Tuesday, April 18, 2017

When Will The Arctic Sea-ice Be Gone?

Fig. 1 Arctic Sea-ice history
I. Background

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.
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."
(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.

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).

V. Conclusion

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.

Stay tuned.

2 comments:

  1. Good stuff Dredd! 'Abrupt' change is how nature gets things done. We take for granted the warmth of the Sun's rays and rarely stop to appreciate 'they' are traveling at 671 million miles per hour(1071 kilometres/hour / metric) to reach us!

    Heck, underwater tsunami waves reach 500 mph easy-just a bit quicker than pyroclastic gases leaving a volcanic eruption. When the 'mission' is to restore or create a new equilibrium, Nature is very judicious in the spend of time-fast transformation is usually preferred. Ice being ice and requiring enormous heat inputs to phase change to liquid is generally a surprisingly slow process. If the conditions are such that ice will melt, it won't surprise or disappoint. Ice certainly deserves a lot of respect as it's unique in how stubborn it can be and this reflects how important it will always be.

    I expect the new temp measurements of deeper (warmer) water in the Arctic and how they are being influenced by the warming Atlantic piercing north and eastward, will align with your data sets. Everything points towards a final moment when the last piece of ice becomes liquid but at least it won't occur instantaneously ( it's pretty tough). But when this occurs, Earth will waste no time in finding a new equilibrium.

    https://theconversation.com/heat-from-the-atlantic-ocean-is-melting-arctic-sea-ice-further-eastwards-than-ever-before-76108

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  2. "The Arctic Ocean Is Becoming A ‘Dead End’ For Your Trash" (link)

    When the ice is gone the plastic garbage will be easier to see.

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