Wind and solar power are even more expensive than is commonly thought

> Do you have a source for this?

"The roles of carbon dioxide and water vapour in warming and cooling the earth's troposphere", Jack Barrett. Maybe there's not the number (99.94%), but it says about absorption saturation on the first 100 meters above the ground.

The 99.94% number is here: http://nov79.com/gbwm/hnzh.html

>> Water is even more potent

> Yes and that would be a huge problem if it built up instead of falling out of the sky.

It would be not. Maybe you don't know it, but water is already present in the atmosphere at the level of ground. Moreover, while some of water "falls out of the sky", some other part of it vaporizes at the same time. It doesn't disappear from the air.

> This is actually what I was thinking of when I said "we don't know for certain is if there is another currently unknown cause with a larger contribution to global warming" though I believe this particular theory has been debunked.

At this point it doesn't matter whether this particular theory has been debunked or not. You say that "we don't know for certain is if there is another currently unknown cause with a larger contribution to global warming". So we don't know if the global warming is actually caused by greenhouse effect. There's no magic in greenhouse effect that would cause it important when proven unimportant. Having this, it's way, way too early to panic about the greenhouse effect.

> The fact that green house gasses increase temperature does [give causation].

It would, if it was fact. It's merely a hypothesis that these gasses increase the temperature of Earth. And again, it doesn't stand direct measurement with calculations (i.e. absorption saturation).

> The only missing piece here is how much of the increased temperature is caused by our greenhouse gas emissions

...if affected by these emissions in any way over measurement error...

> and how much is caused by other unidentified forces.

So basically, we don't know if there are any other forces, but it must me human emission that causes global warming. So we focus on CO_2 and methane, which is nowhere near what water can absorb.

>> We have no way to verify the claim the greenhouse effect takes the place

> Actually we can. We can measure the radiation before it hits earth, when it hits the ground and when it leaves the atmosphere as well as measure what radiation is absorbed and emitted by various gasses.

You know that this doesn't tell whether the greenhouse effect takes place? It only shows how much radiation is absorbed before entering the atmosphere and after leaving it. We have no way of checking if increasing CO_2 or methane concentration affects the radiation absorption. Sorry, but there are too many variables to make this a realiable experiment, and having effectively only one data point is too little to draw any conclusions.

> Adding more water has only a short term effect unless it somehow changes that equilibrium.

It doesn't matter. The water already present in the atmosphere absorbs almost all IR radiation. Add anything and you won't get bigger greenhouse effect, assuming it actually works.

> Water has a large greenhouse effect and without that effect Earth would be much colder.

Or not. We don't know it. You said yourself that we don't know if there is any bigger effect taking place. And the greenhouse effect is mainly accepted among climatologists. Physicists who work on thermodynamics don't quite agree the very reasoning about energy balance done by climatologists is credible at all.

> If that effect were to increase Earth would get hotter, but fortunately the excess water simply falls out of the sky instead.

Really? What "excess" do you mean? You know that it's not only the "excess" which causes IR absorption? And if there's little radiation left to be absorbed, adding more greenhouse gases doesn't make the temperature grow.

>> It would, if it was fact

> It is an observation. We can literally observe it happening.

No. It's just a hypothesis that greenhouse effect takes place. We do not have enough data to confirm the effect.

> That does not tell us precisely how it would function under different conditions (such as increased CO2), so for that we must rely on theory.

And there goes f*ck your claim that it was a fact.

> This does not seem to be correct. The earth's is gaining a significant amount of energy from the sun. [...]

Right. It should be: "the water already present in the atmosphere absorbs almost all IR radiation on wavelengths for CO_2, methane and water itself".

Adding more methane or CO_2 will not cause more radiation be absorbed, because there is nothing left to be absorbed.

Solar is the most abundant, but on a density/device basis is somewhat less cost-effective than wind, which is preferable locations (not all) provides a high return for investment. Overall, wind energy is less abundant than solar (it's effectively a byproduct of solar insolation).

Other renewables: geothermal, hydro, biomass, tidal, and wave power generally have issues with scalability, costs, or both. Geo, hydro, and biomass actually do already contribute significantly to energy budgets, and costs are fairly good, but their growth potential is limited. Tidal and wave power are limited and require large capital and operational expenses to be effectively utilized.

Nuclear's a wildcard, though I'm generally skeptical.

There are a number of sources which give detailed breakouts of renewable energy potential or possible scenarios.

David MacKay's Sustainable Energy Without the Hot Air, and Jacobson & Delucchi's "Providing all global energy with wind, water, and solar power" give a pretty good overview.

Turns out that with solar + wind and some form(s) of storage, you can approach a pretty good overall budget.