Re: Detecting ETI via CO2


"Mike Williams" <nospam@xxxxxxxxxxxxxxxxxx> wrote in message
news:Vtg2UBAhU63CFwrn@xxxxxxxxxxxxxxxxxxxxx
> Wasn't it Bjorn Damm who wrote:
[....]
> >
> >A collision with another object could probaby cause a rapid change in the
> >atmosphere of the planet.

Makes sense.
But that would probably happen within the time span of 1 year or so.
Much faster than fossil-fuel burning...

>
> Plate tectonic movements can cause natural climate changes that cause
> vast forests to become deserts. All the carbon locked up in those trees
> has to go somewhere. That would be somewhat slower that the man-made
> rise in CO2, but might be in a feasible range for a civilization that
> wasn't quite so reckless with its planetary resources.

What kind of plate-tectonics can cause forests to turn to deserts ?
Are we not talking about millions of years here at a minimum ?
If plates are moving much faster, then would that not cause
massive vulcanic activity ?

>
> Supervolcanoes can cause drastic changes in the atmosphere, but that
> would be too fast. However, there might be volcanic events on other
> planets that are slower than supervolcanoes (like Yosemite)

I think you mean Yellowstone here...:o)

> but faster
> than bigger events like the Dekkan Traps.
>
>
> Note also, that an artificial rise in CO2 probably only ever happens
> once in the lifetime of a planet. If the inhabitants survive the effect
> without using up all the planet's fossil fuel reserves, they probably
> learn how to avoid repeating the effect. So you're looking for an effect
> that lasts a century or two in a planetary lifetime of many billions of
> years.

This might not be the case.

We are currently pumping oil which is 40 - 80 million years old or so.
There does not seem to be oil that is much older than that
or we just did not find it yet.

So if our civilization comes to an end, Earth can take 60 million years
to build-up carbon in the soil again. With homo-sapiens gone
and globally warm / wet climate with high CO2 levels, forests
will re-grow and new species can evolve.

And if there is an intelligent species evolving 60 million years
from now, there is no guarantee they won't make the same mistakes
we are making now. They probably have no idea that we ever
existed. 60 million years does a lot of erasing...

Wildly speculative : Maybe Nature can easily evolve an intelligent
species every 100 million years or so, once life reached a certain
complexity.... But for Nature to evolve an intelligent species that is
smart enough to sustain technology for more than 1000 years
might be very hard to do.... It WOULD explain the limited lifetime
of technology civilizations, and thus explain the Fermi paradox.

More wildly speculative :
Is it possible that an intelligent species evolved 250 million years
ago, (just before the dinasaurs), reached technology, burned
fossil fuel for 300 years, ran out of fuel, caused massive global warming,
degraded to sub-technological levels, climate change and peak CO2
levels caused massive forests and scale-growth for species,
which triggered the dinasaus era.. They ruled the planet sub-technology
level for 200 million years....

>
> --
> Mike Williams
> Gentleman of Leisure


.

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