No snowball on habitable tidally locked planets
Stabilizing Cloud Feedback Dramatically Expands the Habitable Zone of Tidally Locked Planets
Tidal obliquity evolution of potentially habitable planet
And this modeling was confirmed to be accurate... how, exactly?
This strikes me as a classic case of goosing the model until it says what you want it to say, and then getting in the news. We have no reason to believe these models. We have no reason to believe prior models, either. We have no reason to have any confidence in our ability to model a tidally locked planet, of unknown and arbitrary chemistry, around an unknown star, for unknown periods of time, with unknown orbital characteristics across geological time, with zero data points. We particularly have no reason to believe in any estimates of how long such a system could last; it doesn't seem to do life much good if there's a place for it to exist for a couple of million years, followed by freezing. The simulation is almost certainly unstable here; very small changes in the stability of this configuration will have massive changes to the result over even a few million years.
There's also more to life than just a comfortable temperature. Life is possible on Earth in part because we have a moon and plate tectonics keeping this stirred up, so some of our vital nutrients don't just sequester themselves somewhere chemically convenient after a couple of million years and then hang out there for the rest of the planet's existence. Do these types of planets have a solution for that? We have no idea. (One advantage of the Earthlike planets is that we do in fact have an idea... we know it's at least possible once.)
What is your level of expertise or knowledge of planetary astrophysics and climate modeling?
This does not require extensive study.
Furthermore, as a bona fide, credentialed expert in computer science, I observe with the full power of my credentials that other fields frequently abuse modeling to get into the news, and that as I said, this shows all the hallmarks of being one of those. There is a profound, mathematical way in which models simply spit back out at you what you put in. This profound mathematical understanding seems to be broadly lacking, and it makes people grant wildly excessive credence to unverified models. As just a single for instance, I expect you have no idea how many models they ran that produced lifeless planets until they finally found one that yielded a result conducive to life. Given the almost-certainty that these systems are deeply, deeply unstable, I expect it is almost certainly the case that they had a large number of runs where the system simply ran away in one direction or another.
Edit: I challenge the downmodders to produce a single data point about an eyeball planet in a habitable zone and demonstrate a model that correctly represents it. "We have to have data before we can verify a model" is not some sort of wild anti-scientific statement; the belief that a model can be trusted without validation is the wildly anti-scientific position!
If some of you are mistaking this for a position on the climate debate, note that we do have data for Earth's climate. Not as much as we might like (could always use more!), but it's certainly much greater than zero. You can literally get more than zero data just by walking outside and observing the temperature right where you are. This point has nothing to do with the climate debate on Earth.
3d General circulation models and basic energy balance models are verified against range of temperatures, pressures, and atmospheric conditions in the Earth, Mars, Jupiter and Venus. The same model used for exoplanets is used to model paleo-Mars, paleo-Venus, and Titan. If the model is somehow completely wrong outside known limits, so is the parent model that is used in the Earth Climate change studies. The models work just fine at this level of required accuracy. You put parameters that describe the Earth, Mars or Venus into the and you get good description of atmosphere and climate in Venus and Mars that matches observations.
We don't have to model specific planets to get interesting information. In generally the interest is to model different categories of the planets and discover how their environments vary when we vary the parameters. It's possible to say something generic about tidally locked planets and their climate. This is what these simulations do.
GISS modelE GCM
ROCKE-3D version of GISS modelE GCM
Besides the examples you mention, research groups are now doing data assimilation for Mars (https://www2.physics.ox.ac.uk/research/geophysical-fluid-dyn... https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/201...).
Other groups are testing and improving models for Jupiter and Saturn, as you mention, based on various remote sensing observations. (For Saturn, see: https://theoryofclimate.sciencesconf.org/conference/theoryof...).
All of these cases have allowed modelers to observationally test their models and model physics against non-Earth conditions. This work has been going on for a decade now, but it somehow has not reached the technically-aware audience.
The case of tidally-locked planets is another step beyond the above solar-system planets. Thank you for the references you supplied, in your original comment, on GCMs for this case.
I enjoy modeling, and I think it's useful, interesting as well as respectable work. But a little humility would in science is always a good things.
Regardless, it's more useful to point to particular areas of uncertainty than to point to a general miasma of uncertainty around climate modeling as though nothing can be learned. It doesn't really move any conversations forward.
Just because we can't predict when an individual hurricane will occur doesn't mean that we can't predict "hurricane season".
edit: Apparently it's not even certain whether the Sun will engulf the Earth or not!
That's alright. I'm a credentialed expert in computer science myself and I'm also always right about everything, including entire scientific fields I know next to nothing about.
If you understand how computers work, you understand how everything that uses computers works!
She said, "That's like SlimFast."
Since it was marketed for tech guys, it was a tech discovery.
Somewhere in an alternative universe, there must be an astronomers' forum talking crap on developers because Heartbleed and Spectre show they all misunderstood Goedel's theorem, and believe me, I totally know what I'm talking about, I use computer every day.
But apparently the same is not valid for complex fields like astrophysics, spacephysics or astronomy.
Btw tidal locking can cause tectonic activity, as in the case of the Jovian moons.
Things are finally settling down to the point where models match independent data, e.g. the recent research into sea level changes as measured by satellite.
So now, finally, we can start making informed policy choices based on cost benefit analysis. (Actually, no, who am I kidding - Greens worldwide will keep hating on industry and capitalism, and everyone else will keep pretending AGW isn't real. But at least we could start forming rational policies if we wanted.)
Back on topic, to assume that we can make any kind of predictions about the climate of life bearing exoplanets seems like the height of arrogance given the state of the art in climate modelling.
Predicting whether life might exist on a planet can probably tolerate ±10% temperature accuracy. There's no reason to believe that smart geophysicists can't achieve that level of accuracy.
My point, perhaps snarkily made, was that we are only now getting the hang of this, after decades of work.
Unless I'm missing something, we're not going to be approaching anything like 10% error bars for planets for which we have far less data.
At the risk of misunderstanding “eyeball planet”, you’re living on the most obvious example.
Elsewhere in Sol, Mars is in the “optimistic” habitable zone (I think that means “it would be if only it had been massive enough to retain an atmosphere”).
Earth climate models you already believe in so I won’t bother to name.
Can anyone else tell me the accuracy of The Ames Mars General Circulation Mode?
You should read the articles on this website please.
There is such a gigantic massive amount of information we dont know.
Any words spoken about how life is created should be met with the same skepticism we have toward religion. We require evidence and the scientific method, a simulation made my students who need to be correct for a PhD isnt evidence.
I don't understand this anger about having untestable models. How would science progress without having theoretical possibilities before testable possibilities?
Every challenge he puts forth requires at best high school level critical thinking skills.
By his own "logic", we can't even be sure they're tidally locked (because how did we determine that? Modeling!) Which I mean, is technically true because hey welcome to science where confidence intervals are a thing.
Surely the specialist knowledge comes after the general knowledge? If a Nobel prize winning Astrophysicist says "there are exoplanets where you can make a perpetual motion machine" you would not let him get away with that?
The guy further up was just saying that there are general things about modelling (a very broad topic that reaches across all of science) that don't add up.
Ultimately, reasoning about observations are authoritative, not credentials.
You're demonstrating exactly why general knowledge isn't enough to analyze specialized concepts! Your rhetorical question may seem to the layman to be a witty retort but it just demonstrates ignorance of the topic at hand.
In the case of your perpetual motion machine example, anyone with even slightly specialized knowledge of (astro)physics would know that there are no fundamental phenomena like the conservation of energy that prevent life on an eyeball planet, unlike with a perpetual motion machine. This is the rhetorical equivalent of comparing a Mount Everest expedition to intergalactic teleportation.
> The guy further up was just saying that there are general things about modelling (a very broad topic that reaches across all of science) that don't add up.
No, he was just saying that there are general things about how modelling is used. He didn't say a single concrete thing about the article itself and proceeded to demonstrate vast ignorance wrt this specific subfield of scientific modelling.
He did say something concrete, which is that we have no observations to compare the model to.
Which is wrong. That's my point. You wouldn't know that without some specialized knowledge in astrophysics and how the models are developed and verified.
The people with the highest credibility tells the rest how it is, and we don't question it. Now it's magic eyeball planets, next year it's spinning discs with Santa in the middle.
As long as credentials are impressive, it all checks out doesn't it...