Earlier today in part1, I posted about the new record low claimed by NSIDC: Sea Ice News – Volume 3 Number 11, part 1 – new Arctic satellite extent record. The number given is 4.1 million square kilometers:
That of course is being trumpeted far and wide, new life has been given to Mark Serreeze’s “Arctic death spiral” in the media. But, here’s a curiosity, another NSIDC product, the new and improved “multi-sensor” MASIE product, shows no record low at ~ 4.7 million square kilometers:
Note the label at the bottom of the image in red. NSIDC doesn’t often mention this product in their press releases. They most certainly didn’t mention it today.
Another product, NOAA’s National Ice Center Interactive Multisensor Snow and Ice Mapping System (IMS) plot, also shows no reason for claiming a record at all:
Their number is (for 8/22) ~ 5.1 million square kilometers. (NOTE: NSIDC’s Dr. Walt Meir points out in comments that IMS and MASIE use the same base data, but that this one product from IMS only updates weekly, unlike all other sea ice plots which are daily. They should be in sync on the next update cycle, but right now MASIE and IMS should both be at 4.7 million sqkm. -A)
Another curiosity is here. On the NATICE interactive maps on demand page (click on Arctic Daily in the pulldown menu):
The numbers they give for 80% and marginal ice add up to an extent of 6,149, 305 square kilometers.
So who to believe? It depends on the method, and who thinks their method is most representative of reality. Measuring sea ice via satellite, especially when you use a single passive sensor system that has been show in the past to have degradation problems and outright failure (which I was told weren’t worth mentioning until they discovered I was right and pulled the plug) might be a case of putting all your eggs in one basket. I suspect that at some point, we’ll see a new basket that maybe isn’t so worn, but for now, the old basket provides a comfort for those who relish new records, even though those records may be virtual.
Note that we don’t see media pronouncements from NOAA’s NATICE center like “death spiral” and “the Arctic is screaming” like we get from its activist director, Mark Serreze. So I’d tend to take NSIDC’s number with a grain of salt, particularly since they have not actively embraced the new IMS system when it comes to reporting totals. Clearly NSDIC knows the value of the media attention when they announce new lows, and director Serreze clearly knows how to make hay from it.
But this begs the question, why not move to the new system like NOAA’s National Ice Center has done? Well, it is a lot like our July temperature records. We have a shiny new state of the art Climate Reference Network system that gives a national average that is lower for July than the old USHCN network and all of its problems, yet NCDC doesn’t tell you about the July numbers that come from it. Those tasks were left to Dr. Roy Spencer and myself.
In fairness though, I asked Dr. Walt Meier of NSIDC what he thought about MASIE, and this is what he wrote to me today:
It can provide better detail, particularly in some regions, e.g., the Northwest Passage.
However, it’s not as useful for looking at trends or year-to-year
variations because it is produced from imagery of varying quantity and quality. So the analyses done in 2007 have different imagery sources than this year. And imagery varies even day to day. If skies are clear, MODIS can be used; if it’s cloudy then MODIS is not useful. Another thing is that the imagery is then manually analyzed by ice analysts, so
there is some subjectivity in the analysis – it may depend on the amount of time an analyst has in a given day.
Our data is from passive microwave imagery. It is not affected by clouds, it obtains complete data every data (except when there may be a sensor issue), it has only consistent, automated processes. So we have much more confidence in comparing different days, years, etc. in our passive microwave data than is possible using MASIE.
Finally, MASIE’s mandate is to try to produce the best estimate they can of where there is any sea ice. So they may include even very low concentrations of ice <15%. In looking at visible imagery from MODIS, in the few cloud-free regions, there does appear to be some small concentration of ice where MASIE is mapping ice and our satellite data is not detecting ice. This is ice that is very sparse, likely quite thin. So it will probably melt out completely in the next week or two.
MASIE has tended to lag behind our data and then it catches up as the sparse ice that they map disappears. This year the difference between the two is a bit larger than we’ve seen in other years, because there is a larger area of sparse ice.
You can thank the big Arctic storm of August 4th-8th for that dispersal.
“The Great Arctic Cyclone of 2012″ effect on Arctic sea ice is seen in this before and after image:
Figure 4. These maps of sea ice concentration from the Special Sensor Microwave Imager/Sounder (SSMIS) passive microwave sensor highlight the very rapid loss of ice in the western Arctic (northwest of Alaska) during the strong Arctic storm. Magenta and purple colors indicate ice concentration near 100%; yellow, green, and pale blue indicate 60% to 20% ice concentration.
Credit: National Snow and Ice Data Center courtesy IUP Bremen
Trends -vs- records, just like July temperatures. One system might be better at trends, another might be better at absolutes used to determine records. In this case we have three other respected methods that show absolute values higher than that of NSIDC’s older method which they have a high confidence in. I suppose these systems are like children. In a competition, you always root for your children over the children of the other parents, so it is no surprise that NSIDC would root for their own well known media star “child” over that of NATICE’s IMS and NSIDC’s own lesser known child, MASIE.
Oh, and then there’s Antarctica, that other neglected ice child nobody talks about, with its above normal ice amounts right now:
No matter what though, its all just quibbling over just a little more than 30 years of satellite data, and it is important to remember that. It is also important to remember that MASIE wasn’t around during the last record low in 2007, and IMS was just barely out of beta test from 2006. As measurement systems improve, we should include them in the discussion.
UPDATE: Andrew Revkin reports on the issue in his Dot Earth article here
He’s a bit skeptical of the sound byte hype coming from NSIDC writing:
That’s one reason that, even with today’s announcement that the sea ice reached a new low extent for the satellite era, I wouldn’t bet that “the Arctic is all but certain to be virtually ice free within two decades,” as some have proposed. I’d say fifty/fifty odds, at best.
…
But is this a situation that is appropriately described as a “death spiral”? Not by my standards.
Revkin also takes Al Gore to task on Twitter:
help him out, retweet this
UPDATE2: Commenter Ron C. provides this useful information in comments that helps explain some of the differences and issues:
The main point is that NIC works with images, while the others are microwave products.
“Polar orbiting satellites are the only source of a complete look at the polar areas of the earth, since their orbits cross near the poles approximately every two hours with 12 to 13 orbits a day of useful visible data. This visible imagery can then be analyzed to detect the snow and ice fields and the difference in reflectivity of the snow and ice. By analyzing these areas each day, areas of cloud cover over a particular area of snow and ice can be kept to a minimum to allow a cloud free look at these regions. This chart can then be useful as a measure of the extent of snow and ice for any day during the year and it can also be compared to previous years for climatic studies.”
http://www.natice.noaa.gov/ims/snow_ice.html
“NIC charts are produced through the analyses of available in situ, remote sensing, and model data sources. They are generated primarily for mission planning and safety of navigation. NIC charts generally show more ice than do passive microwave derived sea ice concentrations, particularly in the summer when passive microwave algorithms tend to underestimate ice concentration. The record of sea ice concentration from the NIC series is believed to be more accurate than that from passive microwave sensors, especially from the mid-1990s on (see references at the end of this documentation), but it lacks the consistency of some passive microwave time series. ”
http://nsidc.org/data/g02172.html
Some have analyzed the underestimation by microwave products.
“We compare the ice chart data to ice concentrations from the NASA Team algorithm which, along with the Bootstrap algorithm [Comiso, 1995], has proved to be perhaps the most popular used for generating ice concentrations [Cavalieri et al.,1997]. We find a baseline difference in integrated ice concentration coverage north of 45N of 3.85% ± 0.73% during November to May (ice chart concentrations are larger). In summer, the difference between the two sources of data rises to a maximum of 23% peaking in early August, equivalent to ice coverage the size of Greenland.”
From Late twentieth century Northern Hemisphere sea-ice record from U.S. National Ice Center ice charts, Partington, Flynn, Lamb, Bertoia, and Dedrick
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1058&context=usdeptcommercepub
The differences are even greater for Canadian regions.
“More than 1380 regional Canadian weekly sea-ice charts for four Canadian regions and 839 hemispheric U.S. weekly sea-ice charts from 1979 to 1996 are compared with passive microwave sea-ice concentration estimates using the National Aeronautics and Space Administration (NASA) Team algorithm. Compared with the Canadian regional ice charts, the NASA Team algorithm underestimates the total ice-covered area by 20.4% to 33.5% during ice melt in the summer and by 7.6% to 43.5% during ice growth in the late fall.”
From: The Use of Operational Ice Charts for Evaluating Passive Microwave Ice Concentration Data, Agnew and Howell
http://www.tandfonline.com/doi/pdf/10.3137/ao.410405
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Just for grins, lets look at this situation the way scientists would have 35 years ago, before climatologists became perpetual government lobbyists mostly interested in trying to secure their grant-dependent paychecks (and when I was in graduate school). We have now a way to measure ice extent (NSIDC) that goes back a number of years, and for the last several years there is also a new and different way to measure ice extent (MASIE). The two methods disagree to the tune of around 0.6/4.1 or 0.6/4.7 — depending on what is chosen for the denominator — say, approximately, 13% to 15%. This is great, because now we can go back to all the past NSIDC measurements and put 13% to 15% error bars on them. Not only that, we can compare the MASIE and NSIDC measurements over the last few years and see whether their difference is mostly random, mostly constant (which suggests bias) or somewhere in between.
Of course scary ice-shrinkage graphs are going to look a lot less frightening with these sorts of error bars attached to the data points, so there’s no point holding your breath waiting for the science establishment to produce them …
“Why not ask an Eskimo?”
Well, for starters, because there aren’t any “Eskimo”–it’s a misnomer not used by the folks it is supposed to describe.
But perhaps this lady would fit what the questioner had in mind:
http://www.more.com/news/womens-issues/faces-climate-change-canada
The NSIDC methodology seemed good enough for the http://wattsupwiththat.com/2012/06/01/sea-ice-news-volume-3-number-6-sea-ice-outlook-forecasting-contest-for-2012-is-online/ with the “4.9 million square kilometers” for the ARCUS submission.
REPLY: But we aren’t allowed to compare to others and ask questions. Check -A
SHIZUKU Observation Data Acquired by AMSR2
July 4, 2012 (JST)
Japan Aerospace Exploration Agency (JAXA)
The Japan Aerospace Exploration Agency (JAXA) has released some observation images on the Earth acquired by the Global Change Observation Mission 1st – Water “SHIZUKU” (GCOM-W1). The SHIZUKU was launched from the Tanegashima Space Center at 1:39 a.m. on May 18, 2012 (Japan Standard Time) and entered into the A-train orbit on June 29, then has started regular observations since July 3, after increasing the antenna rotation of the onboard Advanced Microwave Scanning Radiometer 2 (AMSR2) to 40 rpm.
Figure 1 is a one-full-day observation image of the Earth by the AMSR2 aboard the SHIZUKU from 9:00 a.m. on July 3 (JST) to July 4. In this image, whitish-yellow color parts indicate areas with heavy rain or sea ice, light blue color areas are with little water vapor in the atmosphere or thin clouds, the dark blue color sections are areas with more water vapor in the atmosphere or thicker clouds, and the black color parts are areas that were not observed.
See http://www.jaxa.jp/press/2012/07/20120704_shizuku_e.html
The melting is great news, scientifically. This is the first time so much melts since we’ve had satellites to measure ice. So this means a wealth of interesting data to study in the years to come.
coeruleus says:
August 27, 2012 at 8:15 pm
“We could do a little something about it: oh noes! We will all suffer an economic fate at least one 20th as bad as the ’08 economic meltdown which occurred because we didn’t do anything about it! And millions of people will die because we feared what the alarmists told us!”
And what would you do about it? Erect tons of wind turbines and PV modules like we here in Germany and produce one percent of our primary energy consumption via these contraptions and feel very smug indeed about it? While spending 0.5% of our GDP in subsidies on all of this activity.
You think that’ll make a difference?
Come on. Only a near-complete shutdown of all civilization would make a substantial difference to CO2 emissions. Say, 80% reduction in energy consumption. Let’s talk some real numbers here.
You think that’ll have only a minor impact? In that case, I can only recommend you get better medication.
But we know what you really want, don’t we? You’d like to get your teeth into that half a percent of GDP in subsidies, who wouldn’t, and in return assure society that now everything is very fine and just on the right track indeed. We have many such crooks in my country, and they’re very successful.
Tez says:
August 27, 2012 at 5:13 pm
“There was less arctic ice for a period of over 400 years when the vikings were farming Greenland.
If this current situation continues for 400 years then I might start to get concerned. ”
Greenland, especially southern Greenland where the farming Vikings were, is not part of the Arctic Ocean where the floating ice (or lack thereof) being discussed in this post is located. I don’t recall reading anything about floating Arctic Ocean ice during the Vikings-farming-Greenland period. I would greatly appreciate a link.
————————————
Tez, you must be a long-lived alien for I’m fairly certain none of the rest of us expect to be around to share your concern in 400 years.
owl905 says:
August 27, 2012 at 6:08 pm
owl905 says:
August 27, 2012 at 5:15 pm
No, it was meant for you here. hth.
REPLY: Hope this helps…uh no, there’s still no Tony T. nor forecast you refer to. – Anthony
That’s about as swift as your IMS=MASIE responses. Go check your notes on how the funk in the Solar Cycles will put an end to the warming Tony. Or parrot another weak response, your choice.
REPLY: Ah, a smartass who speaks in tongues, noted for future bit bucketing. – Anthony
===================
Gosh dang it, Anthony.
Ever heard about leaving a morsel, for the troops to feed upon 🙂
.
“Today though, looking at the NSIDC extent graph, he [Mann] seems happy, declaring it ‘official’.”
I never understand the warmists. On the one side they say they are alarmed by the “catastrophic” global warming, but at the other side they are happy that the polar ice is melting. Now, what do those guys really want: warming or cooling?
RTFM! The primary thesis of the article makes no sense because you cannot compare the NSIDC extent numbers that are based on a 15% or greater ice concentration with the MASIE extent numbers because they are based on a 0% or greater ice concentration.
You can find the documentation for NSIDC here: http://nsidc.org/cryosphere/quickfacts/seaice.html.
You can find the documentation for MASIE here: http://nsidc.org/data/docs/noaa/g02186_masie/index.html
I tried finding a good definition for the IMS extent numbers, but I could not find that. If someone does find it, please post.
The extent numbers that include all ice down to a concentration of 0% will naturally be larger, so the differences in the data make sense. And the differences in their purpose also makes sense. So if you are navigating in arctic ice and want to avoid a Titanic event, you should use the 0% extent numbers, as that will help you avoid outlier chunks of ice. But if you are trying to represent the total amount of ice coverage, you should not let your numbers be distorted by outlier chunks of ice that could be many miles out in open ocean. Scientists have settled on the 15% number for this purpose, so the NSIDC values are appropriate. NSIDC’s numbers are also appropriate because they strive to provide a consistent method of measuring the ice over the entire 1979 to present period.
Jean, Mann’s mood is not described by any witness. It is interpreted by Anthony.
Regarding the fascination with sea-ice for warmists, it’s a two-edged sword.
On the one hand it is an indication – observable evidence – of what they fear and lament. It bothers them.
On the other hand, it is, for them, an easily observable, fast-moving metric that may wake the populace to the anti-CO2 emissions cause. It is also a thumb in the eye to skeptics that have been promising that 2007 was the year that would begin to see sea-ice rebounding back to previous levels; that recovery is nigh.
And I think for them there is a kind of morbid fascination with watching a train wreck in slow motion. Certainly for myself, the idea that I could see a North Pole free of ice within my lifetime – well, I’d be dead if it didn’t energise me in some way. This is an event that won’t have occurred in the history of human civilization, and perhaps not for millions of years, and it is on a grand scale. Rarer than a blue moon, and as big as a continent: the decline portends an awesome event, regardless of belief or otherwise in AGW.
Seems to me that IMS and MASIE (paired but different) are outliers in a general swathe of indices recording record melt already. And I believe IMS is still at the record low for this time of year, if not the total record.
https://sites.google.com/site/arcticseaicegraphs/
Clear record-breakers this year, already the lowest in their records and with more melting left to go:
Cryosphere Today – Area
DMI – Extent (>30%)
IJIS – Extent
NSIDC – Extent
Uni of Bremen – Extent
Arctic Roos – Area & Extent
The institutes in this list are looking specifically at long-term sea ice behaviour and are trying to refine their estimates to that end. NIC outlook and methods are not designed for that purpose.
Walt Meier :
“There may be some slight differences in numbers….”
If Walt thinks 0.4m KM is a “slight difference” then he should not have a job in a scientific discipline.
The question would have been what would MASIE have shown in 2007, presumably that would have estimated high also. I don’t see too much of a problem with continuing to use the passive microwave system they have as long as it is consistent from year to year. All these ways are not 100% of course. Ideally it would be nicer for the passive microwave to show a better more accurate result in summer though as summer is where all the action is.
If concentration is less than 15% then is that actually an ice field? Where is the dividing line between the ice edge and the sea which is full of icebergs? I guess that is open to debate.
I never understand the warmists. On the one side they say they are alarmed by the “catastrophic” global warming, but at the other side they are happy that the polar ice is melting. Now, what do those guys really want: warming or cooling?
DISASTER !!!!
From NickP on August 27, 2012 at 11:36 pm:
Seems you should follow your own advice. Read The Facts, Moron!
The info on the IMS numbers is found about halfway down the MASIE documentation page, which you should have noticed if you had actually read it. It’s the section titled “General Derivation of IMS Sea Ice Coverage at NIC”.
Note this description:
Got that? IMS marks off 4km cells as ice or no ice, using 40% coverage. IMS goes into MASIE. So while you whine about how MASIE extent numbers “are based on a 0% or greater ice concentration” you’re just showing off your ignorance. How can you get 40% coverage from 0% concentration?
mortis88 says:
August 27, 2012 at 4:16 pm
ummm, Philip, “begging the question” means that there is an obvious, unanswered question. Wiki is a horrible reference tool
My tuppence ha’penny worth, Pocket OED:1925, Petitio principii, begging of the question, from the Latin, begging of the principle! A classic example is as said previously, upon the discovery of the so called “hole” in the Ozone Layer, “how do you know it hasn’t always been there?” An important question so far unanswered in 50 years! Current data suggests this is a regular oscillating occurrence. Then again awkward questions of detail are best swept under the carpet, better to creat panic & fear instead, sarc off!
All I want to hear from Warmists is the following:
What is / are the cause(s) of the low extents since 1979?
Before you answer please consider the following for the Arctic:
* Air temperature
* Currents
* Soot
* Wind
And please let me know what the minimum extents were between 1800 to 1975?
http://noconsensus.wordpress.com/2009/06/16/historic-variation-in-arctic-ice-tony-b/
http://dx.doi.org/10.1016/j.quascirev.2010.08.016
http://adsabs.harvard.edu/abs/2007AGUFMPP11A0203F
http://geology.geoscienceworld.org/cgi/content/abstract/21/3/227
@ur momisugly Tez
Greenland, especially southern Greenland where the farming Vikings were, is not part of the Arctic Ocean where the floating ice (or lack thereof) being discussed in this post is located. I don’t recall reading anything about floating Arctic Ocean ice during the Vikings-farming-Greenland period. I would greatly appreciate a link.
This paper from Ribeiro et al does so.
Presently, the Baffin Bay southern sea-ice boundary extends from Disko Island to the southwest, towards Canada. This would imply that prior to AD 1250 this boundary was more northerly and gradually moved towards the vicinity of the core site until after AD 1500 (Little Ice Age), when it was positioned south of the core site.
http://notalotofpeopleknowthat.wordpress.com/2012/01/21/little-ice-age-coldest-period-in-the-last-7000-years-in-greenland/
Hooray I hate ice and cold, sooner its gone the better.
@Nick Pain
RTFM! The primary thesis of the article makes no sense because you cannot compare the NSIDC extent numbers that are based on a 15% or greater ice concentration with the MASIE extent numbers because they are based on a 0% or greater ice concentration.
Not according to the MAISIE documentation you quoted, which says
A cell is considered ice covered if more than 40 percent of the 4 km cell is covered with ice. The 40 percent threshold on ice demarcation for the IMS product is not directly related to 40 percent ice coverage estimated from derived passive microwave sources. At a 4 km2 resolution, several IMS cells fit within each coarser passive microwave derived sea ice concentration cell that are 12.5 km2 or greater. These IMS cells can reflect a mixture of areas with and without ice.
Interestingly it goes on to say
Furthermore, the use of visible and SAR imagery during summer melt seasons means that IMS product accuracy does not degrade as much as does the accuracy of products based solely on passive microwave data, when surface melt water attenuates the passive microwave signal. This microwave attenuation leads to underestimates of the ice concentrations, particularly along the marginal ice zone during the summer.
http://nsidc.org/data/docs/noaa/g02186_masie/index.html
Yeeeahh… just wake me up when subs surface.
D. Cohen says:
August 27, 2012 at 8:19 pm
Of course scary ice-shrinkage graphs are going to look a lot less frightening with these sorts of error bars attached to the data points, so there’s no point holding your breath waiting for the science establishment to produce them …
————————————–
The NSIDC Arctic Ice Extent graph at the top of this post normally has error bars for the 1979-2000 average included on the graph.
http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
For some reason Mr. Watts prefers to remove the error bars when he shows the graph in WUWT.
The first thing that everyone working in science understands is that we need comparable data. Really, it’s not a good idea to suddening change the method of collecting/calculating data after about 30 years. If the NSID did this, not doubt that scientists and skeptics alike would be up in arms complaining.
The BBC ran this yesterday and interviewed some Oxford ‘expert.’ He claimed that ‘they’ had forecast this for years. He also predicted zero ice in summer at sometime in the future. Where have we heard this before? However, there was no mention of differences between the various survey methods.