Thursday, August 10, 2017

When Will The Arctic Sea-ice Be Gone? - 2

Fig. 1 Arctic Sea Ice extent (9 Aug 2017)
Since the date of the first post in this series (April 18th), significant changes have taken place.

For example, the record setting low Arctic extent continued until late May when it fell below the record low of 2012 once again.

So, for a couple of months now, 2012 is the record low (Fig. 1).

However, as the graphs at Fig. 2 and Fig. 3 show, the impact of the low ice extent up until late May, combined with the low ice extend from last year, caused a drop to take place in the projected time that Arctic Sea-ice will disappear from the Arctic Ocean in the summer.

Fig. 2
The change was surprising, in that the projection came closer by one year to 2023 from 2024.

Nevertheless, the long term projection, when the ice extent will be gone is still the same.

The lesson is that the software projection model takes all the changes into consideration when calculating projections into the future, which means that sometimes counter-intuitive results will be generated.

In a couple of months, if the 2017 extent continues to be below the 2012 record low for this time of year, I expect that there will be a different projection, most likely adding a year (back to 2014) when the first ice-free summer happens.

The reason for these oscillations is that the projections are based on real-time changes in
Fig. 3 (from here)
polar weather that adds ups and downs to the sea-ice extent, in combination with the fixed historical record.

The take-home lesson from these changes is that weather up there at the North Pole oscillates in the sense that there is no consistent downward track in the picture on a year to year analysis, but there is a consistent downward track in the picture in the longer term trend consisting of a decade of weather records.

The previous post in this series is here.

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