All these charts that zero out at some point are missing an important element. I would call it a stall line. In this case it would apply only on the lower limit, which I do not claim to know, but I guarantee it is not zero on the vertical axis. Anyway, once it is reached, the curve no longer applies.
I have been thinking similar thoughts. In human disease models there is often an early exponential decay (death rate) followed by a reverse slower decline. The path to zero survivors usually has an S shape, better described by a Weibull distribution than exponential.
The underlying reason for this is that there are usually two or more underlying populations in our disease group. Call them the weak and the strong. The strong survive, sometimes a long time and eventually cause the curve to kink. The proportion of weak and strong drives the location of the kink. Even in something as dire as recurrent pancreas cancer there is a kink.
So, I've been wondering if the distinction between weak and strong may be influenced by land based ice. Will it protect some sea ice, produce a kink and delay the ultimate date of an ice free summer day in the arctic?
schnitm,
Welcome to the Forum. I appreciate that you used the analogy of how the ratio of weak to strong can and will impact the final shape of the curve. While I haven't had the time recently to post very often, I do check the various charts Neven has provided us on a daily basis.
When it comes to defining the ratio of "sick" ice to "healthy" ice you need to clearly define which metric you are using. The ratios of "sick" to healthy for Extent will differ greatly than the ratios for Volume.
In the 5 years I've following the demise of the Arctic ice, I can quite certainly state that when using the metric of Extent, as an example, there are significant visual differences in the ratios between "sick" and "healthy" ice. For the sake of this discussion I'm using only thickness as the measurement and I'm calling"sick" ice less than 2 meters thick and "healthy" ice greater than 5 meters thick. I fully realize that other factors such as the cohesiveness of the individual floes is an important assessment of the true health, in terms of survivability. 5 years ago the northern shores of the Canadian Archipelago and Greenland provided a safe haven for thick multi-year ice. In the last few years, we have seen a great deal of damage to these formerly invulnerable floes of ice.
Now for my thoughts as to what may happen during 2017's melt season. While everything will depend on when each of the three metrics reaches their maximum, how long the plateaus last, when the serious declines begin and what the weather patterns provide during the following six months.
However, using IJIS Extent as one example, if the maximum is between
13.5 Km2 and
13.8 Km2, the maximum is reached before the end of February, the plateau is short-lived and serious declines start by the Equinox, we are in for an interesting ride this year. An average melt year will end with the a new record low, although not by much. An ideal melt year will result in shattering the old records and most probably will flirt with meeting the requirements for being declared
"ICE FREE", if only for a few days in September.
