[watsisname]

Solar power alone is indeed not a feasible solution in and of itself, especially after considering next decade or so of energy market outlooks versus what is required to have designated climate targets remain viable.  My post in reply to Wobble is pointing out that, given options of building solar power farms, you're better off not trying to build them in polar regions.

The path to sustainable, climate-wise energy is multi-faceted, with improved methods of energy consumption being as important as alternative methods of energy production.  And the more time that passes with 'business as usual', the more dramatic and challenging the solutions will need to be if established climate targets are to remain viable, eventually reaching a point where we would require negative emissions -- i.e. some combination of reduced emissions and carbon capture techniques.

Added:
Personally I would be happy to see nuclear power take a more leading role.  It has a smaller carbon footprint and higher safety by the watt-hour produced.  But it is also only a temporary solution (though much less so than fossil fuel) and has its own unique share of problems, such as waste management. 
Again, there's no single best solution to climate and energy issues.  It is a problem just about as complicated as the climate itself.

[Grizzly]

Heck, even phasing out coal  in favor of gas would help a great deal (althoug, obviously, you then only delay the problem instead of solving it).

[WheelSpin]

I think the situation with nuclear is similar to the irrational fear of flying - - statistically, aircraft travel is much dagger. Of the accidents, however, they are catastrophic and much more likely to be fatal if you are involved in one. The overall safety of both nuclear power  and aircraft travel is higher, but people freak out because, when things do manage to go wrong, they go very wrong. So, regardless of the actual safety, let's go with the less safe option because it's scary (media rather does not help this at all).

The thing is, though, with modern reactor designs, "very wrong" can't really happen outside of the most extreme circumstances.  Even Fukushima, the absolute worst case in recent times, running a relatively-outdated reactor, managed to survive a massive earthquake with the safety systems functioning properly...it was only the almost-unprecedented tsunami, coupled with the asinine placement of the diesel backup generators, that did it in.  The sheer amount of FUD surrounding nuclear power is just absurd.

Reactors based on thorium rather than uranium would be safer & cost less to build. Thorium reaction is "self-regulating" & doesn't have to rely on a control medium to prevent a critical mass event.  Rather, it requires controlled removal of its fission byproducts to maintain a steady state reaction/output.

[Dragon]

But it is also only a temporary solution (though much less so than fossil fuel) and has its own unique share of problems, such as waste management. 

I think that by the time nuclear becomes a real problem, we'd long have fusion plants, which literally have none of the problems of other plants save one: they're bloody expensive to develop, build and maintain. Safe (it's hard enough to keep fusion running, any deviation shuts the whole thing down) no emissions save helium (a very good thing, since we're running out of that), relatively cheap and common fuel (if you have water, you have deuterium. Lithium is cheap as well) and incredible output to boot. The only problem is, it's highly experimental and even after we actually build a fusion plant providing power to the grid, they're gonna have quite a price tag attached. There are some issues with neutron activation of reactor components, but the results aren't gonna be radioactive for long (or at least, not as long as nuclear waste).

[X3N0-Life-Form]

I think that by the time nuclear becomes a real problem, we'd long have fusion plants,

Not so sure about that. By the time fusion reactors get cheap and common enough, there's gotta be a rather enormous amount of radioactive wastes to dispose of and old powerplants to dismantle. As far as I know, neither of these problems are efficiently solved right now, and aren't likely to be for quite a while.

[WheelSpin]

I think that by the time nuclear becomes a real problem, we'd long have fusion plants,

Not so sure about that. By the time fusion reactors get cheap and common enough, there's gotta be a rather enormous amount of radioactive wastes to dispose of and old powerplants to dismantle. As far as I know, neither of these problems are efficiently solved right now, and aren't likely to be for quite a while.

There was supposedly a waste processing plant being built at the Hanford, WA facility that would employ vitrification process to bind the waste material to glass-forming compounds to effectively convert it to a solid medium.  Still radioactive & requires millennia to decay, but far better for it to be in a solid, rather than liquid state.

[Dragon]

1) Find an aerosol which can scrub CO2 from the athmosphere

This is the basic problem with your solution. Why do you think CO2 is so common? That's because it, very, very chemically stable. The bonds are among the strongest out there. Breaking up CO2 exothermically (because for an endothermic reaction, you need to deliver energy, which is hard to do in your scenario) requires finding a chemical that forms a stronger bond with either carbon or oxygen. And I'll tell you, there aren't many of those. Such a chemical would be incredibly reactive, which translates to also being incredibly nasty in both handling and storage. And it would definitely be far from something you'd want to spread in the upper atmosphere. We're talking stuff like elemental fluorine or other such hellish oxidizer (likely fluorine-based, too, since it's about the only thing stronger than oxygen). Unless you literally want to set the atmosphere on fire, I'd stay away from this idea. And no, if you think we could substitute carbon, we can't. Carbon is the lightest element in it's group, and also very reactive. I don't think there's any way of removing it from CO2 save thermally breaking down the compound (I don't know how hot you need to get to get CO2 to decompose, but something tells me it's around the point the whole thing turns into plasma anyway).

 Chemical CO2 scrubbers exist, but they're either just trapping CO2, emergency devices using some incredibly nasty chemicals, or consuming a lot of energy in order to "force" a normally impossible reaction to take place (Sabatier reaction and photosynthesis are good examples of the latter).

[666maslo666]

Added:
Personally I would be happy to see nuclear power take a more leading role.  It has a smaller carbon footprint and higher safety by the watt-hour produced.  But it is also only a temporary solution (though much less so than fossil fuel) and has its own unique share of problems, such as waste management.

Using breeder reactors it is not temporary. Then it makes sense to extract uranium from seawater and thorium from very low grade ores. According to some sources there is enough such fissionables to last beyond the lifetime of the Sun, which would make nuclear more sustainable than renewables. Breeders also go a long way towards solving the waste issue because they produce much less of it (and their waste is radioactive for much shorter time) per energy produced and also burn existing waste stockpiles.

[Hellzed]

As a french citizen, I used to think nuclear power was a clean energy source (75% of our electric energy consumption), because it emits no carbon dioxide. At least that's what the media say. And carbon emission records are actually pretty low compared to other same size economies.
Then, Fukushima catastrophe happened (in which AREVA was involved), and things started to change.

You may want to read what working conditions actually are in this industry, and I guess it's the same in the US or Japan :
http://pastebin.com/gBC3X5VQ (translated with Bing, this is taken from the biggest mainstream newspaper, not exactly known for being anti-nuclear energy)

How is uranium mined, and what it means to local people in Africa :
http://www.facing-finance.org/database/cases/areva-controversial-uranium-mining-operations/ (this is from a NGO, but their sources are non partisan)

Also, it is a huge bet on our future political stability : in the event of a war or massive public unrest, power plants are critical sites.
Maybe (yeah, maybe...) this is suited for some western countries, but I don't see it as a global solution.
Same applies for environmental hazard safety.

My point is that conventional (uranium fission) nuclear energy can never be a solution, because no society (no matter how advanced), no company (public or private owned), can handle it the way it should.
Catastrophes are only a few (Three Miles Island, Chernobyl, Fukushima), but smaller incidents also matter (individual radiation poisoning, minor radioactive exhaust...).

+
Thorium powered molten salt reactors are a great idea, but it wouldn't fix small scale incidents rates. With a lot more smaller reactors, it could actually make things worse.
And no country would want to use it because you can't use them to build bombs.

[666maslo666]

As a french citizen, I used to think nuclear power was a clean energy source (75% of our electric energy consumption), because it emits no carbon dioxide. At least that's what the media say. And carbon emission records are actually pretty low compared to other same size economies.
Then, Fukushima catastrophe happened (in which AREVA was involved), and things started to change.

You may want to read what working conditions actually are in this industry, and I guess it's the same in the US or Japan :
http://pastebin.com/gBC3X5VQ (translated with Bing, this is taken from the biggest mainstream newspaper, not exactly known for being anti-nuclear energy)

How is uranium mined, and what it means to local people in Africa :
http://www.facing-finance.org/database/cases/areva-controversial-uranium-mining-operations/ (this is from a NGO, but their sources are non partisan)

Also, it is a huge bet on our future political stability : in the event of a war or massive public unrest, power plants are critical sites.
Maybe (yeah, maybe...) this is suited for some western countries, but I don't see it as a global solution.
Same applies for environmental hazard safety.

My point is that conventional (uranium fission) nuclear energy can never be a solution, because no society (no matter how advanced), no company (public or private owned), can handle it the way it should.
Catastrophes are only a few (Three Miles Island, Chernobyl, Fukushima), but smaller incidents also matter (individual radiation poisoning, minor radioactive exhaust...).

+
Thorium powered molten salt reactors are a great idea, but it wouldn't fix small scale incidents rates. With a lot more smaller reactors, it could actually make things worse.
And no country would want to use it because you can't use them to build bombs.

I dont think small irradiation incidents matter. They will always happen but they are statistically quite insignificant. I dare to say that a lot more people would die falling off of solar panels and wind turbines than those small incidents combined.

Three Mile Island was no nuclear catastrophe, it was only a minor radiation release.

Fukushima is also hardly a catastrophe, credible estimates on the number of victims are somewhere between zero and few hundred. It was not even an economic catastrophe because while it will cost many $ tens of billions to clean up, Fukushima created something like $ half a trillion worth of electricity during its lifetime. It is a testament to the efficiency of nuclear that even a plant in uncontrolled meltdown borderline makes economical sense, lol.

Uranium mining can be dirty business, but dont forget that uranium is very energy dense so we dont need that much while it takes a lot of mining to fuel the coal and renewable industry, too. I doubt those mining operations are any more environmentally conscious in third world nations..

[Dragon]

Uranium mining can be dirty business, but dont forget that uranium is very energy dense so we dont need that much while it takes a lot of mining to fuel the coal and renewable industry, too. I doubt those mining operations are any more environmentally conscious in third world nations..

This is actually one of the most valid arguments against nuclear power I've seen brought up. It's not talked about it much, but Uranium mining is indeed a dirty business. But then, so's coal and oil mining, especially in 3rd world. You see all those pretty buildings in Abu Dhabi and Dubai? Well, more people died to get the Sheiks money for this than were ever killed by nuclear accidents. Nobody even counts the incidents in 3rd world coal mines. And even in the "first world", it's sometimes very bad. Coal mining in Poland is an example. Methane readings are often fudged, miners are overworked and safety inspectors are bribed. The result is, once in a while, a methane explosion that makes the news and is a national tragedy. It blows over and then it's back to normal, at least until another explosion...

This is another argument towards developing fusion, IMO. Getting hydrogen does not require working poorly paid miners to death, and lithium is needed is such quantities that it's consumption shouldn't rise by much.

[Mongoose]

I remember somewhere seeing a case study on the mortality rates associated with the various types of energy production, and nuclear was by far at the bottom of the list.  I mean, even solar power is more dangerous, believe it or not.

[jr2]

http://nextbigfuture.com/2011/03/deaths-per-twh-by-energy-source.html

It is indeed.