# How much energy would be required to actively reduce the temperature of the oceans of Earth by 1℃?

Is there a way to calculate the energy required to reduce the heat of oceans?

Am I wrong in thinking it is not as simple as reversing the calculation for specific heat of sea water?

• it is literally as simple as calculating hte specific heat of seawater unless you are trying to coll it in some specific manor.
– John
Apr 19, 2019 at 15:35
• Thanks - so the calculation would just be specific heat x mass of the oceans? I.e. the energy to raise by 1 degree is equal to the energy to reduce by 1 degree? Apr 19, 2019 at 15:54
• Note the very significant difference between the energy you need to extract from the ocean to cool it by 1°C and the energy required to extract that energy. In a similar way the energy used by a fridge to cool the food inside it is MUCH more than the energy actually extracted from the food, Apr 19, 2019 at 19:38
• as your question is now it is a little theoretical so in real life you will need a plan for where you are going to dump the heat and that is the hard part of this(in the light of your tag climate-change) Apr 20, 2019 at 5:32
• @trondhansen, my thoughts exactly and this is where I'm going with this line of thought; we can store it in a manner that we can later utilize it, or somehow 'vent' it to outerspace. Two immediate ideas: 1) Using a form of evaporation and salt storage (en.m.wikipedia.org/wiki/…). 2) Using the upper atmosphere to cool bodies of water by cooling something high up and then placing it in the ocean, kind of like a man made ice cube. I currently can't see how either might work at scale or what that scale would need to be. Apr 20, 2019 at 14:32

The question is slightly confused, because reducing the temperature of the oceans, in a direct sense, doesn't require energy - it releases it. The amount that is released is simply related to the mass and specific heat capacity of seawater, as you suggest.

The missing question, though, is why the ocean is cooling. For it to happen naturally and simply release energy, it would need to be because its surroundings (e.g. the air) were cooler. If you want to actively cool the sea, then yes, that is going to consume energy. If the cooling has approximately the same level of performance as building-sized air conditioning, the power used by the cooling apparatus will be about 40% of the rate at which the energy is removed (and remember that this is not just the total energy divided by the time, because more heat will be leaking back in while you do it).

Leaving aside the, uh, engineering challenges of this scale of cooling, this leads to a question as to why one might want to do this. Remember that unless you devise some complex system to radiate this heat into space from above the atmosphere, you're going to be releasing the same heat into the same global climate system, plus the additional 40% that you've used to move it around.

• this is how my closest city uses heat from a river for heating and cooling houses and industry bbc.com/news/business-31506073 May 23, 2019 at 3:58
• Thanks @semidiurnal-simon, I was hoping my question implied 'active', but I grant you it isn't explicit - I've corrected that. May 23, 2019 at 6:46
• OK, in response to your answer, thank you. Starting with the last paragraph first, as per my last comment above - the why is environmental; the oceans are a huge influencer of climate and have a lot of heat energy stored, so as I see it, having the capability and system in place would be beneficial (that's not a topic for here though). May 23, 2019 at 6:51
• @the4thv air conditioners are heat pumps. Same technology. The coefficient of performance (the 40% I mentioned) will vary, maybe a lot, but it's going to be more than zero and less than one. May 23, 2019 at 15:27
• @the4thv this is almost certainly counterproductive for combating climate change, because you have to answer more questions: 1. Where are you going to put this heat (I imagine the only useful answer is "radiate it into space" ) 2. How are you going to do that? 3. How much energy will it take to do that (what we've been talking about here may be the tip of the iceberg) and 4. Where is that additional energy going to end up? May 23, 2019 at 15:30

Assuming a surface ocean temperature of 288 K and a deep ocean temperature of 277 K, let's assume a mean temperature around 282.5 K.

The specific heat capacity of seawater at constant pressure is 3,890 joules per kilogram per kelvin.

The mass of the ocean is 1.39 x 1021 kg.

Therefore the "thermal content," if I can call it that, of the ocean is 1.528 x 1027 J. At 281.5 K, it would be 1.522 x 1027 J. The difference is 5.407 x 1024 J using all the significant figures Excel gives me. That's a lot of energy!

• Thank you the interesting answer Dec 16, 2021 at 21:38

Heat capacity is the amount of thermal energy it requires to heat a gram of "A substance" one Kelvin degree. Salt water of oceanic variant average salinity (3.5%) has specific heating of 3.993 J/(g K) or 3.993 Joules of energy per gram of water to raise it ONE degree kelvin.

using Metric; Water has a specific heat capacity of 4.186 J/g°C, meaning that it requires 4.186 J of energy (1 calorie) to heat a gram by one degree Celsius. With an Oceanic volume of 321 Million Cubic miles (1.338 Quintillion! cubic meters) with roughly one million grams of water per cubic meter it would take the removal of nearly a Yottajoules worth of energy, 500 TIMES current human annual energy consumption.

• ≈ 1 yottajoule? Isn't it 4,183*1,338 ≈ 5,46 (* 10^18 * 10^6) -> 5,46 * 10^24 = 5 yotta joule
– d-b
Dec 10, 2022 at 21:20