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Lower Thermal Radiation Input Needed To Trigger Planetary 'Runaway Greenhouse'
vinces99 writes with this excerpt from the UW news service: "It might be easier than previously thought for a planet to overheat into the scorchingly uninhabitable 'runaway greenhouse' stage, according to new research (abstract, article paywalled) by astronomers at the University of Washington and the University of Victoria. In the runaway greenhouse stage, a planet absorbs more solar energy than it can give off to retain equilibrium. As a result, the world overheats, boiling its oceans and filling its atmosphere with steam, which leaves the planet glowing-hot and forever uninhabitable, as Venus is now. One estimate of the inner edge of a star's 'habitable zone' is where the runaway greenhouse process begins. The habitable zone is that ring of space around a star that's just right for water to remain in liquid form on an orbiting rocky planet's surface, thus giving life a chance. Revisiting this classic planetary science scenario with new computer modeling, the astronomers found a lower thermal radiation threshold for the runaway greenhouse process, meaning that stage may be easier to initiate."
If correct, the habitable zone shrinks a bit and a few exoplanets might lose their potentially habitable status. And the Earth will leave the habitable zone in a billion and a half or so years as the Sun gets brighter.
Just think, both of those planets someday could have been very similar to our Earth.
They are our sister planets, each expressing an ultimate degree to which things can go, and with what we've been discovering recently, remarkably little 'input'.
I don't know about the rest of you, but I found the last two lines of the summary to be quite anticlimactic. Where's the fear-mongering?
so long as we aren't responsible for it?
Sheesh, evil *and* a jerk. -- Jade
At least according to the abstract of the research paper (couldn't read the paper itself) if Earth is brought into the hot moist athmosphere state, that state would maintain itself. From the abstract (emphasis mine):
Therefore, a steam atmosphere induced by such a runaway greenhouse may be a stable state for a planet receiving a similar amount of solar radiation as Earth today. Avoiding a runaway greenhouse on Earth requires that the atmosphere is subsaturated with water, and that the albedo effect of clouds exceeds their greenhouse effect. A runaway greenhouse could in theory be triggered by increased greenhouse forcing, but anthropogenic emissions are probably insufficient.
So we will probably not manage to terraform Earth into Venus just by continuing CO2 emissions. But maybe if the Vogons help a bit ....
Well, until someone comes along and terraforms it back using a sunshade.
A billion years or so should be enough for everybody.
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
This article is so affordable. Only 22 pounds. We are so privileged to have the opportunity to read this study. Just imagine a world where such study results were just given away for free. Communism!
It really is a much better world where only paying customers have access to scientific research. It is destructive and dangerous to allow poor people access to knowledge. In that way lies anarchy! The horror. Next we'll be arguing not only that information wants to be free, but that it should be free. Cats and dogs living together and all that.
Quite an experience to live in fear, isn't it? That's what it is to be a slave.
What puzzles me is the absence of discussion of rain storms. These transfer a lot of heat to the upper atmosphere where it is radiated to space. They also pump energy into wind, increasing the circulation of air and increasing the heat loss from those convection effects.
Also, I gather the relative heating depends on the spectrum of the star to some degree. I gather there's some degree of transparency of water to the lower frequency UV so a bluer star with the same energy influx might have a bit more energy penetrate the atmosphere than a redder star.
"And the Earth will leave the habitable zone in a billion and a half or so years as the Sun gets brighter"
There, you said it, has nothing whatsoever to do with "climate change" here on earth, it's all the S-U-N!!! ;)
I wish I could read the actual studies. Most are paywalled. Can we change this? I want to learn!
Free Martian Whores!
Actually, steam should glow spectacularly in the far IR spectrum.
Clearly, you are unfamiliar with blackbody radiation, and with what the primary absorption/emission bands are for water vapor.
To be fair, they said a billion and a half years, not 50 billion years. Although the chance of us being around in a billion years is non-existant. Certainly not in our current form. We'll have either evolved by then (look how far we've come in the last 100,000 years alone) or run ourselves into extinction.
I'd say we have quite a bit longer than 'a few thousand years', though. We've been around as mature homo sapiens for more than a few thousand years already. Oh sure, we may manage to wipe out "most" of us through war or pestilence, but some folks will manage to hang on.
However, if we manage to overcome, then in a billion years there's no expectation we'd still be stuck here on Earth. Also, by then Mars would be right smack-dab in the middle of the habitable zone.
"The true measure of a person is how they act when they know they won't get caught." - DSRilk
I can try to explain why. So far only known life form is our carbon based, situated exclusively on planet Earth - it includes every living organism on Earth, from amoeba to whale. We do not know it for sure, but it is possible (but unlikely) that it is the only life form existing in the universe. More likely is that life is like a sparkle in time in space - that there were (insert arbitrary large number) of life forms before us, and will be even more after us, but on cosmic time scale life expectancy of average life form is very small, so most of time/space is kinda lifeless and boring, and, most important of all, lacks an observer.
It's easy to think about observer as about god - it's something that everybody have or it lives inside everybody who's alive, it does not include any part of personality, it does not have any properties at all - so everybody have the same observer, or, you can say, it's one for everybody. If you think about it this way - it does not die after your death, so it makes you almost immortal - if you define 'me' such it does not include your personality, which I believe is right - as personality is just a sum of your genes and previous life experience.
So, what can be our purpose in life, and what can be the purpose of a humane race? Based on above I believe it should be protecting and expanding areal of carbon based life form. This runaway greenhouse scenario will end up with earth without liquid water on a surface - it can possible kill all life as we know it, so we should try to prevent it, even if it will happen after our personal deaths. Anyway, on a long enough time line, chances of survival of life on planet Earth drops to zero - so I believe we should do what we can to extend life, not necessary humans - maybe just a seeds from which evolution can begin - to as many planets as we can.
While this may be true, I'll take warding off the next ice age in 10,000 years if global warming is the cost. Between the two, higher sea levels is a no-brainer.
I think it's a , it's a , gh-gh-gh-greenhouse gas global warming monster!
Quick you assclowns! Get into the mystery hybrid mobile! *Vrrrrooooomm*
I think it's still chasing us! How could that be? We left the Hubbert peak way behind with our super efficiency!
Uh-oh, if my calculations are correct, the only people our efficiency was helping was the *gulp* big oil companies themselves.
*poof* The monster appeared in the mystery hybrid mobile! The monster tore its own mask off!
"Will you kids shut the **** up? I'm not global warming I'm your planet's inevitable heat death. In, like, a billion years."
GET HIM! *pow* *kbam* *kick* my glasses!
"Stratigraphically the origin of agriculture and thermonuclear destruction will appear essentially simultaneous" -- Lee
Plus... it's nice to eradicate the human race anyway - there are just too many such vermins on this planet anyway
You go first. The rest of us could do with fewer of you self-loathing, emo douchebags.
Me? I don't give 2 shits about "the planet" aside from its use as a suitable habitat for human life. I also don't' give a crap about other life, except for its function in maintaining a suitable ecosystem for humans to thrive in.
In short, if you eradicate humans, would the planet be better off? The correct answer to this question is "Who gives a fuck?"
Oh, ok, I thought it said a Million and half years. I was worried.