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As you frame it, 4 year old MYI which is only 1-2m thick is of equal value to what 4 year old MYI *used* to be - 3m thick or more for the most part, and far more robust than the scattering of dots the current maps present.
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When MYI is that thin, can it survive another year of melt? Because when ice gets thicker, it freezes at the bottom
It all very much depends on the melt conditions the ice is exposed too.
It can survive, but will be much different in nature - "Hybrid" if you will - than older, thicker MYI was in the past.
MYI which is seriously degraded (down to under 2M in thickness) will not be as robust even if it manages to gain thickness during the refreeze. New ice will not be as consolidated - of the same quality, hardness and physical structure - as the surviving older ice. There's fertile ground for a doctoral thesis there, assuming the ice survives long enough for research to capture what it looks like and how it behaves.
For me, it helps to understand what is going on by approaching the overall outcome season over season as a sum of probabilities. For example, some small fraction of it may actually be thicker and miraculously thicken further over the refreeze, but key there is the "bell curve" for thickness distribution is shifting badly against thicker older ice.
The distribution of the mechanisms generating those probabilities - insolation, cloudiness, wind, melt ponds and more - hasn't really altered that much, exceptions being increased WAA and indirectly things like lower albedo.
But to some degree they are not structural changes in the original system dynamics as the are derivative modifications of it, produced by increased overal enthalpy in Arctic and northern hemisphere climate systems.
As a metaphor - consider the Arctic's heat reservoir as a bucket with strategically drilled holes in it, and it's heat budget as a hose playing water into it. The system in balance will have the water level rise and fall predictably based on relative inputs. Add another small hose or just increase the flow slightly (WAA, Atlantification, increased spring continental run-off, etc.) and change the size of the holes (decreased albedo for example, or stronger greenhouse blocking of outgoing radiation), and eventually the water will rise until it finds a new balance.
Key dynamics of the system - phase change physical chemistry, insolation, black body radiation, greenhouse physics, et. al. remain mostly the same.
What they are playing out on has not.
This of course is a tremendous simplification but I found it useful as a mental exercise to help understand and put in context the dynamics of what we see playing out before us.
That's well illustrated by what's happening this year. While warm, melt conditions haven't been nearly as extraordinary as they were in 2012. Yet, here we are at 2nd lowest in most metrics, with a slim chance still of catching 2012. We got here because of a cascade; the same inputs, but the shift in probable outcomes for each event means less ice and increased capture of heat in the system. I think we all know how it will eventually play out. Most of our arguments about it are over timing.