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).
There they go again Rewriting history. If you don’t like the past just change it.
MikeUK says:
July 22, 2014 at 10:48 am
Eliza beat me to it, Arctic Ice reduction is a favourite meme of the Planet Savers, except that the reduction appears to have stopped in 2007:
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.arctic.png
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“Appears to” would being the operative word. In fact it’s pretty unclear from thier graph what is happening since 2007 because the annual variation is much larger and the “anomaly” method is pretty uninformative.
That is why I did this study using an adaptive method to remove the annual variability. It becomes much clearer what is happening:
http://climategrog.wordpress.com/2013/09/16/on-identifying-inter-decadal-variation-in-nh-sea-ice/
The decadal trend has dropped considerably but has not “stopped” since 2007.
That article was featured on Judith Curry’s too.
That pretty much kills off the idea of run-away loss in the Arctic. Once you’ve reached a “tipping point” you don’t slow down for a bit on the way down. It’s ever faster.
This disproves the idea of run-away melting, once and for all
Again send a research ship out there and let them sail around the edge of the Antarctic Sea Ice and record the extent of the Sea Ice. If we can fly to the moon surely we can send a research ship to measure the extent of Antarctic Sea Ice.
I am quite sure it will agree with cryosphere today data. This would put an end to this latest nonsense.
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Steven Mosher says: July 22, 2014 at 12:49 pm
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
They also have something else in common. They write the actual blog articles.
So that others can learn from them, argue with them, provide additional information, point out potential mistakes, share some of their own expert knowledge, etc.
speculative model of Arctic change since 2011
http://climategrog.wordpress.com/?attachment_id=972
In this look at the duration of arctic and antarctic melting seasons, there is a notable ( though not unique ) deviation in the two:
http://climategrog.wordpress.com/?attachment_id=965
Both were springing back from a very short melting periods in 1989. Artic, being more volatile responded fastest. this does not seem abnormal.
I don’t know whether the Cryo Today data set I used for that uses Bootstrap since their documentation is virtually non existent and they ignore requests for explanations or doc.
They prefer to focus of pretty pics and alarmism than science.
“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
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GISS has the same problem. because two sensors give different readings, they assume only one of them is wrong, and adjust that one.
earth to climate science. just because two sensors give different readings doesn’t mean one is right and the other is wrong. they can both be wrong, or both could be right. no instrument is exact, nor is the operator.
for example. one sensor reads 11.0+-0.5, another sensor reads 12.0+-0.5. Both sensors are reading correctly and neither is wrong. another sensor reads 11.0+-0.5. GISS says this makes the 12.0+-0.5 sensor wrong, and adjust this to 11.0+-0.5 to match the other 2, but this adjustment itself is wrong. All three sensors were reading correctly and there was no reason to adjust, except to satisfy confirmation bias.
This graph of the rather surprising similarity between Antarctic ice and Arctic oscillation, suggests melting season was longer than would be expected by this ( speculative ) correlation.
http://climategrog.wordpress.com/?attachment_id=208
If you look carefully, the trends for AR4 and AR5 agree within experimental error: 5,600 ± 9,200 km2/yr vs 16,500 ± 3,500 km2/yr. The longer record and the clear increase in sea ice since 2007 allowed the authors of AR5, but not AR4, to conclude that the increase in sea ice was significant. No discrepancy has been found. Even if a discrepancy had been found, trends don’t have to remain the same when it has been reassessed over a longer period of time.
If you look at Figure 1B, both Version 1 and Version 2 of the algorithm a large positive trend in Antarctic Sea Ice: 16,500 ± 3,500 km2/yr for Version 2 and about 10,000 km2/yr for Version 1. Since the natural variability/noise in both records is similar, the confidence interval will be similar. Changing to Version 1 wouldn’t change the IPCC’s conclusion that there has been a significant increase in Antarctic Sea Ice. Version 1 does give a smaller trend, but it is still significant. However, the politicized scientists who wrote this paper conveniently forgot to mention this fact.
Don’t we rely on the same sensors and algorithms to detect changes in Arctic and Antarctic Sea Ice. Why didn’t these researchers look for breakpoint in the data for both locations?
” Frank says:
July 22, 2014 at 2:31 pm
Don’t we rely on the same sensors and algorithms to detect changes in Arctic and Antarctic Sea Ice. Why didn’t these researchers look for breakpoint in the data for both locations?”
Because only one region’s facts fit the theory…(and it ain’t the one that’s getting more ice).
The Ship of Fools was not a one off outbreak of Antarctic insanity it seems, even the algorithms have caught the disease!
Oh what a freaking joke these self important, self promoting people are. Pixie people in the back yard pracitising their pirouettes trying to impress the adults.
Is it just a coincidence that this paper is released just as there is an uncharacteristic fall in the Antarctic sea ice anomaly?
When will these people realise if you change the method of measurement then you are no longer doing a comparative test with previous results you have changed the conditions of the experiment.
Mosher says I should read more. Well, I did read the whole paper. I also read section S1.3 of it’s supplemental information document, and I perused the rest of the supplemental info. I read the paper from which S1.3 takes many of it’s cues, “Enhanced Sea Ice Concentrations from Passive Microwave Data” by Josefino C. Comiso, NASA Goddard Space Flight Center. This paper discusses the Bootstrap model referred to in the first paper. Keep in mind that I’m not criticizing the Bootstrap models per se, only the formality and record keeping of their provenances, the inadequate provenances of datasets they spawned, and that the study chose the latter over the former as the best way to study sea ice extent changes.
I particularly remembered reading this passage from the first paper, which joins me to the authors, editors and peer reviewers in the crime of inadequate reading:
That seems pretty clear, and pretty unfortunate at the same time. Is there anything else you think I should read that would make this shit sandwich taste any better, Steve?
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 –
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and together we have a record high…….and they expect someone to keep reading after saying that
..so what’s new
All they are saying is that all the ‘science’ that’s been shoved down our throats for the past 30 years….
…was wrong again
” tim says:
July 22, 2014 at 2:57 pm
When will these people realise if you change the method of measurement then you are no longer doing a comparative test with previous results you have changed the conditions of the experiment.”
Never.
re Arno Arrak says: (July 22, 2014 at 10:12 am). I’m interested in your comment, but it raises questions. You say that the warming effect of CO2 is balanced by the reduction of atmospheric water vapor. I would be grateful if you could explain this in a bit more detail. My understanding is that increasing temperature leads to increasing ocean evaporation and hence more atmospheric water vapour (Clausius-Clapeyron; ~6-7% per deg C), not less. So yes, it does rain more, but there is an increase in the whole hydrological cycle, including an increase in atmospheric water vapour, not a net reduction.
This is too much like: “The data do not agree with our model so the data must be wrong.”
I am confused, how come you are not required to understand how things work before you comment on them?
http://www.populartechnology.net/2014/07/nasa-and-usgs-does-not-know-difference.html
Why should anyone take advice from someone who does not know the elementary difference between Windows ME and Windows 2000? Yet feels compelled to post “tutorials” on their ignorance?
Sounds like some of the $1bil/day spent on the whole AGW scam needs to be diverted to some serious “homogonization”.
An article on Yahoo actually consulted with Comiso to get his view.
“The apparent expansion is real and not due to an error in a previous data set uncovered by the Eisenman et al paper,” that scientist, NASA’s Josefino Comiso, wrote in a response to the new study that he sent to Live Science. “That error has already been corrected and the expansion being reported now has also been reported by other groups as well using different techniques.”
Comiso agrees that a change in the Bootstrap algorithm introduced bias into the data. However, he contests the new findings, which are published today (July 22) in the journal The Cryosphere. The changes made in 2007 improved the algorithm and corrected problems, he told Live Science. The satellite data, updated using this correction, shows large increases in Antarctic sea ice, and other groups who have examined the data using different techniques have come up with similar findings, he said. In other words, Comiso believes that version two of the dataset, adjusted after 2007, is correct, reflecting a real increase in Antarctic ice, and that the error was in version one.
“The sea ice extent showed basically no trend in the earlier period because the inter-annual changes in extent were more uniform and the errors were large,” Comiso said. In recent years, he said, the longer record and better quality control has yielded a more trustworthy dataset — and one that shows more extensive ice cover.
“The trend in extent in the Antarctic sea ice has been shown to be positive in different publications,” he said. “It is even more positive now than ever, and the Eisenman et al paper is providing a misinformation instead of a resolution.”
But the rest of the global ice data is correct and that stupid idiot didn’t get stuck in his ship at Christmas. Bloody lying pack of ideologue dogs. They are fiddling everywhere to spin AGW, as for those who say “why would they do that?” Two words
Lois Lerner
It is rotten to the core. I would only say this by way of explanation: In the past kids were inspired to become part of NASA for the excitement of Space Travel. Now all the recruits are ideologue’s who pray and pray that AGW is real . Have you ever noticed how these people instead of cheering for say the global temperature pause they seem rather disappointed by it ; they actually want AGW to be real and all the dire predictions as well. These people are insane.
So the algorithm for assessing the Antarctic ice extent is wrong if we are to believe these pseudo scientists.
Which then raises the subject of the veracity or all those innumerable algorithms used by the alarmist climate scientists.
If the Antarctic ice algorithm is wrong then the Arctic ice algorithm will be wrong as will the Greenland ice cap algorithm
Then we have the sea level algorithms with one of those algorithms programmed to add a spurious invented 0.3 mms per year to sea level rises [ which are now known despite past algorithm based claims to be all over the place ] to compensate for isostatic rebound in ocean basins.
The sea surface temperature algorithms which still haven’t got it any where near right.
The deep ocean ARGO based algorithms that calculate changes of a hundredth of a degree some 2000 or more metres down in the ocean deeps [ Yeh! Right ! ]
Then there are the hurricane / typhoon / cyclone predicting algorithms,
The failed useless algorithms for predicting the ENSO which a few months in advance they can’t predict if there will be an ENSO event.
A couple of months out and they can’t predict if it will be an El Nino or a La Nina .
A few weeks out and they can’t predict how strong it will be .
A week out and they can’t predict when it will actually start.
And when it does start they find they have got about every prediction wrong in any case.
And then of course the algorithms upon which the entire claims for CAGW lay ,
Those algorithms that daily adjust, infill, estimate, smear, zombie, homogenise, corrupt the national and global temperature data, both long gone 100 year old historical data and the current data to the point where nobody actually knows anymore if the claimed publicised temperatures have any relation with reality.
Or whether those algorithm generated temperatures should be at all trusted in any way let alone using that algorithm corrupted temperature data to formulate policies that costs hundreds of billions of dollars to implement, that destroy entire industries, that raise energy prices to unaffordable levels for the low income earners and create dissension and destroy the societal trust in political and scientific processes.
Climate alarmist science and it’s advocate scientists depend entirely on models and algorithms to shape and change the data to fit their dogma and promote their cause.
The models are wrong without a doubt.
And now when one algorithm that outlines a situation that doesn’t agree with the CAGW meme is slated as being wrong then every single algorithm so beloved of the CAGW believers must also be seriously classed as being wrong as well.
But as said above, this after all is claimed to be a science called “climate science”
“I love the snark . . . ”
snark – a very common characteristic of:
Barack Obama
Albert A. Gore, Jr.
…
long list follows
…
Joseph R. Biden, Jr.
John F. Kerry
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Steven Mosher has provided very good comments here. Thanks.
Stupid reality… gets in the way every time.
I’ve learnt over the years that scientific papers get published in climate science not because they have scientific value but because they apparently create useful talking points. So a paper gets published that suggests an error has been identified but it hasn’t been quantified yet nor are they sure how it should be resolved. Imagine a paper of this quality getting published in any other field. I can’t.