How does the loss of sea ice affect Earth's temperature?

[stuartmacg]

The paper https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011JD015804

"Estimating the global radiative impact of the sea ice–albedo feedback in the Arctic"​

is the nearest I have come to something narrowly on this topic, from a google search. Only skimmed so far.
It proceeds much as one might expect to estimate the changes in solar energy taken in, and relate the estimates to experimental data.
There is no mention of the corresponding changes in radiative heat loss, which in polar regions one would expect to exceed the change in heat input.

 

[DrJohn]

So imagine we have a totally white planet in space and a totally black planet in space. They happen to be in identical orbitals around the sun, just always on opposite sides of the sun (they are my planets, so yes they CAN do that.)
The totally white planet reflects all the incoming solar radiation, and does not warm up.
The totally black planet absorbs a lot of the incoming radiation, warms up and radiates energy, until the incoming energy matches the radiated energy and then it is in equilibrium.
So which planet is warmer? The black planet.
Which planet is in equilibrium? Surely both planets.
So if the totally white planet then gets some black surface exposed, by scraping off a large amount of the white paint, will it get warmer or cooler?
Now apply the same to an earth that lost a lot of its white, reflective ice. Will it get warmer?

 

[stuartmacg]

You presuppose a cold radiatively isolated body. If there is no energy exchange the word equilibrium is meaningless. The white object will stay at whatever temperature it was, hot or cold. Once coupled to the space around it it will gain or loose energy to approach equilibrium.

[Post edited by the Mentors to remove a mild insult]

 

[stuartmacg]

So imagine we have a totally white planet in space and a totally black planet in space. They happen to be in identical orbitals around the sun, just always on opposite sides of the sun (they are my planets, so yes they CAN do that.)
The totally white planet reflects all the incoming solar radiation, and does not warm up.
The totally black planet absorbs a lot of the incoming radiation, warms up and radiates energy, until the incoming energy matches the radiated energy and then it is in equilibrium.
So which planet is warmer? The black planet.
Which planet is in equilibrium? Surely both planets.
So if the totally white planet then gets some black surface exposed, by scraping off a large amount of the white paint, will it get warmer or cooler?
Now apply the same to an earth that lost a lot of its white, reflective ice. Will it get warmer?

Sorry that last comment was a bit rude. I have just about lost hope of getting any rational on-topic discussion here, and am feeling a bit grumpy.
I might as well amplify my response to you a little:

We are assuming:
1) the insulated white body is in internal equilibrium (unlike earth).
2) the hole created in the insulation to allow radiative coupling sees the average local space temperature e.g. it is not tide locked to the sun or on a spin pole orthogonal to the ecliptic.

Then thermal connection will result in loss of heat if the white body was previously above local space temperature, or gain of heat if it was below.

In the earth polar regions
1) There is an inflow of heat from the rest of the planet to the poles, via water and air, because they are colder.
2) The regions are thus hotter than local thermal equilibrium with the polar skies.
3) Increasing thermal coupling to the polar skies will therefore loose heat from the earth on balance.

 

[Frabjous]

4) Increasing radiative coupling (reducing albedo) increases the net radiative energy flow in both directions equally.

What physically has to happen for the outflow to increase?

 

[stuartmacg]

Uncovering previously protected sea should allow a bit of radiative heat loss that was not there before, in addition of course to the gain from the absorption of polar sunlight over the same area.
Since the cold polar regions are warmed by fluid transfer from the rest of the globe, they will be above local radiative equilibrium with their polar skies. I would thus expect any increase in thermal connection (reduction in albedo) to increase the heat flow in both directions, increasing the existing net radiative outflow from these regions.

 

[stuartmacg]

We don't have any climatologist scientists on our SA staff, unfortunately. That's one reason why we have to take a mostly hands-off approach to Moderation in GW/CC threads (and why we have the rules we do). It's always best if you can find some good references on your own, and post the links to those references to help the discussion along.

One refinement you might try in your Google searching is to confine the results to Google Scholar, which usually returns better search results and more peer-reviewed papers. Let us know what you find.

missed this post somehow , thanks for the suggestion anyway. I did eventually get one paper on Google Scholar on the topic, posted previously.
Question still unanswered. Have tried Quora a few hours ago - no response yet.

 

[berkeman]

Thread closed temporarily for Moderation...

 

[berkeman]

After some editing, the thread is reopened.

 

[hmmm27]

Have tried Quora

URL ? (and is an account required to read). I'm curious how an actual climate-science specialist - if one's available and feeling chatty - would choose to answer that.

 

[Frabjous]

Uncovering previously protected sea should allow a bit of radiative heat loss that was not there before, in addition of course to the gain from the absorption of polar sunlight over the same area.
Since the cold polar regions are warmed by fluid transfer from the rest of the globe, they will be above local radiative equilibrium with their polar skies. I would thus expect any increase in thermal connection (reduction in albedo) to increase the heat flow in both directions, increasing the existing net radiative outflow from these regions.

I would argue that the spot where the albedo decreased becomes warmer which allows it to radiate more. At the level of global energy balance, one can define the spot to be the entire planet.

 

[stuartmacg]

On reflection I can see there are effects due to the sort of photon maxwell demon operation of the atmosphere (greenhouse) which may justify the positive feedback assertion. Not totally fair to call it that, as its action is symmetrical and the asymmetry in photon energy on each side causes the result.
Thanks to the greenhouse demon, most of the sun's energy arrives unscathed at the surface of the globe, but lower photon energy thermal radiation from the surface is impeded in its journey in the opposite direction.
It is the maxwell demon like effect which breaks the normal expectations of symmetrical effects for radiative coupling.
For this reason a newly uncovered patch of thermally black sea will eat sunlight when it shines, but cannot radiate out much of its heat directly. It will heat the local atmosphere by IR emission and by contact night and day and winter and summer, since it will be around 0C and the atmosphere will be much colder. This heated atmosphere will to some extent pass on the heat to space (presumably a linear effect), and the heat loss from the sea's surface will increase sea convection and global cooling.

The net effect will be difficult to analyze and quantify and may easily lead to mistaken conclusions.

 

[Laroxe]

It's an interesting discussion. I did manage to find a paper that appears to confirm the idea that the loss of ice actually increases cooling.
https://www.sciencedirect.com/science/article/abs/pii/S0967064599000284

It also appears that the loss of ice will have little effect on the protection offered by the albedo effect, which because of the low amount of energy the poles receive has a negligible effect on climate.

https://blogs.cuit.columbia.edu/dmw2158/solar-radiation-the-earths-energy-balance/