From the European Geosciences Union
New research suggests that Antarctic sea ice may not be expanding as fast as previously thought. A team of scientists say much of the increase measured for Southern Hemisphere sea ice could be due to a processing error in the satellite data. The findings are published today in The Cryosphere, a journal of the European Geosciences Union (EGU).
Arctic sea ice is retreating at a dramatic rate. In contrast, satellite observations suggest that sea ice cover in the Antarctic is expanding – albeit at a moderate rate – and that sea ice extent has reached record highs in recent years. What’s causing Southern Hemisphere sea ice cover to increase in a warming world has puzzled scientists since the trend was first spotted. Now, a team of researchers has suggested that much of the measured expansion may be due to an error, not previously documented, in the way satellite data was processed.
“This implies that the Antarctic sea ice trends reported in the IPCC’s AR4 and AR5 [the 2007 and 2013 assessment reports from the Intergovernmental Panel on Climate Change] can’t both be correct: our findings show that the data used in one of the reports contains a significant error. But we have not yet been able to identify which one contains the error,” says lead-author Ian Eisenman of the Scripps Institution of Oceanography at University of California San Diego in the US.
Reflecting the scientific literature at the time, the AR4 reported that Antarctic sea ice cover remained more or less constant between 1979 and 2005. On the other hand, recent literature and the AR5 indicate that, between 1979 and 2012, Southern Hemisphere sea ice extent increased at a rate of about 16.5 thousand square kilometres per year. Scientists assumed the difference to be a result of adding several more years to the observational record.
“But when we looked at how the numbers reported for the trend had changed, and we looked at the time series of Antarctic sea ice extent, it didn’t look right,” says Eisenman, who set out to figure out what was wrong.
Scientists have used satellite data to measure sea ice cover for 35 years. But the data doesn’t come from a single instrument, orbiting on a single satellite throughout this period. Instead, researchers splice together observations from different instruments flown on a number of different satellites. They then use an algorithm – the most prevalent being the Bootstrap algorithm – and further processing to estimate sea ice cover from these data.
In the study published in The Cryosphere, Eisenman and collaborators compare two datasets for sea ice measurements. The most recent one, the source of AR5 conclusions, was generated using a version of Bootstrap updated in 2007, while the other, used in AR4 research, is the result of an older version of the algorithm.
The researchers found a difference between the two datasets related to a transition in satellite sensors in December 1991, and the way the data collected by the two instruments was calibrated. “It appears that one of the records did this calibration incorrectly, introducing a step-like change in December 1991 that was big enough to have a large influence on the long-term trend,” explains Eisenman.
“You’d think it would be easy to see which record has this spurious jump in December 1991, but there’s so much natural variability in the record – so much ‘noise’ from one month to the next – that it’s not readily apparent which record contains the jump. When we subtract one record from the other, though, we remove most of this noise, and the step-like change in December 1991 becomes very clear.”
With the exception of the longer time period covered by the most recent dataset, the two records were thought to be nearly identical. But, by comparing the datasets and calculating Antarctic sea ice extent for each of them, the team found that there was a stark difference between the two records, with the current one giving larger rates of sea ice expansion than the old one in any given period.
If the error is in the current dataset, the results could contribute to an unexpected resolution for the Antarctic sea ice cover enigma.
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This research is presented in the paper ‘A spurious jump in the satellite record: has Antarctic sea ice expansion been overestimated?’ to appear in the EGU open access journal The Cryosphere on 22 July 2014.
The scientific article is available online, free of charge, from the publication date onwards, at http://www.the-cryosphere.net/recent_papers.html. *A pre-print copy of the paper is available for download at http://www.egu.eu/news/118/is-antarctic-sea-ice-cover-really-setting-record-highs/*.
The team is composed of Ian Eisenman (Scripps Institution of Oceanography, University of California at San Diego, USA), Walter Meier (NASA Goddard Space Flight Center, USA) and Joel R. Norris (Scripps).
In contrast, satellite observations suggest that sea ice cover in the Antarctic is expanding – albeit at a moderate rate – and that sea ice extent has reached record highs in recent years. What’s causing Southern Hemisphere sea ice cover to increase in a warming world has puzzled scientists since the trend was first spotted.
Just maybe their problem is the algorithm error is in the temperature data claiming a ‘warming world’.
We are missing the obvious, this is Climatology 101, as in good enough for government.
If the measuring method is too precise and yields up data that undermines the intended policy.
Destroy the measuring system.
Environment Canada has been a world leader since 1991.
Shame the meme of CAGW is so weak, that government has had to decimate almost all weather sensing systems.
I am suspecting the launch destruction of past earth sensing satellites has been a boon to the longevity of the CAGW Gong Show.
Antartica record high sea ice partially an artifact of an Al Gore ithm?
If the algorithm’s “problem” had lead to diminishment of Southern Ocean sea ice, it would have met global warmists biased expectations, and no further inquiry needed.
As it is, mainstream Climate investigators are struggling mightily to explain the Sea Ice “growth”…. just more evidence of Climate Science in crisis.
Arno Arrak summarizes a more comprehensive greenhouse theory in which water vapor loss asserts a negative feedback in a normal everyday way that avoids the Sky Dragon denial of any greenhouse effect itself based on paper napkin physics. This ought to be measurable directly though as actually decreasing vapor instead of the increase that climate models predict as a massive positive feedback. This may be oversimplified of a test if it is specific to certain layers or regions but without this support it just sounds like hand waving. I see Roy Spenser has been critical of this claim:
“Again…if Aa does not EXACTLY balance Ed, then Miskolczi has found NOTHING that departs from the fundamental mechanism of the greenhouse effect.
ADDENDUM…his additional finding of a relatively constant greenhouse effect from 60 years of radiosonde data (because humidity decreases have offset CO2 increases) is indeed tantalizing. But few people believe long-term trends in radiosonde humidities. His result depends upon the reality of unusually high humidities in the 1950s and 1960s. Without those, there is no cancellation between decreasing humidity and increasing CO2 as he claims.”
http://www.drroyspencer.com/2010/08/comments-on-miskolczi%E2%80%99s-2010-controversial-greenhouse-theory/
Six month ago I read: Antarctic rescue ship now stuck in ice
I though Antarctic ice expansion was part of AGW (due to increased precipitation) Well OK they have changed their minds AGAIN LOL
Bill Illis says:
July 22, 2014 at 9:13 am
The Anatarctic sea ice has extended right past the South Sandwich Islands. Real images tell the story. Yesterday’s Modis pics.
As is normal between May and November.
Phil, go to Bill’s link and flip between this year and last year (same day…it’s pretty cloud free in that area, both dates, at least around the largest island)…
http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.0020124
One thing that you can be sure of is that research, scientists, governments and other similar organizations cannot be trusted most of the time.
The goal/agenda as well as cognitive bias’s determine results/conclusions and statements.
This has turned out to be the rule rather than the exception in recent decades.
How does one know what to believe and what not to believe, especially if one is not an expert in the field?
Usually people will believe whatever supports what they think they know and discard whatever contradicts it. This is why we have extreme polarization in climate science, even as new information pours in.
The world is being run by white collar psychopaths that understand this. They use appealing propaganda and marketing schemes to capture as many people as possible.
We see all the commercial ads on television and elsewhere. This is just an extension of that using a different realm and technique but the same principle to brainwash people to believe things.
“Mary Brown says:
July 22, 2014 at 11:45 am
Why can’t you just snap a picture and count the area that is white ? I’m serious. All we are looking for here is areal coverage.”
Because you will get pictures of clouds.
There are several data sets.
data from frequencies where you can look thrugh the clouds
visible light datasets
IR datasets
Mary Brown says: “Why can’t you just snap a picture and count the area that is white ? I’m serious. All we are looking for here is areal coverage.”
Nice idea in principle, but probably not so goo in practice.
Your suggestion probably assumes a clean cut edge of the ice sheet which can be photographed at high altitude and mapped. We’d tot-up the ice sheet within the mapped line.
But then, think about glaciers calving into the sea. They don’t have a nice clean cut edge, but a mass of icy “rubble” and slush. Same goes for large parts of the polar ice sheets. And possibly more so during summer retreat (although I’m not so sure on that one).
Do we count the edge as the region of sea with vanishingly small ice floating around (e.g. <1% ice coverage)? Probably not, because we'd count vast swathes of open sea surface as ice – it just wouldn't be credible.
Likewise, we wouldn't count the edge as the start of a region with totally solid ice (100% coverage), because we'd fail to count large regions of ice.
There is no right or wrong answer. It needs a judgement call. Something like 15% ice coverage. This is probably regions of ice chunks surrounded by a slushy water-ice mixture at the edge of the ice sheet. But could be pockets of regions inside the main body of the ice sheet.
Even then, it will not be easy to determine a line to be counted on one side, and excluded on the other. High altitude pictures will lose detail and this will introduce errors. A low altitude survey of the ice sheet would take time to complete, and this would cause errors too as the early observations would be out of date compared to the later.
Not that I'm an expert – just thinking out loud on an interesting question.
“evanmjones says:
July 22, 2014 at 11:29 am
Unfortunately for these researchers, there is no visible step in the Antarctic sea ice anomaly circa 1992. In fact, the graph is unusually flat during this period. On the other hand, starting around 2011, the graph shoots up at an uncharacteristically high rate. The error they describe cannot have produced this.
Good question that deserves a good answer.
And we have the actual images, right? Why can’t we just use those to figure out what is going on here?
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you have cloud free products but generally speaking when you work with a cloud free product you have to handle how to estimate with missing days ( when clouds are present)
but that data product is out there.
get to it
Has the land/ice shelf mask changed over time? The Filchner/Ronne ice shelf is continually losing large bergs – does the algorithm they use to determine sea ice use a fixed ice shelf or does it track the changes to the extent of the ice shelf? Less ice shelf = more sea ice area (if the changes are tracked).
In 1991.77 NSIDC shows sea ice north of South Georgia but the extent in 1991 was unexceptional and sea ice has not got that far north recently:
” Eisenman is skeptical of the data and I believe it’s a good thing.” – Matt L.
Absolutely, but doesn’t justify being biased. – Johan
Johan, you’re right, of course, although erasing bias is a tall order. Ambrose Bierce wrote:
“Impartial – unable to perceive any promise of personal advantage from espousing either side of a controversy.”
Politics distilled is simply how we relate to each other. We are all politicians. The world is not changed by impartial politicians. And that is why access, transparency and reason are fundamental to freedom.
When things are done in secret labs, behind closed doors and info is doled out on a “need to know” basis is when I worry.
(The troublemaker in me wishes the BBC would lead with a headline like:
Climate science team skeptical, finds serious flaws in IPCC reported data)
H/T to John Bills for the YouTube above 🙂
description
http://nsidc.org/data/docs/daac/bootstrap/index.html
“Under ideal winter situations when only thick ice and open water are present, ice concentration can be derived with Bootstrap technique at an accuracy of about five to 10 percent, based on standard deviations of emissivities as used in the formulation. Errors are higher in the seasonal ice region than in the central Arctic region because of higher standard deviations of consolidated ice in the 19 vs 37 GHz plots. This is partly because of spatial changes in surface temperature that are not as effectively accounted for by this set of data.
Constantly changing emissivities of some surfaces present unresolved problems. For example, when leads open up during winter, the open water is exposed to the cold atmosphere and grease ice quickly forms at the surface. The surface then metamorphoses from grease ice, to nilas, to young ice and then to first-year ice with snow cover. During these transitions, the emissivity of the surface can change considerably from one stage to another (Grenfell and Comiso 1986). Since such changes in emissivity are not taken into account in ice concentration algorithms, the derived fractions of open water are therefore not strictly those of open water and may include some mixtures of grease ice and new ice. In spring and summer, the emissivity of thick ice also changes with time, especially over the perennial ice region in the Arctic. The slopes and offsets of the consolidated ice line AD in the scatter plots are adjusted to automatically take this into account during onset of spring in June; original values should be restored during winter freeze-up. Despite this adjustment, the error is still substantial and can be larger than 20 percent due to spatial variations in melt and affects of meltponding.
Several field and aircraft experiments have been performed in both polar regions and in some of them the basic assumptions about ice types and interpretation of the cluster plots have been confirmed. However, validation of satellite ice concentration data using data from these experiments has not been easy. Field data are difficult to use because of limited coverage compared with the large footprint of the satellite sensors (about 30 X 30 km). While generally easier to interpret because of fine resolution and availability of ancillary measurements, aircraft data are useful but need to be validated by ground measurements.
Another strategy has been to utilize high resolution satellite (or space shuttle) data for validation. While the use of high resolution data has its advantages, such strategies degenerate into comparative analysis because the other satellite data also need to be validated. For example, unambiguous discrimination of open water, grease ice, small pancakes, and gray nilas in both visible and microwave channels may be impossible even with high resolution sensors. Generally, however, the passive microwave data provide valuable information about large scale characteristics of the ice cover as well as locations of ice edges, polynyas, and extensive leads. It is, however, useful to note that some of the comparative studies yielded high correlation coefficients.”
I love the snark on this thread from people who have never turnedd a page or lifted a finger to understand the complexities.
You actually become a BETTER skeptic the more deeply you understand an area.
ask Anthony
ask Mcintyre
ask Willis
What do all three have in common.
They read before they write.
They get the data
When they present arguments they have code and data
In so many areas of climate measurement, the noise is the same order of magnitude as the signal.
I always think of that when I watch waves crash onto the beach and remember than we use “mm per century” for sea level changes.
Great post Steven on the complexities of measurement.
Just a wild, kinda out there ‘thought’ – but isn’t all this suggesting a big climb down from the ‘science is settled’ meme? In a ‘let down gently’ kinda way, piecemeal, with revelations of errors (in the algorithms/models/whatever) and such like, gradually over a period of time, but its an error which is in their favour! LOL? Ok, perhaps, I am being a little too conspiratorial but I do think that there will be a gradual climb down and change of emphasis somewhere in the not too distant future.
They have tried various memes already e.g. (heat in the deep oceans, etc) but seemingly still NEED to press on with their agenda (if there really is one?) in order to continue their taxing regime? I don’t know – to be honest I have had enough of the crap AGW ”science” (the vast majority of which would NEVER have passed muster 30 years ago!), the crap political ‘bent’ to everything related to AGW, the loss of weight to real and important green agendas, the waste of resources, even in simple cash terms of AGW (think how many boreholes for clean water could have been drilled with that money?) etc – all in all – I am truly disgusted with the system, the governments and the climate scientists for not upholding the scientific method. oh poop – sorry – I went on a bit….. /rant off
steveta_uk says:
July 22, 2014 at 9:55 am
“does a thermometer measure temperature?”
Yes. I simply define temperature to be the thing that a themometer measures. Q.E.D.
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what ever you say humpty dumpty
then I define that sea ice extent is whatever the data processing system says it it. QED
Well, this does not appear to be a garbage study for PR purposes like Lovejoy’s or Lewandowsky’s.
However, you know that they would not be doing the study if the data showed a decrease in ice extent.
Steven Mosher says:
July 22, 2014 at 12:49 pm
Steve, matey – you are absolutely right ! – but perhaps you are missing the golden nugget in all this – which is that they should have proven the measurement and data analysis regime WELL before NOW!, (in this case, the alleged expanding ice mass) or else they look like a bunch of complete and utter twonks! Ergo, some boneheads produce a mish mash of algorithims for ice analysis, USE them for 30+ years – (PROMOTING them to the WHOLE world!) then someone turns round and notices they might have been wrong!?? FFS – who peer reviewed the original processes – a frigging blind drunk undergrad? – and let me guess the next move – we go back and ‘adjust’ the data for this and that, blah bloody blah!…….’cos that will make it all better, wont it? – sound familiar?
” Both records are monthly mean anomalies from the 1979–2004 mean seasonal cycle. T”
Ice extent and area are produced as DAILY data since 1988. If they are looking for a glitch they should look at “unsmoothed” data. There is also the “NASA TEAM” algo , what does that say?
Just saying that BOOTSTRAP is “most prevelent” means they are aware of other but are not looking at what they tell or, perhaps more likely, not reporting it.
They also don’t report on how this affects Arctic sea ice data. That is a very curious omissions since the same satellites and algos are used for both.
Isn’t such failure to report generally frowned upon and regarded as a form science frawd [ avoiding the F-word 😉 ]
The increase in Antarctic sea ice has been a thorn in the warmist side for quite while. It looks like yet more convienient revisionism to cast the data as being unreliable.
http://nsidc.org/data/docs/daac/bootstrap/index.html
OH furchrisakes , here we go again. Isn’t there anyone that knows that if you do linear regression on a scatter plot you get the wrong figgin answer?
http://climategrog.wordpress.com/2014/03/08/on-inappropriate-use-of-ols/
SAY! Long-range drones could do this work. Their bases could be on nearby land (e.g., Tierre del Feugo (sp?) and islands south of New Zealand). Even if a few were lost, that cost would be bearable. Even if coverage weren’t 100%, they would be able to provide enough corrective feedback from their sample to enable the satellites’ observations to be interpreted correctly.
Drones could also be used to get a better and fuller count of wildlife in polar regions. And spot emerging pingos as they happen. Climate science is awash in money. This wouldn’t take a high percentage of it.