Here's another guest blog, sent to me by Lewis Clark, who is also a commenter on the Arctic Sea Ice Forum. Lewis describes this year's melting season and how several forecasts have played out in relation to it.
I like the term 'thin ice age'. Thin ice makes it more difficult to rely on conventional wisdom, although this year has proven that a lack of melting momentum during May and June followed by weather conditions during July and August that do not favour melt/export/compaction can still prevent a record, even if volume was at a record low for much of the year.
Thanks, Lewis!
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Which Arctic Prediction Models Are Relevant in the Thin Ice Age?
by Lewis Clark
2017 provides a stress-test for Arctic sea ice models. Following an unusually warm winter, the melting season began with record lows (post-1979, the satellite era) for both maximum ice extent and volume. After a slowdown in ice loss, however, measures are back to a near-normal range. This development seems to partly validate some models that predicted a rebound year, but the jury is still out. With a few weeks go before the minimum, large areas of thin ice might yet hold surprises.
This just in, courtesy of Wipneus from the Arctic Sea Ice Forum (ASIF) sea ice area and extent data thread: an update of the Basin-only graphs. On NSIDC's numbers, both area and extent are tracking close to several low but non-record years. (Note that this excludes Barents and Greenland Seas and the Canadian Arctic Archipelago, which collectively aren't likely to alter the trend much in the next month).
Despite the big swing this year in overall ice state, the lack of extreme conditions during the Arctic summer offers a good opportunity to evaluate the performance of prediction models. Weather is always a wild card that can throw off any or all seasonal models in any given year. The head-turning decline in sea ice in 2007, for example, was caused mainly by sunny skies and a prolonged dipole: high pressures over the Beaufort Sea, combined with lows near Siberia, pulled in considerable warmth from the Pacific side and increased ice export to the Atlantic. In 2012 an intense and long-lasting cyclone caused an extra decline in ice cover during August en route to a record low minimum.
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