THE FAINT YOUNG SUN PARADOX IS A REFERENCE TO THE LOWER LUMINOSITY OF THE YOUNG SUN WHEN THE EARTH SHOULD HAVE BEEN A FROZEN PLANET BUT IT WASN’T.

THIS POST IS A BIBLIOGRAPHICAL STUDY OF THE FAINT YOUNG SUN PARADOX IN THE CONTEXT OF THE THEORY OF ANTHROPOGENIC GLOBAL WARMING AND CLIMATE CHANGE AND THE ROLES OF GEOLOGICAL CARBON AND ROTATIONAL SPEED IN EXPLAINING WARMING. A MAINLINE PAPER IN THIS FIELD IS ROSING 2010. THE FULL TEXT PDF OF ROSING 2010 IS AVAIALBLE FOR DOWNLOAD AT THIS SITE WITH THE LINK BELOW. {Note: the word Archaean used in this line of research is a reference to the Archaean Eon, the oldest of the geological periods. It refers to the earth in the period from 4.5 to 0.5 billion years ago}.rosing2010Download

PART-1: THE FAINT YOUNG SUN PARADOX IN THE CONTEXT OF AGW CLIMATE CHANGE

The faint young Sun paradox {FYSP} was first described by Carl Sagan {Sagan and Mullen 1972). The issue is that a contradiction is implied by the evidence for liquid water early in Earth’s history when solar radiation intensity was 60% to 70% of what it is now, an insufficient amount of energy to explain the presence of liquid water instead of ice. At that lower solar radiance the earth should have been a frozen planet. Climate science has proposed various ways to explain this apparent contradiction in terms of low albedo, high greenhouse effect, faster rotation of the earth, and combinations of these.

The high greenhouse effect is described as large transfers of geological carbon from the mantle to the atmosphere by way of geological processes, a phenomenon not considered in the theory of anthropogenic global warming of today where the source of carbon external to the carbon cycle is limited to fossil fuel emissions and geological sources of carbon are overlooked as described in a related post on this site: LINK: https://tambonthongchai.com/2019/08/27/carbonflows/ .

Yet another phenomenon used to explain the FYSP but ignored in the understanding of AGW climate change is rotational speed as a variable in the estimation of earth’s mean temperature due to solar irradiance as shown in a related post on this site: LINK: https://tambonthongchai.com/2020/12/19/the-greenhouse-effect/

Other explanations for the FYSP involve changes to planetary albedo, geothermal heat, and astrophysical influences. In most such explanations of the FYSP, the evidence provided for the existence of the proposed causation mechanism to explain the paradox is that it explains the paradox, a form of circular reasoning. Yet another paradox of this paradox is that despite a significant body of research in this field, the paradox remains a paradox. The word paradox is a fancy defensive way of not having to say that we don’t know. That is, the science that knows all because it is science doesn’t really know all.

A bibliography of a decade of research on the FYSP from the year 2000 to 2011 is presented below. The overall conclusion of this body of research is that climate science can explain the FYSP in ways that are consistent with the theory of anthropogenic global warming by way of the fossil fuel emissions of the industrial economy. However, as noted above significant inconsistencies and contradictions remain unresolved. These are (1) circular reasoning, (2) inconsistencies with today’s AGW climate science where neither geological flows of carbon nor the temperature effect of rotational speed are considered, and that (3) despite a significant body of research since 1972, the faint young son paradox remains a paradox meaning that we don’t really know although we know for sure that fossil fuels cause warming.

ADDENDUM: IN THE FIRST COMMENT BELOW, A COMPUTATION OF THE EARTH’S MEAN TEMPERATURE EXPLAINED BY SOLAR LUMINOSITY WHEN ROTATIONAL SPEED IS TAKEN INTO ACCOUNT EXPLAINS THE FYSP IN AGREEMENT WITH THE FYSP RESEARCH IN THE BIBLIOGRAPHY. THIS COMMENT IS BY CHRISTOS VOURNAS, THE BLOGGER THAT HAS BEEN ARGUING AGAINST THE GREENHOUSE EFFECT WITH THE SAME MATHEMATICS. LINK: https://www.cristos-vournas.com/ . WHAT SEPARATES CHRISTOS FROM MAINSTREAM AGW CLIMATE SCIENCE, BUT NOT FROM FYSP CLIMATE SCIENCE, ARE TWO ISSUES. THEY ARE THE ROTATIONAL SPEED AND EARTH’S WATERY SURFACE THAT HE AND FYSP RESEARCHERS SAY CHANGE THE EQUILIBRIUM SURFACE TEMPERATURE FOR ANY GIVEN LEVEL OF SOLAR RADIANCE.

PART-2: A FAINT YOUNG SUN PARADOX BIBLIOGRAPHY

1. Jenkins, Gregory S. „Global climate model high‐obliquity solutions to the ancient climate puzzles of the Faint‐Young Sun Paradox and low‐altitude Proterozoic glaciation.“ Journal of Geophysical Research: Atmospheres 105.D6 (2000): 7357-7370. There is a general consensus that warm temperatures throughout Precambrian were caused by very high CO₂ or CH₄ atmospheric concentrations. Episodes of glaciation in the early and late Proterozoic were caused by a reduction in these greenhouse gases through intensive weathering or large reduction in the methane producing bacteria population. There are suggestions that these episodes were global because the continents occupied low latitudes at or near the time of glaciation. Here it is reported that high‐obliquity throughout the Precambrian serves as a mechanism for producing warm temperatures throughout the Archean and glaciation in the late Proterozoic. In this paper, Global climate model simulations using high‐obliquity values that range from 54° to 70° are undertaken. These simulations use a simple 50‐m slab ocean, a faster rotation rate corresponding to an 18 hour day, an idealized supercontinent located in the tropics which has a north‐south mountain chain and CO₂ concentrations which range from 170 to 3400 ppmv. Further, four simulations under global ocean conditions, faster rotation rate and reduced solar constant (15 and 20%) using present‐day and high‐obliquity values have been undertaken. The simulations show warm conditions with high‐obliquity but Snowball Earth conditions for the present‐day obliquity in the global ocean simulations. Near Snowball Earth conditions also occur for the tropical supercontinent simulation for an obliquity of 70° and CO₂ concentrations less than 1020 ppmv. Together, these simulations show that for high‐obliquity the ocean remains relatively warm while land areas are cooled because of their lower heat capacity. Large fluxes of latent heat from the ocean balance the longwave energy lost at the top of the atmosphere thereby keeping high latitudes warm during winter seasons. It is suggested from this results that lower and upper limits of 65°–70° for obliquity serve as a solution for the Faint‐Young Sun Paradox and low‐latitude Proterozoic. Finally, the high‐obliquity‐climate relationship sheds some insight on the carbon isotope (δ¹³C) excursions during the late Proterozoic.
2. Gaidos, Eric J., Manuel Güdel, and Geoffrey A. Blake. „The faint young Sun paradox: An observational test of an alternative solar model.“ Geophysical research letters 27.4 (2000): 501-503. We report the results of deep observations at radio (3.6 cm) wavelengths of the nearby solar‐type star π⁰¹ Ursa Majoris with the Very Large Array (VLA) intended to test an alternative theory of solar luminosity evolution. The standard model predicts a solar luminosity only 75% of the present value and surface temperatures below freezing on Earth and Mars at 4 Ga, seemingly in conflict with geologic evidence for liquid water on these planets. An alternative model invokes a compensatory mass loss through a declining solar wind that results in a more consistent early luminosity. The free‐free emission from an enhanced wind around nearby young Sun‐like stars should be detectable at microwave frequencies. Our observations of π⁰¹ UMa, a 300 million year‐old solar‐mass star, place an upper limit on the mass loss rate of 4–5 × 10⁻¹¹ M⊙yr⁻¹. Total mass loss from such a star over 4 Gyr would be less than 6%. If this star is indeed an analog of the early Sun, it casts doubt on the alternative model as a solution to the faint young Sun paradox, particularly for Mars.
3. Ueno, Yuichiro, et al. „Geological sulfur isotopes indicate elevated OCS in the Archean atmosphere, solving faint young sun paradox.“ Proceedings of the National Academy of Sciences 106.35 (2009): 14784-14789. Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of ³²SO₂, ³³SO₂, and ³⁴SO₂ and use them to interpret the geological record. The calculated isotopic fractionation factors for SO₂ photolysis give mass independent distributions that are highly sensitive to the atmospheric concentrations of O₂, O₃, CO₂, H₂O, CS₂, NH₃, N₂O, H₂S, OCS, and SO₂ itself. Various UV-shielding scenarios are considered and we conclude that the negative Δ³³S observed in the Archean sulfate deposits can only be explained by OCS shielding. Of relevant Archean gases, OCS has the unique ability to prevent SO₂ photolysis by sunlight at λ >202 nm. Scenarios run using a photochemical box model show that ppm levels of OCS will accumulate in a CO-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation.
4. Rondanelli, Roberto, and Richard S. Lindzen. „Can thin cirrus clouds in the tropics provide a solution to the faint young Sun paradox?.“ Journal of Geophysical Research: Atmospheres 115.D2 (2010). In this paper we present radiative‐convective simulations to test the idea that tropical cirrus clouds, acting as a negative feedback on climate, can provide a solution to the faint young Sun paradox. We find that global mean surface temperatures above freezing can indeed be found for luminosities larger than about 0.8 (corresponding to ∼2.9 Ga and nearly complete tropical cirrus coverage). For luminosities smaller than 0.8, even though global mean surface temperatures are below freezing, tropical mean temperatures are still above freezing, indicating the possibility of a partially ice‐free Earth for the Early Archean. We discuss possible mechanisms for the functioning of this negative feedback. While it is feasible for tropical cirrus to completely eliminate the paradox, it is similarly possible for tropical cirrus to reduce the amounts of other greenhouse gases needed for solving the paradox and therefore easing the constraints on CO2 and CH4 that appear to be in disagreement with geological evidence. Introduction
   [2] Models for the evolution of the Sun during the main sequence call for a reduced solar luminosity and therefore a reduced Earth’s solar constant of about S = 0.75 S0 around 3.8 Ga (with S0 the present solar constant ∼1353 W/m2) [Schwarzschild, 1958; Newman and Rood, 1977]. At the same time, geological evidence shows the presence of a stable ocean and liquid water in the planet at least after 3.9 Ga (and perhaps even earlier [e.g., Wilde et al., 2001; Pinti, 2005]). The fact that simple models of the Earth’s climate cannot reconcile the reduced luminosity with the presence of liquid water (and the absence of glacial deposits) has become known as the faint young Sun paradox [Sagan and Mullen, 1972]. The paradox hinges on the assumption of a constant atmospheric composition or, more precisely, on the assumption of a constant atmospheric greenhouse effect and a constant atmospheric solar reflectivity (both including gases and clouds). As an illustration, one can use a crude zero‐dimensional energy balance for the atmosphere to calculate the mean global surface temperature as Ts=Tg+((1-A)*S)/(4*sigma))^0.25 [ Catling and Kasting, 2007]. where A is the planetary albedo and Tg is a temperature that encapsulates the greenhouse effect of the atmosphere and clouds. For current climate with A = 0.3 and Tg = 34, Ts = 288 K. According to the standard solar model, the luminosity, and therefore the variation of the solar constant can be approximated by [Gough, 1981] S=S(0)/(1+0.4t/4.6) where t is the time in Ga. Under the assumption of a constant greenhouse effect, the simple zero‐dimensional model gives Ts = 269 K for a solar luminosity of S = 0.75 S0, ∼ 3.9 Ga. Ts rises above freezing for S ∼ 0.79 S0, which corresponds to 2.9 Ga. It might seem that a much reduced value of A in equation (1) could increase the temperature above freezing. However, the absence of clouds (the main driver of the albedo) would also result in a significant reduction of the greenhouse effect. Solutions that involve high CO2 atmospheric concentrations are particularly appealing given the existence of large reservoirs of carbon in the Earth’s mantle and continents. LINK TO FULL TEXT: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009JD012050
5. Goldblatt, Colin, and Kevin J. Zahnle. „Faint young Sun paradox remains.“ Nature 474.7349 (2011): E1-E1. ABSTRACT: The Sun was fainter when the Earth was young, but the climate was generally at least as warm as today; this is known as the ‘faint young Sun paradox’. Rosing et al.¹ claim that the paradox can be resolved by making the early Earth’s clouds and surface less reflective. We show that, even with the strongest plausible assumptions, reducing cloud and surface albedos falls short by a factor of two of resolving the paradox. A temperate Archean climate cannot be reconciled with the low level of CO₂ suggested by Rosing et al.¹; a stronger greenhouse effect is needed. During the Archean eon, the Earth received 76% to 83% of the energy from the Sun that it does today. If the Earth’s greenhouse effect and albedo were the same as now, the Earth would have been in continual deep freeze until one billion years ago, with glaciers reaching the Equator. However, Archean glacial sediments are rare and geological evidence indicates that the Archean was typically warmer than today (we are in a glacial period now). With the amount of energy reaching the Earth given by F = ¼S₀(1 − α) = 239 W m⁻² (using the present-day solar constant S₀ = 1,368 and albedo α = 0.3), the radiative deficit in the Archean would have been (1–0.79)F ≈ 50 W m⁻². Resolution of the ‘faint young Sun paradox’ requires a positive radiative forcing—from reducing the albedo or increasing the greenhouse effect—of more than 50 W m⁻². Clouds have two competing radiative effects: they reflect sunlight but they also add to the greenhouse effect if they are colder than the surface. Reflection dominates in low clouds, and the greenhouse effect dominates in high clouds. Therefore the absolute upper bound on warming by decreasing cloud reflectivity would be found by removing low clouds entirely. This gives a forcing of 25 W m⁻², half of what is needed to resolve the ‘faint young Sun paradox’ (our cloud model is described in the Methods). Any reduction to high clouds would cause a cooling. Rosing et al.¹ justify less-reflective clouds with the incorrect statements that most cloud condensation nuclei (CCN) are from biogenic dimethyl sulphide (DMS), and that DMS is solely produced by eukaryotes. DMS is also produced microbially². Products of DMS contribute only 3% of Northern Hemisphere CCN and 10% of Southern Hemisphere CCN today³. Other biological⁴ and non-biological sources, especially sea salt, provide CCN. If CCN production were to depend only on eukaryotic DMS emissions¹, we would expect to see significant cooling when eukaryotes evolved, but no such cooling is evident. Nevertheless, we can assume no biological CCN supply and quantify the resulting forcing. Over the modern ocean the effective radius r_e of cloud drops rarely exceeds 15 µm (ref. 5) even in remote and unproductive regions (the r_e of 17 µm to 30 µm used by Rosing et al.¹ is too high). For an upper bound, we increase low cloud droplet size by 50% from our standard case, from 11 µm to 16.5 µm. With no change in cloud thickness, the forcing is 7 W m⁻². Clouds with larger drops may rain out faster. Parameterizations of enhanced rain-out vary from proportional to (r_e,0/r_e)¹ to proportional to (r_e,0/r_e)^5.37 (refs 6 and 7); the corresponding extra forcing would be 4–15 W m⁻² (remote sensing data for marine stratus suggest that the low end of this range is more appropriate⁸). The sum is 11 W m⁻² to 22 W m⁻², with the low end being most likely. The authoritative estimate of the global energy budget⁹ gives global mean and ocean albedos of 0.125 and 0.090 respectively. The largest realistic surface darkening is from the present mean to an all-ocean world, which gives a radiative forcing of 5 W m⁻². Increasing the CO₂ mixing ratio to 1,000 parts per million by volume (p.p.m.v.; the upper bound according to Rosing et al.¹) gives a forcing of 6 W m⁻². Rosing et al.¹ rely on 1,000 p.p.m.v. CH₄ for much of their warming, ignoring relevant atmospheric chemistry. As the partial pressure of CH₄ () approaches that of CO₂ (), hydrocarbon haze forms in the stratosphere, the cooling effect of which outweighs the greenhouse effect of CO₂ and CH₄ (refs 10 and 11). Numerical models¹² predict haze production when / = 0.1 and haze production has been seen in laboratory experiments¹³ where / = 0.3. With 1,000 p.p.m.v. CO₂, the maximum CH₄ concentration that can give warming is 300 p.p.m.v., which would contribute 7 W m⁻² of additional forcing. Changes to clouds could in theory considerably reduce the amount of greenhouse gases required, because gaseous absorption depends on the logarithm of gas abundance. But even with the highly unlikely assumption of no biological CCN supply, cloud changes can provide only one-quarter to one-half of the required radiative forcing. Any changes to clouds would require strong justification, which Rosing et al.¹ do not provide. A strong greenhouse effect is required in the Archean. The alternative is an extremely cold climate with continual mid- to low-latitude glaciation, for which there is no evidence.

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THE FAINT YOUNG SUN PARADOX