Is there any way to rapidly repopulate the ozone layer? Assume unlimited funding.
Gamma-ray bursts are a threat to life
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Re: Gamma-ray bursts are a threat to life
#62Greg Egan's fantastic Disaspora begins with a GRB hitting earth. It isn't pretty. Hence the title. Best scifi I've ever read.
Actually the title is "Diaspora"... Nothing to do with disasters.
Admittedly I did make a typo there but the diaspora is motivated/necessitated by the disaster.
Re: Gamma-ray bursts are a threat to life
#63It's really hard to recommend one of my favourite novel this article reminds me of without spoiling the whole story :(.
Re: Gamma-ray bursts are a threat to life
#64Re: Gamma-ray bursts are a threat to life
#65Is this really an explanation for the Fermi paradox? Would a factor of 0.1 or even 0.01 really change the import of the Fermi paradox?
Probably not. Implicitly, the Fermi paradox looks at life in our own galaxy, which has apparently been quite lucky overall cosmologically. Many galaxies out there are hostile to life (GRBs are just one factor, I would argue that being a metal-poor galaxy with no active star formation is an even worse problem for life), but that doesn't have any bearing on life in our own galaxy - of which we have a sample size of one.
That said, even the friendly corners of the universe aren't a pony farm. It's more than likely for any given planet to find itself staring down the barrel of a stellar particle accelerator at some point during its time. Earth probably did, too, and we're still here. Whether it's a complete sterilization event depends on the amount of energy deposited. Depleting the ozone layer isn't enough. A planet would have to be pretty close to the event in order to get annihilated completely, so glancing blows with some limited impact on the ecosystem are probably more common in our cosmic neighborhood.
Re: Gamma-ray bursts are a threat to life
#66Is this really an explanation for the Fermi paradox? Would a factor of 0.1 or even 0.01 really change the import of the Fermi paradox?
Probably not. Implicitly, the Fermi paradox looks at life in our own galaxy, which has apparently been quite lucky overall cosmologically. Many galaxies out there are hostile to life (GRBs are just one factor, I would argue that being a metal-poor galaxy with no active star formation is an even worse problem for life), but that doesn't have any bearing on life in our own galaxy - of which we have a sample size of one…
"Depleting the ozone layer isn't enough."
Unfortunately mixing is good enough that the increased UV will sterilize everything that does photosynthesis for quite awhile, including in the oceans. So yeah its enough.
One interesting part little discussed is that in typical physics fashion, there's many orders of magnitude from weakest (barely detectable, about once a day) to kills everything on the surface not just ozone disruption (Could happen?) and as a rough guess maybe a tenth the strength happens ten times as often.
So the disaster oriented contingent wonders about wiping out all non-ocean vent life on a planet, but its more likely that as a species we'll have way more "fun" with glancing blows or near misses leading to reduced crop yields.
Sometimes I wonder about unexplained civilization collapses and GRBs. All you need to is screw up crop yields to 99% of minimum and the mayans or whatever are all done. Don't need to kill everything green or kill everything living from radiation burns, just a glancing blow bad enough to tip an already tottering civilization over... Maybe there's enough spare capacity in europe / asia that nobody noticed or recorded a 1% hit but it was enough to do the Mayans in.
Re: Gamma-ray bursts are a threat to life
#67Is there any way to rapidly repopulate the ozone layer? Assume unlimited funding.
So, assuming we don't also all die of burns or cancer or natural disasters caused by the sudden influx of energy into the atmosphere immediately...
According to http://www.epa.gov/ozonedesignations/faq.htm , ground ozone tends to be produced by pollutants, i.e. we are ourselves producing this ozone, mostly by burning fossil fuels.
From http://www.ozonelayer.noaa.gov/science/basics.htm , we find that 90% of that is in the upper layer, so 10% is lower layers.
So we have actually already produced at least 10% of the ozone we'd need to repopulate the upper atmosphere, we're just producing it in the wrong place...
From reading these links, it sounds like ground-level ozone is often a seasonal effect, so it could well be that a lot of this ozone is being produced on a regular basis and then dissipates in some fashion.
So... my back of the envelope calculation would be that yes, if we had unlimited funding and a bit of time, we should be able to produce enough ozone just by burning organic matter. The key question would be, can we get that ozone in the right place?
With unlimited funding, and with a deliberate effort to burn fossil fuels at high altitudes, my gut feeling would be yes... I think the key question would be would we be able to do this in time, before we all burn to a crisp along with most of the plant and animal life on Earth...
Re: Gamma-ray bursts are a threat to life
#68How far along the Kardashev scale do we need to before we can build a shield?
Re: Gamma-ray bursts are a threat to life
#69Earlier quoted context omitted.
Probably not. Implicitly, the Fermi paradox looks at life in our own galaxy, which has apparently been quite lucky overall cosmologically. Many galaxies out there are hostile to life (GRBs are just one factor, I would argue that being a metal-poor galaxy with no active star formation is an even worse problem for life), but that doesn't have any bearing on life in our own galaxy - of which we have a sample size of one…
"Depleting the ozone layer isn't enough." Unfortunately mixing is good enough that the increased UV will sterilize everything that does photosynthesis for quite awhile, including in the oceans. So yeah its enough. One interesting part little discussed is that in typical physics fashion, there's many orders of magnitude from weakest (barely detectable, about once a day) to kills everything on the surface not just ozon…
> So yeah its enough.
I realize that was a very imprecise statement on my part. Not enough to sterilize a planet is what I meant. It certainly is enough to cause a dent, even a huge dent, in the ecosystem.
> Sometimes I wonder about unexplained civilization collapses and GRBs
You wouldn't be the first, I think it's certainly probable these events did play a role in both prehistoric population changes as well as civilization collapses.
Re: Gamma-ray bursts are a threat to life
#70Does anybody know if a gamma-ray burst is preceded by an increased neutrino flux? I've heard that neutrinos will actually arrive at earth several hours before the light from a supernova. When the core of a star collapses, the light is physically prevented from coming outwards until the collapse is complete. Since the neutrinos move right through the gas, they are emitted as soon as the explosion occurs. Would detecting neutrinos be sufficient to give up ~4 hours of warning before a gamma-ray burst?