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).
Removing any step change in 1991 would do nothing to change the increasing trend in recent years. If the newer data were modified to a lower level by subtracting out some value, the same increasing trend would exist, but at a lower starting point. And the same question would remain – namely why is Antarctic sea ice increasing.
The data is correct . What they don’t like is the data does not support their claims that Antarctic Sea Ice is not on the decline.
Just more BS about changing the data if it does not agree with what you want.
” … It does not instill confidence that the article is reliable.”
Anytime one sees a modern “paper” or article where the subject matter is climate “science” then one should assume that the paper is unreliable at best and duplicitous at worse. There will be the occasional exception (just like a comment once in a great while by Mosher is worth reading) but one bets on the paper being junk.
Look friends, we are well past any pretense that honest science is going on. This blog, Goddard’s blog, JoNova’s blog, and a score of others have been chronicling the fall of any pretense of honestly for a long time now.
The Anatarctic sea ice has extended right past the South Sandwich Islands. Real images tell the story. Yesterday’s Modis pics.
http://1.usa.gov/1jTvFjP
The change shown in the graph is on the order of 0.1 x 10^6 km^2, whereas the actual values for sea ice area are on the order of 10 x 10^6. which explains why the error is invisible in the 1991 graphs. The current ice anomaly is over 1 x 10^6 so expect to see no change if they retroactively fix the error.
I have no idea where they get the idea that the error caused “a step-like change in December 1991 that was big enough to have a large influence on the long-term trend” because there is no visible step-like change in 1991.
https://weather.gc.ca/saisons/sea-snow_e.html
This data clearly shows that the ocean waters adjacent to the Antarctic Sea Ice and for that matter much of the ocean waters south of 40 degrees South Latitude are BELOW normal.
This data supports the extent of Antarctic Sea Ice.
I suppose this data will also be considered to be wrong since it does not support AGW.
I remember a research ship got stuck in Antarctic Sea Ice last year. Maybe that did not happen either.
http://i2.photobucket.com/albums/y48/mikeishere/noshseaice.jpg
“bit chilly says:
July 22, 2014 at 9:00 am
here is an idea,stop using algorithms and satellites to measure things that can be physically measured ,time and time again it is shown that the method does not work,with the added possibility of confirmation bias.”
try to use a ruler to measure the distance to the moon
try to use a scale to weigh the sun
We “measure” many things by in direct methods.
For example, we might measure the speed of sound by measuring distance and time.
And then we apply an algorithm to derive speed.
Answer this. what can we measure directly?
or try this.. does a thermometer measure temperature?
“On July 1, Antarctic sea ice extent was at 16.16 million square kilometers (6.24 million square miles), or 1.37 million square kilometers (529,000 square miles) above the 1981 to 2010 average. More notably, sea ice extent on that date was 760,000 square kilometers (293,000 square miles) higher than the 2013 extent for the same day, and thus is on pace to possibly surpass the record high extent over the period of satellite observations that was recorded last September.”
http://nsidc.org/arcticseaicenews/
“If”‘, “could” says it all.
But It must be true the ‘ship-of-fools’ got stuck in ice didn’t they?
Wait a second!
Fodder feed for the MSM in the hope they will draw a definite conclusion without noticing its just speculation. More BS for the chickens.
“So when they say they use Bootstrap “to estimate sea ice cover from these data” it does not make sense to me. I does not instil confidence that the article is reliable.”
Thanks because you have not read the literature.
read first, comment later.
Start with the platform they are using.
Then read the documents about the sensor
Then read the ATBDs assocated with the data.
Then read the software descriptions and the validation and calibration plans and reports.
Then read the science papers
Then download some data and look for yourself
Then you are in a position to make intelligent comments.
Do you think Anthony or steve mcintyre got to their level of understanding by reading blogs?
Nope. they rolled up their sleeves. They put on their reading glasses. They dove in.
Think of where the skeptical side would be if more people did what they did.
This is one of the simplest and bulletproof measurements of all time, just a white pixel count in a satellite image. You can quickly do this in Photoshop. Just look at the various images of Antarctica to see how simple the coverage is compared to the rapidly dynamic Arctic, since the continent is surrounded by both wind and ocean currents that are steady in a circle around it rather than constantly in flux. The source images haven’t changed. The contract between sea and ice is striking. There is nearly no land. There isnt even any statistics required or considerstion of thickness at all in ice *extent*. This article is agenda laden, especially the laughable uncertainty of which algorithm is “wrong” that gives the whole paper the character of a preliminary blog post. Then an hour after being posted here, multiple commenters note how magnified the scale is compared to the profound claims being made. The whole field of climate “science” is setting themselves up for a big fall by doubling down on bias in a way that becomes dumbed down too, enough to trigger the BS detectors of many a layperson in a way that spells fraud. A child’s science project might be to calculate the sea ice extent from the satellite pictures by cutting out the paper outline of each fifty two weeks of each year and weighing them on a milligram balance. It only takes a rocket scientist to obtain the images. The rest is child’s play. The whole article uses a little glitch in *extent* to grab headlines with a soundbite wheras the real uncertainty is in much more important ice mass due to land changes happening too. Altimetry says the ice is rising enough to grab half of what Greenland is losing, but a crack team of nearly fifty authors claimed this was due to rock lifting the ice up as it actually was itself thinning, like some alien monster movie scenario.
“Not only should the data sets have version control, but the algorithms that generate those data sets should be version controlled and thoroughly documented as well. I’ve long railed for these kinds of improvements to science in the internet era. I know this is a big issue for Steve McIntyre, too. Science, like real estate has three fundamental demands to insure best value. Replication, replication, replication.”
Go look at the documentation that exists.
you know. read.
Steven Mosher says:
July 22, 2014 at 8:04 am
“C.M. Carmichael says:
July 22, 2014 at 6:07 am
So much for settled science, they can’t even agree on the math.
1. Talk to Roy Spencer about the difficulties in stitching together various sensors. UAH has
gone through numerous versions as Spencer and Christy try to figure out the best
set of ADJUSTMENTS to the raw sensor data. Sensors change. Platforms change,
2. Talk to Leif about the difficulties of stitching together various sensors measuring TSI
3. Talk to Leif about the difficulties of stitching together a resonable sunspot record from
many different observers using different counting techniques, changes in counting
methods and changing instruments.
4. Talk to Anthony. His latest paper uses series where the raw data has been corrected for
changes to instruments. .
Sensors in space do not measure temperature. They dont measure ice extent or area.
They measure brightness at the sensor at various frequencies. Those raw voltages are then
processed by models to create estimated “data” which try to represent things like temperature
of ice extent. The sensors change over time. The algorithms change.
People do agree on the math. 2+2 = 4. But when it comes to turning a raw voltage at the sensor
to a physical property… that’s more than simple math. It typically involves a physics model with
many assumptions.
IF THIS THE STATE OF CLIMATE SCIENCE THEN THEY DON’T HAVE THE SLIGHTEST AUTHORITY FOR DIRECTING PUBLIC POLICY. Basically, It’s CRAP.
“This is an easy theory to test. Use the old algorithm to reprocess the records from 1978 to present. Then use the new algorithm over the same time period. ”
go read the ATBD and the literature.
then you will be in a position to suggest diagnostics.
From the article above:
And, from
Michael D says:
July 22, 2014 at 9:22 am
Small comment: The “blue zone difference” – it may not be “an error” at all! – varies slightly over a decade. The difference starts small (less than 0.05 negative, then increases to 0.12 negative, then reduces again back to about 0.05 negative. There is an abrupt change – as the “scientists” claim! – at 1991, then the “red zone difference” remains almost straight CONSTANT level at 0.065 from 1991 through today 2013 -when their data run stopped. .
Thus, if we look at the past 22 years (2013 – 1991) we see NO CHANGE in this difference between the results of the two programs. Thus we do NOT need to change data for any period since 1991 when talking about Antarctic sea ice trends since 1991!
These climate “:scientists” are so desperate to apply the near-linear increase in CO2 with time since 1959 to ANY and ALL “climate time streams measured since 1959 ” MUST use a linear average across the entire data set to begin their talking points.
But that steady change in this data report did NOT occur. A single step change of very small amount may have happened in 1991.
As Micheal D pointed out: The steady increase in Antarctic sea ice anomaly is now 1.0 million sq km’s – and was more than 2.0 Mkm^2 only a few days ago. Its steady INCREASE extends back to 2007 as a positive: Reducing that 2.0 positive anomaly to 1.9 Mkm^2 will NOT change the trend. Thus, “IF” a correction is needed, the current antarctic sea ice anomaly was more than 2.0 Mkm^2 a few weeks ago – much more than the “correction to the data itself” of 0.1 from negative to positive in 1991.
But it is even worse than they think (for their “religious conviction” in their Cause.
Today’s Antarctic sea ice increase has been a steady, near-linear increase since 2007. Regardless of any step change occurring in 1991-1992 data, a long-term, steady, near-linear INCREASE of Antarctic sea ice now approaching seven years in length is NOT going to change when they apply a correction to data in 1991. Their precious faith in CO2 cannot be explained by such a long increase in Antarctic sea ice – thus, they (1) ignore Antarctic sea ice, and (2) will attempt ANYTHING to reduce the reported extent and demean confidence in their own measurements of that extent!
I don’t know these men and women by name – but I question their conclusion deeply: They have made up their minds, and will continue to promote their Faith regardless of the facts before their eyes. If they could permit themselves to be called “religious” they would be admirable in their Faith.
But as self-promoting “objective scientists”, they are despicable.
Chalk me up on the side that says it’s only ‘noise’, faulty models or bad Al-Gore-ithms when it doesn’t support their mantras.
“does a thermometer measure temperature?”
Yes. I simply define temperature to be the thing that a themometer measures. Q.E.D.
Then we had this little gem from the Cryosat 2 team which was ignored by most of the MSM…
ARCTIC SEA ICE UP FROM RECORD LOW
http://www.esa.int/Our_Activities/Observing_the_Earth/CryoSat/Arctic_sea_ice_up_from_record_low
from the air vent: http://www.youtube.com/watch?v=GHvrjX7AP-8
Has anyone actually looked at the images, they must be the source data. If in doubt go back to first principles look at the images do some measurements then see how what you’ve done compares with what the algorithms say. Steve Mosher’s ruler could be a useful tool in this process;)
As this is so important I’m sure this team will be able to get funding to confirm which algorithm, if any, gives the most accurate results. The images could be made freely available on the web for research purposes, the American public must have paid for them. There are a lot of talented honest people who are interested in the truth.
All this assumes that the dog hasn’t eaten the original data.
Reminds me of when they couldn’t find the hotspot in troposphere so they tried to create one using a computer model.
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.
Which is indeed the operational definition of temperature. But we all know that Mr. Mosher expresses temperature as the inverse of the rate of change of entropy with internal energy, with volume V and number of particles N held constant.
chris moffatt says:
July 22, 2014 at 6:23 am
…………………… Here’s a thought – perhaps increasing antarctic sea-ice is due to the fact that the planet isn’t warming. See – no error needed.
Naa, where’s the funding in that?
I quote: “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.”
There are two problems with the above quote. First is the fact that Arctic sea ice is retreating at a dramatic rate not because the world is warming but because there was a reorganization of North Atlantic current system at the turn of the century. It started to carry warm Gulf Stream water into the Arctic Ocean and this is still going on. You can learn the facts about this in my 2011 paper [E&E 22(8):1069-1083]. Prior to that there was nothing in the Arctic except for 2000 years a slow, linear cooling. If you take away the warming effect of the Gulf Stream water carried north the Arctic would cool at the same rate as the Antarctic does now. This is clear from the fact that in mid-century the earlier flow pattern of North Atlantic currents returned for a thirty year period and this led to cooling at the rate of 0.2 degrees Celsius per decade. It is quite impossible for greenhouse warming which is alleged to be warming the world to switch from warming to cooling and back again on such a tight time schedule. Unfortunately those calling themselves Arctic researchers are simply ignorant of these facts since they have not bothered to read scientific literature about it in their own field. Secondly, they speak of a “warming world” that does not exist. There is no greenhouse warming now despite a steady increase of atmospheric carbon dioxide. And there has been none for the last 17 years. Just what do these guys want to tell us by talking of a “warming world” that does not exist? If they are trying to say that the Arrhenius greenhouse theory predicts that increase carbon dioxide in the atmosphere causes warming they are out of luck. For the last 17 years the Arrhenius theory has been doing that but nothing has happened. If a theory predicts warming and for 17 years nothing happens a scientist has no choice but to regard that theory as false and relegate it to the waste heap of history. There is a place for it near phlogiston, another theory of heat that failed. The only greenhouse theory that can explain the current pause in warming is the Miskolczi greenhouse theory (MGT). That is because it is able to handle the general case of multiple GHGs absorbing IR in the atmosphere. Arrhenius can handle only one – carbon dioxide – and is incomplete. MGT is the theorythat IPCC and its puppets have been trying to suppress since 2007 because they do not like its predictions. The time has come to admit that only MGT can describe the real world. According to MGT the GHGs in earth atmosphere that count are water vapor and carbon dioxide. There exists a common optimum absorption window in the IR that they jointly support. Its optical thickness in the IR is 1.87, calculated from first principles by Miskolczi. If you now add carbon dioxide to the atmosphere it will start to absorb in the IR, just as the Arrhenius theory tells us. But as soon as this happens, water vapor present will begin to diminish, rain out, and the original optical thickness of their absorption window is thereby restored. Absorption by the introduced carbon dioxide is still active of course but its warming effect is just balanced by the reduction of atmospheric water vapor that is happening simultaneously. This has been going on for the last 17 years and explains the absence of warming today. If rising carbon dioxide did not cause any warming for 17 years laws of nature tell us that it never has caused any warming at all. Any alleged greenhouse warming that happened before this time is nothing more than natural warming, misidentified by over-eager climate scientists anxious to prove that greenhouse effect is real. Total absence of the greenhouse effect also nullifies any claims that adding carbon dioxide to the atmosphere will cause anthropogenic global warming or AGW. And with it, alarmist mitigation and emission control schemes become irrational irrelevances, a waste of public resources that must not be allowed to continue.