There are those who disagree with that opinion – including me. And I'll just leave it at that.

Some things are nebulous. Some things are subjective... but some things are fact, not subject to opinion... details, maybe, but not as defined.

For example, it is not "up for discussion" how far it is from New York to London as long as we define the points like the exact geographical centers or the furthest or closest outskirts. It could be argued that the Earth does expand and contract some with average temperature but that miniscule difference is insignificant. You can round off or average but as long as you keep to that standard the answer is always the same. It's simply fact... done and done.

It is simply a fact that volcano produced CO2 is measurable and has been measured the world over. It is simply a fact that human created CO2 is measurable and has been measured. It is a fact that the amount of human caused CO2 production is 16 TIMES that of volcanoes on average over centuries. It is a fact that the last times CO2 levels were anywhere close to this high, average Earth tempertature rose significantly and it is doing that again, now. We only need look at the Hell of or sister planet Venus to witness and verify that CO2 plays a hugely important role in climate change.

It is up for discussion, a somewhat matter of opinion, whether we can stop or reverse it or whether it is too late to do more than slow it down but, make no mistake, it IS happening, so do what you will, but denying facts staring one in the face is unwise at best, however "open-minded" and amenable it may feel.

If you insist upon trying to apply the Second Law of Thermodynamics to the earth or her oceans, global or oceanic warming would have been impossible in the first place. According to the Second Law of Thermodynamics, total entropy would have to be increasing over time, and total thermal energy decreasing.

(This might be a hopeful thing. Perhaps - just perhaps - if global and oceanic thermal energy gains are due to Man's activity, perhaps we need do nothing but turn our own burners down, stop adding to the heat, and perhaps the Second Law of Thermodynamics entropy thing would mean that the earth and her oceans would eventually revert to their more natural thermal stasis without our having to do anything.)

Meanwhile, the First Law of Thermodynamics tells me that one form of energy can be converted to another form. That seems to be the primary gist of the OPs original question, whether this could be done with excess oceanic thermal energy. Most LQers here, most notably Hazel and business_kid, seems to be ignoring the original question and laboring over how it would be impossible or non-feasible to extract thermal energy from the oceans. But the question of converting that thermal energy to another form of energy has not been addressed. Such a process could result in a net gain of usable energy, in contrast to conventional engineering such as refrigeration or heat pumps.

I do not know how this might be done. Nor would it seem that any one else here in this thread can give a definitive answer to the OP. Theoretically, it should be possible. How? I haven't a clue. But if one or more outside-the-box creative engineers and (gasp!) venture capitalists would want to apply the First Law of Thermodynamics, and see excess thermal energy as an opportunity to make some hay, I'm not going to insist that it can't be done.

I don't think hazel was saying it can't be done, just that it requires work/energy. I'm not at all sure the 2nd Law of Thermodynamics applies in the case on Earth since it is at least a partially closed system. There's nothing in the Law that disallows local decrease in entropy regardless of whether or not thermal energy is decreasing or increasing. In fact you hinted at that while bring up conversion.

Nevertheless, it's rather moot, since currently there is no practical means of getting sufficient energy from the entirety of our oceans to manage climate change. Especially now when we are at a point that we need something that can be implemented sooner the better and there aren't even any proposals to explore extracting large scale energy from the oceans.

Our best bets seems to be current technology that's nearing completion such as commercial electric air travel (commercial flights dump just shy of a billion tons of CO2 every year into our atmosphere), electric cars, and the means to produce electrical energy whether by continued increase in output and reduction in cost of photovoltaic, improved battery design, and ultimately some form of nuclear energy, ideally in time likely fusion, but much closer in time is fission such as with molten thorium salt reactors. Some deployment of hydrogen devices is likely a possibility as well either directly or as fuel cells.

The cool thing is besides staving off continued increase in climate change, cheaper, cleaner, abundant energy is simply a necessity if Humanity wishes to progress in socio-economic and political arenas as well.

If you follow the link in the original question, you'll see that nobody is actually proposing to extract thermal energy from the oceans.

Which link? This one https://en.wikipedia.org/wiki/Ocean_...rgy_conversion broaches the subject of oceanic Delta T, and subsequent posters brought it up, too... hardly Off Topic, just a tad impractical yet.

Personally I feel the biggest problem is the heat not in the oceans, but in the atmosphere, and the ice.

Seriously, anybody who still questions human-made climate change, and that we urgently need to do something about it, should be shot into the sun immediately.

In Germany some folks went on hunger strike for climate change in front of the parliament. This seems appropriate.
We all need to do our part, but it's not enough - politics and law need to do the bigger part, and in an atypically quick and uncapitalistic manner.
I hope Fridays for Future will continue, until 100% of all young people take part. All those counter-arguments "we all want it but it isn't so easy, the economy yadda yadda" - are pointless in their eyes.
Well, it's not only young people, but a certain naïve insistence seems to be required here.

Yes, that one and https://www.seasteading.org/clean-re...UaAlfFEALw_wcB

They're both about extracting energy from the temperature gradient in the ocean. There's nothing about reducing the ocean's temperature by energy extraction.

It may or may not be practical, but it's at least quite possible according to currently known laws of physics.

If it is possible, it is almost certain that someone will figure out a way to do it. The question then becomes: will it make things better, or worse?

If a way to do it is figured out, and it's done on any meaningful scale, sadly the answer to your question is that we don't have enough time to find out. The time for this kind of thinking was decades ago.

I always feel heat is not going to vanish - maybe it's my simplistic approach. You can take it from shallow water, and put it into deeper water, but it will naturally come back up, like it does in the Ocean Conveyor. We may in fact upset that cycle more than it is upset already. And even doing that requires energy which makes more heat.

The planet sheds heat into space. (Also atmosphere and water, but that is a much longer term problem.)
The options to avoid catastrophic warming are to tie up heat in a form that does not raise the planets average temperature (difficult) or radiate heat faster by cleaning up the atmosphere (reducing greenhouse gasses), improving reflectivity (regrowing the polar ice caps? How?), or some other means I have not thought of yet.

Tying up greenhouse grasses in fast growing plants and embedding them into solids that can be buried are two ways of reducing the gasses. Plants are the easiest and fastest acting, but we will have to plant a LOT of plants! Encouraging the growth of ocean plants that tie up carbon in the seas may help, but that needs some research.

The problem is that starting from 1912 when the problem was clearly detected we had time to act and failed to use it. Starting from 1974 when it first became clear that the problem was about to become urgent we had time for research and incentive to stop using fossil fuels, and failed to use it. Starting from NOW we have very little time and are limited in our options. We may need to use everything in our bag of tricks, and unless we are lucky that STILL might not be enough.

We will not survive a Permian level extinction event. Avoiding creating one would be good. If we can extract energy form the oceans to protect them, and radiate that energy off planet to reduce the problem, it might help. The question is if we can figure out how to make that work in time for it to make a difference.

We're on the same page, then. I agree 100%.

Mind you, you and I both probably know we're headed for a Permian or near-Permian level event unless something big happens, and there's no sign of anyone casting national selfishness aside…

On that I think we have to disagree. There is no solid pattern, half of humanity seems to want to dig in and pretend nothing can (or should) be done. The other half seems to be doing what they can to make progress on defending the world (okay, LIVING world rather than just the rocks) and convincing the rest that it will cost less to join them than to put up with the damages. There are LOTS of signs of things happening, and people putting selfishness aside. It is, however, unclear if that will suffice.

ICT has bigger Carbon Footprint than Aviation.
https://hardware.slashdot.org/story/...usly-estimated
If we can convince the kids to play outdoor (instead of gaming), it will be a win-win situation.