Thursday 26 October 2017

It is sea ice VOLUME that matters, not extent

This is one of the first times I have known Guy to be be TECHNICALLY incorrect. It is true that there has not been a decline in sea ice. However,what is incontrovertible is that there has been no refreeze and sea ice volume has gone from fourth lowest to (only just) second lowest.

The ice is so thin that I would expect that things could go in either direction depending on the weather.

This is (like rain during the dark winter) absolutely unprecedented.

More on Arctic sea ice in late-October

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«We are headed for an ice–free Arctic. I’m stunned it didn’t happen this September, in fact. Although, this is shocking, truly shocking, and I believe it’s unprecedented: The Arctic ice is actually declined in terms of volume in October! We’re in the midst of what is supposed to be the refreeze season for Arctic ice, and ice volume has declined during the course of the month of October so far.»

---Guy McPherson


For the geeks, these are the best figures we get for daily ice.

Daily volume: 5,872 km³ (2nd lowest for the date) Δ +72/day+214/week, +1120/month, –247/year, +61/5year (+1%)
Daily extent: 7,408,271 km² (5th lowest for the date) Δ +101k/day
+632k/week, +2653k/month, +727k/year, +327k/5year (+4.6%)
2017 volume maximum 20,756 km³ on April 18th (*lowest*)
2017 volume minimum 4,539 km³ on September 11th (4th lowest)
2017 extent maximum 13,878,287 km² on March 6th (*lowest*)
2017 extent minimum 4,472,225 km² on September 9th (6th lowest)

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However, the above daily numbers carry a taste of 🍒. If you don’t want to cherry–pick your data to make a point, you may want to look at the latest, updated, running annual average. The ice, after all, has to be out there and survive those waves 24/7, 365 days of the year.

Annual volume: 12,598 km³ (*record* low) Δ –0.7/day
1.4/week, +16/month, –1,460/year, –1,084/5year (–7.9%)
Annual extent: 9,852,065 km² (*record* low) Δ +1.99k/day
+16k/week, +40k/month, –21k/year, –156k/5year (–1.6%)

Source: JAXA / PIOMAS (app estimate) for October 25th 2017.

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