I expect AWS us-east-1 now adds up to over a gigawatt of critical load so if submerged in the ocean off Virginia what would be the effects, and how would those be different from terrestrial datacenters?
Given the mechanics, the overall ratio of heat in the atmosphere vs heat in the oceans is fixed by the Rtheta of the atmosphere/ocean boundary. If the atmosphere gets warmer, more heat is transferred. If the atmosphere is colder less heat is transferred.
The other question (which Jacques alluded too) is what about the local conditions. And here to the thermal mechanics give our underwater data center an advantage. Given the thermal conductivity of water, and seawater in particular, heat dumped into any spot rapidly diffuses to the rest of the ocean. That is not the case with air, which has a much lower thermal conductivity. Dumping lots of heat into unconstrained air locally can cause a localized "hot spot" which creates an interesting thermal plume and localized winds as cooler air around it comes rushing in.
To get a good understanding of just how effective the ocean is at diffusing heat, consider any of the hydrogen bomb tests in the Pacific. Prodigious amounts of heat dumped into the ocean creating a local hot spot (and a lot of steam!) and an undetectable change in overall ocean temperature. Kilauea volcano, same effect.
The ocean has a lot of thermal mass, without something like an asteroid from space, its hard to move the needle on its temperature overall.
[1] There are some pretty interesting thoughts around using harmonic resonators to convert ambient heat into IR radiation at a wavelength that can more easily pass through the atmosphere but those are just lab experiments at the moment AFAIK.
Thank you, it is precisely that which I was wondering about.
But, if you're heating the oceans, you're putting an entire other mass (the atmosphere) between yourself and space. So you're heating the water, the water is heating the atmosphere, and the atmosphere is radiating that into space. It's adding a step to the overall cooling process.
This works through emitting mostly infrared frequency light for which, just like visible light, the atmosphere is mostly transparent.
That said, the physics are "heat is heat". If you put it into the air or you put it directly into the ocean the only way it leaves the planet is by black body radiation. As a result locally heating some seawater nearby has (on a global scale) the same impact as heating the air the same amount.
Now we know there are some ecosystems in the ocean that prefer thermal vents and you might find that around the data center itself you have a wider variety of sea life than is found in the general vicinity due to different thermal conditions. Not sure if you could map out that was a positive or negative change.
Generally though, the ecological impact of doing this at scale is not going to be different in scale than land data centers.