The Young, Faint Sun Is Still a Problem

More than three years ago, I wrote about the young, faint sun paradox. The problem is fairly simple: Based on everything we know about the thermonuclear reactions that power the sun, it is getting more luminous over time. In other words, the sun is producing more light now (on average) than it did in the past. As a result, the farther you go back in time, the dimmer it should have been. This presents a problem, because the dimmer the sun is, the cooler all the planets (including the earth) are. According to what we know right now, the earth would have been too cold to support life 3.6 billion years ago. Modern paleontology assures us, however, that there was life on earth at roughly that same time.

How do those who believe both modern paleontology and our current understanding of the sun resolve this problem? Unfortunately, the all-too-often response is to deny that there is a problem at all. For example, one old-earth website claims that this used to be a problem, but it has since been solved. It cites a 2010 study1 that merely suggested a possible issue that might reduce the problem. Based on that single study, the website proclaims:

The solving of this paradox provides us with a clear answer that is easily understood, and should eliminate this paradox from being used as evidence of a young earth. Once again, science has prevailed over the claims of young earth creationism.

Of course, nothing could be further from the truth. Indeed, in just over one year, the very same journal published a paper that categorically showed that the solution proposed by the 2010 paper was insufficient. Even giving the proposed solution the widest possible latitude, it fell short of resolving the paradox by a factor of two!2

In fact, this problem is still so difficult to resolve in the old-earth view that the Space Telescope Science Institute hosted a two-day symposium in hopes of starting to find a solution to it.

The symposium was entitled “The Faint Early Sun: Paradox, Problem, or Distraction?,” and in his introduction, here is what Dr. David Soderblom said:

According to standard solar models, at a billion years of age the sun had something like 75% of today’s luminosity, and under those conditions, we would get the earth freezing over and it wouldn’t recover because it would have a high albedo.

In case you don’t understand the word, albedo refers to how much light is reflected from a surface. If the earth really was a frozen ball, it would reflect so much of the sun’s light that even with the conditions we have now, it could not warm itself enough to support life.

So here’s what Dr. Soderblom is saying: If the sun acts the way we think it does, and if the earth/sun interaction wasn’t substantially different in the past, not only would the earth have been inhospitable to life 3.6 billion years ago, it would not even support life today; it would still be a frozen ball. Obviously, then, this is a serious problem for the old-earth view.

In fact, the problem is so difficult that the symposium invited scientists from many disciplines such as astrophysics, geochemistry, and geophysics, to work together to try to solve it. What kinds of solutions were proposed? Well, some proposed that earth’s atmosphere was different from what it is now, although the evidence suggests that it couldn’t have been much different. Others proposed that the earth was actually really cold for a long time and that life only existed in narrow bands around the equator, although that doesn’t seem to square with the fossil data that we currently have. Others proposed that the sun was more massive in the past, but that doesn’t seem to be consistent with what is known about how stars lose mass over time. Others proposed that the earth was closer to the sun back then and has since migrated to its current position, although there are problems reconciling that scenario with today’s structure of the solar system.

In the end, then, it seems that if old-earthers are going to solve this paradox, it will have to be a cross-disciplinary approach. I think Dr. Soderblom said it best near the close of his introductory talk, which is linked above. He thinks the goal of the symposium is to get the participants:

To think about is there a product that we can produce from this meeting…that kind of summarizes the state of knowledge based on what observations and models we have right now and figuring out what are the next steps to try to reign in the parameters of the problem.

In other words, unlike some old-earthers, these scientists recognize that the way the sun changes over time is a serious problem for the old-earth view, and they understand that if there is a solution to the problem, it won’t come quickly or easily. I applaud these scientists for at least recognizing the problem and understanding that they must wrestle with it. Of course, I think they are barking up the wrong tree; I don’t think the earth or the sun existed a billion years ago. Nevertheless, it will be interesting to see what (if anything) comes out over the next few years as a result of this symposium.


1. Minik T. Rosing, Dennis K. Bird, Norman H. Sleep, Christian J. Bjerrum, “No climate paradox under the faint early Sun,” Nature, 464:744-747, 2010
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2. Colin Goldblatt and Kevin J. Zahnle, “Faint young Sun paradox remains,” Nature 474:E1 doi:10.1038/nature09961, 2011
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6 thoughts on “The Young, Faint Sun Is Still a Problem”

  1. Definitely seems to be a dilemma for those holding to an old Earth view. I wonder if scientists will ever allow for a younger Earth, especially as the evidence builds?

    Thanks for sharing Dr Wile.

  2. Hugh Ross points to a recent study that suggests that the Faint Young Sun model itself might be part of the problem: Resolving Faint Sun Paradoxes.

    Observations of stars that old-Earth astronomers would call analogs to the Sun of 3.8 billion years ago indicate that they are losing a significant amount of mass. If this was true for the young Sun, it would have had greater mass, and therefore greater luminosity than the Faint Young Sun model has predicted. Combined with mechanisms that are insufficient by themselves, such as increased greenhouse gas concentrations on the early Earth, there may no longer be a paradox.

    ICR has written a non-technical response to this idea that doesn’t really say anything: Can Solar ‘Belch’ Solve Sun Paradox.

    I am sure this isn’t the final word regarding the issue, but you may be acting a little prematurely to have this one on your list of “Top Five” reasons for believing in a young Earth.

    1. Kevin, Dr. Ross’s article is quite out-of-date. As Dr. Minton says in his talk at the symposium:

      The real problem is you need this sustained mass loss rate for 2 billion years. And as was alluded to before, when you compare the mass loss rate you need with the inferred mass loss rates from stellar winds from some like stars as was done in the Lewinski talk just recently, these fall orders of magnitude below what you need.

      So mass loss is not the solution. You might have missed it, but I mentioned that proposed solution in my article and pointed out that it is not consistent with what is known about how stars lose mass over time. That’s what Dr. Minton said in his talk. Now please understand that Dr. Minton was one of the authors who proposed that very solution, but he is admitting that the solution doesn’t work. Thus, as this symposium demonstrates, there is currently no reasonable solution to the young, faint sun paradox.

      I am certainly not acting prematurely. This paradox was pointed out by Dr. Carl Sagan and Dr. George Mullen in 1972, and no workable solution to the paradox has been found. When physicists work on a problem for 40 years and then have to call a symposium to get scientists from multiple fields involved, you know it’s a real problem. In addition, when the physicist who begins the symposium says that his goal is just to figure out “what are the next steps to try to reign in the parameters of the problem,” you know that any reasonable solution is, at best, a long way off.

  3. I’m just wondering if, perhaps, things were able to live just fine in extremely cold temperatures a billion years ago. Just because we cant doesn’t mean nothing could…

    1. That’s a good thought, Nick, but the problem is with water. Life as we know it (even the oldest fossilized life forms, which are bacterial) requires water in its liquid phase. To support life, the earth has to be warm enough for that.

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