"I find it prudent to accept that ANY conclusion could in fact be false. "

Personally, I find it prudent to not smoke, listen to my doctor, and not test the conclusion that licking a frozen flag pole is a bad idea. Accepting that any conclusion could be false - a fundamental aspect of the scientific method - is radically different than asserting that any that you don't like could be false and can therefore be ignored.

An increase in global temperatures if atmospheric CO2 concentrations increased was predicted over a century ago. The big question in climate change is why we haven't seen much warming - what are the buffer mechanisms.

"Correlation does not equal causation. Ever."

What? Every case of causation I've ever heard of also showed correlation. Correlation does not PROVE causation, but it is a big flashing sign with a buxom topless girl waving pom poms jumping around it pointing in the right direction.

Note that at this point, the link between smoking and lung cancer still doesn't have a definitively proven causation.

"That is not what I understand to be science."

What I see is the scientific establishment diligently working to identify flaws in the existing theory of climate change and freely publishing any flaws found. The FACT is that the scientific community is vigorously collecting data to challenge and correct where necessary climate change theory, and has been for over two decades now. Note this is the same scientific community that has endorsed the current climate change theories and it's predictions - which include pretty fat error bars you know.

I understand that to be science and is why I respect the consensus of National Academies of Science (or equivalent bodies) across the first world in this matter (and not Mr Gore or Exxon or the headline of the week).

I have a 20,000 sf building in Missouri where the ground temperature swings 20F over the heating to cooling season. The ground is a thermal storage medium. You can do the numbers on it's thermal capacitance and thermal resistivity and get pretty close estimate of how quickly it will heat and if it is an appropriate approach. Note that I am assuming vertical bore systems. Horitzontal bore systems are much more closely coupled to above ground weather and serve more to average out the diurnal swings on a scale of weeks rather than average out the seasonal swings like a vertical bore setup. Ground coupled systems do not work for cooling only applications, unless they are actually serving as a heat exchanger to an underground moving body of water. (Or you have something really funky going on like season snow pack storage above the well field.)

The water treatment takes care of pathogens - no one that I know of just runs drinking fountains directly into the tower sump (the most common grey water sources I know of are rainwater from a cistern and RO reject water, which is not available for datacenters but a great option for cleanroom fabs). The largest concern I'd have is actually synthetic pharmaceuticals getting dumped down the sink, but that can be a concern with some tap water sources too. As a sidenote, there isn't much done on opinion in this area. You'd be surprised at the research that has gone into this - kill one or two people and suddenly everyone wants you to measure stuff. Sheesh.

Yes, if you grab surface water (as it commonly done by electrical generation plants, as you note) it is a fine idea, but it is not as much of a home run as one would think. Piping is frightfully expensive and the maintainable can be a pain.

Evaporating a single gallon of water rejects about 8330 btus. If you want to schlup water in and out of the system, you have to move about 50 gallons through to get the same cooling as that single gallon. You can do it, but only in rare situations. I've only pulled it off once, and that was for a water municipality who literally owned the water stream at the point we hooked in a side car loop setup to reject heat. Might pull it off once more if we can convince the water company it's OK as long as we tap their feed line prior to the treatment plant. But usually there is no appropriately sized water stream near the datacenter site and, even if there is, water companies freak out about you injecting anything back into their mains (backflow preventors are mandatory on all connections to their mains).

It's a lot of sucking to get 12,000 gpm of really deep cold water up and put right back in. If you can do that, you're in the rare situation of sitting on top a subterranean river. Which can work great, but why not just build next to a surface river or lake?

Actually, yes. You don't have to boil the water to evaporate it. However, most datacenter facilities do not want to be in the desalination business and even with the free heat I don't know if it would be cost competitive with reverse osmosis plants. Note that free low grade heat is not a very rare commodity - most low-water locals can get the same grade of heat with very cheap solar collection.

I would be no more concerned about grey water than I am about city water used in a tower. The typical infection path for legionella is city water, usually to immune-system-compromised patients in hospitals taking showers. Cooling towers (properly operated) actively treat the water specifically to deal with Legionella.

Nope. If you're pushing 15 MW out of a couple towers 24/7 they will not freeze up. You do run the cooling tower fans backwards for a few minutes every once in a while to thaw any ice that forms from splashing on the intake louvers, but the tower itself doesn't freeze up. Last time I put a tower into a 0F design climate, I used a dry sump so if the tower wasn't on the basin was dry.

An annoying fact of physics is that when it gets really cold, evaporative cooling becomes less effective. The air just can't hold much water, and it's the phase change from liquid to vapor that gets rid of your heat. So, it's not freezing that make low temperatures worrisome but actually loss of capacity.

Datacenters, like 99% of facilities with large cooling loads, evaporate water to reject the heat. The water comes in and is essentially boiled off through devices called cooling towers. You reject 1000 btus per pound of water evaporated - there is no more efficient way to reject heat. Not coincidently (if you believe in evolution), your body rejects heat the exact same way.

It doesn't really work for a couple reasons. First, heat doesn't get destroyed in the ground or wicked away (unless you have an underground river, which changes the whole story), it is stored. This is awesome for a building that pumps heat into the ground in the summer and then needs to pull it back out in the winter, but sucks for a datacenter that is pumping out MW of heat 8760 hours a year. Second, massive quantities of heat. A rule of thumb would be 200 feet of well per 3.5 kW of cooling. A modest datacenter is around 15 MW of waste heat, so you need 860,000 linear feet of well (with double that much piping making a U down each well). And after a year you're screwed anyhow because of issue #1.

I'm guessing you must not be from the US because evaporation based cooling systems are THE standard for state of the art industrial and commercial cooling in the US. If you have over 250 tons of load, you have an open cooling tower - dead standard ASHRAE design. The evaporation of water via a cooling tower is THE way you reject heat. If you want to do it dry (as is common in Europe due to much higher fear of Legionella and local code officials freaking out about it), it is FAR less efficient in almost every case, even in monsoon climates like Banglore a wet cooling tower is more efficient.