People are still trying to work out if we can make black bodies that are biased to radiate more heat in frequencies that the atmosphere is permeable to.
We have some materials that are much more thermally conductive in one direction than the other. Pair the two, and it might just be possible to shed some heat into space at night.
Entropy always wins. It’s the heat trapped in the atmosphere that’s killing us. The universe is a mighty big heat sink though.
Search for radiating heat into space. There were some reports about 8-10 years back. Occasionally you will see people working on materials that have narrow emissions spectra, but I think they may have other things in mind, like combining them with photovoltaics to make solid state heat engines. Which has the potential to be much more efficient than thermocouples. Thermocouples are so far from their theoretical limits that boosting the conversion rate by single digit percentage points is more than doubling efficiency, which is how we ended up with a new thromocouple material on the front page of HN a month ago.
Why the atmosphere? Deep ocean water is already super cold right? Plus water does a good job of absorbing heat.basically transfer the surface heat energy to deep waters,that way surface level glaciers are kept frozen?
Water is a good insulator, but not a perfect insulator. If the temperature difference between the bottom and top changes so does the heat transfer and given time the effects will spread. But most important is, warm water/moisture is less dense than cooler water, that means large heat transfer by convection currents in addition to the low conduction (inverse of insulation).
Good curiosity, but they would have to put out atleast an equal amount of heat into the atmosphere! (2nd law of thermodynamics).