Sunday, 11 September 2016

Looks like an extended sea ice melt season

This is what I thought when I looked at sea temperatures around the Pole on Climate Reanalyzer.

"Temperatures for most of the Arctic basin in ice-covered areas are expected to again push to -2 C to +2 C. Generally, air temperatures below -2 C are needed to prevent melt, but in warm water and rough ocean conditions, which have tended to dominate the Arctic recently, air temperatures probably need to average around -4 to -6 C over most of the Arctic to fully halt melt."

Robertscribbler, despite describing the situationvery well repeats that this is a comparitively weak melting year - and objectively air temperatures have been lower because of higher cloud cover.  But the destruction of the ice is coming from  a different situation and the future situation depends on sea temperatures and weather conditions over the sea ice melt.

A blue sea event this may not be but the ice that has been destroyed over this summer season is never coming back.

Coming Big Arctic Ocean Warm-Up May Extend Sea Ice Melt Season


10 September, 2016
It’s September in the Arctic, a time of year when temperatures should be cooling off. But with sea ice at second-lowest levels on record in most monitors and the globe experiencing an unprecedented hot year, it appears that the next week may see the Arctic Ocean reverse its typical seasonal cooling trend and significantly warm up over the coming five to six days.
arctic-heat-september
(GFS model runs show a significant warming is in store for the Arctic Ocean over the coming week — and that’s bad news for sea ice running at second-lowest levels on record in the current daily measures and lowest levels on record for the first eight months of the year so far. Image source: Climate Reanalyzer.)

GFS model runs show a strong pulse of warm air will rise up over the Atlantic Ocean and Barents Sea in the next 72 hours. This warm air then will ride in over the Greenland Sea and invade the Arctic Ocean north of Svalbard. Local temperatures over water are expected to be between 4 and 8 degrees Celsius above average over a broad region of the Arctic. Meanwhile, general departures for the entire region above 66° North Latitude are expected to hit around 2 to 2.5 C above average.
Temperatures for most of the Arctic basin in ice-covered areas are expected to again push to -2 C to +2 C. Generally, air temperatures below -2 C are needed to prevent melt, but in warm water and rough ocean conditions, which have tended to dominate the Arctic recently, air temperatures probably need to average around -4 to -6 C over most of the Arctic to fully halt melt.
Threats to Ice Coming From All Directions

During summer and early fall, the Arctic Ocean tends to help to moderate temperatures over the region, so these are very high predicted temperature departures for this time of year. Such high temperatures are likely due to the effect of added heat bleeding off recently ice-free waters. While sea-ice area and extent measures are in the range of second-lowest on record, there is some indication that sea-ice concentration in the Arctic may be at or near record-low levels.
amsr2-animation-neven

(AMSR2 animation constructed by Neven shows vigorous ice export and melt through the Canadian Arctic Archipelago. This is a heavy blow to the thin veil of multi-year sea ice remaining in the Arctic. Animation by Neven at the Arctic Sea Ice Forum. Images byUniversität Bremen.)

The ice, generally, is extraordinarily weak, thin and dispersed. Large gaps run across an arc covering the Atlantic and Siberian side of the polar zone. In addition, large cracks are appearing in the very thin and unstable multi-year ice north of Greenland (below) as sea-ice export now threatens melt in the Beaufort Sea, Canadian Arctic Archipelago, the Nares Strait, the Fram Strait, and on into the northern edge of the Barents Sea.
Risks Rise for a Long Melt Season

Recent animations by Neven over at the Arctic Sea Ice Forum (above) show particularly strong export and melt in the Canadian Arctic Archipelago — which is a pretty unprecedented melt feature. What this means is that the ice is basically being hit from all sides and that the factors necessary to melt ice are compounding.

last-bastian-of-multi-year-ice-breaking-up
(Large section of multi-year ice breaking up north of Greenland on September 9, 2016. In recent years, less and less ice has survived summer melt to make it to the following winter. Ice with an age of more than five years has grown quite scant in the Arctic. The ice shown breaking up in the above image is part of the last bastion of old, thick ice in the Arctic. When that’s gone, the Arctic Ocean will only be a seasonally frozen sea, a possibility that may occur as soon as 2017 to 2025 and will probably occur before 2035. Image source:LANCE MODIS.)

If the big warm-up does occur as predicted this week, there is risk that ice losses will extend through to September 15 and possibly beyond. These melt rates should not be particularly severe, given the time of year, but it is possible that 50,000 to 300,000 square kilometers or more will go. This would be enough to solidify 2016 as the second-lowest year on record for extent and area at the end of melt season. It would also help to fill the big gap between 2007 and 2012 — solidifying already significant decadal melt trends.
Overall, this is a pretty weird forecast, but set in the backdrop of a year that’s on track to be about 1.2 C above 1880s averages — the hottest year on record by far — the possibility of a late-season Arctic warm-up and a late end to a near record melt season is an entirely valid one.
Links:

Hat tip to Greg
Hat tip to DT Lange


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