NSIDC - 15 September - Arctic Sea Ice At Minimum Extent (Preliminary)

[hatrack]

Arctic sea ice at minimum extent

Arctic sea ice appears to have reached its lowest extent for the year. The minimum ice extent was the second lowest in the satellite record, after 2007, and continues the decadal trend of rapidly decreasing summer sea ice.

Please note that this is a preliminary announcement. Changing winds could still push ice flows together, reducing ice extent further. NSIDC scientists will release a full analysis of the melt season in early October, once monthly data are available for September.

Overview of conditions
On September 9, 2011 sea ice extent dropped to 4.33 million square kilometers (1.67 million square miles). This appears to have been the lowest extent of the year, and may mark the point when sea ice begins its cold-season cycle of growth. However, a shift in wind patterns or late season melt could still push the ice extent lower.

This year's minimum was 160,000 square kilometers (61,800 square miles) above the 2007 record minimum extent, and 2.38 million square kilometers (919,000 square miles) below the 1979 to 2000 average minimum. Note that our estimated uncertainty for extent is plus or minus 50,000 square kilometers (about 20,000 square miles). The minimum ice extent this year is very close to 2007, and indeed some other research groups place 2011 as the lowest on record. At this point, using our processing and sensor series, the 2011 minimum is a close second.


Figure 1. Arctic sea ice extent on September 9, 2011 was 4.33 million square kilometers (1.67 million square miles). The orange line shows the 1979 to 2000 median extent for that day. The black cross indicates the geographic North Pole.

Conditions in context
The last five years (2007 to 2011) have been the five lowest extents in the continuous satellite record, which extends back to 1979. While the record low year of 2007 was marked by a combination of weather conditions that favored ice loss (including clearer skies, favorable wind patterns, and warm temperatures), this year has shown more typical weather patterns but continued warmth over the Arctic. This supports the idea that the Arctic sea ice cover is continuing to thin. Models and remote sensing data also indicate this is the case. A large area of low concentration ice in the East Siberian Sea, visible in NASA Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, suggests that the ice cover this year is particularly thin and dispersed this year.


Figure 2. The graph above shows daily Arctic sea ice extent as of September 13, 2011, along with daily ice extents for previous three lowest years for the minimum ice extent. Light blue indicates 2011, dashed green shows 2007, dark blue shows 2010, purple shows 2008, and dark gray shows the 1979 to 2000 average. The gray area around the average line shows the two standard deviation range of the data.

EDIT/END

http://www.nsidc.org/arcticseaicenews/

[GliderGuider]

1. Neven calls the final score

Final score: 2011 vs 2007

Where 2007 had an absolute perfect melting season, 2011 had some severe hiccups in the final 8 weeks of the melting season. Despite all of this 2011 beat 2007 on some of the graphs, and came within spitting distance on others.

Like I wrote last weekend in my guest post on ClimateProgress:

This is a sure sign that the ice is very weak and thin in large parts of the ice pack, which means that perfect weather conditions conducive to melting and compacting are no longer necessary to break records. The ice will melt out in place, regardless of what the weather does. That doesn’t bode well for years to come.

It underscores the new abnormal in the Arctic: despite adverse weather conditions this melting season is on a par with the exceptional 2007 melting season. If these general circumstances persist, the Arctic will be very close to becoming ice free by the end of summer before 2020. Sooner, if we get a melting season with the same weather conditions as 2007.

No one knows what this will do to Northern Hemisphere weather patterns in the short run, and what happens with the permafrost and methane clathrates in the medium to long run. I don’t find that a particularly comforting thought.

[hatrack]

2. And then this tiny, absolutely fascinating item from a shipping news blog:

Something strange
Posted on September 14, 2011 by rusfedmin

Commercial shipping through the Northeast Passage over the last couple weeks has reported the seas bubbling as if they were boiling. Their observations have been reported to the science ministry who have sent scientists to investigate.

Posted in Uncategorized | Tagged arctic, bubbling, northeast passage, Shipping | Leave a comment

http://arctictransport.wordpress.com/

I know absolutely nothing about this site, and there's no sourcing for the item posted above. Many grains of salt advised, but that said, it certainly sounds like a description of what the start of a clathrate release would look like . . .

[truebrit71]

4. Oooooooooh shit.....

Definitely not good if true...

[hatrack]

5. "If true" - indeed. If such is the case, things are getting . . . interesting very quickly

:beer:

[hatrack]

7. Apropos of this topic, New Scientist article on methane releases

Methane bubbling out of Arctic Ocean – but is it new?

A wide expanse of Arctic Ocean seabed is bubbling methane into the atmosphere. This is the first time that the ocean has been found to be releasing this powerful greenhouse gas into the atmosphere on this scale.

The discovery will rekindle fears that global warming might be on the verge of unlocking billions of tonnes of methane from beneath the oceans, which could trigger runaway climate change. The trouble is, nobody knows if the Arctic emissions are new, or indeed anything to do with global warming.

Between 2003 and 2008 Natalia Shakhova of the University of Alaska Fairbanks and colleagues collected 5000 samples of seawater over the East Siberian Arctic Shelf, the world's largest area of continental shelf, and measured the levels of methane at different depths. They also measured levels of the gas in the atmosphere above the shelf in 2006.

The team located more than 100 hotspots where methane is leaking from seabed permafrost. Most of the water in the region had methane concentrations more than eight times the normal amount in the Arctic Ocean, and concentrations of the gas in the air above averaged four times the Arctic norm.

EDIT

http://www.newscientist.com/article/dn18614-methane-bubbling-out-of-arctic-ocean--but-is-it-new.html

Also, this:

At the high pressures and low temperatures which are found at the bottom of the deep ocean, methane gas and water combine to form a solid, crystalline substance: methane hydrate. It is very widespread in the parts of the deep ocean nearest to the continents. If the ocean warms, the hydrate can become unstable and methane gas is unlocked and can make its way into the ocean, forming plumes of bubbles. A research cruise to the same area in 2008, also aboard RRS James Clark Ross, discovered numerous such plumes, as well as evidence for the presence of gas and the movement of fluids beneath the seabed. What was unclear though was how the gas was escaping into the ocean.

The current expedition is led by the University of Southampton's Professor Tim Minshull, who is based at the National Oceanography Centre, Southampton, UK. The shipboard team - including scientists from the National Oceanography Centre Southampton, its French counterpart, the French Research Institute for Exploration of the Sea (Ifremer) and the University of Tromsoe in Norway - used a range of new technologies to probe the seabed beneath areas where methane gas was found to be escaping, due partly to recent warming of the ocean.

Ifremer's SYSIF sonar system produced detailed images reaching 100 to 200 metres beneath the seafloor, which show how gas is in some places trapped and in some places is travelling upwards through narrow fractures and pipes to the seafloor. A seismic system towed across the sea surface provided images of deeper gas pockets beyond the reach of the towed sonar.


Professor Minshull, who is Head of Ocean and Earth Science at the University of Southampton, said: "Methane gas escaping from the Arctic seabed might make an important contribution to global climate change, but we need to understand the origin of this gas and its escape route to work out how the amount of gas escaping might change as the ocean warms. We now have very clear images of the gas escape routes and also of many places where gas is trapped and not yet escaping."

EDIT

http://www.hydro-international.com/news/id5048-Methane_Escape_Research.html

[The Croquist]

8. So what happened 20,000 years ago

when all the ice on North America melted? Did all that methane kill us?

[hatrack]

9. Well, no, as it was far colder when "all the ice on North America" melted

Maybe there weren't massive clathrate deposits under the glaciers, given the tendency of slowly moving vertical miles of ice to produce pressure and temperature conditions somewhat more extreme than those present in marine sediments where clathrates are found today.

Maybe the Canadian Shield wasn't a terribly favorable environment for the formation of clathrates.

Maybe "all the ice in North America" didn't melt all at once. Since the generally accepted peak of N. American glaciation was about 18,000 YA, and the glacial period didn't actually end until about 12,500 YA, that would indicate a melt period of about 6,500 years, more or less - IOW a period of ice loss approximately 160 times longer than the roughly 40 years for which we have reasonably comprehensive satellite data for the Arctic Basin, and during which very substantial losses in ice volume and extent have both taken place.

[The Croquist]

12. Lots of maybes there...

Maybe there weren't massive clathrate deposits under the glaciers
Maybe there were massive clathrate deposits under the oceans along the coast near where the glaciers were. Do you think that the coast of Maine 20,000 years ago would be different then the arctic coast today?

Maybe the Canadian Shield wasn't a terribly favorable environment for the formation of clathrates
Correct me if I'm wrong but doesn't the Canadian shield border the Arctic? If so why would you claim that the Canadian shield wasn't a favorable environment for clathrates while, at the same time, claiming the opposite?

Maybe "all the ice in North America" didn't melt all at once.
I agree 100%. all the ice didn't melt at once. In fact some of it is still melting. The ice has been melting for 20,000 years. If you want to go with 18,000 years that's fine with me. The bottom line however is that over the last 20,000 years sea level has risen 400 feet. That's 2 feet per century. Over the last 30 years or so we are averaging a bit under a foot a century. So please explain why a recent rate of one-half of the average for 18,000/20,000 years is so shocking.

IOW a period of ice loss approximately 160 times longer than the roughly 40 years for which we have reasonably comprehensive satellite data for the Arctic Basin, and during which very substantial losses in ice volume and extent have both taken place.
How much do you think melted it the last 20,000 years? Do you not think that there was ice off the coast of Maine 20,000 years ago? If there were 2 mile thick glaciers ashore do you not think that sea ice would extend out into the Atlantic? Bad news. The ice has been melting for 18,000/20,000 years and will probably continue to melt. Why is that so shocking?

By the way hatrack you forgot to include a few quotes from your link.

Between 2003 and 2008 Natalia Shakhova of the University of Alaska Fairbanks and colleagues collected 5000 samples of seawater over the East Siberian Arctic Shelf, the world's largest area of continental shelf, and measured the levels of methane at different depths. They also measured levels of the gas in the atmosphere above the shelf in 2006.

The team used their measurements to calculate that the region is releasing about 7 million tonnes of methane a year – about 2 per cent of overall methane emissions to the atmosphere, half of which result from human activity.

"The subsea permafrost has been degrading and leaking methane beneath for thousands of years,"

So what we see is that their measurements go back less then 10 years, accounts for just 2% of all methane released annually and that the arctic methane has been leaking for thousands of years. So exactly why should we start panicking?

[hatrack]

13. "Methane bubbling out of Arctic Ocean - but is it new?" - sorry to be so . . . alarmist

If you can't read the article titles cited, or the uncertainty I've emphasized in my own postings, then I am happy to have wasted your time.

[The Croquist]

14. You're right hatrack. I apologize

I actually did read your quotes and the article and when I started my reply I confirmed that quotes 2 & 3 were not in your post. I added # 1 later but I listed them in the order that they appeared in the article. I "FORGOT" to confirm that you did not post it. In short, I blew it.

I also saw the title but since you didn’t post the quote from Graham Westbrook I thought it worth noting. I will add however (correct me if you think I’m wrong) that Westbrook doesn’t know that The subsea permafrost has been degrading and leaking methane beneath for thousands of years, I think he’s right but he doesn’t “KNOW” that. Does he have any evidence?

[GliderGuider]

6. With apologies to Don Ho

Tiny bubbles (tiny bubbles)
In the sea (in the sea)
Make me happy (make me happy)
Make me feel free (make me feel free)

Tiny bubbles (tiny bubbles)
Make us warm all over
With a feeling that we're gonna
Drown at the end of time

[XemaSab]

10. .

:popcorn:

[Odin2005]

11. OH SHIT! That is NOT good news!

:wow:

[truebrit71]

3. Sonofabitch...

:wow: