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Misleading Hype Over Antarctic Ice Loss

May 21, 2014

By Paul Homewood

 

image

 

WUWT has already thoroughly covered the latest scare story of how the Antarctic is melting and we’re all going to drown.

But here are a few of my thoughts.

 

1) It has been widely reported that “the Antarctic is shedding twice the amount of a few years ago”. I have picked out the Guardian, but the BBC run with the same story, and doubtlessly many others too.

Quite simply, the claim is false. The study finds that the new figure is “twice as much as when it was last surveyed”. These are two totally different things.

The new Cryosat-2 radar altimeter dataset allows much more detailed analysis, leading to a fivefold increase in the sampling of coastal regions where the vast majority of all ice losses occur.

Therefore, most of the newly identified ice loss was happening before, but just was not spotted.

 

2) Their new survey covers just three years, up to 2013. The previous period, that they compare against, was 2005-11.

Would any serious scientists use such short periods to make claims about trends?

 

 

3) Of the figures they quote, by far the largest area, East Antarctica, is only losing 3Gt/year. Given that the margin of error is stated as +/-36, this is effectively zero, and it is quite likely that ice mass is growing there.

 

4) We need to put these findings into historical perspective. Antarctic land ice has been steadily disappearing since the end of the Ice Age, some 18,000 years ago.

 

LGM_timeslices

http://www.antarcticglaciers.org/glacial-geology/icesheet_evolution/

 

5) More recently, there is evidence of a neoglacial advance, coinciding with the early stages of the Little Ice Age. Just as in the Northern Hemisphere, there has been a natural retreat since that readvance.

6) There is evidence from ice cores of much lower temperatures in the Western Antarctic between 1300 and 1800 AD, than existed in the previous 300 years.

This complements many other studies which show that Antarctic temperatures during the MWP and earlier centuries were comparable with or higher than present.

There is no evidence therefore that current conditions are anything other than natural.

7) It is claimed that the current ice loss in the Antarctic is enough to raise global sea levels by 0.45 millimetres each year, but much of this rise has already been occurring throughout the last century.

As there has been no noticeable change in the rate of sea level rise since 2010, there is no evidence that the new figures claimed for Antarctica represent any significant increase.

 

http://sealevel.colorado.edu/content/2014rel3-global-mean-sea-level-time-series-seasonal-signals-removed

 

8) According to the abstract, the ice mass loss per year since 2010 has been:

  Gt / yr
West Antarctica 134
East Antarctica 3
Antarctic Peninsula 23
TOTAL 160

 

It also claims that mass losses from West Antarctica are now 31% greater than over the period 2005–2011. The implication is that there are no significant changes elsewhere.

On this assumption, we can calculate WA has increased from 102 to 134 Gt/yr, giving a total increase from 128 to 160 Gt/yr.

If 160 Gt/yr yields an increase in sea level of 0.45mm, the increase from 128 to 160 would be responsible for just 0.09mm of this.In other words, over a century an extra 9mm of sea level rise.

Hardly apocalyptic!!

5 Comments
  1. Mikky permalink
    May 21, 2014 6:32 pm

    Any mention of ice loss is probably a quick and easy win for the consensus, because many non-technical people (and even some technical ones) assume that ALL ice loss is due to global warming, and journalists and press release writers are in no hurry to correct that view.

    The 160 Gt/year loss sounds like a lot, but in reality that is the relatively small NET loss, the difference between the annual ice gain and the annual ice loss, BOTH OF WHICH ARE AROUND 2000 Gt/year. Total ice there is around 26 MILLION Gt.

    Since ice gain and loss are completely different physical processes there is no reason at all that they should balance, and the NET is likely to fluctuate a lot, giving the likelihood of many sensational headlines in the years to come.

    Link to a readable document (pdf) by Zwally that gives the 2000 (actually 1900) Gt/year figure:

    Click to access Zwally.pdf

  2. May 21, 2014 10:32 pm

    Thanks, Paul. Good analysis.
    I had the story earlier today directly from ESA-Cryosat, it sounded scary, but baseless.

  3. May 23, 2014 4:06 pm

    Wow the BBC have a scary new story about Glaciers decline rate doubling loaded with spin words.
    – Conclusion : “extraordinary claims require extraordinary evidence” ..and the DramaGreens have a record of making such claims on flakey evidence , so I expect the claims to be shown to be flakey
    – Voila Paul Homewood shows the mega-claims are indeed extremely flakey.
    ..You can’t trust the BBC on Climate cos they nevr chllenge properly such wild claims .

  4. Mikky permalink
    May 23, 2014 6:47 pm

    Just to point out that the area shown in this article is the Antarctic Peninsula, whereas the “unstable” glaciers are much closer to the pole. The Peninsula, being generally warmer, will have more rapid melting than the “unstable” area.

    The Antarcticglaciers.org site is very readable, but sadly is following The Party line that ice loss is due to warming, which is like saying that coastal erosion is due to climate change.

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