30% (in close to a straight line) over time.
That means solar irradiance at the top of the atmosphere was just 1186 watt/m2 about 2 billion years ago (versus 1366 watts/m2 today).
The equilibrium temperature would have been about 10C lower than today and, in that situation, the mid-latitudes would be frozen over permanently and the ice-albedo feedback would leave the Earth as a frozen snowball. There would not be enough greenhouse gases to overcome this.
Now if the cloudiness of the early Earth was about half what it is now and there was more ocean versus land then, the lower solar irradiance would have been completely offset and the average temperature would be about the same as today.
It is the only answer that works.
Or the Earth was created as it is today and scientists can’t deal with that.
Leif Svalgaard (12:36:52) :
better, but still a little bit far fetched: I am still thinking a more direct regulation should be responsible, Svensmark theory is interresting too but it has a feel of second-order effect, just like the CO2 in fact.
Thermostat hypothesis is my current favorite one, with the strongly related “heat engine” apporach. Intuitively it feel powerfull enough to be a first-order regulator…
I also like it a lot because it emphasize the timing and spatial distribution of the cloud cover, something I do not have encountered in other theories…and to emphasize this is strongly needed: often the distinction is made between lower and higher clouds, always discussing the average cloud cover, with a lot of uncertainties regarding feedback: do more clouds warm or cool the surface? Well, imho, the incertitude just comes from the fact that average cloud cover is a really really bad metric: at night or near the poles, it is a warming effect, in the day closer to the equator, a cooling. Like any insulator, the net effect is cooling when it is “warmer outside”, warming when it is “cooler inside”.
So just mentioning average cloud cover without discerning by latitude or time or the day looks like utter nonsense, like asking what will be the effect on temperature of increasing the insulation without knowing if you insulate near a hot spot or a cold spot: Either a lot is lost in the simplified versions of many theories, or climate modelers never have used the same thermos to keep their ice tea cold and their coffee hot 😉
oups – warming when it is “cooler outside” of course….
Wasn’t the Earth, like, much smaller back then? (ducks) 😉
Phillep Harding (12:02:13) : “In South East Alaska and Iceland, cloudy weather is warmer than clear weather (all else equal). Where does the heat come from, if clouds are supposed to keep it from reaching the ground?”
Easy. Clouds also retain heat, preventing heat at ground level from radiating off at night-time.
gkai (13:41:28) :
Radiative Transfer Models used by GCMs are reasonably good at modeling both incoming and outgoing radiation, based on a given set of parameters.
“In South East Alaska and Iceland, cloudy weather is warmer than clear weather (all else equal). Where does the heat come from, if clouds are supposed to keep it from reaching the ground?”
When it is cloudy in South-Iceland (say Reykjavik where I live) the wind is usually blowing from the south and is mild. At the same time it is usually sunny in North-Iceland (say Akureyri) and the weather there often very warm.
When it is sunny in Reykjavik the (cold) wind is often blowing from the north. Then the weather can be beautiful but not very warm. At the same time it is cloudy, rainy and cold in Akureyri, with the cold and wet wind blowing from the sea.
gkai (12:28:22) : “Nope, I do not buy it: like the greenhouse gas hypothesis, this “albedo” hypothesis demand that an opposing effects happen to quite precisely counterbalance the increasing solar output, and this just by chance because both the greenhouse and albedo are independent from solar output (at least, the authors do not explain what mecanism would increase albedo (or decrease greenhouse gas for the greenhouser) in proportion of solar radiation – on the contrary both are considered positive feedback mecanism – at least among the warmist).
This is too much chance for me”
Perhaps chance is what happened and the only reason that we are here today is because that chance just happened to be right enough for Earth to become a place where plants and animals could evolve and a species such as humans could wonder about these things.
Hugo M (13:05:13) :
An expanding earth too could explain that, assuming the amount of water was the same then.
The Earth has not been expanding [rather contracting a bit when cooling]
some context of your Zircon argument?
Oxygen isotope studies indicate that the magma from which the zircons originated was recycled rock that had interacted with surface waters, showing that continental crust existed and was eroded by water [like today], and that tectonic processes like subduction were also operating.
What is the evidence that the earth lost its hydrosphere? And by what mechanism the earth regained it’s hydrosphere?
The ‘heavy bombardment’ that stopped about 3.9 Gyr ago would have evaporated the hydrosphere intermittently with new water being added by the very impacts that scour away the old, indicating a very dynamic, chaotic, and changing environment. Bottom line: we don’;t know and can’t just assume that everything was quiet.
rbateman (13:09:06) :
Are we assuming that the solar nebula (as currently seen via the zodiacal light and the gegenschein) was much thinner due to the higher solar winds billions of years ago?
No, there was also generation of new dust from incessant collisions.
Carla (13:19:52) :
And what kind of interstellar medium would the sun have been embedded in then. Very hot, hot, medium, cool or cold would you say..?
Probably didn’t matter because of the strong solar wind blowing everything away.
Rob (13:37:21) :
Or the Earth was created as it is today and scientists can’t deal with that.
Or it was created last Tuesday [with everything – including we and our memories – included]. 🙂
What’s that they looked at the rocks to find out if there was more CO2 billions of years ago? Don’t they know you aren’t suppose to look at data, you are suppose to make computer models, and the computer models will tell you that there was more CO2 back then.
Hugo M: Prof. Svalgaard, could you give some context of your Zircon argument? What is the evidence that the earth lost its hydrosphere?
He’s probably using the old assumption that the early Earth grew so hot that all the volatiles, including water, had outgassed and been lost to space. It was suspected that all the water came from comets/meteors, but that also ignores the water which exists in molten rock. There is evidence that full outgassing did not happen, including very old material inside zircons which required temperatures which imply an ocean was present. When the Moon was formed, we may have had a rock atmosphere but it apparently only lasted a thousand years or so, and there was an ocean immediately afterward.
Rob (13:37:21) :
Or the Earth was created as it is today and scientists can’t deal with that.
According to the scriptures it wasn’t created as it is today. There was no rain, for one thing. And there’s that whole fall from perfection thing.
So… 🙂
Since all the oxygen was locked up in CO2 there would not have been an ozone layer and hence UV would have been absorbed at the surface. The lack of an ozone layer would also mean completely different atmosphere dynamics since there would have been no stratospheric zone. Of course we are in an ice age so earth is normally a lot warmer than now to.
Leif Svalgaard (12:05:26) :
The existence of 4+ Gyr old Zircon grains indicates presence of continental crust early in the Earth’s history…
No, the existence of 4+ Gyr old zircon grains indicates the presence of partial melting of oceanic crust resulting in the formation of felsic (or granitoid) rocks at depth. These rocks may have not made it to the surface for 100’s of millions of years. There is evidence of crust at 2.8 Gya, island arc volcanics. The presence of the zircons does say that plate tectonics was active early in earth’s history.
I would suggest that the mechanism is convection versus conduction that increases the absorption of heat in a fluid compared to a solid.
So just how did they manage to keep the water from becoming a greenhouse gas and form clouds ?
To me, this “faint sun” hypothesis, is no paradox.
It is simple demonstrative proof (here I go way out on a limb and accept their assertion that there was such a faint sun) that the temperature comfort range here on earth, is feedback controlled almost entirely by the Physical and chemical properties of the H2O moloecule. And I should add, that probably biological processes (eventually) became part of the total chemistry of H2O.
If that simple concept is in fact true, that cloud cover modulation is the negative feedback regulation mechanism, that defeats any attempt by CO2 or any other GHG (including H2O) to overheat th planet; then it must be equally obvious, that the same feedback loop is also capable of filtering out real actual changes in solar output; either increases or decreases.
So there is no faint sun paradox; a variable sun is just another driving signal that is regulated by the cloud feedback.
No I don’t plan to ask for grants to spend the rest of my life proving this simple and quite obvious regulatory mechanism; but long after AGW rots on the trash heap of history along with ancient astrology; I’m sure it will be standard educational fair for new generations of young mush heads.
Paul Hildebrandt (15:01:27) :
These rocks may have not made it to the surface for 100’s of millions of years.
The amount of 18Oxygen in the zircons indicate that they were formed interacting with surface water.
It is strange that no-one discusses the concentration of Methane in the early atmosphere. In the “greenhouse warming” stakes, Methane leaves Carbon Dioxide streets behind.
The paper described actually talks about Methanogens – bacteria which produce Methane – as being part of the early earth system. With a low level of Oxygen in the early atmosphere, the Methane would have been relatively long-lived and so would surely have built up to a relatively high concentration. If that was the case, who needs Carbon Dioxide to produce warming – the Methane will do it all on its own…
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.”
Water is not black. Oceans appear black because there is not much or no light coming back out. As you descend in water it gets darker and darker until it is pitch black. I have always experienced the warmest sea water in the shallows perhaps because the sun can warm sea floor particularly if it is sand. And, unlike a black top oceans are also highly reflective. I have never seen a photo of tarmac with the sun reflected in it’s surface.
If there was a greater surface area of oceans in the past then perhaps there were significantly more shallows also.
I have to recall 1976 again as my benchmark. The sea in Bournemouth that summer became warmer and warmer until it was possible to walk in without any of the usual acclimatisation. Bournmeouth bay is a large sheltered and shallow bay with a sandy bottom. The same summer I also visited a place called Dancing Ledge, just along the coast. There is no beach here, just a vertical rock face into 3 or 4 metres of water. It was disappointingly cold.
Leif Svalgaard (15:17:05) :
Paul Hildebrandt (15:01:27) :
These rocks may have not made it to the surface for 100’s of millions of years.
The amount of 18Oxygen in the zircons indicate that they were formed interacting with surface water.
——
I should clarify this: the zircons formed at depth, but the magma they formed in was recycled from surface rocks that had interacted [retained] with water, hence the 18 O ratio.
Negative feedback is a very powerful regulation mechanism.
Back when I was working on my Master’s Thesis (on electronically discriminating between Gamma rays, alphas, betas, and neutrons) using high counting efficiency Scintillation Crystal detectors such as stilbene or anthracene, I had to use a standard rack mounted vaccuum tube pulse amplifier, to amplify the output from a photomultiplier.
This pulse amplifier was of a fairly standard architecture for that day and age. Two nearly identical “ring of three” vaccuum tube feedback amplifiers in series.
The input to each stage contained both a high pass, and low pass adjustable cutoff frequency filter, and in between the two stages was a wide band attenuator to com=ntrol the input to the second stage.
Each “ring of three” amplifer, contained two cascaded common cathode gain stages, plus a final cathode follower output to drive output loads. Then overall feedback around the amplifier set the Voltage gain at a fixed Gain of +100, so the total gain could be 10,000, if no interstage attenuation was used. The outprut ring differend from the input one only in that the input stage employed a very low noise input tube, while the final stage, included a high power output tube to drive heavy loads.
The maximum bandwidth was from about DC to 20 MHz, relatively fast for that day and age, and the output stage was supposed to be able to deliver 100 Volt peak output pulses, with a certain noise performanbce.
Well when I got this amplifier, which had been around the place for eons, it worked very well, but fell short of its specs in two ways. First off, it was a good bit noisier than I had expected from the spec; and I couldn’t get more than a 90 Volt peak pulse out of it, although the spec claimed 100.
It also had a faint blue glow, which wasn’t mentionewd in the specs, but I used it any way. I asked my thesis supervisor if he thought the spec shortfalls were a problem, or whether I should just get the best results I could and not worry about it.
He offerend that since the amplifier had been in the department for years, it might have a bad tube in it. A bad output tube certainly would limit the output drive, and a bad input tube would make it noisier. So he suggested I test all the valves on a tester we had that measured the Gm of tubes, and other parameters; so I could find the bad tube.
So I pulled out all six of the tubes, and labelled them so they would go back in the same places, and went off to the tube tester, to see whether any of the tubes had less Gm than the data sheet said in the RCA handbook.
Well Glory be; lookey here ! To my utter astonishment; there wasn’t a single one of those six vaccum tubes that showed any measurable Gm when tested in the tube tester with the standard setting for that tube type.
All six of them were stone cold dead; they just hadn’t burned out their cathode heaters yet; but the cathodes had long since vaporized off most of the thermionic emission material from the cathode.
So a quick trip to the local valve emporium for what were relatively standfard radio type RCA tubes, and a new set of tubes was purchased.
When I fired up the amplifier, with new living vaccuum tubes, I found I could easily get 120 Volt output pulses, and the amplifier was as quiet as a church mouse.
Now the former dead amplifier, had still exhibited a stage gain of about 100 in each stage, since that was set by two precision wire wound resistors; and the gain really didn’t change perceptibly with the new tubes.
The ring of three architecture was a common feedback amp type, that was developed back in the “Rad Lab” days of MIT for Radar, and other purposes, and it permitted the use of an enormous amount of negative feedback to control its properties, which my experience showed were damn near entirely independent of the properties of the active gain elements; the tubes; which were dead on their feet and still kicking A***.
Well you see; old sol out there which Leif Svalgaard watches, and keeps tabs on its Gm, and its blue glows if any, is like one of those ring of three feedback amplifiers driving my system.
Yes it wanders around and doesn’t change a lot as regards its TSI, sso its Gm isn’t changing much; despite all the other skullduggery that that place may get up to; which will affect us indirectly; But I doubt that one can find mcuh solid linkage between the sun’s TSI and earth’s climate.
Sure it is the driving energy source, and as Leif constantly reminds us, plays other games besides TSI; but I believe that it is those two precision wire wound resistors that Gaia made and put into the cloud system; by her choice of physical properties for H2O; including that 104.5 deg bend; that is what is defeating all our efforst and all of geology’s efforts to screw things up royally.
So no I don’t beleive in any “weak sun” paradox. Weak sun maybe; but H2O takes care of that too.
Everyone reading this should realize that this is just one more THEORY explaining how the so-called young-sun paradox could be explained.
There are several others, some of which seem to still indicate the presence of much larger amounts of methane during this early time period. See for example:
http://www.nature.com/nature/journal/v440/n7083/pdf/nature04584.pdf
There is no proof of anything here, and even if this theory is correct, which it could be, it does not in any way affect or negate the dynamics of our current time period, as we have a completely different set of atmospheric dynamics, solar dynamics, ocean dynamics, etc…i.e. CO2 is still a greenhouse gas as is methane, and this study wasn’t meant to refute the basic physical properties of these compounds…rather, it is ONLY meant to provide one possible theory for the so-called young sun paradox. For AGW sceptics or believers to attach any importance to this particular theory related to the AGW debate is unwarranted.
The early proto-continents were quite dense and subducted back into the mantle much more readily. It took some time for these processes to distill out the lighter silicates which became our current lighter density and far more enduring continental plates. This more rapid overturning of the earlier and denser proto-continents promoted the burial and formation of the zircons.