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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The albedo of mafic rock is really low…
IANAS, but let me get this straight.
The greenhouse theory of early Earth warmth assumed that there must have been high levels of CO2 in spite of a lack of evidence of said gas. Bird and Rosing have explained how early Earth warmth happened within the evidence.
Is that right?
“”” James F. Evans (19:50:02) :
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’m having some difficulty with this statement James. Arguably it is true that electromagnetic radiation (a)ffects radio-carbon dating; so one wouldn’t then quibble that it has been scientifically established.
But in what manner does that happen; and how was that established ?
The earliest radio-carbon dating was based on the premise that 14C was created at a constant rate out of Nitrogen, by Cosmic rays; which may or may not be “electro-magnetic” radiation. The radio-carbon is assumed to be taken up by living things, till they die, and then the 14C decays by ordinary beta decay (emits an electron) with a half life of 5770 years.
So ten half lives, or 57,700 years would reduce the 14C in the sample by a factor of 1024. Twenty half lives, or 115,400 years reduces it by over amillion. I somehow doubt that even a mass spec can reliably recover 14c that is diminished over one million times from any normal sample.
So radio-carbon dating is hardly a useful tool for anything more than 100,000 years; and I suspect that it is more like 50,000 years. That is hardly a useful measure of earth versus universe ages.
The original assumption of constant manufacture rate, of course was proven wrong, by RC dating each ring of old Bristle-cone pines, from the White Mountains near the California/Nevada border. One of the very few things that tree-rings analysis is good for.
The result of that study did enable a correction table to be derived for the RC age of samples.
But you talk of the samples themselves, being subjected to “”” strong electromagnetic radiation “””, and that implies that you believe that somehow, such radiation can affect the existing sample.
How would that work; and in what physical sense to you refer to the radiation as “strong”? Is that high intensity radiation; or do you mean high photon energy radiation (short wavelength)
Photons of a wide range of energies could temporarily place a 14C atom in some excited (electron) state; but somehow, I don’t think the carbon nucleus, would even know that was going on; so I don’t see how that migth either induce or prevent a beta decay from the nucleus. I’ve never heard of stimulated radioactive emissions; but you may be on to something.
You could have higher energy photons/particles actually hitting the nucleus, and soemhow transmuting the 14C prematurely into something else.
So I have no knowledge of electro-magnetic radiation of a sample, somehow affecting it RC dating result.; and in any case that is only a very short time dating system, in geological terms; ok for human history time scales; but otherwise not too useful.
George E. Smith (11:14:45) :
I accept your point that radio-carbon dating isn’t viable beyond 100,000 years.
Then we move into radio-metrics like uranium or thorium radioactive decay.
All dating techniques have assumptions. Whether those assumptions allow for the accuracy that proponents typically boast of — I apply reasonable skepticism.
Yes, the Earth’s age is immense, of that I’m sure, but trying to pin it down to the hundred thousand year place is hubris and arrogance.
If there is one thing I’ve learned in my recent study of Science…there is much folly in Science due to human arrogance.
James F. Evans (16:38:27) :
All dating techniques have assumptions. Whether those assumptions allow for the accuracy that proponents typically boast of — I apply reasonable skepticism.
Ignorance is a heavy shield and will shield you well from the truth. Skepticism must be based on facts, not just on refusing to know. The main assumption is that the laws of physics in the past were the same as today. All our evidence points to that they were.
Dr. Svalgaard:
In Science, ignorance typically results from a refusal to consider evidence because that evidence contradicts strongly held opinions and assumptions. People (scientists are people, too, you know) would rather ignore evidence than have their world-view subject to revision.
But getting back to the specifics of the assumptions of radio-metric dating:
Radioactive isotopes, Uranium, Thorium, Potasium, and strontium, are used to date rocks. These radioactive isotopes have a constant rate of decay which can be used to measure time passage. In example: Uranium has a constant radioactive rate of decay into Lead.
(Parenthetically, carbon-14 dating can’t be used on rocks as the rocks were never living tissue.)
So, with a rock embedded with Uranium one can tell how old the rock is by how much Lead is also embedded in the rock as the Uranium decays at a constant rate into Lead…sounds good.
But hold on, there are a number of assumptions.
First, one must assume that all the Lead in the rock is a product of the Uranium’s decay into Lead, but there is natural Lead that isn’t a product of Uranium decay and so the question becomes, what was the percentage content of ‘natural’ Lead in the rock to begin with — hard to tell, maybe impossible to determine. So any radio-metric dating has to decide what percentage of Lead is naturally occuring in the rock to begin with (an assumption) and what is the product of Uranium isotope’s radioactive decay into Lead.
So, there is a need for an assumption which clouds the ability to use radio-metric dating to determine how old a particular rock is.
Also, second, most metals don’t exist as pure elements in rocks, they exist as salts bound up with other elements. Of course, salts are soluble in water and so salts will disolve out of the rock when exposed to water, including radioactive salts. Most rocks have been exposed to water.
Consequently, a rock with Uranium salts exposed to water will have a percentage of Uranium salts leached out of the rock. This will effect the appearance of age for the rock derived from radio-metric dating because there is an assumption of what percentage of the Uranium salts are in the rock to start with (another assumption).
Finally, rate of decay of radioactive isotopes can be effected by things like bombardment with nutrinos or an increase in cosmic rays the result of supernova (also, I suggest intense bombard of electromagnetic particles will effect rates of radioactive decay, likely speeding the decay rate) these events are acknowledged as happening periodically in the past, and, so, thus, have a potential effect on the assumed constant rate of radioactive decay of these isotopes (so there is another assumption that the rock hasn’t been exposed to these physical forces).
So, again, “All dating techniques have assumptions. Whether those assumptions allow for the accuracy that proponents typically boast of — I apply reasonable skepticism.”
Yes, Dr. Svalgaard, ignorance is a heavy shield and it will shield you from the truth, but the first place to look for that ignorance is in ourselves, and not in others.
It is much easier to throw out sweeping statements than to back them up with evidence and reasoning.
And, yes, I subscribe to the idea that the laws of physics in the past were the same as today. What gave the idea that I didn’t — might I suggest there was an assumption made — how very typical for those so sure of themselves that they feel free to ignore evidence at their own capricious whim… because they know better than the rest of us.
Well, the rest of us mortals will continue to consider ALL observations & measurements as they are made available to us.
James F. Evans (05:47:45) : The other problem is the plurality of laws, everyone expaining reality as they “correlate” with local aspects of it and they have a technical and abosolutely valid application. It is the rejection to universal laws which could apply to every aspect of reality, wonderfully represented by Pitagoras Monochord.
James F. Evans (05:47:45) :
First, one must assume that all the Lead in the rock is a product of the Uranium’s decay into Lead, but there is natural Lead that isn’t a product of Uranium decay and so the question becomes, what was the percentage content of ‘natural’ Lead in the rock to begin with — hard to tell, maybe impossible to determine.
This is where your willful ignorance shows. Lead has many isotopes, and only 206Pb [decay product from 238U] and 207Pb [decay product from 235U] result from radioactive decays, while e.g 204Pb does not, so the ratios of the Lead isotopes shows what the natural content of Lead was. So, no assumption here.
is an assumption of what percentage of the Uranium salts are in the rock to start with (another assumption).
It is not the amount of Uranium that matters but the ratio of the two isotopes U238 and U235, so no assumption here either, apart from the fact that the interior or Zircon crystals [often used for dating] has not been leached.
Finally, rate of decay of radioactive isotopes can be effected by things like bombardment with nutrinos or an increase in cosmic rays the result of supernova>/i>
None of these things have any effect on the decay rate. This is an [unwarranted] assumption on your part.
because they know better than the rest of us.
In your case that is not hard, but you could learn, if willing.
Well, the rest of us mortals will continue to consider ALL observations & measurements as they are made available to us.
Well, you can begin now. Read up on Uranium-Lead dating. E.g. here http://geology.about.com/od/geotime_dating/a/uraniumlead.htm or
http://planetearth.nerc.ac.uk/features/story.aspx?id=121
And why, given all of the assumption involved, was Mars warm and wet at the time, as well?
Dr. Svalgaard:
I welcome your response.
I didn’t know you were an expert on geologic radio-metric dating…I’ll assume you aren’t, unless you provide some personal professional background that says otherwise.
(What I do know is that you are an arch defender of the scientific status quo — even in the face of overwhelming contervailing scientific evidence. Perhaps that explains your assertions that the Sun’s variance of irradiance and variance of total energy ouput makes no difference to Earth’s climate, and, thus, reinforces the arguments of AGW proponents — I’ve read your comments to this effect many times, here, on this website.)
So, since you aren’t an expert on geologic radio-metric dating, I’ll assume we are on a more equal scientific footing than normal.
And, so, I’ll assume the information you have given is principly from the links you have provided, unless you provide further evidences.
That said, let’s consider the evidence you provided from your first link, about.com: geology – Uranium-Lead Dating:
http://geology.about.com/od/geotime_dating/a/uraniumlead.htm
From the lead paragraph: “…[Uranium-Lead Dating] when done carefully, the most reliable. Unlike any other method, uranium-lead has a natural cross-check built into it that shows when nature has tampered with the evidence.”
So, the second thing we learn (the first is that Uranium-Lead Dating is reliable) is that, one, it must be “done carefully”, and, two, nature can tamper with the evidence, and, therefore, make it unreliable.
Further down in the article, we learn that, “If nothing disturbs the grain to release any of this radiogenic lead, dating it is straightforward in concept.”
What does this tell the reader?
Obviously, there are natural causes that disturb the grain (or the author wouldn’t have mentioned it), and, therefore, make the radio-metric dating unreliable.
Dr. Svalgaard (09:23:27) wrote: “Lead has many isotopes, and only 206Pb [decay product from 238U] and 207Pb [decay product from 235U] result from radioactive decays, while e.g 204Pb does not, so the ratios of the Lead isotopes shows what the natural content of Lead was. So, no assumption here.”
The article doesn’t say that 206Pb is ONLY caused by radioactive decay from 238U, unless you provide scientific evidence to the contrary, one can conclude there is natural 206Pb as well. The same can be said about 207Pb being a radioactive decay product from 235U; the article doesn’t say that 207Pb is ONLY caused by radioactive decay from 235U.
You have made an unwarranted assumption.
“There are four stable isotopes of primordial lead, namely
204Pb, 206Pb, 207Pb and 208Pb. The last three isotopes, however,
are also radiogenic, formed by radioactive decay in the 238U
(half-life 4.56109 years), 235U (half-life 0.76109 years) and
232Th (half-life 14.16109 years) decay series, respectively.” — “The changing nature of the 206Pb/207Pb isotopic ratio of lead in
rainwater, atmospheric particulates, pine needles and leaded petrol in
Scotland, 1982±1998”
I take it that “primordial lead” means the lead has four isotopes which are ‘natural’ and is not necessarily a product of 238U radioactive decay, although, the last three can be a product of radioactive decay, but it is not exclusive.
The same would hold true about 235U as well.
Dr. Svalgaard, your argument is dismissed as an erroneous assumption.
Dr. Svalgaard wrote: “It is not the amount of Uranium that matters but the ratio of the two isotopes U238 and U235, so no assumption here either, apart from the fact that the interior or Zircon crystals [often used for dating] has not been leached.”
Again, your assumption only holds true if nature has not tampered with the Uranium.
The About.com geology article goes on:
“First, its chemical structure likes uranium and hates lead. Uranium easily substitutes for zirconium while lead is strongly excluded. This means the clock is truly set at zero when zircon forms.
Second, zircon has a high trapping temperature of 900°C. Its clock is not easily disturbed by geologic events—not erosion or consolidation into sedimentary rocks, not even moderate metamorphism.”
This says nothing about whether Uranium not being able to be leached out of zirconium. Also, pay special attention to the phases, “This means the clock is truly set at zero when zircon forms.”, and, “Its clock is not easily disturbed by geologic events…”
So, apparently, the clock can be re-set to zero for any of a number of natural causes, principly being heated to a certain temperature. Also, this, here, discussion is about using radio-metric dating for determining the age of the Earth to a high level of accuracy — within one hundred thousand years. So, it becomes apparent from the About.com article that any number of natural physical events could intervene and “reset the clock to zero”.
Here’s the money quote from the About.com article”
“But even the best geologic methods are imperfect. Dating a rock involves uranium-lead measurements on many zircons, then assessing the quality of the data. Some zircons are obviously disturbed and can be ignored, while other cases are harder to judge.”
Dr. Svalgaard presents Evans’ statement (05:47:45): “Finally, rate of decay of radioactive isotopes can be effected by things like bombardment with nutrinos or an increase in cosmic rays the result of supernova>/i>”
And, Dr. Svalgaard responds: “None of these things have any effect on the decay rate. This is an [unwarranted] assumption on your part.”
This is false or misleading.
During the time of bombardment or ‘event’, the rate of radioactive decay is increased. It is true that after the bombardment or ‘event’ the rate wil return to its normal rate of decay, but for the time during the ‘event’ it is effected, and thus will “chop-off” an amount of decay, thus, leading to erroneous assessment of age using radio-metric dating.
As to the second link provided, it does what you attempted to do: Claim an exactitude beyond what the scientific evidence allows Science to know, which is a common occurance — as you typically comment when a NASA press release announces a new set of observations & measurements that assets a new scientific understanding — it’s “hype”. In your case, you put down evidence that upsets the status quo applecart — your modus operandi.
So, what do we have here?
Dr. Svalgaard posed as somebody who “know[s] better than the rest of us.”
And has been exposed as “the emperor without clothes.”
What no one, researchers included, seem to consider here, though I haven’t read all the posts, is that the atmospheric pressure 3.8E9 yrs ago was somewhere in the range of 200 – 300 bar, yes – ca. 3700 psi!!. What huge effect would only a few percent methane have on the earths temperature, let alone the massive quantity of water vapor in the dense atmosphere?
@Steve Schaper – the same goes for Mars too.
A higher atmospheric pressure of 1.5 to 2 bar, and possibly slightly higher O2 conc. in the Carboniferous explains how the huge insects of the time could get O2 into their bodies and how they could fly.
No, methane and ammonia were always a trace gas in the atmosphere.
Yes, there is “geologic evidence in these rocks for really high concentrations of a greenhouse gas like carbon dioxide.” Calcium carbonate rocks of the time are composed of low ratios of aragonite. Aragonite forms in an atmosphere with low concentrations of carbon dioxide, and it dissolves in an atmosphere with high concentrations of carbon dioxide. Any hypothesis claiming low atmospheric concentrations of carbon dioxide must reconcile those claims with the high and low ratios of aragonite in those calcium carbonate rocks.
James F. Evans (12:03:12) :
I welcome your response.
But you didn’t learn much.
I didn’t know you were an expert on geologic radio-metric dating…I’ll assume you aren’t, unless you provide some personal professional background that says otherwise.
My major was Geophysics, but every natural scientist knows these things, just like they know that the Earth is the 3rd rock from the sun.
I’ll assume we are on a more equal scientific footing than normal.
It is hard to stoop to your level.
one, it must be “done carefully”, and, two, nature can tamper with the evidence, and, therefore, make it unreliable.
Every scientist in that that field works carefully and any tampering shows itself in the data, so tampered-with data can be excluded, i.e. the method itself shows you when it is reliable.
The article doesn’t say that 206Pb is ONLY caused by radioactive decay from 238U, unless you provide scientific evidence to the contrary, one can conclude there is natural 206Pb as well. The same can be said about 207Pb being a radioactive decay product from 235U; the article doesn’t say that 207Pb is ONLY caused by radioactive decay from 235U.
You have not understood that the 206Pb and 207Pb amounts result by two different processes and that from this one can determine how much is caused by what. No assumption.
Again, your assumption only holds true if nature has not tampered with the Uranium.
Nature itself shows us if tampering occurred.
This says nothing about whether Uranium not being able to be leached out of zirconium.
You have not understood that no matter how much Uranium leaks out, the only thing that matters is the relative proportions of 238U to U235.
any number of natural physical events could intervene and “reset the clock to zero”.
Again you misunderstand what ‘reset’ the clock means. It means that the age is now determined as the time time the last rest, e.g. melting. This is the only definition that makes sense. The Uranium atoms themselves may be anywhere from 13 to 5 billion years old.
“None of these things have any effect on the decay rate. This is an [unwarranted] assumption on your part.”
This is false or misleading.
During the time of bombardment or ‘event’, the rate of radioactive decay is increased. It is true that after the bombardment or ‘event’ the rate will return to its normal rate of decay
No, that is simply not true. I don’t know where you get that erroneous idea from, but Nature doesn’t work like that.
As to the second link provided, it does what you attempted to do: Claim an exactitude beyond what the scientific evidence allows Science to know, which is a common occurrence
The second link explains the efforts underway to drive the precision even higher, from 1% to 0.1% or better.
Dr. Svalgaard posed as somebody who “know[s] better than the rest of us.”
Just than you, judging from your response.
Jim F (09:59:18) :
Continents, not the present continents, must have come into existence as the Earth’s crust cooled enough to solidify.
Nobody has mentioned the formation of the moon-earth pair as a source of considerable heating via tidal friction, when the moon was orbiting the earth much closer in the past. Solar radiation and nuclear fission are not the only sources of heat on earth.
Squarebob Spongepants (10:17:58) :
Nobody has mentioned the formation of the moon-earth pair as a source of considerable heating via tidal friction, when the moon was orbiting the earth much closer in the past.
There is good evidence that the Moon was formed by a gigantic collision with a Mars-sized proto planet. That probably melted or even vaporized much of the Earth and flung the Moon rather far out, meaning that tidal friction [although higher] may not have been very important.
Squarebob Spongepants (10:17:58) :
Tidal heating is negligible relative to the other processes underway. The Sun was in its T-Tauri phase typical for a young Main Sequence star. The Earth’s iron core had not yet established or re-established itself as a dynamo, so there was no significant magnetosphere to shield the first atmosphere from scouring by the itense T-Tauri solar winds. Presumably, the first atmosphere was something like 105 to 250 atmospheres in mass, depending on the source/s consulted, and was composed primarily of the same hydrogen and helium as the nebular cloud from which it condensed. The massive atmospheric pressures combined with the intense solar winds and cooling from the collisional formations would have been a tremendous source of heating. The Late Heavy Bombardment (LHB) would then have renewed heating of the lithosphere to something on the order of perhaps 900C as the highly frequent impacts occurred. By the time the LHB was coming to an end, probably something like 90% or more of the first atmosphere would have been lost to the intense T-Tauri solar winds, lack of a magnetosphere, and ejections by asteroidal and cometary impactors. Remnants of the first atmosphere consisting of the heavier elements and compounds such as water vapor, carbon dioxide, sulfur dioxide, and nitrogen would have been augmented by cometary impactors and vulcanism with water vapor, carbond dioxide, nitrogen, and traces of methane, ammonia, sulfates, and more. This second atmosphere would still have been many times more massive than the present atmosphere with all of the consequences of higher atmospheric pressures in a reducing atmosphere.
In addition to the radical changes in the solar environment, atmospheric composition, and atmospheric pressures; you also had a much faster and shorter diurnal rotation, the greater tidal effects you mentioned, the effects of an atmosphere lacking oxygen and its effects, and a emergent biosphere.
Walter Munk of Scripps did some of the calculations based on the then known rate of the Moon’s recession from the Earth in this 1968 paper: http://adsabs.harvard.edu/full/1968QJRAS…9..352M
(Once again-Tidal Friction. Quarterly Journal of the Royal Astronomical Society, Vol. 9, p.352)
Leif, what evidence is there that the moon was “flung…rather far out”, rather than an initial close orbit and then a gradual recession over several billion years?
I am told that for temperatures above the curie point for iron, 1043K, it ceases to be ferromagnetic.
As such, the core of the earth being supposed to be largely made up of this metal is irrelevant since the supposed core temperature for any estimate is above 2000K. Any dynamo activity is within fluid ionised portions of the globe – mantle, ocean or ionosphere.
meemoe_uk (12:18:47) :
‘Paradox’. That is one of the most misused words in academia.
_______
Two orthodontists walk into a bar. One says to the other “Are we othodox?”
Reply “No we are a paradox.”
Squarebob Spongepants (12:14:13) :
Leif, what evidence is there that the moon was “flung…rather far out”, rather than an initial close orbit and then a gradual recession over several billion years?
Scant, but some. If the Moon was formed by fission of the Earth [i.e. not collision] it would have been VERY close by definition. Put the angular momentum the Moon now has back into the Earth and the rotational period would be VERY short. The rotational period of the new Earth is unknown, but many asteroids have periods near six hours, so if we go by that and assume that the angular momentum [between that and now 24 hours] has been transferred to the Moon we can estimate the early angular momentum of the Moon and hence its distance [assuming the mass did not change much]. I’m writing this from memory so don’t have the actual figures handy, but remember from somewhere that the Moon was flung out to a respectable distance. Since tidal forces go with the inverse cube of the distance there is a very steep falloff. PS: you might want to play the numbers and see what distance you can come up with, based on the method I outlined.
Squarebob Spongepants (12:31:33) :
Any dynamo activity is within fluid ionised portions of the globe – mantle, ocean or ionosphere.
The Curie point is irrelevant. It is enough that the matter is a conductor, and Iron is [at any temperature].
The temperature in the Atmosphere falls on average 2 deg C pr 1000 ft.(305 M).
Above the seasurface 1 hpa per 8m = 1hpa per 27 ft.
So lets say that the standard atmosphere historically has not been standard, 1013.2 hpa, and in order to increase today’s global temperature 2 deg C from 15 deg C to 17 deg C we just have to add more atmosphere so that it gets 1000 ft. thicker or the standard seasurface pressure increases from 1013.2 hpa to 1050 hpa!
If we dont know what the historic “standard” thickness of the atmosphere has been we are “lost” if we try to solve this “paradox”?
Jon-Anders Grannes (14:44:14) :
Increased temperatures increases atmospheric volume. Atmospheric volume increases atmospheric altitudes and drags down LEO (low Earth ordit) satellites. Increased atmospheric volume and altitude places more atmospheric mass at higher altitudes, where the decreased gravity exerts less gravitational energy upon the atmospheric pressure, while the increased thermal pressure increases atmospheric pressure?!?!? Then there is the magnetosphere……..and all of those new fangled windmills swatting around the air…..
Parameterizations anyone?