The Faint Young Sun Paradox: 3 Solutions?

For the Wednesday news article Tim Clarey writes Sun Paradox Challenges Old Earth Theory.

To recap, the faint young Sun paradox comes from an apparent contradiction between observations in the fields of astronomy and geology. On the one had we know that many stars on the “main sequence” get hotter and brighter as they age: the Sun appears to be on the main sequence, and so a couple of billion years ago in the Archean it would have only around 75%-80% if its present output. Reduce the Sun to that level now and Earth would freeze over.

On the other hand the geological record of the Archean is sketchy at best, but evidence from fossil cyanobacteria (blue-green algae) and raindrop imprints show that there was at least some liquid water somewhere on the planet at this time. There were some glaciations at the end of the period, but clearly not throughout.

A paradox then, and one that creationists are predictably fond of. Clarey concludes his short article with the following:

Creation scientists do not wrestle with this paradox, because the sun, planets, and Earth are all young and were created whole. Solar radiation on Day Four of the creation week, near the beginning of time itself, was not much different from today and perfectly suited for life—an explanation that frees scientists from this unnecessary conundrum.

Now, there have been various attempts to resolve this paradox. Back in 2012 we heard of a group planning to investigate the possible existence of “stretch marks” on the Sun that would show that it had lost significant mass and was therefore not actually a main sequence star and therefore dodging the paradox. More orthodox methods involve investigating levels of greenhouse gasses in the early atmosphere, which if higher than they are at present could warm global temperatures above freezing levels just as they do today. The obvious suspect for a long term increase in temperature is of course carbon dioxide, but evidence from paleosols (fossilised soil) shows that the concentration of this gas was not nearly high enough.

On idea that has been tossed about recently is that if there were more nitrogen in the atmosphere than there is at present this could significantly aid the greenhouse effect from the CO₂ and lead to the warmer temperatures. The paper Clarey focusses on in his article, Nitrogen Isotopic Composition and Density of the Archean Atmosphere (press release), looked at fluids trapped in quartz veins to determine these and other facts about the Archean atmosphere. Their results were largely negative for this hypothesis – the press release quotes Dr Ray Burgess as saying:

The amount of nitrogen in the atmosphere was too low to enhance the greenhouse effect of carbon dioxide sufficiently to warm the planet. However, our results did give a higher than expected pressure reading for carbon dioxide – at odds with the estimates based on fossil soils – which could be high enough to counteract the effects of the faint young Sun and will require further investigation.

One door slams shut, while another reopens a crack. Clarey’s response is predictable:

While the study authors point to a slight chance that the high carbon dioxide (CO₂) pressures they found in the gaseous rocks might have helped sufficiently warm the earth, no conclusive research has yet proven this point. So, where did the 3.5 billion-year-old algae come from if it grew in a cold era without even the existence of atmosphere-warming gases?

At the end of the day, when all the high-tech laboratory equipment has completed its tasks, the “faint young sun paradox” remains a “mystery” in the evolutionary time scale. But if these scientists considered that Earth is only thousands of years old—as clearly stated in the Bible—then there would be no need to reconcile old life with an old sun.

This was not, however, the only paper published recently on this topic. A second paper, A Closer Earth and the Faint Young Sun Paradox: Modification of the Laws of Gravitation or Sun/Earth Mass Losses?, appeared a couple of days ago in the open access journal Galaxies. This paper makes the relatively trivial observation that if the sun was 75% of its modern luminosity then if the Earth was slightly closer to the Sun then a sufficient level of heating could be achieved, and then goes on to explore how the planet could from there have gotten to its present location. The author, Lorenzo Iorio, first notes and then dismisses the amusing coincidence that the rate of movement required is of the same order of magnitude as the rate of expansion of the universe as a whole, and then goes on to explore other possibilities.

It should not be surprising to you that I don’t particularly like this option: playing with the laws of physics or positing mass loss fail Occam’s razor without solid evidence that they happened or are even possible. Taking another route, the aforementioned journal is open access and recently founded, meaning that it potentially suffers from the same flaws revealed in John Bohannon’s recent sting and may not be credible. Regardless, divorced from any evidence this approach seems unlikely to be very helpful, and this paper may serve only as fodder for those who claim that scientists are desperate for an ad hoc explanation for the paradox (I’m looking at you, Uncommon Descent – you’ve been doing a lot of that kind of thing lately).

There is a third paper on this subject, published a few weeks before the first but which could have done with the nitrogen studys conclusions. Published online on the 19th of September in the Journal of Geophysical Research Atmosphere is a paper called Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3-D GCM. They claim that previous attempts to model the Earths climate during the Archean have only used “1 dimensional” models, and that results from a “3-D global climate model” (GCM) paint a decidedly more positive picture. They conclude:

Our GCM supports some of the main conclusions of 1-D models, but it also reveals some interesting 3-D behavior of the climate. There is a decrease in clouds above continents that compensates for their higher surface albedo and there is especially an important cloud feedback. For the same surface temperature, there are less clouds during the Archean due to the weaker evaporation. This leads to a lower planetary albedo. In our model, another strong cloud feedback appears in cold climates. The decrease of clouds particularly close to the freezing line counteracts the ice-albedo feedback and allows water belts to exist with a mean surface temperature far below the frozen point. Such a resistance against glaciation mitigates the faint young Sun problem.

And:

This paper constitutes the first full study of the Archean Earth with a 3-D GCM coupled to a dynamic oceanic model. Coupled 3-D models applied to the early Earth provide new tools for achieving progress in a field where there is still a lot to understand. Three-dimensional GCMs have to be as general (less tuned) as possible. As for global warming, comparison between several GCMs will be required to refine predictions. Our study consolidates many results obtained with 1-D radiative-convective models and emphasizes some particular behaviors inherent to 3-D as well. There are many ways to solve the faint young Sun problem. According to our results, it is not so difficult a task, particularly if cold climates with water belts can be maintained. New geological constraints for the early Archean on CO₂ and N₂ partial pressures, as well as the H₂ abundance of the atmosphere, are necessary to have a good picture of the atmospheric composition.

(Emphasis added) As you can see from that last sentence they could do well to compare notes with the people who wrote the first paper. But if other models come up with the same conclusions – and better yet, the increased CO₂ levels suggested earlier pan out – this could well be the end for the faint young Sun paradox.

Why wasn’t this study reported on by the ICR in the same manner as the more negative one has been? Maybe Clarey doesn’t have access to the Journal of Geophysical Research Atmosphere and couldn’t find the arXiv link. Maybe lots of things – I don’t have an insight into how their process of inspiration works.

Regardless, watch this space. This wont be the last we hear of the faint young Sun paradox, not by a long shot.

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Turns out this was my 500th post.

Wow I’ve been doing this for a while…