The expectations and predictions concerning the loss of the "polar ice cap" or Arctic sea-ice are varied.
That is, they are much like sea level rise expectations and predictions in the sense that the span of time when relevant events could take place covers spans of time of a decade or so in variation (Independent, June, 2016).
For example, one expert who has extensive experience indicates that it is going to take place sooner than expected:
"The Arctic is on track to be free of sea ice this year or next for the first time in more than 100,000 years, a leading scientist has claimed.(ibid, Independent, June, 2016). The sea-ice extent did reach the lowest ever, or close to it, in September of 2016, but did not quite get to where he expected.
Fig. 2 Arctic Sea-ice projection
'My prediction remains that the Arctic ice may well disappear, that is, have an area of less than one million square kilometres for September of this year,' he said."
“I think there’s a reasonable chance it could get down to a million this year and if it doesn’t do it this year, it will do it next year."
The looks of things now are that it will have a better chance of doing so this September, as he also indicated ("this year or next").
II. Calculation Module
As I indicated in a previous post, I am working on a module to project when it will happen (The Evolution of Models - 21).
The graphs at Fig. 1 and Fig. 2 were produced by the first beta version of the module.
The Fig. 1 graph is pure history generated by using the NSIDC database, while Fig. 2 is that history, plus calculations projecting the expected future based on the known and recorded past.
III. Some Sea-ice Nomenclature
If you read the post in the link I quoted from, "ice free" is not an absolute concept, as you can discern from Professor Wadhams' definition: "an area of less than one million square kilometres".
With that in mind, the module I wrote uses a high / low concept, meaning that the Arctic will at first be ice free in some future September, but some ice will reappear during the following winter.
The graph at Fig. 2 shows the low extent time frame as to when to reach the first phase circa 2024, but reaching Professor Wadhams' definition of "ice free" a year prior to that in circa 2023 (ice free in 6 or 7 years from now).
The remainder is calculated to be "ice free" circa 2037-2038 (20-21 years) according to the initial calculations (an IPCC-type conservative estimate).
IV. Historical Gyrations
As you can see from the actual historical figures (Fig. 1), the highs and lows show some intense gyrations from year to year.
It is not a smooth ride.
That is why models can give a true general projection, but are less able to project abrupt climate change events, even though abrupt climate change is a certainty (Climate change stole a Yukon river almost overnight).
The drawback in the module I am working on is that it does not yet do partial years.
The NSIDC data began late in 1978 (March highs missing), and the current year 2017 is just now underway (September lows missing), so I do not include those two partial years in the history handling section of the module.
I plan to do some work in that area so that even partial years can be reasonably used in the module's CSV file generation.
That means better graphs in the future.
The next post in this series is here.