Eat that GW believers!

TallDave · Post by **TallDave** » Sat Nov 21, 2009 6:33 pm

--posting error--

TallDave · Post by **TallDave** » Sat Nov 21, 2009 6:35 pm

alexjrgreen wrote: It's a little early to make that claim, but suppose, for the sake of argument, that atmospheric methane levels have stabilized at a new level of 1800 parts per billion by volume.

At more than double the 400-800 ppbv levels seen over the past 400,000 years, that still represents a significant source of warming to set against all the other effects regularly discussed here.

It's definitely more plausible than the CO2 claims. I'm not opposed to throwing some money at methane capture research, to develop tech that could deployed on a large scale if temperature keeps rising for a few decades.

Geoengineering might end up being cheaper and nimbler, though.

Skipjack · Post by **Skipjack** » Sat Nov 21, 2009 6:50 pm

Well, methane capturing might have the advantage that one could at least use the methane then for something to get at least part of the cost back...
That said, I am not opposed to geoengineering either, as long as it is easily reversible. E.g. I am opposed to putting sulphur into the atmosphere, because it has side effects that are not easily reversed.
I dont see any issues with deploying large sun- shades in space though. If we ever find that we need it be warmer again, they can be taken down or redirected easily enough, emmediately negating their effect.

TallDave · Post by **TallDave** » Sat Nov 21, 2009 7:33 pm

I dont see any issues with deploying large sun- shades in space though. If we ever find that we need it be warmer again, they can be taken down or redirected easily enough, emmediately negating their effect.

Exactly my thought! We probably only need to block a percent or so.

Plus, in the long run the technology might let us terraform Venus.

Skipjack · Post by **Skipjack** » Sat Nov 21, 2009 7:49 pm

Exactly my thought! We probably only need to block a percent or so.

Yepp, I also think the location of the shade is at least equally as important, if not more important than just the size. It would be an interesting challenge to figure out above what location of the earth it would be most useful at what point in time and where it would have to be repositioned to ocasionally (I assume that this might be beneficial).

Plus, in the long run the technology might let us terraform Venus.

Venus would probably pose other challenges as well. The chemical composition of its atmosphere is very unfavorable for life, even without the extreme temperatures.
I have been trying to think of ways to get rid of at least the most volatile components, but so far have not been able to come up with a concept.
I e.g. considered increasing temperatures on specific locations in such a way as to cause atmosphere to be lost into space.
On Venus, less is actually more, as far as atmosphere is concerned.
That would be a fun brainstorming experiment one day.
From a pure location POV, Venus might actually be the better planet to terraform than Mars.

TallDave · Post by **TallDave** » Sat Nov 21, 2009 8:07 pm

The chemical composition of its atmosphere is very unfavorable for life, even without the extreme temperatures.

The two are closely related, though. If Venus can be cooled, the CO2 content of the atmosphere should fall. It actually has about the same overall amount of carbon as Earth but lacks a carbon cycle.

We'd probably want to drastically accelerate the process, perhaps with some kind of hardy engineered microbes. Might get it down to thousands or even hundreds of years depending on humanity's resources.

Or we could cut off nearly all sunlight and just let the CO2 precipitate out as it gets really cold. Not sure how long it would take Venus to cool to -78 C with no heat source. We should try to calculate that at some point (I can't waste much more of a perfect Corvette day in November).

I think that would be the first step in terraforming, because until you do that the pressure at the surface is crushing.

Helius · Post by **Helius** » Sat Nov 21, 2009 8:49 pm

Isn't there the one missing ingredient on Venus? *No Water*. There is nothing to lube plate tectonics, so the planet turns itself inside out every billion years or so. Wouldn't it be just our luck to get the planet at the perfect temperature, and atmospheric pressure and then.....oops; The planet erupts across the entire surface.... Beside, It's in a gravity well that approaches that of earth, and it doesn't even have any water.

At least on Mars it might be possible to release enough C02 to warm the place up enough to melt some ice and make the place livable.

What about Ceres? I heard that may have a ocean core....

rcain · Post by **rcain** » Sun Nov 22, 2009 12:34 am

TallDave wrote:
I dont see any issues with deploying large sun- shades in space though. If we ever find that we need it be warmer again, they can be taken down or redirected easily enough, emmediately negating their effect.
Exactly my thought! We probably only need to block a percent or so.

....

.. youll be needing one hellofa thermostat for then then..

MirariNefas · Post by **MirariNefas** » Sun Nov 22, 2009 1:55 am

Helius wrote:Isn't there the one missing ingredient on Venus? *No Water*. There is nothing to lube plate tectonics, so the planet turns itself inside out every billion years or so. Wouldn't it be just our luck to get the planet at the perfect temperature, and atmospheric pressure and then.....oops; The planet erupts across the entire surface.... Beside, It's in a gravity well that approaches that of earth, and it doesn't even have any water.

Having the crust turn inside out as a result of terraforming would be great. It would mix things up, bring out more of the elements stored in the mantle, probably spread a bunch of nitrates through the regolith. We'd just have to wait for it to settle down again, but we've got nothing but time to kill.

We need that Mach Effect physics to actually pull through so they can build some spiffy wormholes. Before we move up to wormholes through interstellar space, maybe we could just link Mars to Venus for a few years, let some atmosphere spill through. Be good for both bodies. Then stick a link into one of the gas giants and bleed some hydrogen onto Venus. Before you know it the solar system would be crawling with life.

MirariNefas · Post by **MirariNefas** » Sun Nov 22, 2009 2:07 am

Skipjack wrote: I have been trying to think of ways to get rid of at least the most volatile components, but so far have not been able to come up with a concept.
I e.g. considered increasing temperatures on specific locations in such a way as to cause atmosphere to be lost into space.

You know, wormhole silliness aside, I've been wondering this too. Let me know if you come up with anything good. The sort of solar shades they'd be using to block sunlight would give them a lot of energy to play with for things like concentrating heat in locations.

I've been trying to think up how to make a tether system work that could harvest gasses, ionize them, and fling them into space. Of course, the tether can't touch the ground and the ionized gasses would be a hugely destabilizing propulsive force. Somehow, if there were an engineering way to make it possible, flinging off that gas could be a good thing for the rotational period of Venus. It could launch counter to its direction of spin, speeding up and developing a more reasonable day period.

Skipjack · Post by **Skipjack** » Sun Nov 22, 2009 2:25 am

One thing that has been suggested in the past is to crash asteroids into the surface of terraformable planets. By choosing the right composition favorable chemicals can be introduced into the atmosphere. E.g. one could crash a water containing comet (in that case probably) into Venus to introduce water. I could imagine that there are other chemical compositions of asteroids and comets that might be favorable.

MirariNefas · Post by **MirariNefas** » Sun Nov 22, 2009 2:31 am

Yeah, but then you get into the whole planetary chauvanism debate. It really would be more efficient to use those resources elsewhere, so can we justify something like what when there is limited asteroid/comet mass to draw from?

*edit: there's enough mass in he solar system, I wasn't meaning to imply that we'll run out. The gas giants really do have stupid amounts of hydrogen. It's just the availability issue. Harvesting from planets will always be more expensive than harvesting from comets/asteroids, and it arguably would take mroe effort to make a decent Venus than it would take to build an equivalent surface area in habitats, so dumping comets like that seems rather crude.

If you have terraforming methods that don't compete with other human expansion methods, the debate defuses a bit.

TallDave · Post by **TallDave** » Sun Nov 22, 2009 3:32 am

Isn't there the one missing ingredient on Venus? *No Water*.

The water evaporated off because of the heat, then the hydrogen split off in the upper atmosphere.

E.g. one could crash a water containing comet (in that case probably) into Venus to introduce water

That's one solution. There may be water vapor locked under the crust too.

The planet erupts across the entire surface....

Yeah, I'm guessing we would have to do some serious geoengineering to keep the pressure from catastrophically overloading. It might also be useful for getting water out.

I think there's a real possibility this could actually be finished in the 2200s. The resources required would be gargantuan, a very large multiple of current world GDP, but if you believe people like Kurzweil those resources may grow exponentially. By 2300 we may be building a Dyson sphere.'

It really would be more efficient to use those resources elsewhere, so can we justify something like what when there is limited asteroid/comet mass to draw from?

I imagine we'll keep some planets around and habitable for their sentimental value.

MSimon · Post by **MSimon** » Sun Nov 22, 2009 7:29 am

rcain wrote:
TallDave wrote:
I dont see any issues with deploying large sun- shades in space though. If we ever find that we need it be warmer again, they can be taken down or redirected easily enough, emmediately negating their effect.
Exactly my thought! We probably only need to block a percent or so.

....
.. youll be needing one hellofa thermostat for then then..

And who decides what it gets set at? The people of Equatorial Africa or the people of Alaska?

Helius · Post by **Helius** » Sun Nov 22, 2009 1:24 pm

And who decides what it gets set at? The people of Equatorial Africa or the people of Alaska?

It depends on who put it up there I imagine. I guess it'll probably need defending, which seems like it'd be an impossible task. All space faring nations would need to buy off.