From the AGU weekly highlights:
Evaluating solutions to the faint young Sun problem
During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. With less sunlight to warm the Earth, the oceans should have been frozen over, but geological evidence suggests that this was not the case.
Some proposed solutions to this problem, known as the faint young Sun problem, include an atmospheric composition with higher concentrations of greenhouse gases, higher atmospheric pressure, increased cloud droplet size, and changes in land distribution and Earth’s rotation rate.
Charnay et al. used a three-dimensional global climate model coupled to a dynamic ocean model to examine these possible solutions.
They find that an atmosphere that had 100 millibars of carbon dioxide and 2 millibars of methane 3.8 billion years ago, and 10 millibars of carbon dioxide and 2 millibars of methane 2.5 billion years ago—levels corresponding to 25 to 250 times the present level of carbon dioxide and 1000 times the present level of methane—would have made it possible for Earth to have had a temperate climate with a mean surface temperature between 10 and 20 degrees Celsius (50 and 68 degrees Fahrenheit), close to the current climate.
The authors suggest that these levels of greenhouse gases are consistent with geological data, making such an atmospheric composition a viable solution to the faint young Sun problem. Cloud feedbacks were also shown to prevent a full snowball Earth from developing during that time period. The authors find that some of the other potential solutions could have produced some warming during the Archean, but none individually produced enough warming to avoid widespread glaciation.
Source: Journal of Geophysical Research-Atmospheres, doi:10.1002/jgrd.50808, 2013 http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50808/abstract
Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3-D GCM
[1] Different solutions have been proposed to solve the “faint young Sun problem,” defined by the fact that the Earth was not fully frozen during the Archean despite the fainter Sun. Most previous studies were performed with simple 1-D radiative convective models and did not account well for the clouds and ice-albedo feedback or the atmospheric and oceanic transport of energy. We apply a global climate model (GCM) to test the different solutions to the faint young Sun problem. We explore the effect of greenhouse gases (CO2 and CH4), atmospheric pressure, cloud droplet size, land distribution, and Earth’s rotation rate. We show that neglecting organic haze, 100 mbar of CO2 with 2 mbar of CH4 at 3.8 Ga and 10 mbar of CO2 with 2 mbar of CH4 at 2.5 Ga allow a temperate climate (mean surface temperature between 10°C and 20°C). Such amounts of greenhouse gases remain consistent with the geological data. Removing continents produces a warming lower than +4°C. The effect of rotation rate is even more limited. Larger droplets (radii of 17 μm versus 12 μm) and a doubling of the atmospheric pressure produce a similar warming of around +7°C. In our model, ice-free water belts can be maintained up to 25°N/S with less than 1 mbar of CO2 and no methane. An interesting cloud feedback appears above cold oceans, stopping the glaciation. Such a resistance against full glaciation tends to strongly mitigate the faint young Sun problem.
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Maybe there’s a fundamental problem with the understanding of the sun, and maybe that explains why scientists are surprised at every new thing the discover about the sun.
Here’s an alternative:
http://www.holoscience.com/wp/sciences-looming-tipping-point/
thomasinga says:
September 24, 2013 at 11:30 am
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I agree that there is every reason to suspect that orbits were different in the very early years of the solar system, if only because the mass of the sun was greater and therefore exerted a greater gravitational pull.
Further, the earth’s rotation was considerably quicker, if I recall correctly a day lasted somewhere between 4 to 7 hours, ie., the speed of rotation was 4 or more times quicker. This has a significant impact on how much warmth is retained since the times between receiving full incoming sloar irradiance is shorter and the time for heat to be lost (night) is much shorter. This is particularly material with respect to heating the oceans and heat retatined by the oceans given their latent heat capacity.
Further, I understand that the solar spectrum was different in the early yearsof the solar system. I understand that it consisted of a greater proportion of high energy photons. Now I am aware that some consider that TSI as a whole is the only factor, but that has yet to be established. The different spectrum of the sun in the early period may be significant. I am not saying that it is, just may be and that it is a factor that should be thrown into the mix.
Finally, when you see such studies posturing upon the freezing of the oceans, one never sees calculations as to how much energy is required to keep the tropical ocean liquid. This is relevant since even if there is enough incoming solar energy sufficient just to keep some relatively small proporation of the tropical ocean liquid, the water cycle begins and hence the atmosphere contains water vapour which in itself is a GHG and which accordingly would ‘theoretically’ lead to some warming thereby encouraging a wider region of the tropical ocean to become liquid thereupon releasing yet more water vapour leading to yet more warming leading to even more of the tropical ocean being liquid leading to yet more…..etc. etc. there may be no need for any role to be played by CO2. That said, of course, at some stage there must have been very high levels of CO2 which subsequently has become sequested particularly in carbonated rocks. But given this, and given the claimed warming effect of CO2why was there not runaway greenhouse warming?
There is much that we do not understand but I doubt that computer models will help solve matters since they do no more than tell you the conclusions of the assumptions fed into them and if you know the assumptions made, you already all but know the conclusion that will be drawn from those assumptions without the aid of a computer model to tell you.
PS. Have we not seen this study before. I recall having seen a post a few months back on this 9or similar) computer model led study.
Michael Cook says:
September 24, 2013 at 6:04 pm
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Look at Io.
it is the most geologically active body in the solar system. all due to gravitational pull (its position b’twix jupiter and the other Galilaen moons).
Personally I consider that there may be a failure to appreciate how much work/energy is involved in moving the tides and the atmospheric bulge. People argue that whilst pressure leads to heat that that heat dissipates over time when the pressure remains constant. But on Earth, the pressure is not really constant since the atmosphere is continually bulging being displaced by the tides from below and being pulled by gravity by the moon and sun above. Further even the distribution of pressure is in constant flux. I do not know to what extent this is relevant but is in my opinion a factor to be evaluated and not dismissed out of hand.
It is well known that slight flexing of the side wall of a tyre will maintain temperature in the tyre. This is seen all the time in racing, and is why car lining up to the grid swerve right and left etc to built up/retain temperature in the tyre which temperature is then retained during the race by way the tyre side wall flexes during the course of the race itself. You do not need much movement (the pressure in the tyre does not vary greatly between that when on the straights and that when the car is cornering) to retain temperature which was put in the tyre when it was first filled up with air.
Does not the earth’s crust itself (not just the water above the crust) move up and down about 12 inches as the moon goes overhead each day?
Religion, idology and their Policy based science claims likes to stay in areas where there is a low degree of scientific knowledge or high degree of uncertainty?
Mars does not have a magnetic field so the Sun removed Mars atmosphere and water much quicker.
.
As I did mention once before, and as Paul and Spartacus point out again above, to a geologist this is silly, pointless controversy about nothing. It is founded on the incorrect assumption that everything at the Earth’s surface, apart from the incoming the energy of the sun, was the same as today 2-3 billion years ago, when in fact nothing could be further form the truth.
The geothermal gradient was much higher during the Archaean. What that means is that the rate of temperature increase with depth as you go down through the Earth’s then much thinner crust would have been much higher. As a result, the heat flow from the core up through the immature mantle and the crust would have been much greater, and much of this heat flow would have come up into the overlying oceans.
The Archaean rocks that we find preserved at the surface today in the world’s continental greenstone belts are dominantly volcanic rocks, and volcanic rocks of the type that you nowadays only find in areas of thin, high heat flow oceanic crust: mafic volcanics, basaltic and ultramafic lava flows, basaltic pillow lavas (extruded under water), etc., and these rocks are also full of the sort of hydrothermal mineral deposits that you nowadays find restricted to the thinnest areas of modern oceanic crust, now found at mid ocean ridges.
The Archaean crust was thin, hot, intensely volcanic, with a very high heat flow and widespread hydrothermal venting. Current best guesses as to the likely emergence and continuation of life in this environment is as ‘extremophile’ organisms, inhabiting vesicular cavities in the sulphidic ‘chimneys’ and porous eruptive rocks around subsea hydrothermal vents, where they initially obtained energy not from respiration or photosynthesis, but directly from the chemical potentials present in this sort of environment.
What was happening at the overlying ocean surface, or in the thick, and to most of present day life highly toxic atmosphere above that was probably of little concern to these early forms of life.
(As it may also be to the possible current inhabitants of ice-encased celestial bodies such as Saturn’s moon Enceladus)
“During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. “.
Wow. Gotta laugh at that one! So we know this for sure, do we? Did somebody measure that billions of years ago?
Answer: No. We do not. It is a *theory* of the evolution of stars. The sentence should read:
“One theory predicts that during the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun may have been about 20 to 25 percent fainter than it is today… this is presents a paradox because…”
What is the freezing point of water that has salts, iron and manganese dissolved in it?
The freezing point of salty water is -1.6C to -2.0C (depending on the salt concentration).
But what about when iron is also dissolved in it as well and there is no oxygen available to pull the iron out?
Do the properties of the oceans change as well with vast quantities of iron dissolved it. I know it becomes more green and much more dense, but what about other changes.
I note, the first evidence of large glaciation (which turned into a large snowball event) is at 2.4 billion years ago, just the oxygen rose to high enough level to start pulling most of the iron out of the early Earth ocean. Before that, there is no evidence of glaciation on land.
MattS says:
September 24, 2013 at 11:53 am
Latitude,
“I thought it was logarithmic”
Yes it is, but the authors are talking about a 1 to 2 order of magnitude increase from current CO2 levels. That is going to make a noticeable difference even if the effect is logarithmic.
At those concentrations the dependence on concentration would be square-root not log.
The Standard Solar Model (SSM) is the origin of the ‘faint young sun’. It is also a purely computational model. Feynman would have advised us to re-examine our models when they don’t agree with the measurements.
thomasinga says:
September 24, 2013 at 11:30 am
“Amazing that nobody is considering planetary migration as a factor, which could greatly vary the amount of radiation receives from even an cooler sun. Gravitational forces from other planets, even ones not currently counted in our existing solar system, could migrate the earth’s orbit by a very large degree. Consider the moon, at it’s formation ~4 billion years ago, it was 80-90% closer than its current oribt. Tidal forces alone likely were the sole cause of this migration. Not a stretch to think that that Earth was much closer to the sun in its early history.”
This post notes an excellent sampling of many of the exogenous variables, other than GHG’s, which could explain the weak sun/warm earth issue. Per your comment, it is also not a stretch to consider tidal forces upon the earth’s core and huge ocean tides due to the much closer moon causing internal heating as well as continuous roiling of the waters keeping them from freezing. Fun to think about all the possibilities as long as they are not taken as dogma. Just too many possibilities and questionable paleo data.
Leif,
Where are you? Thoughts on the “faint young sun” theory?
Salvatore Del Prete says:
September 24, 2013 at 12:02 pm
Just as the anti-scientists have tried to get rid of the Medieval & prior Holocene warm periods, now they’re trying to get rid of the Jurassic-Cretaceous cold epochs:
http://www.nature.com/srep/2013/130313/srep01438/full/srep01438.html
Few are the earth & life science disciplines that have not been corrupted by the baleful influence of the corrosive CACA scam.
Re: Titan
Here is an interesting chart of Temperature Profiles (polytropic or adiabatic) for all planets + Titan – Venus.
At the bottom of The Oil Conundrum, March 17, 2013.
It says it is from Class 14 – Earth, Venus, Mars – 4 of Planetary Atmospheres ASTR3720
Spring 2005 Fran Bagenal
Astrobiologists have hypothesized three possible kinds of life on Titan, although NASA nixed a proposal to send a probe to test the first one (or two, depending upon thickness of rock-hard water ice crust above presumed ocean):
1) Strange life based upon liquid hydrocarbons rather than water;
2) More Earth-like life based upon water around seafloor hydrothermal vents, &
3) Earth-like life based upon surface water billions of years in the future, after the Sun goes red giant.
Personally, I don’t see that much problem. A 25% weaker Sun means more like 1000 W/m^2 TOA incoming which averages out to be around 250 W/m^2. At present, after albedo is accounted for, we have around 239 W/m^2. Water (oceans) have rather low albedo, rock has moderately low albedo – like Moon & Mars so having an albedo of around 10% assuming little to no clouds is possibly even overly generous. Having similar temperatures and outgoing absorption not all that different from today with the lower albedo due to less cloud cover would give us similar temperatures. Granted this post doesn’t rise to the level of a back of the envelope calculation but I just don’t see it obviously demanding serious variations in atmospheric ghg concentrations or in temperatures.
Regarding cosmic rays, where in the galaxy was the sun 2.5 to 3.8 billion years ago. If it orbits the galaxy every 224 to 251 million years then it was in and out of the spiral arms a lot. The cosmic radiation would vary a lot. So clouds would vary a lot or would the fast spinning sun with it’s high solar wind output make being in or out of a spiral arm not matter.
Could this be evidence that the metric expansion of space is felt at small scales?
The Charnay hypothesis fighting to defend CACA orthodoxy, and also most of the alternative hypotheses presented in the thread take the following form:
the sun’s heat input steadily increased over the last 4 billion years
BUT
as it happens
oddly and coincidentally
my favourite climate river: [insert CO2 / moon orbit / earth orbit / thin basalt crust / atmosphere blown away by solar wind / etc etc… ]
JUST
happened to change steadily in such a way as to
EXACTLY
counteract the increase in solar input
SO THAT
the earth’s temperature varied by a small fraction of the 25% solar input change
DUDE
thats a coincidence
IS THERE A GOD!!
Sorry but no. All these fail Occam’s razor. A far less tortuous and more likely explanation is regulation arising from nonlinear dynamics, Lyapunov stability of a nonlinear system. The main players are life and water. This is the essence of Lovelock’s Daisyworld.
milodonharlani says:
September 25, 2013 at 10:25 am
Salvatore Del Prete says:
September 24, 2013 at 12:02 pm
Just as the anti-scientists have tried to get rid of the Medieval & prior Holocene warm periods, now they’re trying to get rid of the Jurassic-Cretaceous cold epochs:
http://www.nature.com/srep/2013/130313/srep01438/full/srep01438.html
Few are the earth & life science disciplines that have not been corrupted by the baleful influence of the corrosive CACA scam.
Yes, this is sinister indeed. “CO2 uber alles” from the very first to the last word of the paper.
“”””””…..wayne says:
September 24, 2013 at 10:40 pm
“Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.”
and
“And don’t give me any Beer’s Law claim of a theoretical foundation. Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.”
Whew… if you are saying that the absorbance becomes linear with the concentration, true, opaque is total absorption. But the transimttance is dependent on the concentration times length of path through the media (exponentially), the optical mass that hinders passage that can be via scattering, refection or absorption, the tau.s in I = I0 * exp(-m(τa + τb + τc + … )). Am I not right?
The story of my life. No matter how many words, I write to explain some simple concept, it’s still not enough to convey the idea to some people.
Item 1/ We are talking about optical absorption in optically homogeneous media.
Ergo, there are NO scattering processes. CO2 molecules in the atmosphere ABSORB EM radiation; they do not SCATTER it.
Beer’s law, which strictly speaking applies to optical absorption in dilute solutions of absorbing species in a non absorbing liquid, as a function of the molar concentration of the absorbing species.
All that matters is the no of molecules of the absorbing species in the optical path of the ray. You can have them all in a thin layer of high density of the absorber, or a longer path of lower density.
What is meant by “absorbing species concentration” in my post that you quoted from, is simply that number of molecules in the path. So you can have a variable path length at a fixed molar fraction or a fixed path length and a variable molar fraction. What matters, is that each molecule in the path has some finite probability of absorbing a photon or not.
If 1 mm length absorbs 90% of the photons, the next mm will absorb 90% of the remainder of the input stream of photons.
So for example, if our input radiation is say a 441.6 nm HeCd blue laser, we will have blue 441.6 photons constantly being peeled off by absorbing molecules in their path; for example perhaps by a Cerium ion in a YAG crystal. The remaining 441.6 nm photons follows the normal exponential decay curve, much the same as the decay of radioactive isotopes.
The ASSUMPTION in all of these examples is that “The fraction of input photons TRANSMITTED” is simply 1 – “the fraction of input photons ABSORBED.” That is the Beer’s law assumption, and it is followed in many non scattering optically homogenious absorption situations.
So what is the problem ? The problem is:- The same is NOT TRUE for the TRANSMITTED ENERGY.”
Beer’s law naively assumes that the absorbed energy disappears, in direct conflict with the first law of thermodynamics. Energy is neither created nor destroyed. Those absorbed 441.6 nm blue photons refuse to stay DEAD ! They are re-incarnated , perhaps as yellow photons at say 580 nm wavelength, or red ones at 650 nm; they might even be re-emitted at a wavelength of 10 microns, in the infra-red, due perhaps to heating of the specimen by all that absorbed energy.
Now of course, it is assumed that the incoming photons are in a directed beam. The re-incarnated photons, at some longer wavelengths, are of course emitted isotropically; they go in every direction but they do go on living.
Same thing is true in the atmosphere, the photons absorbed by CO2 do not stay dead, so the energy transmission doe not obey Beer’s law. There simply is no basis, either theoretical of experimental for presuming that the atmosphere retains radiant energy as a logarithmic function of the molar abundance of CO2 or other GHG molecular species; or that the Temperature follows such a law. The available data is not statistically different from a simple linear relationship, nor is it dependent on any time offset between the two data sets (Temperature and CO2 abundance.)