[Vision2020] Will Arctic Sea Ice Extent Set New Record Low in 2011?

[Ted Moffett]

>From a credible climate science website, moderated by competent
climate scientists, below read a recent discussion on Arctic sea ice
minimum, that as anyone following the issue knows in 2011 is very
close to the 2007 record minimum for sea ice extent, though the PIOMAS
ice volume indications are that 2010 set a record low for Arctic ice
volume, a record low volume that has continued into the 2011 summer
season.

We will know in this month Septemer if 2011 sets a new record low sea
ice extent, though given the thining of the Arctic sea ice, as PIOMAS
indicates, this portends a record loss of Arctic sea ice extent is
only a few years away, given polar amplification under anthropogenic
global warming:  Manabe is well know
for publishing in 1980 what is sometimes considered the first serious
discussion of "polar amplification": Manabe, Syukuro, and Ronald J
Stouffer, 1980: Sensitivity of a global climate model to an increase
of CO2 concentration in the atmosphere. Journal of Geophysical
Research, 85(C10), 5529-5554. available in full (26 pages pdf) free
here: http://www.gfdl.noaa.gov/bibliography/related_files/sm8001.pdf

Manabe of course in 1980 was a deep cover operative of the Knights Carbonic:
http://www.monbiot.com/2009/11/23/the-knights-carbonic/
He is still publishing in science journals, 164 publications, from
1955 to 2011, counting articles now "in press:"
http://www.gfdl.noaa.gov/bibliography/results.php
a tribute to the triumph of our quest for world domination!  In the
name of the Master, go forth and terrify!

http://www.realclimate.org/index.php/archives/2011/09/arctic-sea-ice-minimum-discussions/

1Andrew says:
1 Sep 2011 at 8:10 AM
Hope the next IPCC report has a better section on the retreat of sea
ice. It has already retreated faster than all models under all
scenarios; obvious bias in the models. Also, the IPCC chart comparing
models was a display of the average extent during the months of July,
August and September. The implication being that there can’t be any
sea ice during those months before the arctic can be said to be
seasonally ice free arctic However, sea ice reaches it minimum in
September with August and October the next lowest months.

Looking at trends in sea ice volume, it’s apparent that the arctic
will reach a minimum of zero within the next decade.

2Chris G says:
1 Sep 2011 at 9:33 AM
I take back some of what I said last month. I really like what
Didactylos and Sphaerica (Bob) did with a monochromatic graph keyed on
year, last month that started here.

http://www.realclimate.org/index.php/archives/2011/07/arctic-sea-ice-discussions/comment-page-3/#comment-211290

My favorite color would be light-blue = more distant past and
dark-blue = more recent, and maybe on offset color for the current
year. I can’t make a pattern out of the color schemes used above.

I used to hope that people would wake up when they saw the trend in
ice melt (How can they reconcile a huge decline in ice with no real
warming trend? Yeah, I know, not all people in denial say there is no
warming, but that zombie keeps walking around.), but that hasn’t been
the case.

3Philip Machanick says:
1 Sep 2011 at 10:31 AM
The 2011 graphs so far look to be tracking almost as low as the 2007
minimum for area and extent and the downward trend in volume is still
clear. Another good picture at PIOMAS shows the daily volume trend in
a format more comparable to the JAXA graphs. If the volume trend
persists, it will take only one slightly warmer than average summer to
break all records for minimum extent and area. With the current solar
cycle still looking like peaking on the low side, this is not too
surprising but we can’t rely on that to save us long term.

#2 Chris G: we may only really “wake up and see the ice melt” at the
peak of the next solar cycle if this one tops out lower than average
as expected.

4Pete Dunkelberg says:
1 Sep 2011 at 10:31 AM
Jacobson: Soot’s the thing.

“Soot emissions account for about 17 percent of global warming,….”

“Jacobson says his calculations show controlling soot could reduce
warming above parts of the Arctic Circle by almost 3 degrees
Fahrenheit within 15 years, virtually erasing all of the warming that
has occurred in the region during the last 100 years, a society
release reported Wednesday.”

That does not compute.

5Pete Dunkelberg says:
1 Sep 2011 at 10:41 AM
There is also Bremen sea ice extent:
http://iup.physik.uni-bremen.de:8084/amsr/ice_ext_n.png

6floundericious says:
1 Sep 2011 at 10:44 AM
http://www.msnbc.msn.com/id/44353322/ns/us_news-environment/

New photographs taken of a vast glacier in northern Greenland have
revealed the astonishing rate of its breakup, with one scientist
saying he was rendered “speechless.”

In August 2010, part of the Petermann Glacier about four times the
size of Manhattan island broke off , prompting a hearing in Congress.

Researcher Alun Hubbard, of the Centre for Glaciology at Aberystwyth
University, U.K., told msnbc.com by phone that another section, about
twice the size of Manhattan, appeared close to breaking off.

But when they returned in July this year, they found the ice had been
melting so quickly — at an unexpected 16-and-a-half feet in two years
— that some of the masts stuck into the glacier were no longer in
position.

7floundericious says:
1 Sep 2011 at 10:47 AM
MSNBC Article reporting that a second huge ice island is set to break
off the Petermann Glacier

Sorry if this is old news to you all!

8JohnN says:
1 Sep 2011 at 11:35 AM
Can I ask for some help understanding the set of graphs? The first two
appear to show not much in the way of trend at the peak ice but
upwards of a 1/3 (!) loss in ice extent at the minima – yet 2007 may
be a bit worse than 2011. However the trend line appears to show 2011
being significantly worse than all previous years including 2007? What
am I missing?

[Response: Different metrics. Arctic sea ice is not easily condensed
to a single number, and each of the graphs show different aspects of
the situation. The resolution of the apparent contradiction is that
the ice is roughly equally spread out this year compared to 2007, but
overall is thinner. I am not aware of any analysis that says that one
metric is more indicative or predictive than another in any general
sense. It's just part of the complexity. - gavin]

9David Miller says:
1 Sep 2011 at 12:39 PM
I have reservations about the volume numbers and ice thickness models.
The piomas version 2 model that was introduced this spring shows
considerably higher thickness values. The navy, for example
(http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictnnowcast.gif)
reports two to three meter thick ice all around the north pole.
Russian and American science vessels recently met at the pole and
reported actual thickness of a meter or less.

Given that we currently have ~3 million square km of ice it would have
to average more than 2 meters thick to reach the current piomas volume
of a bit over 6 thousand cubic km. Given the thin and fragmented ice
the Healy went through on the way to the pole I personally find that
average doubtful.

Given the disagreement between volume models and real-world
measurements – admittedly limited spatially – I’m left wondering what
the actual volume is. I’m looking forward to cryosat results once
they’re done with the calibration phase.

Note that there’s no good reading on arctic ice. If the models are all
right wrt volume the ice is declining alarmingly. If the real-world
measurements are closer and volume has already declined to 4,000 cubic
km or less then we’re in even more trouble.

10Kevin McKinney says:
1 Sep 2011 at 1:39 PM
#8–To elaborate a bit on Gavin’s response, the top graph is “extent,”
which means the total area of map gridboxes containing more than 15%
ice.

The next is “area,” which attempts to quantify the area within those
grid boxes which is actually ice-covered.
Area is thus always going to be smaller than extent-well, for any
realistic case, anyway. And the two track fairly well in general,
though ice can spread out, which can increase extent but not area, or
the reverse.

For these measures, variability does change throughout the year; as
you noted, the biggest change is in the warm part of the year (though
the biggest change in Arctic temperature is the trend in the winter.)

The third graph is volume, but the difference is greater than that,
because it’s also graphing anomalies, not just the values themselves.
It’s a useful way to display things in that it eliminates the annual
cycle, which is so evident in the other graphs. You can also graph
area and extent that way (and I know just where to find a couple of
graphs like that–when I’ve posted this comment, I’ll go and fetch the
links.)

You can read more about these matters, and many other related ones, too, here:

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

11Kevin McKinney says:
1 Sep 2011 at 1:48 PM
Sorry for the double link in the previous. Here’s the promised links:

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_N_min_to_date.png

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_UBN_min_to_date.png

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_VOL_min_to_date.png

These bar graphs are all by L. Hamilton; be aware that they don’t all
come from the same data source, so processing algorithms and therefor
results may differ a little, apart from the fact that they are showing
different metrics.

They (and much, much else) can be found here:

https://sites.google.com/site/arcticseaicegraphs/

12Doug Bostrom says:
1 Sep 2011 at 3:28 PM
David Miller says:
1 Sep 2011 at 12:39 PM

Russian and American science vessels recently met at the pole and
reported actual thickness of a meter or less.

Can you direct us to a pointer on that? Over on Neven’s Arctic ice
blog there’s speculation that ships visited the N Pole this year and
didn’t gather that information. Sounds most unlikely that researchers
on these ships would be so myopic.

13Hank Roberts says:
1 Sep 2011 at 3:36 PM
The Navy site says “system and web page are a demonstration and are
not an operational product. NRL is providing the INFORMATION on an “as
is” basis. NRL does not warrant or represent this INFORMATION is fit
for any particular purpose ….”

– I wonder if the report there showing ice thickness not as an average
but as a navigation aid (as in, low hanging ice, don’t bang your
submarine ….)

Pure speculation. Perhaps someone knows.

14L. Hamilton says:
1 Sep 2011 at 5:47 PM
The three bar graphs (annual 1-day minimum CT area, UB extent & PIOMAS
volume 1972 or 1979-present) that Kevin McKinney linked above are
being updated frequently while the melt season continues.

They’re intentionally simple, losing that “complexity” Gavin alludes
to, but pretty easy for anyone to follow.

I should have a new graphic within a day or two at Neven’s blog,
comparing the five main area & extent time series.

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_N_min_to_date.png

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_UBN_min_to_date.png

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_VOL_min_to_date.png

15Jathanon says:
1 Sep 2011 at 5:55 PM
Polarstern, not Healy (still on its way there)
http://neven1.typepad.com/blog/2011/08/polarstern-reaches-north-pole.html

16Philippe Chantreau says:
1 Sep 2011 at 6:21 PM
The latest data on NSIDC suggest that this year’s extent coud break
the 2007 all time low. In any case, it will be very close. The
Petermann glacier just lost a huge chunk of ice, according to blurb on
Yahoo I just noticed. The comment thread was a pathetic display of
ignorance, name calling and libertarian type ranting. Not very
encouraging.

17spyder says:
1 Sep 2011 at 7:31 PM
Thanks for bringing this forward; i was just checking to look for it
after reading about the Greenland ice sheet depletion.

18Candide says:
1 Sep 2011 at 8:38 PM
I do have one friend who is very much on the denialist bandwagon, and
is a devoted fan of wattsupwiththat.com. I mentioned this issue about
the thinning Arctic ice to him, and his reply was that the melting is
being caused by “thousands and thousands of underwater volcanoes.” I
have to admit, I hadn’t expected that reply – I thought he would just
deny that any ice thinning was taking place. Intrigued, I pressed a
little further, and asked if he thought there was an increase in the
number of underwater volcanoes, and if so, why that might be. Again,
he provided a sincere but entertaining response, saying that yes
indeed, volcanoes were becoming increasingly active all over the world
(he offered up the recent eruptions in Iceland as proof). The reason,
he says, is that the planets are all lining up, a process that will
come to a head in 2012, and cause the Yellowstone Super-volcano to
erupt with disastrous results. He suggested I rent the video “2012″, a
Hollywood blockbuster which until now I’ve managed to avoid watching:

2012
http://www.imdb.com/title/tt1190080/

Well, there you go. We have a full explanation for the thinning Arctic
ice, and it has absolutely nothing to do with CO2 emissions. And here
I was needlessly worrying about AGW. Silly me.

19Kevin McKinney says:
1 Sep 2011 at 10:06 PM
#18–Well, then, “glitter and be gay!”

20KAP says:
1 Sep 2011 at 10:08 PM
If the ice were melting as a result of underwater volcanoes, then we
would expect the oceans to be warming from the bottom up. But actual
(non-Hollywood) data shows that the oceans are warming from the top
down, i.e., the heat is coming from above, not from below.

Don’t expect evidence to change your friend’s mind, however.

21David Horton says:
1 Sep 2011 at 10:11 PM
Well yes Candide, but those rapidly increasing volcano numbers are a worry!

22Phil Scadden says:
2 Sep 2011 at 12:08 AM
Candide – you friends needs medication – quickly. That is seriously
detached from reality.

[Response: I don't know. Is the idea of planetary alignments causes
mass climate change in 2010 really so different than the idea that
keeps popping up (e.g. J. Curry) that the increase in CO2 in the
atmosphere might not actually be related to human activities? You
start medicating the astrology buffs and you'll start medicating
everyone. --eric]

23EFS_Junior says:
2 Sep 2011 at 12:14 AM
#9 David Miller says …

NAVO’s PIPS 3.0, aka ACNFS, over 15 years in the making, is still a POS IMHO.

The end user is NIC, and the best use of NAVO’s model is for ice edge
detection, it’s meant for operational use only, meaning navigation in
open waters.

Read their own calibration report here;

http://www7320.nrlssc.navy.mil/hycomARC/prologue.html

http://www7320.nrlssc.navy.mil/pubs/2010/posey1-2010.pdf

It overpredicts ice thickness by over a meter when compared to USACE
CRREL (I use to work at CRREL way back in 1975) buoy data.

It overpredicts fly over data by about 0.4 meters (Note: Not much of
this type of data to compare against, if you were to ask me).

In total it isn’t much of an improvement over PIPS 2.0, sorry but,
Navy 0 Army 1.

Have you been to the PIPS 2.0 site lately?

It’s offline, after twice predicting a POLE HOLE where none existed,
and I saved all those daily GIFS (from their 2nd failed attempt), to
make a nice animated GIF of that absurd model.

Further, I’m building a collection MODIS imagery where PIPS 3.0 shows
5+ meter thick ice, but there are actually open leads and much
scattered/broken up sea ice, 5+ meters my AZZ!

NOTE: You can stop with the Goddard type talk, now there’s a real
******** if ever there was one.

24EFS_Junior says:
2 Sep 2011 at 12:29 AM
#18 Candide says …

2012? IMHO the worst movie ever made, it’s like Transformers One
raised to the power of Transformers Two, itself raised to the power of
Transformers Three, …

See;

http://en.wikipedia.org/wiki/Tetration

25Dave Werth says:
2 Sep 2011 at 12:46 AM
I think what JohnN is missing is that the bottom graph is for volume
anomalies which takes the thickness of the ice into account. An area
covered with 3 meters of ice has 3 times the volume of the same area
covered with 1 meter of ice. There has been a significant loss of
thicker multi-year ice over the past few years so the volume has
dropped more than extent or area.

26Edward Greisch says:
2 Sep 2011 at 1:34 AM
18 Candide: http://www.imdb.com/title/tt1190080/ says: “the crust of
the earth is becoming unstable” like on Venus.
Follow the links and the continents re-arrange themselves in a few
hours. All because the planets are lining up.

Yet your friend can’t believe CO2 is indirectly melting the Arctic
ice? I need one of Joe Romm’s head clamps!

27JimCA says:
2 Sep 2011 at 2:52 AM
Comparing apples to apples (I think), the JAXA ASMR-E graph shows sea
ice area as somewhat under 4 million km^2, but the cryosphere today
graph shows sea ice area at 3.1 million km^2.

Is there some way to reconcile those? Do they purport to measure the same thing?

28Lawrence Coleman says:
2 Sep 2011 at 2:55 AM
Just been looking at Prof Kevin Trenbeth latest findings..ie. for
every 1 deg F. of ocean warming there is a 4% increase in water vapour
in the atmosphere resulting in a 6-8% increase in rainfall. The
spurious 6mm decrease in ocean height was the result of that
riculously intense la-nina last year causing a hell of lot of rain to
fall on land that is still perculating and meandering it’s way back to
the oceans. Another study involving a tightly spaced convoy of 5
satellites 2 sec apart collecting data on cloud formation and extent,
reports an over 50% decrease from the norm in arctic cloud cover. This
is allowing even more sunlight to reach the remaining sea ice and
cause accelerated warming not just from above but also below due the
warming arctic ocean this is probably the ice area and extent graphs
are so woeful this year and as I thought this year will most likely be
the worst on record.
One question I have that someone might know the answer to is….. due to
6-8% increase in rainfall over land could the change in river temp of
all the thousands of swollen river waters emptying into the sea have
any near future impact on the ocean’s temp. Logic says yes but I would
like to have a rough idea as to what extent, whether it is negligible
or yet another pos’ feedback system?

29Pete Dunkelberg says:
2 Sep 2011 at 7:33 AM
Lawrence Coleman @ 28, do you references for those statements?

30Kevin McKinney says:
2 Sep 2011 at 7:35 AM
[Response: I don't know. Is the idea of planetary alignments causes
mass climate change in 2010 really so different than the idea that
keeps popping up (e.g. J. Curry) that the increase in CO2 in the
atmosphere might not actually be related to human activities? You
start medicating the astrology buffs and you'll start medicating
everyone. --eric]

Well, the friend only needs to be medicated for a year or so, to
contain his anxiety about imminent death until such time as the fear
can be, er, superannuated.

31Kevin McKinney says:
2 Sep 2011 at 7:43 AM
“Comparing apples to apples (I think), the JAXA ASMR-E graph shows sea
ice area as somewhat under 4 million km^2, but the cryosphere today
graph shows sea ice area at 3.1 million km^2.

Is there some way to reconcile those? Do they purport to measure the
same thing?”

Yes, this is indeed apples to oranges, and no, they don’t purport to
measure the same thing. See my comment #10 above.

Extent is probably becoming obsolete as a measure, in that it makes
less sense as a metric the less cohesive (or the more minutely
fragmented) the pack becomes. (Just my opinion.) But area is harder to
measure, and of course backward-compatibility in data is highly
desirable.

32cRR Kampen says:
2 Sep 2011 at 7:58 AM
#3 “If the volume trend persists, it will take only one slightly
warmer than average summer to break all records for minimum extent and
area.” by Philip Machanik.

Not exactly. A ‘cool’ or ‘warm’ summer doesn’t have much meaning in
that region. Summer 2007 was actually on average somewhat cooler than
normal, even during the flash melts in that season:
http://ocean.dmi.dk/arctic/meant80n.uk.php . This was also during
solar dip and onset of a very strong La Niña.

Sunshine and wind are more important factors. And most of the melting
appears to happen from beneath, what with ever warmer waters lapping
around and underneath the pack.

I do agree with the gist of the message. The pack could disappear any
summer now. Volume decrease is accelerating, catastrophe theory needs
to be incorporated in modelling the phenomenon (
http://en.wikipedia.org/wiki/Catastrophe_theory ).

33pete best says:
2 Sep 2011 at 8:27 AM
The NSIDC have an graph of total volume of ice and it down on 2007 as well.

http://nsidc.org/images/arcticseaicenews/20110816_Figure5.png

Joseph Romm often has articles stating that Arctic Sea Ice is in a
death spiral.

http://thinkprogress.org/romm/2011/07/08/262576/arctic-death-spiral-sea-ice-volume/

The very last graph seem somewhat interesting. I believe that Richard
Alley has stated that the models are running 100 years behind schedule
and that warming in the Arctic is 4x faster than predicted.

34arcticio says:
2 Sep 2011 at 8:33 AM
On latest Envisat radar images sea ice concentration looks even worse
compared to low resolution microwave echo images. Check out for
example the North of the Laptev Sea.

http://www.arctic.io/zoom/ouYS/0.45;0.3;1.37/Envisat-Radar-2011-09-02

Here’s a close-up of the ‘ice pack’ bulging into East Siberian Sea
waiting for compaction.

http://www.arctic.io/zoom/y60y/0.45;0.46;2.77/East-Siberian-Sea-2011-09-01

35Jim Eager says:
2 Sep 2011 at 8:53 AM
KAP (@20), the fact that the ocean would need to be warming from the
bottom up is not a problem for the delusional, since they don’t even
consider the water column between all these ‘new’ volcanoes and the
ice. They simply assume that the warmth jumps straight from the
volcanos directly to the ice.

I’m not making this up: one of the more numerate denizens at WTFUWT
actually calculated a ball park heat value emitted by these phantom
volcanoes and declared that it would in fact be just enough to account
for the 2007 melt…., except that he did not include the mass of the
water column in his calculations.

36JimCA says:
2 Sep 2011 at 8:57 AM
#31 — How is “sea ice area” for one apples and for the other oranges?
What are they doing differently to measure ice area?

37Lars Kaleschke says:
2 Sep 2011 at 9:16 AM
#33 Envisat ASAR does not show ice concentration since the radar
signal of water and ice can not easily be distinguished, in particular
during summer.

But yes, it is quite a mess! The colleagues on RV Polarstern are
searching for suitable ice floes for drilling without much success
http://www.geo.de/blog/geo/polarstern-blog/wissenschaft/schollensuche?LTblog=681ae33de5eb42054ef5d251977fe021

38Hank Roberts says:
2 Sep 2011 at 10:06 AM
JimCA, where are getting confused by trying to compare?
Cite/point to the site definition; they do differ.

JAXA: http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

“Definition of sea-ice cover (extent and area)
The area of sea-ice cover is often defined in two ways, i.e., sea-ice
“extent” and sea-ice “area.” These multiple definitions of sea-ice
cover may sometimes confuse data users…..”

Wattsup explained it at his blog back in 2008; I don’t recall how well.

39Kevin McKinney says:
2 Sep 2011 at 11:08 AM
#36–Sorry, JimCA, I misread your original comment somehow. I was
thinking one was for ‘extent.’

However, you might imagine different area products as being, say Fuji
apples versus Red Delicious (or something like that.) Significant
differences still exist, even if they are all ‘apples.’

One is the sensor used–IJIS uses the instrument on the Aqua satellite,
which is why their data only goes back to 2002, while NSIDC uses data
from a series of older instruments, suitably spliced together.

Some products choose different resolutions, looking at 6.25 km2 grid
boxes versus 12.5 k, and so on. This, too, can make a difference to
the area result.

Finally, the statistical presentation can make a difference. For
example, the IJIS extent number is actually (I am told) a two-day
moving average, whereas NSIDC extent presents a 5-day average. (This
is all IIRC; I haven’t checked my memory on this.) So you’d expect
NSIDC extent to be higher at this time of year, since it would be more
affected by values ‘less far along’ in the melting process. (Haven’t
checked if that’s the case just now, and of course other differences
play into it, too.)

If you want to specifically reconcile IJIS area and CT area, you’d
want to search the ‘metadata’ that applies to each and see if you can
infer what’s causing the difference you observe.

It’s confusing, I know, and can be misrepresented by those naive or
obfuscating folks who expect (or claim to expect) that these
measurements should be an exact ‘truth.’ They are, as Gavin said,
‘metrics’–measurements–that are intended to give information about the
ice. They are not the ice itself!

One good thing about having all of these different metrics is the fact
that, despite the differences of detail, they all show basically the
same big picture. That gives us some additional reassurance that said
“big picture” is not somehow the artifact of a particular way of
measuring things.

40Paul S says:
2 Sep 2011 at 11:36 AM
#38, Hank Roberts – Take a look at the RC article. There is a graph
showing JAXA sea ice extent AND a different one showing sea ice area.

JimCA is asking what the difference is between the JAXA data labelled
‘Sea Ice Area’ and the Cryosphere Today ‘Sea Ice Area’.

ReCAPTCHA: Response rticatic

41L Hamilton says:
2 Sep 2011 at 1:19 PM
Although the various ice measures disagree from day to day, their
long-term agreement is striking. Here is a graph comparing five time
series (NSIDC area & extent, UB extent, IJIS extent, CT area) of
August means for 1972-2011.
http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_time_series_Aug.png

42JimCA says:
2 Sep 2011 at 1:43 PM
Thanks for all the responses, everyone. I tried to be clear what I was
asking, but should have been more explicit to avoid confusion.

I think I see now how the difference might emerge, but then have to
wonder if these folks talk to each other. Assuming there is a ground
(so to speak) truth, it should be possible to perform spot checks on
small areas to calibrate both, which presumably would reduce or even
eliminate the discrepancy. But maybe that is easier said than done.

43JimCA says:
2 Sep 2011 at 1:47 PM
Everyone, thank you for the responses. (And damn you captcha for
eating the previous version of this message.) I tried to be clear in
my question, but should have been more explicit to avoid confusion.

I think I see how the discrepancy might arise, but then must wonder if
those people talk to each other. It would seem to be straightforward
to find small areas for which a ground (so to speak) truth can be
found, then calibrate both series to that, in which case the
discrepancy should mainly vanish. But maybe that is easier said than
done.

44Rich Hendricks says:
2 Sep 2011 at 2:36 PM
Any bets on another harsh winter for the CONUS this year? I’m betting
on it happening again, caused by the lack of ice coverage in the
Arctic.

45Hank Roberts says:
2 Sep 2011 at 3:18 PM
JimCA, they’re working on it. Examples:
http://scholar.google.com/scholar?hl=en&q=arctic+sea+ice+satellite+area+estimation+pixel

Your input could help:

http://www.aip.org/fyi/2011/040.html

“NASA Administrator Charles Bolden …. described problems confronting
some earth satellite replacement programs, and starkly warned the
committee “we are in dire straits as a nation when it comes to weather
and climate prediction.” He was blunt in calling, as “dumb things”
congressional attempts to defund a satellite program that would
measure, among other data, shifting changes in the world’s climate. “I
don’t do global warming, I do earth science,” he said emphatically.”

46Eli Rabett says:
2 Sep 2011 at 3:20 PM
Why always JAXA and not IUE Bremen?

47Kevin McKinney says:
2 Sep 2011 at 3:22 PM
#41–”It would seem to be straightforward to find small areas for which
a ground (so to speak) truth can be found, then calibrate both series
to that, in which case the discrepancy should mainly vanish. But maybe
that is easier said than done.”

I think it would be a moving target, since the differences are
effective at different times, or in different situations. So the
discrepancies wouldn’t stay vanished for long (although they might
conceivably “phase in and out.”) Plus the data sets would lose that
backward compatibility I mentioned. (The jargon is that they would
become internally “inhomogenous.”)

#42–I wouldn’t bet on it myself–I think there’s more to NH winter
weather conditions than just the ice cover–but neither would I be
terribly surprised if it came about as you expect. There is, after
all, some support for it in the literature.

48Chris R says:
2 Sep 2011 at 3:27 PM
#42 Rich Hendricks,

I don’t know this CONUS of which you speak. ;)

But if you’re talking about the very cold winter periods we’ve been
having in the Northern Hemisphere recently: I suggest you google for
‘Judah Cohen Siberian Snowfall’, link.

I’m researching this at present for a post on my blog, should post in
the next week or so. Cohen makes a fairly convincing case that
anomalous Siberian snowcover has a pivotal role.

49L Hamilton says:
2 Sep 2011 at 4:15 PM
Although the various ice measures disagree from day to day, their
long-term agreement is striking. Here is a graph comparing five time
series (NSIDC area & extent, UB extent, IJIS extent, CT area) of
August means for 1972-2011.

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_time_series_Aug.png

50Brian Dodge says:
2 Sep 2011 at 4:56 PM
@ Candide — 1 Sep 2011 @ 8:38 PM Re sea ice melt and volcanoes

see http://www.realclimate.org/?comments_popup=576#comment-90991 and
http://www.realclimate.org/?comments_popup=576#comment-91077

About the time I was posting that comment, I came across a skeptic who
used a slightly different set of metrics, and calculated that a
Vesuvius size eruption would melt an area of Arctic sea ice slightly
larger than the ENTIRE state of Massachusetts!!!(assuming all the heat
made its way through 4km of strongly stratified sea water) – then
realized the relative scale of melt. The difference between average
NSIDC minimum extent and current (or 2007) melt is ~2e6 km^2; the area
of Massachusetts is 2.15e4 km^2. Yah think someone might have noticed
100 (give or take) Vesuvian scale eruptions, even if they were hidden
beneath the Arctic ice?
A mole! WHACK!!!

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Vision2020 Post: Ted Moffett