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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847. 0741
2:01 AM GMT on October 13, 2007
have low from 94l move over water it look like it still over land on coast ???
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846. pcola
9:00 PM CDT on October 12, 2007
House, alias HOG, are you ok? Please let us know.
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845. HadesGodWyvern (Mod)
1:55 AM GMT on October 13, 2007
you're welcome. It has all the worlds High Sea Advisories and Tropical Cyclone Warnings, if available.
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844. Weather456
9:51 PM AST on October 12, 2007
HadesGodWyvern,

thanks
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843. pottery2
9:38 PM AST on October 12, 2007
Hello.
I posted a comment 4 hrs ago. Then I had to leave. ( it was my turn to cook!)
Re: the shrinking ice, and the effects of that ( the post was on page 13 )

2 comments in respose to that post, I have to respond to.

1. FLOODMAN , yor view is that things will deteriorate and eventually come full circle ? Based on some pretty vaque models of what will happen, and in any case, how long do we wait before things move from no Gulf Stream to a new version ? 10 yrs. / 1000 yrs ??
Sounds kind of hopeful/hopeless to me, that idea.

2. KEEPEROFTHEGATE, I dissagree that we have passed the point of no return. We dont know that. And the point is, not doing anything at all is a serious cop-out. ( not that I think we are going to do anything, we are victims of comfort for sure )

Keep up the lobby/pressure for change in attitude, and maybe.........
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842. HadesGodWyvern (Mod)
1:43 AM GMT on October 13, 2007
Weather456:

METRAREA VIII-S

click on the South Tropical Cyclone Warning link on that page.
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841. pcola
8:47 PM CDT on October 12, 2007
(A Lurker), what happened to the blog? No posts. Weathr was beautiful in Pensacola today. Woke up cold with the windows open. Where is everybdy? Please tell me it's over?
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840. Weather456
9:41 PM AST on October 12, 2007
91S - Tropical Disturbance 01R

This image separates the low level cloud field from the convection...useful for looking at the low level structure of storms despite the blockage of the cirrus canopy or CDO.

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839. Weather456
9:40 PM AST on October 12, 2007

835. HadesGodWyvern 9:34 PM AST on October 12, 2007


can i have a link to that info..i dont get it in that format.
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838. Weather456
9:38 PM AST on October 12, 2007
825. TheCaneWhisperer 9:04 PM AST on October 12, 2007 Hide this comment.
Wrong basin in your pic 456 if your referring to 91L. That is the southern hemisphere.


sorry i meant 91S
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837. beell
1:38 AM GMT on October 13, 2007
835. HadesGodWyvern 1:34 AM GMT on October 13, 2007

Perturbation Tropicale

I like it. Sounds...soothing...
Member Since: September 11, 2007 Posts: 145 Comments: 16921
836. moonlightcowboy
1:32 AM GMT on October 13, 2007


GOM shear dissipating
Member Since: July 9, 2006 Posts: 184 Comments: 29610
835. HadesGodWyvern (Mod)
1:28 AM GMT on October 13, 2007
Tropical Cyclone Warning Number 3
Perturbation Tropicale 1
Issued by RSMC La Reunion
0000z 13October 2007


Location: 10.8S 58.4E
10 min sustained winds: 25 kts
Central Pressure: 1005 hPa

Tropical Cyclone Discussion
============================
The main center is located on the northeastern edge of deep convection (Thunderstorm Activity) which has favorable conditions in high level (Good Upper Level Outflow, mainly in the southern part), but neutral to unfavorable environment in low level. Good low level tradewinds inflows but no equatorward wind inflow and energetic conditions limitated because the system is tracking over seas with Sea Surface Temperatures of 26C, which is just the minimal threshold for development or persistence of a tropical low.

The Tropical Disturbance has curved west-southwest on the northern edge of high pressures building to the south. It is forecasted to track west, then westnorthwest without significant intensification. It should come the closest to Agalega (Where pressures remains rather high despite the approaching disturbance) during this afternoon

Forecast Intensity
=================
24HRS - Perturbation Tropicale 25kts
48HRS - Perturbation Tropicale 25kts
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834. UYA
1:28 AM GMT on October 13, 2007
Oh goody! I like presents.
Which one is mine?
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833. moonlightcowboy
1:25 AM GMT on October 13, 2007
Yeah, CW and it's probably gonna leave us a present behind.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
832. TheCaneWhisperer
1:15 AM GMT on October 13, 2007
831. SamTeam
8:13 PM CDT on October 12, 2007
820. sceerdycat 7:52 PM CDT on October 12, 2007
Great avatar, Sam. Did you take it?


Thank you, I'm proud of that picture. I did take it, on the Texas/New Mexico border last year on the back from the west coast.
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830. UYA
1:08 AM GMT on October 13, 2007
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
306 PM CDT FRI OCT 12 2007

ANOTHER FACTOR...WHICH
HAS BEEN DISCOUNTED FOR NOW...BUT IS WORTH MENTIONING...IS THE
DEVELOPMENT OF A TROPICAL WAVE OVER THE SOUTHERN GULF OF MEXICO
FROM A BROAD AREA OF LOW PRESSURE CURRENTLY OVER THE YUCATAN
PENINSULA. BOTH THE GFS AND ECMWF TRY TO DEVELOP A WEAK SYSTEM IN
THE CENTRAL GULF EARLY NEXT WEEK...BUT THE TIMING AND EXACT TRACK
OF THIS LOW IS HIGHLY UNCERTAIN. AT THIS TIME HAVE JUST DECIDED
TO REFLECT THE INCREASED MOISTURE...
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829. SRQBoogieMan
1:08 AM GMT on October 13, 2007
Looks like some convection firing around Honduras associated with 94L. Just might make re-entry into the WCab some fire in its belly. If the shear begs off....it does have some prospect. IMHO
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828. weatherg8r
8:10 PM EST on October 12, 2007
sceerdycat 7:48 PM EST on October 12, 2007
Yes, I am sceerdy. Lived through F&J. Former wishcaster, never realizing how much a hurricane can affect your life. Very thankful we did not have an Andrew or Katrina. Still, many people I know lost their homes. Very sad...



I know what you mean...I work for the local utility so we worked 18 hour days for a month and then tons of overtime to catch up after...not to mention not being able to do anything at our house because my husband and I both do the same work. It messes up your entire life for a while!
826. 0741
1:01 AM GMT on October 13, 2007
it look like form 94l should be in carribbean sometime on sat unless it want stay over land longer
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825. TheCaneWhisperer
1:00 AM GMT on October 13, 2007
Wrong basin in your pic 456 if your referring to 91L. That is the southern hemisphere.
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824. weatherg8r
8:02 PM EST on October 12, 2007
ok...I have been gone...what is going on with 94L?
823. TheCaneWhisperer
12:52 AM GMT on October 13, 2007
Agree JP! The monster of a ULL in the C-Atl responsible for the hung up trough and the shear is diving SSW fast. Looks like a more zonal flow setting up from a look west in the CONUS.
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821. moonlightcowboy
12:50 AM GMT on October 13, 2007
There's rotation over land in sBelize, but it appears to be moving ne, and could emerge over water close to 18n,88w. jmho
Member Since: July 9, 2006 Posts: 184 Comments: 29610
820. sceerdycat
8:50 PM EDT on October 12, 2007
Great avatar, Sam. Did you take it?
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818. sceerdycat
8:46 PM EDT on October 12, 2007
Yes, I am sceerdy. Lived through F&J. Former wishcaster, never realizing how much a hurricane can affect your life. Very thankful we did not have an Andrew or Katrina. Still, many people I know lost their homes. Very sad...
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816. 0741
12:46 AM GMT on October 13, 2007
it look like low(ex94L) want move in carribbean again
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814. SamTeam
7:43 PM CDT on October 12, 2007
I'm working on it!
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811. KoritheMan
12:42 AM GMT on October 13, 2007
It's like trying to learn a new language.

Tell me about it. But once you do, you feel proud of yourself. :)
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810. Weather456
8:33 PM AST on October 12, 2007
Expected Rainfall Amounts from 91L ending OCT 15 2007

BBL

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809. KoritheMan
12:40 AM GMT on October 13, 2007
with 60 to 80kt of wind shear? for get it

I agree with you Taz. The season is definitely not over yet though. Still expect at least 1 storm. I have a feeling Noel will be a hurricane, too.
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808. BahaHurican
8:36 PM EDT on October 12, 2007
BBL
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807. SamTeam
7:34 PM CDT on October 12, 2007
mlc, you are correct in that the season is not yet over. Anything that kicks up surely warrents watching!

Novice? You're a pro compared to me! I'm still trying to learn how to read the dang forcast links! It's like trying to learn a new language.
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806. Tazmanian
5:35 PM PDT on October 12, 2007
792. weathers4me 5:11 PM PDT on October 12, 2007
Once former 94l emerges into the GOM it will be the next depression IMO. Night all



with 60 to 80kt of wind shear? for get it
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805. moonlightcowboy
12:27 AM GMT on October 13, 2007
SamTeam, thanks. The whole time many eyes were glued on the prospects of 93L, there were a few of us that had concerns about something forming off the tail of the trough near Jamaica. And, with the fronts, etc...that's come into play, the best have been guessing, too. So, it's been very perplexing to us of novice to say the least! lol...tricky for sure. October storms usually have a plethora of variables for influencing intensity and track. Often these fronts have a way of pulling the storms n and ne and often the wcoast of FL gets in their way.

...just keep an eye, because the season is definitely not over yet.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
804. BahaHurican
8:29 PM EDT on October 12, 2007
GFS is forecasting increased vorticity on that Caribbean wave as it moves towards Nicaragua . . .

Link
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803. UYA
12:30 AM GMT on October 13, 2007
BANCO CHINCHORRO.....Shall not be forgotten.
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802. BahaHurican
8:20 PM EDT on October 12, 2007
I remember it because I was so surprised to hear about it. I always thought only keys off Yucatan was Cozumel et al.

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801. UYA
12:26 AM GMT on October 13, 2007
94L Poofed. So anything around the NW Carib or Belize is something new.
Where might it go?
We'll all be watching the models to mess that up!
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799. SamTeam
7:16 PM CDT on October 12, 2007
MLC, thanks for the write up; I think that you are correct about the sleeping giant, this week should be interesting.

I don't think you missed 94 earlier in the week, I think she just put a detour in her path that you didn't plan on!!

Thanks again for sharing your thoughts! :)
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798. UYA
12:16 AM GMT on October 13, 2007
Yeah, thanks Baha. I do know about it....just the name had slipped my memory.
I am obviously not a diver.
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797. Weather456
8:15 PM AST on October 12, 2007
Tropical Disturbance 01 heading towards N Madagascar.

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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.

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