Shame On The Climate Spin Merchants

This press release says  "much of the increase measured for Southern Hemisphere sea ice could be due to a processing error in the satellite data". the trouble is that the research does not support the spin.

This press release says “much of the increase measured for Southern Hemisphere sea ice could be due to a processing error in the satellite data”. The trouble is that the research does not support the spin.

For a few moments yesterday it looked as though one of the great scientific puzzles of recent times had finally been solved.

How can it be in an era of global warming, with average surface temperatures at record highs for much of the last two decades and with the Arctic polar ice cap shrinking, that the extent of sea ice around Antarctica has been growing? Only last month, the Antarctic chalked up a new record sea ice extent.

This mystery has puzzled climate scientists for much of the last decade and provided succour to climate change sceptics although it has been strangely ignored by much of the mainstream media – even when the Akademik Shokalskiy got stranded back in December – presumably because it does not fit with the prevailing climate change narrative.

And then on Tuesday 22 July a press release from the European Geophysical Union (EGU) announced that the scientific journal The Cryosphere is publishing a paper that states, in the words of the press release, that “much of the increase measured for Southern Hemisphere sea ice could be due to a processing error in the satellite data”.

And, following this attention-grabbing intro, the press release went on to report that: “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.”

And sure enough the story was picked up and run by some in the mainstream media including the usually sceptical Daily Mail.

Error

The cause of the problem was a switch-over in the satellite instruments that are used to measure sea ice extent that took place in December 1991. There appears to have been a basic mistake in what is known as the calibration of these instruments – in simple terms, matching up the record from the new instrument with the record from the old instrument. And this error may have resulted in an overestimate of the growth in Antarctic sea ice.

 From the paper. Difference between sea ice extents in the two satellite data sets. This amounts to a difference in sea ice extent of around 200,000 square kilometers. Both records are monthly-mean anomalies from the 1979–2004 mean seasonal cycle. Transitions between satellite sensors are indicated by vertical dashed lines. The difference in ice extent appears to be dominated by a spurious jump in one of the data sets coinciding with the December 1991 sensor transition. Courtesy: authors and Cryosphere.

From the paper. Difference between sea ice extents in the two satellite data sets. This amounts to a difference in sea ice extent of around 200,000 square kilometers. Both records are monthly-mean anomalies from the 1979–2004 mean seasonal cycle. Transitions between satellite sensors are indicated by vertical dashed lines. The difference in ice extent appears to be dominated by a spurious jump in one of the data sets coinciding with the December 1991 sensor transition. Courtesy: authors and Cryosphere.

The authors of the paper, led by Ian Eisenman of the Scripps Institution of Oceanography at University of California San Diego in the US, point out that the lack of control over changes to the data documentation mean that they can not be sure whether it is the data prior to the switch-over that is wrong or the data since. Either way, it amounts to a scientific embarrassment as it means that key parts of one of two key scientific reports from the Intergovernmental Panel on Climate Change (IPCC) must be based on flawed information.

“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,” the EGU press release quotes Eisenman as stating.

Spin

The trouble is, as with so much else in life, the reality of what the research actually says does not live up to the spin in the press release. A reading of the actual paper shows that the scale of the error in December 1991 amounted to around 200,000 square kilometres. A big number, you might think, until you realise that it is just a fraction of the 1,000,000-plus square kilometre growth in Antarctic sea ice recorded since 1990. Not exactly what you describe as “much”.

00antarctic 23july
Latest sea ice extent data showing a long term increase since 1990 of circa 1,000,000 million square kilometres. Courtesy: University of Illinois.

So the bottom line is this: there appears to have been an error in the way satellite data was processed in the early 1990s; that error accounts for around 20 per cent of the observed growth in Antarctic sea ice seen since 1990; there is still no completely satisfactory explanation for what has driven the vast majority of the recorded growth. The fundamental mystery remains.

This research has been spun into something that it was not. The impression is given by the press release that the majority of the observed growth in Antarctic sea ice has been an illusion. This press release was circulated to mainstream media outlets, many of which have, at best, a patchy record on reporting science stories.

Climate change is too important for key facts and important research to be spun in this way – especially by a supposedly reputable publisher of scientific journals.

Shame on all concerned.

Sources

EGU press release here.

The Cryosphere scientific paper abstract here.

The Cryosphere scientific paper here.

Latest University of Illinois data on Antarctic sea ice extent here.

Daily Mail story here.

See my report on the record June sea ice extent here.

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