Tag Archives: North West Passage

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I thought it was time to look at the sea ice data as the summer Arctic melt proceeds.

The image below shows the mean sea ice extent 1989-93 on 22 July, the sea ice extent 22 July 2017, and the difference between the two data sets. Reds imply less sea ice than the mean 1989-93, and blues an increased sea ice extent.

The mean Arctic sea ice for the years 1989-93 on 22 July, the sea ice concentration on 22 July 2017 and the difference between the two data sets. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.
The mean Arctic sea ice for the years 1989-93 on 22 July, the sea ice concentration on 22 July 2017 and the difference between the two data sets. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.

As we would expect, compared with the 1989-93 data the sea ice edge is consistently further north. Things that stand out for me are the virtually open water in the Barents and Kara Seas. This region was very slow to freeze over in the autumn and winter of 2016, so I would have expected the sea ice there to be relatively thin at the end of the Arctic winter.

Also the Chukchi Sea is opening.

Overall the area of the Arctic Ocean covered with sea ice is low. Some will note it is currently above the record low in 2012, but it's only 90,000 kmabove that. To me that is not that significant.

Arctic sea ice extent to 22 July 2017 from NSIDC.
Arctic sea ice extent to 22 July 2017 from NSIDC.

What is significant is the sea ice 22 July 2017 is ~1.7 million kmbelow the median extent from 1981-2010.

I looked a couple of days ago at the sea ice in the North West Passage (19 July 2017), and it is starting to open up.

The North West Passage. Image 22 July 2017 from the Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite.
The North West Passage. Image 19 July 2017 from the Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite.

The yellow line traces out possible ship routes through the North West Passage and whilst there is still ~1200 km of sea ice on that route, when you compare the region to the longer term data you can see how low this is compared the historical record.

The difference in the sea ice in the NW Passage on 22 July 2017 compared with the mean for the years 1989-93 on 22 July. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.
The difference in the sea ice in the NW Passage on 22 July 2017 compared with the mean for the years 1989-93 on 22 July. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.

It may be this year that the passage may not open at all, but taken together the two plots are a a good example of how we can expect the north west passage to become consistently open as the Arctic continues to warm.