By Steve Goddard

Barrow, AK early this morning

Darkness is returning to the Arctic as the sun moves towards the horizon. In four weeks, the sun will disappear completely at the North Pole.

Solar Energy as a function of latitude and date

The Canadian Ice Service shows that there is still low-medium concentration ice blocking the Northwest Passage.

http://ice-glaces.ec.gc.ca/Ice_Can/CMMBCTCA.gif

If you owned a ship, would you send it through a route knowing it will face shifting pack ice, possible icebergs, fog, darkness, wind, storms and the possibility of an early freeze?

“The plans that you make can change completely,” he says. This uncertainty, delay, liability, increased insurance and other costs of using the Northwest Passage are likely to deter commercial shipping here. A ship with a reinforced hull could possibly make it intact through the passage. But if it got stuck, it would cost thousands of dollars for an icebreaker like the Amundsen to come to the rescue. So even if the Northwest Passage is less ice-choked than before, the route may not become a shipping short-cut in the near future, as some have predicted.

The Arctic Oscillation was negative for a few days, which allowed colder air to escape from the Arctic and warmer air to invade the Arctic. Note that the period of positive AO starting in early July corresponded to the Moscow heat wave. The cold air was trapped in the Arctic.

The negative dip this week allowed a blast of southerly air to melt and compact the ice during the past week, as we forecast in last week’s sea ice news.

http://ocean.dmi.dk/arctic/icecover.uk.php

Ice extent loss has dropped off dramatically in the last few days, as seen in the DMI graph above and the JAXA graph below.

Note that there was little loss in ice extent during 2006, after August 22.

What does the remainder of 2010 hold? Difficult to say. NCEP forecasts freezing temperatures over the broken ice in the Beaufort Sea during the next two weeks.

http://wxmaps.org/pix/temp2.html

If the remainder of the summer follows a path like 2006, 5.5 million is the right number. Another blast of southerly wind during the next few weeks. and it goes below 5.5. All of the ice indexes currently show 2010 ahead of 2008. DMI and NORSEX show it ahead of 2009 as well. JAXA also shows that the ice area curve has flattened. Ice area is always less than extent, and area trends tend to lead extent by a week or two.

There are large areas of low concentration ice which are vulnerable to compaction, spreading or melt.

My forecast remains unchanged. 5.5 million, finishing above 2009 and below 2006. Same as it has been since May.

The video below shows ice movement in the Beaufort Sea this week. Earlier in the week, it was compacting rapidly, now it is slightly expanding.

It all comes down to the temperature and wind over the next few weeks.

PIOMASS forecasts continue to stray further from the mark. Areas in red are places where PIOMASS incorrectly forecast melt. Solid green is the opposite misprediction.

Lindsay and Zhang forecast a minimum of 3.96 million in July.

The modified NSIDC image below shows ice loss during the last week. Mainly in the Beaufort Sea.

The modified NSIDC image below shows ice gain since 2007 in green, loss in red.

I’m not going to make a forecast for the next week, because there aren’t any dominant indicators either way.

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