Monday, July 25, 2016

Global Sea Ice Extent Sets a Record Low Early Maxima

Global sea ice extent -- the sum of Arctic SIE and Antarctic SIE -- has two maxima in a year: one, the smaller of the two, usually in July, and the second, larger maximum, usually in November.

I don't think there's anything deep about this; it's just the way the nonsymmetric timing for the two poles works out, and the Arctic thawing more than the Antarctic.

This year, the first, lower maxima is a record low:

The trend in this local maxima is -40,400 km2/yr. This year is low mostly because Antarctic sea ice extent is low -- it's current anomaly (7/24/16) relative to a 1981-2010 baseline is just slightly negative, but that's a big change from recent years. Indeed, the trend for Antarctic SIE from the beginning of its record in 1978 is +21,700 km2/yr, while the Arctic has an overall trend of -53,800 km2/yr.

The overall trend in global SIE is -24,300 km2/yr.

There has been a recent paper on Antarctic SIE, by Meehl et al, that puts the increase due to the negative phase of the Interdecadal Pacific Oscillation, which is like the Pacific Decadal Oscillation (but I've never been able to find the data page for the IPO; if you know it, please let me know).


Unknown said...

David Appell said...

Thanks Richard.