Fabled Northwest Passage begins to re-freeze

By: Dr. Jeff Masters , 2:29 PM GMT on October 12, 2007

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This summer's dramatic loss of Arctic sea ice peaked on September 15, and the polar ice cap is finally beginning to re-freeze, according to a press release issued by the National Snow and Ice Data Center on October 1. Extent of the September polar sea ice fell 39%, compared to the 1979-2000 average. To put this loss in perspective, in one year we lost as much ice as we lost during the previous 28 years. Summertime Arctic sea ice is now at 50% of what it was in the 1950s (Figure 1). One may look at at graph and wonder, but what about sea ice loss in other seasons? It hasn't been nearly so severe. True, but it is the summer ice we care most about, since summer is when the thick, multi-year ice melts, which can then precondition the Arctic for much greater ice loss in future years. As sea ice melts in response to rising temperatures, more of the dark ocean is exposed, allowing it to absorb more of the sun's energy. This further increases air temperatures, ocean temperatures, and ice melt in a process know as the "ice-albedo feedback" (albedo means how much sunlight a surface reflects). There is an excellent chance that the summer of 2007 will be remembered as the "tipping point" for Arctic sea ice, when an irreversible ice-albedo feedback process firmly established itself.



Figure 1. Arctic sea ice extent since 1900, as estimated from satellite and ship reports compiled by Walsh and Chapman (2001). Image credit: University of Illinois cryosphere group.

Northwest Passage opens for the first time in recorded history
Long before the Panama and Suez Canals made commercial trading between the Atlantic and Pacific Oceans economically feasible, ships made the long and perilous trip around the African and South America continents. Explorers, traders, and world leaders looking for faster and less dangerous shipping routes to far-away areas of the world have long eyed two routes through the ice-choked Arctic Ocean--the fabled Northwest Passage, through the cold Arctic waters north of Canada, and the Northeast Passage, extending along the northern coast of Russia. The first recorded attempt to find and sail the Northwest Passage was in 1497, and ended in failure. The thick ice choking the waterways thwarted all attempts at passage for the next four centuries. Finally, in 1905, Roald Amundsen completed the first successful navigation of the Northwest Passage. It took his ship two-and-a-half years to navigate through narrow passages of open water, and his ship spent two cold, dark winters locked in the ice during the feat. More recently, icebreakers and ice-strengthened ships have on occasion battered their way through the ice-blocked route.



Figure 2. The Northwest Passage shipping route (red line) and Northeast Passage (green line) superimposed on an ice coverage map from August 22, 2007. The Northwest Passage was ice-free and navigable for 36 days between August 14 and September 18, 2007. The Northeast Passage was blocked by a narrow strip of ice most of the summer. Image credit: National Snow and Ice Data Center.

Times are changing. In 2001, the Bering Strait, a key portion of both the Northwest and Northeast Passages, was completely ice free. This was followed in 2005 by record-breaking sea-ice melt in the Arctic, leading to the first ever recorded opening of the Northeast Passage. The fabled Northwest Passage remained closed in 2005. Arctic ice recovered a bit in 2006, and both passages remained closed. But the unprecedented melting during the summer of 2007 saw the Northwest Passage become ice-free and navigable along its entire length without the need for an icebreaker as of August 14, 2007. Remarkably, the Northwest Passage remained ice-free for 36 days, finally refreezing over a small section on September 19. The Northeast Passage was blocked by a narrow strip of ice all summer. However, this strip of ice thinned to just 30% coverage on September 25 and 26, making the Northeast Passage passable for ordinary ships on those days.

When is the last time the Northwest Passage was open?
We can be sure the Northwest Passage was never open from 1900 on, as we have detailed ice edge records from ships. It is very unlikely the Passage was open between 1497 and 1900, since this was a cold period in the northern latitudes known as "The Little Ice Age". Ships periodically attempted the Passage and were foiled during this period, and the native Inuit people have no historical tales of the Passage being navigable at any time in the past.

A good candidate for the last previous opening of the Northwest Passage was the period 5,000-7,000 years ago, when the Earth's orbital variations brought more sunlight to the Arctic in summer than at present. Prior to that, the Passage was probably open during the last inter-glacial period, 120,000 years ago. Temperatures then were 2-3 degrees Centigrade higher than present-day temperatures, and sea levels were 4-6 meters higher.

Final thoughts
If we have reached the tipping point for Arctic ice, what are the implications? I'll discuss this more in a future blog. Sea ice is very complicated, and it is not a sure thing that we have reached the tipping point. For more on the complexities of sea ice, read wunderblogger Dr. Ricky Rood's latest blog.

NASA has posted a beautiful satellite image of the Arctic ice cap at the September 15 2007 minimum, showing the open water of the Northwest Passage.

I thank Edalin Michael of the University of Michigan's School of Natural Resources and Robert Grumbine of NOAA's Sea Ice Group for their contributions to this blog.

References
Walsh, J.E and W.L.Chapman, 2001, "Twentieth-century sea ice variations from observational data", Annals of Glaciology, 33, Number 1, January 2001 , pp. 444-448.

Jeff Masters

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447. weathers4me
7:30 PM GMT on October 12, 2007
Hows it goin gang? Anything brewing? I see we got diverted a bit earlier. Focus people. Lord knows some of these pics doesn't make it easy with a bunch of weather guys (and gals) LOL. Looks like a nice weekend weather wise for the SE. Have a good one.
Member Since: May 24, 2007 Posts: 0 Comments: 118
446. CaneAddict
7:31 PM GMT on October 12, 2007
Guyys good afternoon! Blog updated!
Member Since: October 5, 2007 Posts: 3 Comments: 2151
442. aubiesgirl
7:31 PM GMT on October 12, 2007
Ike this will be the one time I will say noo noo rain...I like the cooler weather soooo much better...low humidty is great!!
441. Floodman
7:29 PM GMT on October 12, 2007
Sorry, folks...I'll be in and out this afternoon...some how or another a big pile of work appeared on my desk and I'm apparently required to do something about it...geez!
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439. IKE
2:29 PM CDT on October 12, 2007
seflagamma 2:28 PM CDT on October 12, 2007
LOL!!! it's all in fun...

I just don't like to see real "conflict" and nastiness on this blog... this blog should be for everyone.. the other blogs the owners can do what they want with them ... and some are pretty fun! LOL


I skipped over "conflict" and nastiness...and don't feel like going back and reading it.

Come on EX94L...hang in there and bring the northern gulf coast some rain...(fingers crossed).
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438. NEwxguy
7:29 PM GMT on October 12, 2007
433. IKE 7:29 PM GMT on October 12, 2007
all I said was I had beer waiting in the cooler for the game tonight, and it took off from,gotta learn to just keep my mouth shut and just talk invests and TDS

Game...cooler and beer sounds like an invest with promise.

yeah,and don't have to worry about shear
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436. aubiesgirl
7:29 PM GMT on October 12, 2007
LOL Ike..Iagree
429. NEwxguy
7:25 PM GMT on October 12, 2007
421. weatherg8r 7:25 PM GMT on October 12, 2007
419. NEwxguy 7:22 PM GMT on October 12, 2007
415. seflagamma 7:21 PM GMT on October 12, 2007
LOL!!! jp, well... yes anything is better than that bickering that was going on in here earlier! LOL but so many newbie's here don't know about the other blogs you can use to have off topic conversations.

See what happens when you get a bunch of bored weather guys.

AND girls

sorry and girls,
all I said was I had beer waiting in the cooler for the game tonight, and it took off from,gotta learn to just keep my mouth shut and just talk invests and TDS
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428. tampabayfish
7:25 PM GMT on October 12, 2007
Debating debates is funny and ironic... I just need to waste another half hour before happy hour... Carry on.
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427. nrtiwlnvragn
7:18 PM GMT on October 12, 2007
Another analysis of the Caribbean.



International Tropical Discussion

"THE CYCLONIC CIRCULATION OVER GUATEMALA...HOWEVER...IS FORECAST TO PERSIST THROUGH 72-84 HRS...IF NOT FOR LONGER PERIOD OF TIME. FURTHERMORE...ALONG THE BASE OF THE TROUGH...A CLOSED LOW FORMED ALONG THE EASTERN PACIFIC ITCZ...A FEW DEGREES SOUTH OF ACAPULCO MEXICO. SOME OF THE MODELS FORECAST THIS LOW TO INTENSIFY AND EVOLVE INTO A TROPICAL CYCLONE."
Member Since: September 23, 2005 Posts: 14 Comments: 11211
426. LakeShadow
7:25 PM GMT on October 12, 2007
See what happens when you get a bunch of bored weather guys.

AND girls


yeah it turns into a virtual shark tank!
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422. LakeShadow
7:24 PM GMT on October 12, 2007
and then the debate vs. arguement debate? (shich I personally found very amusing)
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420. LakeShadow
7:22 PM GMT on October 12, 2007
jp...remember the climate change debate?
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412. Tazmanian
7:20 PM GMT on October 12, 2007
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1100 AM PDT FRI OCT 12 2007



EXTENDED...A SERIES OF SHORTWAVES EMBEDDED IN A FAST WESTERLY FLOW
CENTERED ALONG 42N WILL BRING PERIODS OF RAIN TO THE NORTHERN HALF
OF CA WED WITH ANOTHER CHANCE OF RAIN BY LATE THURSDAY. ANOTHER
CHANCE OF RAIN WILL COME IN BY LATE SATURDAY INTO SUNDAY. AGAIN
THESE RAIN CHANCES APPEAR TO BE CONFINED TO I-80 NORTHWARD. THIS
IS AN ACTIVE JET STREAM FOR THIS TIME OF YEAR AND TIMING OF THESE
SHORTWAVES CAN BE DIFFICULT. WOULD APPEAR THAT THE LA NINA PATTERN
HAS ALREADY ESTABLISHED ITSELF RATHER EARLY IN THE SEASON. IF THIS
PATTERN CONTINUES SHOULD SEE ABOVE NORMAL PRECIP FOR NOR CAL AND
DRY CONDITIONS FOR THE SOUTHERN HALF OF THE STATE INTO NOV. WOULD
ALSO BRING AN EARLY SKI SEASON TO THE NORTHERN SIERRA.

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406. LakeShadow
7:15 PM GMT on October 12, 2007
ha! pablo! LOL
Anyone with updates on the itcz blob? Floodman says its a no-go...anyone with ideas?
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404. tampabayfish
7:14 PM GMT on October 12, 2007
Hey cattle, I would say theres a better chance at it hitting the W Carib for now. Nothing is making it into the Gulf for few days, too hostile.
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401. NEwxguy
7:14 PM GMT on October 12, 2007
399. cattlebaroness 7:14 PM GMT on October 12, 2007
Guess there is no tropical weather to discuss. Pathetic.

Can Flood or someone who is not salivating tell me their opinion of 94 hitting the gulf. Also know it is early but what is projected intensity. TIA. The rest of yall should invest in bibs to catch the drool. Just my opinion. :)

can we get a TS spinning out there in a hurry.
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399. cattlebaroness
7:07 PM GMT on October 12, 2007
Guess there is no tropical weather to discuss. Pathetic.

Can Flood or someone who is not salivating tell me their opinion of 94 hitting the gulf. Also know it is early but what is projected intensity. TIA. The rest of yall should invest in bibs to catch the drool. Just my opinion. :)
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397. beell
7:11 PM GMT on October 12, 2007
299. nrtiwlnvragn 6:04 PM GMT on October 12, 2007
Marine Weather Discussion

Weak high press ridge over the northern gulf of mexico with light n to ne winds over most area. The models differ some on the movement of the low pres currently over the nw caribbean. Overall the gfs differs the most then the other models...a it brings the low across the yucatan peninsula into the eastern bay of campeche mon night and into the central portion of the sw gulf mon afternoon and se of the mouth of the mississippi tue and into the florida panhandle wed. The other models are a little more similar bringing the low across the yucatan peninsula into the bay of campeche mon but keep it in the sw gulf through wed. Either way in the sort term winds should increase across the eastern gulf will increase with the low to the s and ridge to the n tighten the gradient.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.