Once More To The Western Antarctic Ice Sheet

Steve McIntyre is back, posting on the latest exchange between Jay Zwally, who recently published a paper saying that Antarctica is gaining ice, and Jonathan Bamber, who attempts a rebuttal over at Real Climate. McIntyre shows that Zwally’s position is worth considering and that Bamber’s criticism is either naive or disingenuous. As usual, McIntyre’s post is careful and logical. It seems clear that although we can’t be certain, the balance of probabilities is that ice in the Antarctic is increasing, despite significant losses in the Western Antarctic Ice Sheet. That’s because the WAIS is small and the rest of Antarctica is large. Ice is increasing at a very small rate in the large part and decreasing at a rapid rate in the small part. Yeah, McIntyre explained it better.

The total is a drop in the bucket, almost literally. Zwally wrote in 2015 that ” that there had been ice mass gain gain of ~112±61 Gt/year over 1992-2001 and ~82±25 Gt/year over 2003-2008. ” Bamber doesn’t give an estimate at Real Climate, but says (incorrectly) that Zwally is an outlier and that additional lines of evidence suggest that Antarctica is losing mass, estimated by the IPCC in AR5 at an of 147 ± 74 Gt/year.

There are about 150 million Gt of ice in the Antarctic ice sheets. Antarctica won’t even notice either Zwally’s gain or Bamber’s loss. But will we?

It takes 361 Gt to raise ocean sea level by one millimeter, 9,137 Gt to raise sea level by one inch. So, at the current rate of even the IPCC’s view of loss, not any time soon.

But that’s not what we’re worried about. The Western Antarctic Ice Sheet is not stable and may disintegrate over a period of 100-200 years, although this disintegration has not yet started. That’s the reason that the WAIS figures in climate conversations.

But this has nothing to do with climate change. As T. Hughes wrote in 1973, “A study of published data concerning the past and present ice cover of West Antarctica indicates that during the last few million years the ice sheet has been retreating in stages, each retreat stage being preceded by an advance of comparable duration. Thus disintegration of the west antarctic ice sheet seems to follow the disintegration pattern of other continental ice sheets and may be the last phase of the worrldwide Late Cenozoic ice age.” As Conway et al wrote in 1999, “Current grounding-line retreat may reflect ongoing ice recession that has been under way since the early Holocene. If so, the WAIS could continue to retreat even in the absence of further external forcing.”

This conversation, motivated by those wishing to attribute a drop in the bucket of ice melt to human contributions to climate change, is typical of the fevered state of the climate conversation. It is also insane.

drop in the bucket


7 responses to “Once More To The Western Antarctic Ice Sheet

  1. Good post. Your conclusion, in light of what has happened in San Bernardino, is a perfect description of those in Paris who think that “climate change” is the most important thing in the world.

  2. Another bit of insanity comes from the current issue of the University of Texas Alumni magazine, the Alcalde, with a cover article about potential Antarctica ice melt. They show a map of the Texas coastline when all of that ice melts, and the sea level rises 197 feet!


    • Don B,
      The climate kooks have long since left the pretense of rational reason based arguments behind.
      From Obama on down the choice seems to be use fact-free, inflammatory, deceptive claims and demands to silence the reasonable and critical thinking that might lead to effective outcomes.

  3. Don B, by the way a clearly worded letter threatening to stop giving to the Texas Exes if they keep publishing claptrap like that might get their attention.

  4. On the other hand, the very long delay between availability of IceSat results (2003-2008) and Zwally’s presentation of results to IMBIE in 2012 and their eventual publication in late 2015 – far longer than the usual cycle of publication of satellite data e.g. the numerous GRACE articles – is disquieting. Zwally was clearly worried that his results would “give fodder to the skeptics” and/or “dilute the message” (to borrow terminology from Mann’s correspondence about hiding the decline), worrying to Nature that “some of the climate deniers will jump on this”. One hopes that this concern did not contribute to the overlong publication delay, but one fears that it might have.

    Disquieting, yes. Or possibly just quieting. Words fail me at telling how these guys work as a tribe. So the ice sheet level was measured, and they thought it was melting, when it actually was pushing mantle down under its huge, growing weight.

    And, they managed to publish the result without any media asking some inconvenient questions. These pal-review tribe members, they really know how to do their PR.

    • Next they’ll downgrade sea level rise estimates, because oceans just lost >100 Gt yr-1 water. Or no, they will increase OHC estimates, because the rise is caused by warming water, not melting ice sheets.

    • So the culture Tom revealed in the Crutape Letters has completely corrupted anything to do with climate science. They are all completely bought in to their apocalyptic claptrap. And they have the influence with our current crop of gullible easily led political hacks to get their way.

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