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Comment by seszett | Hacker News Reader

If my calculation is correct, the total annual electricity production in the world (I used 20 279 PWh) would heat up the oceans (1 347 000 000 km³ of water) by 0,0129°C.

It's rather easy to calculate because one calorie is the energy required to heat up one gramme of water by one degree Celsius, the rest is just unit conversions, but I could have messed up anywhere of course.

Even if I'm off by a few orders of magnitude I'm confident that datacenters won't be noticeably heating up the sea for a long time.

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> Even if I'm off by a few orders of magnitude

I'm not saying there is a problem with your calculations, but if you were just one order of magnitude off, then after 10 years that would be 1°C, which is a colossal amount. The main problem with global warming, as I understand it, is that 1 or 2 degrees change to the atmosphere would melt a huge amount of polar ice. I imagine that if the sea were increase in temperature by that amount, given that water has better thermal conductivity than air and that's kinda where the polar ice mostly is, the effects would be at least as bad (?)

Edit: given that some of the heat would dissipate into the atmosphere and sea bed, maybe it would need to be more than one order of magnitude higher to have this effect.

> I'm not saying there is a problem with your calculations, but if you were just one order of magnitude off, then after 10 years that would be 1°C, which is a colossal amount.

That is assuming that all the electricity produced on Earth is used to heat the oceans, which is not realistic. Oceanic datacenters are not likely to ever amount to more than a few percent (and even that is unlikely) of the total human electric consumption.

For reference, apparently datacenters used 416 TWh in 2015, which is 0,002% of the total electricity usage.

That's why I'm confident that there is a lot of margin in my calculation.

> all the electricity produced on Earth

Oops, I misread your comment, sorry. I thought you were talking about all electricity used in data centres worldwide.

> then after 10 years that would be 1°C,

or 1000 years if off in the other direction

You can't assume that the ocean is perfectly mixed. For example, desalination plants dump highly saline water into the ocean that can have adverse effects on local ecosystems, even though their effect on the entire ocean may be negligible.

According to https://en.wikipedia.org/wiki/List_of_countries_by_electrici... , total electricity production is about 24816400 GWh/year (~25 PWh/year, so you were 3 orders of magnitude off).

  $ units -t '24816400 GWh / (1347000000 km^3) / (1 kg/dm^3) / (4200 J/kg/K)'
  1.5908368e-05 K

Looking again, I think I got caught off by the "." being used as a decimal separator in some places.

So that is to say, all the worlds energy production directed toward heating the oceans, could increase global oceanic temperature by 0.00001 degree C in a year.

Units is a wonderful program; don't be afraid to use their definitions (/usr/share/units/definitions.units):

  $ units -t '24816400 GWh / (1347000000 km^3) / waterdensity / water_specificheat'
  1.5851925e-05 K

There's even definitions like `oceanarea`, etc ;-)

And if there's 7.62 gigapersons on earth, that's about 3.2MWh/year per person or 271 kWh/month per person.

Since that's the same order of magnitude as, say, a US household, that does seem credible.

One thing to note is that heat diffuses much slower through the ocean than the atmosphere - even if the impact on the average temperature of the ocean is negligible, local thermal pollution could still cause major issues. I don't know how much effect a pod of this size will have; hopefully Microsoft will fund and publish a comprehensive review.

I understand that this is just a back-of-the-napkin calculation, but I feel like the heating will have a more noticeable impact on the local environment (think 5km³), rather than considering all of our planet's oceans all at once.

> I understand that this is just a back-of-the-napkin calculation, but I feel like the heating will have a more noticeable impact on the local environment (think 5km³), rather than considering all of our planet's oceans all at once.

You're not putting all of the planet's datacenters within 5km^3 either. The calculation is fine.

You are indeed off by 1000 (assuming your inputs are correct)

I'm not surprised! Which way though?

Lower. You probably mixed kilograms and grams.

Now you can calculate by how much the water level would rise and how many square feet land would be flooded...

however will these values change depending upon the depth and hence more pressure?

>(I used 20 279 PWh) would heat up the oceans (1 347 000 000 km³ of water)

Your calculation is stupid because you dont need to heat up whole ocean, heating up small areas it will be butterfly effect, enough to badly affect bigger areas. Look at this:

>As the concentration of carbon dioxide in the atmosphere rises due to emissions of fossil fuels, more of the gas is dissolving in the ocean. That is lowering the pH of the water, or making it more acidic, which can make it harder for reef-building organisms to construct their hard skeletons.

Minor change in CO2 changed pH of water, which kills organism in wider area.

https://news.nationalgeographic.com/2016/03/160321-coral-ble...

There are also closed seas like Baltic that need over 100 years to fully mix sea water with ocean water, it's much less salty than other seas and warmer, also much more polluted from toxins that were sinked there during and after WW2.

>Your calculation is stupid because

No need to be rude. "There is an issue with your calculation because" would have worked :/

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