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).
Well, there is one fix that always works. Those who control the present must rewrite history. The future is at stake. Just up the figures for antarctic ice in the past and we are back on track.
I know the world’s ice is melting quickly. I have it from the highest authority, President Obama: “the planet will boil over” if we do not find “new ways of producing energy”.
I contacted the primary author of the paper by email and he was kind enough to answer my question on the processing methodology and provide a non-paywalled link to his paper.
To test the old and new algorithms they did process the entire data series with both algorithms separately and then compare them. The main difference was a step-like change in 1991 which corresponded with a satellite transition calibration. The new algorithm reports greater ice extent over-all compared to the old algorithm. They’re not sure which algorithm is more accurate. It’s possible.
“The main difference was a step-like change in 1991 which corresponded with a satellite transition calibration. ”
Others here have found no “step-like change in 1991”
That’s a problem.
http://hockeyschtick.blogspot.com/2014/07/the-large-increase-in-antarctic-sea-ice.html?spref=tw
As I had thought.
So hockey sticks in Antarctic sea ice are not allowed but in temperatures they can be used to tax us to death?
There is no ice in the Antarctic, and any ice you do see there is merely a figment of your imagination.
Apologies to Mister Adams.
Michaels and Knapenberger take this on…
http://www.cato.org/blog/molehill-antarctic-ice-becomes-mountain
“””””…..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…….””””””
A thermometer DOES measure the Temperature (of the Thermometer).
Most people are interested in measuring the Temperature of “something else.”
That’s where the problem lies.
george e. smith
in an LIG thermometer the thing measured is length
length of an expanding liquid.
“Dude, it’s white pixels on a perfectly dark background ocean. There simply *is* no sensor dilemma to this measurement in the Antarctic. ”
Those white pixels can be clouds bozo
that is why the sensor is not visible light.
“NikFromNYC says:
July 22, 2014 at 7:59 pm
Here Mosher condescendingly obfuscates in personally insulting fashion the simplicity of white Antarctic ice pixel area counting by dragging in rounding error level complexity of perforated Arctic dynamics, shamelessly implying that simple measurement of ice area is yet another complex affair for experts alone to be able to judge, as *if*! It’s white pixels in a picture, folks. Learning to simplify after considering complexity is what sets too notch scientists from careerist hacks who always wallow in minutia. ”
white pixels can be
1. clouds
2. fog
3. ice.
That is why one doesnt simply use the visible light.
This commenter sounds like Goddard who has made similar mistakes in the past
Has Chris
TurkeyTurney been informed?NikFromNYC says:
July 23, 2014 at 12:15 am
Mosher is piling the BS up so high in this thread as to be a clown about it:
“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.”
Dude, it’s white pixels on a perfectly dark background ocean. There simply *is* no sensor dilemma to this measurement in the Antarctic. It’s a five minute Photoshop job with nearly no error.
It isn’t that simple because frequently the size of the ‘checkerboard’ squares are smaller than the pixel size of the camera. Depending on the satellite used the pixel square can be 25km^2 in area.
Over time, fog and clouds would be easy to remove from the ice/sea picture.
ferdberple says:
July 22, 2014 at 7:15 pm
/////////////////
Pleased to see this pointed out. It is important that people are aware that there are issues regarding ARGO.
Whenever I commentn on ARGO, I usually try to throw in a line about this adjustment having been made.
ARGO may be our only worthwhile data set on ocean temps (I myself am very familiar with ship’s data and I know from experience how flawed it is – not worth the paper that it is written on), but there are genuine issues over its tuning and calibration, and it has never been properly evaluated to see whether there is some inherent bias caused by the fact that the buoys are free floating and are swept and carried alonng currents which themselves are temperature dependent.
Of course, one should never splice one data set onto another. That is a big no no, and that is why there appears to be a spike in OHC when ARGO ccame on stream.
“Phil. says:
July 23, 2014 at 1:45 pm
It isn’t that simple because frequently the size of the ‘checkerboard’ squares are smaller than the pixel size of the camera. Depending on the satellite used the pixel square can be 25km^2 in area.”
So, you are saying that the satellites Google gets the images for their maps deom have cameras that are many times better than what is supposed to be determining the amount of ice and thereby the fate of the world (at least economic)?
… and meanwhile, another ‘ship of fools’ sets sail to attempt the North West passage. Apparently,
Which does not agree with my understanding. But why let facts get in the way for a good story, eh?
http://www.bbc.com/news/science-environment-28247175
NikFromNYC July 22, 2014 at 12:00 pm says: ” 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.”
You are quite right, NIck, and I am glad to see that someone is actually thinking about climate. It is measurable directly as you point out. Ken Gregory has a guest post on Anthony’s blog on March 6th 2013 entitled ” NASA satellite data shows a decline in water vapor.” His figure 5 shows that atmospheric relative humidity, measured at 300, 400, 500, 600 and 700 mb pressures, declined steadily throughout the period of 1948 to 2012. That sure is not the feedback you need to triple the Arrhenius warming that IPCC uses as they cook their predicted future temperatures. You can ignore Roy Spencer because the only thing that he really has is a complaint about the imprecision of early radiosonde measurements. The only way to check this is to divide the database into subsets based on different time periods and see if this has any influence on the observed flux. Miskolci did this in 2011 for the EGU meeting in Vienna. His results showed that when the database was subdivided into seven subsets the observed flux did not change. I used his results as figure 6 in my E&E paper.
Mike Jonas July 22, 2014 at 3:11 pm says: ” My understanding is that increasing temperature leads to increasing ocean evaporation and hence more atmospheric water vapor (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 vapor, not a net reduction.”
Your first problem is the assumption that there is increasing temperature. There is none and global temperature has not changed for 17 years. There has been some jerky, stepwise warming indeed since the twentieth century began. The first warming was a thirty year stretch that started in 1910 and stopped in 1940. It must be classified as natural warming because of two key observations. First, there was no increase of atmospheric carbon dioxide when it started. Second, it stopped suddenly and was followed by WWII cooling. Both are quite impossible for greenhouse warming to execute. The second warming of the century was a step warming that started in 1999, raised global temperature by a third of a degree Celsius in only three years, and then stopped. Since then there has been no warming whatsoever. It is likely that its origin is related to the super El Nino of 1998 but research on it has not been done because the billions spent on climate research are all used up trying to prove that the non-existent greenhouse warming is real. This quest for the greenhouse effect started with Hansen 26 years ago and is still going strong. Up to now, no one, including Hansen, has actually observed the greenhouse effect in action. Attributions are abundant but they all depend on theory, not observation. Hansen said he observed the greenhouse effect but he cheated. He said there was a hundred year warming that proved the greenhouse effect was real. Turned out his hundred year warming included a thirty year stretch of non-greenhouse warming, something you can’t use if you are trying to prove the greenhouse effect. And now let us look at the increase of atmospheric water vapor that concerns you. I already covered that above in answering Nik. NASA observations show a decrease, not an increase of atmospheric water vapor since 1948. There are irregularities there but the trend has persisted for a good sixty five years. It just might have a long-term connection with other climate happenings going back to the Little Ice Age, but I simply don’t have the information I need to explain anything that old.
Record extent again today
http://iceagenow.info/2014/07/antarctic-sea-ice-extent-breaks-daily-record-65000-sq-miles/
btw it would be nice to have this graph at WUWT
mjc says:
July 23, 2014 at 4:55 pm
“Phil. says:
July 23, 2014 at 1:45 pm
It isn’t that simple because frequently the size of the ‘checkerboard’ squares are smaller than the pixel size of the camera. Depending on the satellite used the pixel square can be 25km^2 in area.”
So, you are saying that the satellites Google gets the images for their maps deom have cameras that are many times better than what is supposed to be determining the amount of ice and thereby the fate of the world (at least economic)?
Three points, firstly the paper is referring to a change in sensors in 1991, what resolution camera was Google using in 1991?
Secondly, most of Google’s high resolution imagery is made from planes flying at about 1000′, not by satellites.
Finally, the extent/area measures of sea ice are made using microwave sensors not visible cameras so have significantly different resolution. The wavelengths are about 3000 times longer.
Phil…
But using BOTH microwave and photos provides a sanity check each way…and that’s the point. It’s a pretty easy way to figure out which version of the data is ‘right’ (if there is actually anything wrong with either one…the difference could be within the margin of error of the equipment used…and yes I read the paper and didn’t see anything in that definitely would eliminate that as a possibility) and how much of a trend there is.