Here is an apparent conflict between physics and 'experience'.
You do know that there are no "sources" of cold?
Of course there are sources of cold. If I have a glass of warm water and I need a source of cold I just go get some ice and throw it in.
<Snippage>
OK, while creative, not really A Thing.
You don't really have "sources of cold" any more than you have "sources of vaccuum". What "cold" indicates is a difference in enthalpy - net heat content components of a system, and thanks to the laws of thermodynamics heat will attempt to equilibrate across it - thus your ice cubes melting.
There wasn't any "cold source" here, just the heat of varying levels being redistributed.
This does bring me to a point which I feel people have been overlooking. It unfortunately is one for which we probably have the least instrumentation for - net enthalpy of the Arctic ocean and surrounding seas.
*This* will be the key factor in the tipping point.
<<a great deal of material removed - it is basically Arctic-specific.>>
In the northern hemisphere mid-latitudes when a 'cold North wind' blows, it gets colder. A balloon floating in that cold air physically goes south, so I say the cold air came south too. The source of that cold air was 'someplace' north of me. Yes, it is a 'distribution' thing, but in the local sense, it sure seems like there is a 'source'. The balloon 'came from the north', why can't the 'cold'? OK: the 'air packet' came from the north, and it happened to be cold. That air packet is cold because it lost its heat to the heavens [angels, I guess, lug the heat up when taking breaks from harp playing]. So, a source for the air, but not the cold.
(Those drink-cooling ice cubes were clearly made by a 'heat-redistribution machine'.)
How wrong did I go, physicists of the world?
In daily parlance, having a "source" of cold is quite normal. Having just had my air-conditioner fixed has made me thankful for that particular source of cold when I'm trying to sleep.
But when talking about larger systems, hemispheric and global weather for example, one has to be clear that there is never a source of cold, only sources of heat.
I started this whole "source of cold" discussion after reading a post by Archimid about how there were this and that source of cold that could have this and that effect on the Arctic. That was so obviously a wrong way to talk about weather and climate that I had to ask, and he has been strangely reticent in agreeing with the physics.
I also wanted to point out (
and perhaps get a little bit closer to the topic of this thread? Edit: Didn't realize that this was a new and more appropriate thread for this sort of thing) that space is a great sucker of warmth, a massive sink of heat, and would be by very far the hugest "source of cold" ever.
And the Arctic, during the winter months, loses massive amounts of heat to space and will continue to do so. Losing summer ice is only going to increase this heat loss, and if there ever is an equitable climate, this heat loss is going to get even bigger, leading to a fall in temperatures elsewhere.
Which all counts as a huge negative feedback, reducing the speed of global warming and generally working to cool the planet down.
Of course, there is another, very potent positive feedback in losing Arctic ice, so an ice-free Arctic ocean will presumably have a significant net effect of warming rather than cooling the planet. But never forget that negative feedback that's going to have it's say as well!
And once all the ice is gone, the positive feedback of losing ice stops. But the negative feedback of losing heat just keeps growing with increasing temperatures. How this will all play out is a total mystery to me, but some people seem to think they've got it all worked out.